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Oil pressure & how to install bearings

Oil Pressure & How to Install Bearings

Hello to all; Well today was (is) a wonderful day.  After three years and
two months into restoring our 150dhc we got to hear it run for the first
time.  What a beautiful sound.  I saw a posting a few days ago about oil
pressure, and I understand that the pressure should be about 40psi at idle.
Is this correct?  I also think I remember reading there is an adjustment on
the oil filter housing to adjust the pressure. Is this something we should
do?  Presently we have 20psi at idle. - Regards, Skip Smith

Skip, I am real glad to hear you got it started. Several of us were
successful this year in getting their cars started, including myself.
Replacing your bearings might help oil pressure. - E.W. Blake

Every part in the engine is new, except the block, and raw head. Crank and
cams were reworked, new line bore to both top and bottom. Anyone else have
any input.  Oil pressure gauge rebuilt by Nisonger.  I also pulled a gauge
off the e and it showed the same. - Regards, Skip Smith

Hi Skip Smith & all -- re:  oil pressure -- on ALL of our XK engines (for
me, '52 thru '59, owned from '63 to date), the book calls for 40 PSI at
2,000 RPM -- no value listed for idle, but my experience has always been
15-20 PSI at idle -- with my current original MK IX, stuck on the Bay
Bridge on a 104 degree day, I've seen 10 PSI at idle -- just slip into
neutral and rev to 2,000 -- always goes to 40.  There IS an adjustment on
the filter assembly for pressure, but if it reads 40 PSI at 2,000 hot or
cold, I recommend you don't bother.  I hope this helps - Larry Martz [USA,

Skip, my owners manual for the XK-120 says not less than 40#sq" at high
sustained rpm.More exactly My MK-1 3.4 lt saloon manual read 40 at
3000rpm.A good XK will idle above 20 and considerably more than 40 at
3000-(65 or so.) On temp my 120 runs around 70-80c on summer days in the
high 80s lo 90s F.A recent long run,100+ miles,it nudged above 90c .Air
temp 107f ,pavment temp .....! I agree with the previous comment on a clean
and unobstructed cooling system throughout and plenty of oil. - Vic Larsen

Vic; Thanks for the feed back. - Skip

re oil pressure' simple conversion to spin off  type filter can gives an
astounding increase in pressure ,makes oil changing apleasure,and cheaper
too. - regards TERRY HILTON

Terry, I ordered the conversion from XKs back in July and it was
backordered. I spoke with them yesterday and they are shipping today.  Any
problems with the conversion? - Regards, Skip

Many years ago I had a MKVII with bad oil pressure. A mechanic convinced me
to have him replace main and rod bearings. After the job was done there was
no improvement in pressure just a sharp decrease in the bank account. After
this episode I started to look carefully at the oil system in XK engines.
The conclusion was the most common cause for consistant low oil pressure is
a worn relief valve. An adjustment can increase the cold starting pressure
but not the hot running pressure. If you remove the relief valve assembly
there will be a worn seat possibly worn off centre as well the valve head
can show off centre wear. You can replace both units or you can try lapping
the valve head into the seat with valve grinding paste. Another method is
to replace the valve head with a hardened CV joint ball and lap it into the
seat. I did this on a high milage engine (abt. 190 thousand). When I
started the engine the pressure  went up to abt. 100 lbs. I quickly shut it
off. I had to play > with spring lengths to get a cut off pressure of 60
lbs. This engine had 55 to 60 lbs. on the highway and would idle hot at
abt. 20 lbs. at 600 RPM with 20W50 oil. The engine I have in my car now has
an original valve body head and spring. The valve head has been lapped into
the seat and adjusted to a startup pressure of 65 lbs. about 55-60 running
hot and abt. 25 lbs. at 600 RPM idle using  Castrol Syntec 5W50. - Bill
1955 XK140 OTS S811719

Bill; Thanks, this is great, I'll try this right away. - Regards, Skip

Skip, I would appreciate some details of what is required to carry out this
conversion (to spin-off filters). - Kind regards, Col Haywood XK150S OTS,
Perth West Aust

Congrats on getting it running again.  That is always the first step to
wanting to finish a car. What is the RPM at idle?  I can adjust my 120 oil
pressure from 15 to 60 psi at 550. Sounds like you need to do the same.
Watch the pressure at higher revs, and again when it is warm. - Larry J

To Terry Hilton and others, From whom did you purchase your kit to convert
to a spin on oil filter assembly?  Is there more than one out there??
Also, did the kit  include replacement of the oil relief valve which  Bill
said recently could be the cause of low pressure? I have a 1958 xk-150. I
overhauled the engine with new bearings and when I started it, the oil
pressure was not much better than before the overhaul.  I have been blaming
myself for not replacing the oil pump at the overhaul, but maybe I can
improve the oil pressure with a spin on conversion.  I appreciate you
thoughts. - Don Sime

DON, later model oil pump goes in ok pipes have to be modified. old type
felt filters reduce pressure/flow. I have run engines at 80 psi hot for
years using spin on filters. The relief valve should be regarded as a
safety valve only, as passing oil over relief only heats it up. -  regards

Col, I am going over to the shop in about tem minutes to put the new unit
on I'll let you know the results latter today. - Regards. Skip

DON oil pressure relief is on dirty side of filter.  gauge take off is on
clean side. oil has to get through filter ,before you read pressure on
gauge. thats if its not blocked, then the bypass operates and passes oil
straight to gallery. the oil relief seat knocks out make a new one from
silver steel. - regards TERRY HILTON

Hello to all; We have a bit of a problem or I think it is a problem.  We
have recently rebuilt the engine in our 3.4 150.  When we crank it up the
oil pressure goes to 20psi and holds.  When we run up the rpm it still
holds at 20psi no increase at all.  Everything in the engine was new or
resurfaced for the rebuild.  My question is should not the oil pressure go
up to about 40psi at some point?  What would cause the pressure to hold at
20psi not to increase or decrease?  We have pulled a gauge from another car
and checked it against the rebuilt unit, it is giving the same reading.
Could air in the line cause this? Has anyone else run into this? - Regards,
Skip Smith

How about the bypass? - Ed Moehagen

Skip, The relief valve spring in your oil filter base may be weak. That
would be my first guess. Much like the contact patch discussion, air in the
oil line to the gauge shouldn't make any difference because if something is
pushing on one end of the air bubble, the other end of the air bubble would
have to push just as hard on the liquid at the other end. In fact, I was
told the coils in the oil line were designed to hold air, as a kind of
shock absorber, for the gauge. (I credit that bit of knowledge to someone
on one of the lists, who responded to my query about why they have the
coils.) - "Mark 1" Mark Stephenson

Hello  Skip - does "Everything in the engine was new or resurfaced" include
attention to the rotor type oil pump and it's internal clearances as well
as the condition of the oil delivery pipe's flange and... the gasket
surfaces to the filter inlet port on the block and... the O-ring that seals
the pipe into the oil pump? Sometimes old o-rings can leave the surface of
the steel tubing with a slight groove which may not be noticed on
re-assembly or the o-ring can be nicked or not fully seated in the groove
machined in the pump outlet (incorrect profile of o-ring, round vs. squared
). How about the pick-up side of the pump? Did that get a new o-ring and
are there no cracks or splits in either of the steel pipes?  Did you
re-tighten  the plug at the forward end of the oil gallery after you rodded
it through to clean out the sludge that lived there? My suggestions are all
directed to the oil pump and gallery because you seem to have had good
feed-back so far in other areas that would be the cause of the problem but
I have one more morbid suggestion: when you got your crankshaft back from
the machine shop, were the plugs for the cross-drilling of the oil supply
passages in the crank journals all intact?  - Cheers, John Morgan

Skip - Sounds like you may have a problem with the oil pickup. It may be
sucking air at a joint. But before you start pulling the pan off remove
your pressure relief valve and check to see if the valve head is seating
properly. Perhaps lapping it into the seat with valve grinding paste, also
make sure that the spring is strong enough. Remove whatever shims were
under the dome nut over the valve. -  Regards Bill Schorse 1955 xk 140 ots

Skip, I saw an earlier message on this and I agree with the actions. Also
consider that the valve bypass spring may be weak and require replacement.
Or that the valve may have jammed open.  Did you replace the pump and
replace the
seals and gaskets? - Cleo Bay Jr. 52 XK120 OTS, 56 XK140 OTS, 62 E-Type
OTS, 65 S-Type Sedan

Ed, Mark, John, Bill & Cleo; Thank you all for the feedback on our fixed
20psi oil pressure.  We are checking each item that has been recommended.
I'll let you know what we find. - Regards, Skip

Skip,  I have a similar oil pressure problem on my 150 (engine rebuilt a
few years ago, only maybe 3000 miles since) - oil pressure suddenly dropped
to a max. 20psi.  My gut tells me it is not something serious (so long as I
do not drive it like that!) - but maybe that is just wishful thinking.  Oil
pressure was of course previously "perfect".  Happened on a blast up from
the ferry wharf.  I will give the car to Gavin King to sort out for me
shortly. - Regards,  John Elmgreen

Hello to all; Well I'm back again with the oil pressure still stuck 20psi.
So far we have pulled the new oil pump again, we had replaced it because we
were only getting 20psi from the old one even though it looked fine, but
everything else in the engine was new so we took no chances.  The condition
of the oil delivery pipe's flange, the gasket surfaces to the filter inlet
port on the block, the o-ring that seals the pipe into the oil pump as well
as the pick-up side of the pump and pipe have all been re-o-ringed,
resealed and rechecked . Everything got new o-rings and there are there no
cracks or splits in either of the steel pipes.  The plug at the forward end
of the oil gallery was also checked.  The  pressure relief valve was check
to see if the valve head is seating properly, we relapped it into the seat
again with valve grinding paste just to make sure, we also checked that the
spring was strong enough, we removing  all the shims that were under the
dome nut over the valve and locked it off so as to not allow any bypass and
checked the pressure. Anyone have any other suggestions before we take the
engine down again. I thought we were nearing the end, I was looking forward
to starting the rewire phase this weekend, and then send it out just after
the first of the year for the new interior.  I "need" to be driving this
car by spring, and my fourteen year old son Brandon, who is my partner on
this project, keeps saying he "needs" to be riding in this car by spring,
(it's a guy thing we keep telling my wife).  We originally planned to take
four years for the restoration and April 28 will be four years. - Thanks
for all the help, Skip

Skip: Maybe I am not tooo smart here, but before I did a bunch of needless
work, darn if I would not install a new or used good mechanical oil press
guage then check the press. I had a problem like that on a car that I built
one time, turned out it was the guage. - Chad Bolles Jaguar Performance,Inc

Skip, My condolences. Did you check the gauge, or did you say you checked
that earlier? - "Mark 1" Mark Stephenson

Chad; Thanks for the input, I guess I failed to include that we have no
less that three guages we are using to check pressure, one of which we just
got back from rebuild with Nisongers.  Each of the guages are reading the
same with each check. - Thanks again. Skip

Skip:  Are these guages mechanical or Elec?? If Elec then I would suspect
the sender is bad. - Chad

Hi, Skip - I think I remember you saying that you had tried another
mechanical gauge, with similar results.  Still possible that you have a
gauge problem; try either a third one or an electronic aftermarket gauge
and matching pickup (maybe $25 at Pep Boys or equivalent).  Don't put the
engine under load until you resolve this problem.  Do I remember you saying
that the engined read OK as to oil pressure prior to the rebuild?  If so,
what did you replace or rebuild internally?   New main bearings and rod
bearings?  New thrust washers (half-round semi-circles on each side of main
bearing number 4 (the center one)?  New camshaft bearings?  Did you check
the diameter of the crankshaft bearings, and check the clearances with
Plastigauge prior to final assembly?  Did you fit all standard size
bearings to a crankshaft that might have had one or more undersize bearings
(sorry, but it's a possibility; in 'the old days', sometimes only a single
bearing was turned to undersize to make it round again, with a rod bearing
being done in the car (without removing the engine or the crankshaft)).
Grasping at straws, for sure, but leave no stone unturned in seeking truth,
Grasshopper!  April 28 is a Great target date!  Hope I can help! - Larry
Schear Twin Cam, Inc.

Chad: Mechanical - Skip

Skip, From your comments and others suggestions, all of the obvious and
easy fixes have allready been investigated or explored.  The problem seems
to be a  maximium oil pressure of only 20 psi.You've detected no knocking
or other worrying noises. A few words about what we did for oil pressure
problems and bearing
fitting, at my grandfathers restoration shop. Oil pressure is created by
the oil pump, any pump unless it is defective should be able to put out at
least 60- 80 psi. The pressure when created at the pump is at its highest
point, most motors employ a bypass valve to regulate the pressure. This is
done by a spring and valve arrangement, when too much pressure is generated
the valve is forced open to relieve the pressure. So the bypass valve by
it's action limits the  oil pressure maximum value. Once past the the
bypass valve oil pressure is maintained by close tolerences on all of the
bearing surfaces ie. the camshaft journals, wrist pins, rod journals,
crankshaft journals.  So if we had an engine that did not knock but had low
oil pressure which was worrysome to the customer( and rightly so), we would
first check all of the easy things (pickup tube blockage, oil pump
problem,bypass valve, defective oil pressure gage, etc) If everything
checked out we would do a leak test, before ripping down the engine. First
we would put the car up on stands, then remove the oil pan, next we would
attach a oil pressure prime tank to the oil gallery. A oil pressure prime
tank is just a small tank ( 2-5 gallons) which is 1/2 filled with oil and
then the tank is pressurised by adding compressd air. A gauge is present
and the pressure is brought up to 80psi. Underneath the engine a tub was
placed to catch the drips. With the prime tank attached to the engine with
a hose the output valve is opened and the pressurised oil will flow into
the engine. By observing how fast the oil leaks from the journals you can
determine if a journal, or several journals have  excessive clearance.  On
the older poured babbit journal engines, they usually had shims which could
be removed to tighten up the journal, which would solve the problem. Of
course this would not be on a newly rebuilt engine, but one that had been
in service for some time, and the customer for what ever reason was not
willing to tear down the engine. If we were rebuilding an engine to insure
that oil pressure was always going to be correct, we would fit all of the
journals, this was the practice on insert bearing motors and also poured
babbit bearing motors.

The procedure to fit bearings goes something like this: First the rods,
crankshaft and block would be sent off to be machined. When the block came
back, it usually was bored, the crank ground and the rods checked in all of
their dimensions. First every passageway in the crank, rods, and block was
cleaned of all grinding debris and swarf. The next step was to fit the rod
bearings. The correct rod for the journal was selected, if it was a insert
bearing motor, the insert would be oiled and installed, then the rod bolts
are tightened to specifications. The rod is then turned 360 degrees on the
journal to feel for any drag or sticky spots. Also the side to side
clearance (thrust, it should be in specification) is checked. If the rod
can twist or rock, that signals looseness, and potential trouble. If the
rod is tight or drags, again that is trouble. Next the rod bolts are
removed and the journal inspected. If it was tight a polished area will
show up on the journal bearing surface, this is a high spot and we would
scrape it down, with a bearing scraper. All high spots if any would be
removed (this is more prevalent in babbited engines). We then would cut a
small piece of newspaper 1/4" wide by 1" (most newsprint measures .0025")
long and place it on the rod bearing journal. We then would again bolt up
the same rod. When the  bolt tourque was correct, the rod should now act
like it was welded onto the crankshaft. If you could still turn the rod,
the clearance was too great,and it had to be corrected. That was done by
again removing the rod and by using a wide fine file a few passes were made
on the mating surfaces of the rod cap. Blue or a coating of magic marker
will insure that you file evenly and flat. Sanding on a surface plate or a
thick piece of glass will also work. After a couple of passes, everything
was cleaned, reoiled, newspaper reinstalled, and the rod tightened once
again. If you filed enough the previously loose rod will now be locked on
the journal. Take apart once more, remove the newspaper, and then reinstall
the rod on the journal. It should now be free with no side to side wobble
or drag. Hooray, you've just correctly fit a rod, in the case of a 16
cylinder Caddy you have fifteen more to go. After fitting all of the rods
to the crank. They are all then removed, set aside in correct order for
later assembly. Next the crank is fit to the block. With the block upside
down all of the new inserts are installed, and then oiled. The crank is
gently lowered into its journals. The center cap is installed, tightened
correctly, then the the crank is slowly rotated. No binding should be felt,
also the oil seals are not installed at this time. Remove the cap place the
small piece of newspaper on the journal, and tighten up again. If the crank
locks up thats good, if it doesn't, you have to file the cap to tighten
that journal up. Same as the rod journal, you have to achieve a fit which
locks solid when the newspaper is present, but turns smoothly and freely
when its removed. After the center bearing is fit, you move out from the
center one journal at a time, alternating front to the back. After all
journals are fit (still with no seals installed) the crank should turn as
nice as it ever will . Usually any bearing can be fit in one or two tries,
if something seems pretty weird, the blocks machining geometry can be out
of wack or the crank could be bent etc. This is not usually the case, but
can happen. Plan a day to fit a set of rod bearings and the crank. Of
coarse the cam journals should be fit as well, the same way the crankshaft
was fit. If all of the journals are correctly fit you will have excellent
oil pressure, improved engine performance, easier starting, cooler running
and long bearing life. When an engine is assembled to the specifications of
the machine shop, and bearing supplier, your fate is entirely in their
hands. If they were accurate you'll probably have no problems, but if they
are not, oh oh .  Don't always assume that because a engine rebuilding
machine shop that has excellent machines and a great reputation is going to
me perfect every time. The proof is in the pudding. - Regards, Wray Schelin

Hi Skip, Mark Stephenson & all -- Once again, the factory literature for
all of our earlier XK (twin-cam 6-cyl) engines calls for 40 PSI at 2,000
RPM with the engine warm (70 degrees c).  Skip, if yours is at 20 warm at
2,000, I'd check again the relief valve on the filter (spring, shims,
etc.); also, hook up a NEW mechanical gauge (doesn't need to be Jaguar) to
the line as it exits the filter and check at 2,000 warm.  If it's STILL at
20 after this, it's beyond my knowledge -- sorry!  Larry Martz [USA, Calif]

Skip, I think you said earlier, that the pressure is constant, regardless
of RPM.  If this is true, then I would be really suspicious of the bypass
valve spring.  You say you checked it, but against what specification?
Perhaps you could try a stonger spring anyway, the worst that could happen
is that it makes no difference. - regards, Mike Morrin

Skip, this problem is rapidly becoming "unreasonable" insofar as the simple
solution is elusive, based on the fact that you seem to have responded and
checked on suggestions and ideas put forward that all seemed reasonable and
have had no luck solving the problem. Before you gut the engine to check on
the bearings etc.. I'd like to put forward an unreasonable suggestion
relating to the fact that you got low readings with several different
pressure gauges. Could it be that there is a separation of the liner in the
flexible portion of the pressure pipe from the filter housing to the
gauge-regardless of whether or not it's a new component?  At a certain
pressure, it "inflates" and blocks further pressure readings. There have
been threads on similar problems (but in reverse) with the rubber inner
linings of brake hoses. Internal inflation of the rubber hose blocks fluid
flow and locks the brakes on . I wonder if this might be a similar
situation? It's an easy one to check out anyway, check for debris in the
whole pressure pipe too while you're at it. - best o' luck,  John Morgan

Thank you Wray, That was an incredible description of bearing adjustment. I
had a shop do all my milling, and I reassembled the engine. It feels good
when I turn it over by hand, so I don't know if it's worth taking it all
apart just to check. It will be interesting to see what happens when I fire
it up -- as
far as oil pressure goes. I will definitely follow your advice on the next
rebuild. I feel like I might have a clue! You are truly an asset. - "Mark
1" Mark Stephenson

You might want to try another oil gage.  Did you replace the cam bearings?
Does this motor have a timing chain sprayer like the 120?  I know of an
engine that was put together without that and the oil pressure would only
go so high because enough oil was coming out of the open hole that the
pressure wouldn't build up any higher. - Larry J 660636

I had an interesting experience similar to yours. I did all the disassembly
testing etc. that has been recommended here..... Only to find that a small
piece of aluminum had lodged in the oil pressure sending tube in the oil
filter housing that prevented a proper oil reading. I found that out by
checking the
pressure from the side gallery opening. - Luck,   Steve '52 Riley, '48
Chrysler NY, '56 140 OTS, '59 MKIX, '54 Buick

Mike; We locked off the bypass to keep it from working, still no change -
Regards, Skip

John; You're right, I think you have hit on one the only item we have not
checked before going in, the flex line at the filter might be a
possibility,  we'll  check it first thing in the morning. - Thanks, Skip

Steve; I was just thinking about that after I responded to John Morgan's
note about the flex line.  Well, tomorrow we use all new line for the test.
- Thanks, Skip

Wray; What an incredible description of how to check out the rebuild.  As I
read it I could visualize every step.  I think when you grow tired of your
art you have a new calling in writing technical journals.  Thanks for help.
BTW John at ABC sends his regards. - Regards, Skip

I hope you find a simple fix, like the kind that John Morgan suggested.
Whatever the result everyone will be the wiser. - Regards, Wray

Adding to Larry J's comment - Something like a chain sprayer in the xk140
engine is a chain tensioner. This is a small piston activated by oil
pressure that moves against the chain keeping it tight.  There is really
nothing that keeps the piston and tensioner in the cylinder except that its
movement is limited to the distance it travels to contact the chain.  If
your chain becomes too loose the piston and tensioner can pop out of the
cylinder.  I would think that when this happens there would be a free flow
of oil now spraying out of the tensioner cylinder.  I had this happen to me
once but all I noticed was chain noise.  I don't remember what the oil
pressure was doing.  You should be able to see if the chain tensioner is
still in place without disassembling the engine. - Just a thought...
Regards; Andy Leavitt

Not an answer but another question.  Is too much oil pressure a problem?  I
just had my 4.2 rebuilt and it runs beautifully, however, the pressure
guage is pegged at the top. Could this result in a leakage problem.
Thanks. - RJBasso

Good afternoon all,

Yes, too much oil pressure can be a problem. 1. Possible bearing erosion
from the oil trying to peel stuff apart. 2. Excessive stress and wear on
the oil pump drive components. 3. Premature leakage of oil. (Could we
tell??) ;-) Seroiusly, your concern of excessive leakage is real. At
elevated pressure a small leak could hemorage massive amounts of oil
compared to normal pressure leakage. Blowing up the filter could happen,
particularly if you're using a spin-on type. It would seem the monster
stock filter housing would stand about as much pressure as one could put
into it with a stock pump. I did once blow up a Fram spin-on mounted on a
440 Chrysler engine. It had a high volume, brandy new oil pump and the
relief valve jambed. We lit it up for the first time and BLEEEWYY. It was a
real gusher. :-) Number two would be my biggest concern. You will be
wearing the drive chain and sprockets very prematurely, as well as
fatiguing same. Not good. Of course #3 isn't too nifty either. I'd check it
out. - Cheers, Ken Boetzer

Too much oil pressure can cause all sorts of problems.  My car, a 120, did
the same thing due to a poorly adjusted relief valve.  Be careful to have
your gauge recalibrated with proper calibration equipement because running
the car at very high presure can effect your gauges accuracy. - Daniel

Thanks for the oil pressure advice. I don't know how he got the oil
pressure up so high, but I don't feel comfortable with it, and I'll have
him bring it down into normal specs. - Regards RJBasso

I put my 150 S into Gavin King's workshop here in Sydney yesterday, to have
the low oil pressure checked out (2-4 psi at idel, 22psi at 2000 rpm,
engine rebuilt and about 3000 miles since).  He has not yet looked at it,
but apart from the obvious (gauge check, relief valve), he said that Jaguar
engines occasionally lose a plug from the crankshaft (the ? hex ? Allen
thing) and a sudden loss of oil pressure is the result (mine happened after
a burst to about 4000+ rpm).  Not hard to fix, but it also happens quite
often with Aston engines he says, and the engine has to come out in that
case (not for the 150 of course). Let you know later in the week what the
outcome was.  No nasty noises by the way. - Regards,  John Elmgreen

Just found out what my 20 psi oil pressure problem was (150 S):  broken
pipe from the oil pump into the engine.  First it had cracked (big drop in
pressure) then broke off completely (near zero pressure).  Mechanic said
this was the first time he had seen this happen.  It was not the pick up
pipe but the other one out from the pump. Incidentally, anyone on this list
ever had their car dyno tuned? readings of power at back wheels for a
survey? - Regards,  John Elmgreen

John - Back when I was serious about racing, I had my car dyno-tuned at
Dynomotive, in New Brunswick, NJ, just across US1 from the Studebaker
plant!  Alas, both Dynomotive and Studebaker are long gone, and I haven't
an idea where to look for the resultant paperwork!  I DO remember that I
built a Corvette-killer - an XKE that would out-drag many 327 'Vettes and
at least one Pantera; I still have the car (and most of the pistons!). Seem
to remember something like 325 hp out the rear, but I wouldn't bet on it;
might have been the computed output at the crankshaft/flywheel.  In case
you're wondering, this was the Turquoise Terror! Glad you finally
identified your oil problem cause - interesting!  These cars never seem to
tire of finding new way to challenge us!  I guess it had to be that; we
eliminated everything else (but you know that something else is lurking out
there, waiting for the next diagnosis of "cracked pipe from the oil pump to
the engine!" - we'll see it eventually!). Cheers, and Merry Christmas/Happy
New Year!   :-)> - Larry Schear

Hello to all; I want to thank every one who offered suggestions regarding
the low oil pressure we were plagued with after rebuild.  Well, on friday,
we disassembled the engine again and found that in fact the plug that fills
the hole where the timing chain sprayer had been fitted on the early 120's
had been left out during the rebuild. So with that in place we have begun
the rebuild again.  Larry J. a special thanks to you, if not for your
suggestion we may never have found the problem.  It seems that this plug is
not mentioned in the spares book or the service book for the 150. - Happy
holidays to all, Skip

I installed a spin-on oil filter conversion kit on the 150 I am completing.
It's a direct bolt on and allows one to reconvert to original at any time.
The engine has not been started so I have no further experience with it.
The car will be a very presentable driver and I'm looking forward to
visiting a local auto parts store to buy replacement filters at a
reasonable cost.  I bought the kit from Bassett's Jaguars (USA) @ $69.95
(USD).  Bob Oates

John, I am not an expert on the XK oil filter arrangement but on a number
of other engines that I know intimately, the pressure relief valve controls
the opening of a bypass passage. If this valve is faulty or mal-adjusted it
will allow oil to bypass to some degree when it it shouldn't and therefore
the flow round the correct lubrication path will not as great as it might
be. I am pretty sure higher indicated pressure means more flow. - Eric
Capron (Beaconsfield UK)

Just a thought here, pressure is a measurement of a force resistant to
flow. Since you are regulating the pressure at the oil filter assembly and
pressure/ flow are functions of each other from the oil pump,  how much
might a higher pressure setting at the adjustment affect the actual flow of
oil around the engine i.e. higher pressure equals more flow or less flow?
My interpretation of the information in the XK Service Manual leads me to
think that when we set our oil pressure for higher pressure at low speed,
using the adjustment valve, we're limiting the actual flow of oil to a
degree but higher oil pressure at higher rpm ought to be a result of more
volume of oil being delivered as the pump speed increases. Comments please
on the above- it's only an opinion and I'd like to hear from those with
some experience on the track for example. Bearing in mind that oil-flow
plays a vital role in actually cooling any engine and that high-pressure
lubrication does not neccessarily mean that the bearing surfaces
experiencing  lubrication will  benefit more from a higher pressure than a
lower pressure in the lubricant, flow itself becomes the more critical
component here for the simple application of the everyday "driver" XK
engine- not the high performance, endurance engines with modified sumps,
higher flow oil pumps etc. Might be splitting hairs here though because I'd
set my pressure as per the book anyway with a fresh engine but for a worn
engine- the temptation to "adjust" in a higher pressure might rob the upper
levels of the engine from what flow is left after pump losses, filter
restrictions, oil-passageway restrictions and increased bearing clearances
have taken their toll on the poor old oil system. BTW, since I have the
torroidal type oil pump with my "G" series XK engine- does anyone know if
(a)  I can retro-fit an XJ6 oil pump and (b) am I really likely to gain any
more oil flow if this change is possible? That's my tuppence worth for now.
- Regards, JM

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