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Fan Belts

Fan Belts

100 miles from home the fan belt wore out. (I noticed a knocing noice in front of the engine, and thought it was worn bearings of the dynamo). I had to place the car in a garage, but it was impossible to get the right belt. It will take appr.10-12 days to get a new one from England. The mechanic told me it may be was possible to get an unoriginal one, if he got the right specifications. I can't recognize the data on the old belt - maybe one of you out there can give me the right data to use, asking for an unoriginal one. (The engine no. is W 8618-8) - Martin Jacobsen -----------------------------------------------------------------------------

Martin - I also just went through the belt replacement thing but removed the old for a spare before it broke.

I ordered a belt from Moss Motors which was for my xk140 with an eight blade fan pulley. The belt they sent me was too large, so when I made arrangements to return it, the sales person told me I would be better off to have the local auto parts match the size since the old belt was still in good condition. The belt I got from Moss was a new style belt called a cog belt as it has crosswise groves on the inside surface. I was told that most of the new belts are like this and that if I wanted an old style belt I should go to the local tractor shop. The size Moss sent was something like AVA-1040.

I took the old belt (no markings of mfg. or size) to the auto parts store where they measured it and gave me a replacement. It also turned out to be too large and it was labeled ???-1030. Since I thought I began to see a pattern here, I exchanged the 1030 belt for a 1020 belt and it fits just right. I am guessing that the 1020 is the belt length in mm.

The difference in belt lengths is not only determined by the size of the fan pulley. I think there are different sized generator pulleys. I am guessing that the crankshaft pulley's are the same size but I don't know for sure.

It seems to be one of those fit and try solutions that you want to do in your garage and not in the middle of nowhere. My solution is to keep the original for a spare and for shows and use the new cog types for driving. On the other hand I am not sure how long these belts will last or how to tell when they are getting worn out. (Good material for another story). Regards; Andy Leavitt

I have the original fan belt from my car (about 20,000 miles on the engine) and it matches perfectly in dimensions with a replacement belt I bought from Welsh Jaguar. - Nick Saltarelli 1954 XK120SE OTS 1968 E-type OTS

On Sunday Oct 14, a car-pal and I drove my 120 FHC to the Los Angeles Concours. The trip is about 100 miles each way. The car ran very well at the freeway 70+ mph speeds. The temp also behaved at 70-80 deg, that is, until on the return trip about 5 miles from home when the fan belt broke. The indications were fairly pronounced; a peculiar sound, the illumination of the IGN light, and the very, very rapid rise of the water temp.

The temp went from 75 deg to 95 deg in about 10-15 seconds and was still rising when I turned the engine off and coasted to a safe area at the side of the road. A lot of coolant was coming out of the overflow pipe (determined later to be about 3 qts).

I have never had a 120 break one of those heavy industrial-sized belts before. This one (a Mintex TK339) had been installed for about 6 years but showed absolutely no signs of wear. I did not have a spare belt with me and the futility of the circumstance became clear when I recalled just how hard it had been to install that ultra-stiff belt in the first place. Has anyone had experience using an emergency-type belt on a 120?

Influenced by the 70-80 mph traffic pasing a few feet away, I swallowed my pride, opened my tool box .... got out my cellular phone and called AAA (road service). About 30 minutes later (as it was getting dark), the Auto Club truck pulled up, loaded the 120 onto the back and took us home.

Next day I removed the radiator to better access the area and started looking for a replacement belt. I had lots of belt reference numbers, including ones from this XK list. I did learn that the 38" NAPA B35 is about 1" too short and the next-size NAPA B38 is 41" and too long. I finally found another Mintex TK339 at a local Jag shop. As before, the belt was so stiff that I had to remove the generator pulley to put it on. I would appreciate a recommendation for a belt which was thought to be "easy" to install, realizing that there may be some pulley-size variables mixed in here.

For a new tool-kit spare/emergency belt I measured and bought a narrow (more flexible) belt which I believe could be temporarily installed without removing the radiator. It is a Goodyear 17375.

Hope there is some information here which will be of use to other XK120 operators.- Dick Cavicke 120 OTS & FHC

Hello Rob, just read your comment about XK 120/Mk 7 fanbelts. My experience is, that the ancient design of the Lions fan belt goes that far back, where there were no differences in technical measurements between England and Metric Europe. In the early decades of the 20th century all agricultural and simple machinery went by inches. That means, if Martin goes to any farm equipment store in Skandinavia and asks for a original fanbelt for his Jaguar the odds are high that he will find one taken out of a shelf for tractors/ lawn mowers or flour mills. - Arno Wahl

Martin, The fan belt on mine is labeled 5L380. This is a generic American size for fractional horsepower applications and it means the width is about 5/8 inch at the maximum (actually it's slightly more) and the periphery is 38 inches around. For you in Norway the metric equivalent is probably 16 or 17 mm width and 965 mm around. Hope you can find something. - Rob Reilly

Hi, my car is on the road again. I got a fan belt at a agriculture shop - 17mm with. It worked ok, but I think I should use appr. 19 mm, because of the belt seems to touch the bottom of the pulley. I hope to get an original one from the UK next week, and will write it all in the parts catalogue. Thanks to all who responded - Regards, Martin Jacobsen

Dick , Sorry to hear about your mishap going home from the Petersen. How did you do in the judging? I went through the same thing with the belt size. I got one from XK's and I eventually got it on but I also had to remove the pulley, it was a B35. I went to the local parts store and ordered a B36 and it seem to be the right size. I got it on without removing the pulley or the radiator. I didn't do too bad at the concours they only got me for no top (I expected that) and back-up light not working. I did well at the British Car meet though this past Sunday as my 120 got "Best Sports Car" out of several hundred cars that were there. I was plesantly shocked at that one. Regards, Jamie D Fiff

Hi Dick,

Emergency type belts - Over here in England we had this ad for 'Pretty Polly Stockings' - they show this long legged beauty driving a 120 - same thing happens to her, fan belt snaps.She gets out of the car looks down at her legs and 'Smiles'. Next thing you see, she's back driving minus stockings!? No guesses as to what she used as an emergency belt. So, there's your answer - always carry a pair of stockings in your tool box :) Sorry coundn't resist the story. - Regards, Lee Aldridge

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