Head Gaskets

Dear XK-fellows, Some weeks ago I wrote about a waterleakage (through the overflow-pipe). I seems like a worn top-gasket. The gasket was not the old asbetsos/copper gasket, but a "simple" pressed steel (?) gasket. The new one I got from my dealer is similar to the old one. Can anybody tell me if there is other and may be better types of gaskets? And: it is recommended to use gasket sealant - a friend of mine mentioned "3M Spray 90". - Thank you, Martin Jacobsen

To all, My head will be going back on soon. I have received a lot of advice on the best way to do it. Some say don't use anythings on the head and block surfaces. Others say smear a little engine grease on all sides. Permatex is out someone else said. What do you guys say? Aloha, Rob XK-140 FHC

Rob, I expect this to open a can of worms on head gasket coatings. First, the head and block surfaces should be clean with no grease or oil on the surfaces. You are asking for trouble if you don't. Second, the head gasket is coated with coppercoat on both sides. I have used this method for over 14 years on my cars with no ill effect. I was told to do this by Jaguar mechanics when I was first rebuilding by XK140. Never had a problem. A friend of mine did not do this and had to replace the head gasket on his E-type because of coolant seepage. Your call on this. Third, the head studs should have a die run over them before reassembly. Incorrect torque readings could occur due to threads being deformed, rusted, etc. Also plan to retorque the head bolts after 400 to 1000 miles are on the motor. - Cleo Bay Jr., 52 XK120 OTS, 56 XK140 OTS, 62 E-Type OTS, 65 S-Type Sedan, 49 Olds Sedan, 57 Triumph TR6 M/C, 96 GMC P/U

Rob, I've only done three or four head replacements, and never on an XK engine, but I've never used a sealant, and especially not an adhesive one. It shouldn't be necessary if the mating surfaces are smooth and flat, and using an adhesive makes future head removal a real pain. - Bob Mullins

The best result with a cast iron block and an aluminum head will result from the use of a gasket that has stainless steel as the seal material around the piston bore and the base of the gasket material made of graphite. This will allow for an excellent compression seal, and allow for the thermal expansion of the head against the block. Because of the difference in the thermal expansion of the different materials, this is the best solution. - Gene Burda

In my enthusiasm to get a really good seal beteween the head and the block on my MKVII many years ago, I carefully doped the new steel gasket with "Permatex". The engine ran great for the warm-up. Shut it down to re-torque the head bolts and surprise! The engine would barely start again and when it did, ran on 5 pots only...Conclusion: Something had gone badly wrong. An autopsy revealed traces of a black, sticky substance clinging to #1 exhaust valve which of course had stuck in the "down" position and was promptly returned to it's rightful place by the ascending piston, resulting in a bent valve and no compression thereafter. Obviously, I had been too liberal with the Permatex and had not noticed a transfer to the valve stem of the small dab of this material in all the excitement of lowering the head onto the block using the "lean over the fender" method which I'm sure is a common cause of most back-injuries amongst XK-Lovers. I use Permatex regularly in my repair work in industry and am very confident in it but I never used it again on a cylinder head gasket. Besides, if everything is correct with the head, block and gasket surfaces, you shouldn't need an adhesive sealant, it makes head removal a real chore. - Regards, John Morgan

Gene Burda. That's great. Who makes one for a Jag XK motor? - George Badger

In reference to what to coat the gasket with .. I was told to use "Copper Coat Gasket Compound" I found it at NAPA Auto parts store. E.W. Blake, XK 120 DHC 54' "Blanch"

I agree with Cleo's advice, and also about use of the high temp copper spray gasket sealer, but with the following exception. Most new high quality head gaskets have a coolent sealer already present on the surfaces. These gaskets are supposed to seal properly without retorqeing, but its always wise to retorque, expecially on an XK motor, with very easy access present. The other older style gaskets: all steel with ridges pressed in; copper on both faces, with a core of asbestos;uncoated but treated black paper, with steel seal rings around the bores; should all be sprayed lightly on both sides with the high temp copper sealant, this will insure you don't have seepage into the bores, or down the sides of the block. All of the old style gaskets should definately be retorqued. - Regards, Wray Schelin

They are available from the Rol Gasket Co. Not positive, but Fel-Pro should also have them available. - Gene Burda

A can of worms is right, Cleo. I understand that to coat or not coat the headgaskets is dependent upon the type of headgasket you are using. In discussing this issue with my mechanic friend (who rebuilds XK series engines and XJ sedan engines for a livelihood; he also supplies rebuilt engines to Bill Welsh), he uses aviation cement (NAPA; comparable to Permatex) on the earlier XK engines. On the XJ sedan engines, he does not use a coating since the new gaskets are already pre-coated. With each approach, he advised that he has had no reported failures. While my experience is much more limited, I have used a coating on the head gaskets of the four XK engines I have rebuilt to date. So far I have had good luck. (I will use a coating on the XK 150 S engine planned for rebuilding. I have a complete NOS Jaguar gasket set waiting for this engine.) Concerning difficulty in removing a head where a coating had been used, he commented that his customers receive engines built to last and he has not experienced any more resistance in removing a head with or without coating applied. Silicone or non-silicone. - Bob Oates

Hello to all, I have removed and replaced the head gasket twice on my 150 (see previous message re camshafts) and never used anything except a good metal gasket properly torqued down. I never had a problem with it leaking. - Best regards, Don Sime, Xk-150 fhc

To all, It has been suggested, by a reliable source, that I use a product called "hylomar" on the head gasket. This product was not mentioned by anyone on this list and I was wondering it this was an oversight, or was for a good reason. Anyone heard of it or have experience using it? I picked up the head yesterday from the machine shop. After checking the valves for tightness and the surface for flatness, it got a clean bill of health. The passages were cleaned even though they were not plugged and there was nothing wrong with anything. So, now I put it all back together with nothing different than when it came apart, except for some cleaning inside the block which wasn't really very dirty. I also received a difference of opinion on how the LEFT side of the block is constructed. One of you said it was made of an upper and a lower chamber. An XK engine rebuilder said it was all one chamber, like the right side. My actual engine is definately of the two chamber type. Perhaps it should be only one, and this is the problem. The water flows freely between the RT. and LT. lower areas of the engine. It appears that the left lower chamber(exhaust side) is not connected to the left upper chamber in any way. Any more opinions on this? It seems crazy to put the head back on without actually repairing something, but there doesn't seem to be anything left to do. Maybe it will turn out to be a bad head gasket and it will work perfectly from now on. By Tuesday we should know fore sure. Aloha, Rob XK-140 FHC

Rob, I am not familiar with the "hylomar" sealer and have not seen it here in Texas locally. My XK 120 block has the webbing creating two water chambers on the left hand side. I will try to look at a XK150 block to see if it has the same system. From memory, I remember that the water inlet acesses both chambers (i.e. if water is put into the upper chamber, water should flow out the front and sides. The same should be true for the lower chamber also.) - Cleo Bay Jr.

Hi, Rob - "hylomar' s a newie to me, too. I typically use a high-temperature copper-filled head gasket sealer (e.g. - Permatex Copper Form-A-Gasket Sealant (part number 101H)) or anti-sieze compaond (e.g. - FelPro C5), depending which is on hand (I prefer the former, and use trhe latter on all manifold bolts in the head). Might have been 'just' a head gasket! Best of luck! Happy New Year, all! - Larry Schear, Twin Cam, Inc.

Rob, I hope this gets to you in time. I have been sick with the intestinal flu, but am up to eating the classic chicken soup now and read your letter about head gaskets late last night. I just wish we could have gotten together when I was in Hawaii last April, but your party must have been a good one. Anyway--Hylomar is a low temperature gasket sealer for things like pan and timing cover gaskets, NOT head gaskets! Also, before you replace the head, I hope you have checked the waterpump impeller and timing cover housing for corrosion and wear, which will affect the cooling of the engine and then you can use the Hylomar gasket sealer. I assume the machine shop checked that the head was true, with no length or width warp. Unless the gasket you are using has some sort of sealent on it, most Jag gaskets are thin steel gaskets, I would strongly recommend, as others have, the use of the Permatex Brand "Copper Spray-A-Gasket". I have used it with no leaks and removed heads 20 years after using Copper Seal with no problems or corrosion effects. It is important that there be some means for the gasket to move while being torqued so the gasket doesn't get a wrinkle in any surface area. Just torque it according to the manual and you should have no problem. Also, as Cleo has recommended, and this is very important, as I know of even American engines that don't torgue correctly unless this is done, the THREADS of the studs and nuts MUST be CLEAN and slightly Lubricated with oil, I use 10-30W, simply wiped on the stud threads with your fingers. A little oil on the washers also. Also, just use regular water in the system to start with, just in case there are any leaks, which I hope there won't be, but you don't need any additives in the oil or on the floor. I will be keeping my fingers crossed that you have no further problems. Good Luck. - Larry J, 660636

In looking at 2 versions of Hylomar that I have, Loctite 819 Hylomar Hi-Temp Gasket Dressing (tube) and Loctite 819 Hylomar Gasket Dressing-Sealant (spray), both specifically say Hylomar is useable for head gaskets as well as other cut gaskets. Temperature range of Hylomar is -60*F to +600*F. This message is not meant to start a discussion re Hylomar vs Permatex Copper Spray (please). It is only to report what Loctite and Worldtech say about Hylomar. As Loctite owns Permatex, sealant properties of various Permatex sealers are listed on the back of the Hylomar packaging for reference. - Mike Plechaty, 680844

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