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The mkiv Supra Owners Club

Annoying Oil Leak


add heywood

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Ok, so the car had quite a big oil leak, found it to be one of the cam covers had cracked at the front and was letting oil everywhere. Got some new (second hand) cam covers for the car and everything seemed fine.

 

Said oil leak is now back, had a very quick check (coil cover off) and couldn't see anything wrong, no cracks etc. It seems the oil must be coming from the front somewhere as the coil cover was dry all the way up to the small foam lip that covers the cam wheels, this was pretty oily, as is the lower cam belt cover. Let the engine idle for a short while and the viscous fan was blowing drops of oil around the engine bay (towards the throttle body/fuse box).

 

The puzzling thing is it was fine through Dragonball, and must have started leaking some point Sunday on the way home.

 

I had just re used the old cam cover gaskets, althought they only have around 3000 miles on them.

 

Should I get some new cam cover gaskets and try that...? Or do we think it could be something else? I find it strange it didn't start leaking straight away though... Can leaky cam covers make a big mess as the leak looks quite large.

 

Cheers

Add

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have a check on the camshaft seals, these can go hard over time and leak alot of oil as the camsharft bearings are pressure feed. I had a major oil leak on my old mK3 supra, the oil pressure had pushed the seals out and the rubber was very hard.

 

regards chris

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Sorry,

 

changed the head gasket and all upper engine gaskets last year, so they have all (cam seals & cam cover gasket) only done about 3k... but the cam cover seals have been taken off the old cam covers and put on the new ones I had done last week, as my old cam covers were cracked. Didnt leak until about 1000 miles after the new cam covers being changed

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  • 3 weeks later...

Going to bump this....

 

So changed the cam cover seals (even though they have only been on 3k miles). Even shelled out for new cover washers. The oil leak is still there. When the spark plug cover is off and I hold my hand towards the turbo side cam wheel it spits up very small droplets of oil every now and then. I saw these dropping onto the throttle body etc first and thought it was the viscous fan blowing them everywhere but pretty sure its coming from there. The front underside of the spark plug cover seems to have most of the residue there aswell. This is starting in my mind to sound like front main crank seal :( I thought this had been sorted previously as my first leak turned out to be a cracked cam cover. Was fine for 1500 miles... started leaking on the way back from Dragonball.

 

Any advice...?

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The front cam caps are probably not sealed correctly. Oil from a leaking crank front seal is highly unlikely to get up to the top of the engine and be flung about by the cam belt drive wheels, unless there's no seal there at all ;) For every 5 engines none pros build I see 3 with inappropriate or no front cam cap sealing. How did you seal the front caps?

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The front cam caps are probably not sealed correctly. Oil from a leaking crank front seal is highly unlikely to get up to the top of the engine and be flung about by the cam belt drive wheels, unless there's no seal there at all ;) For every 5 engines none pros build I see 3 with inappropriate or no front cam cap sealing. How did you seal the front caps?

 

The cams were fitted into a head (off the engine) by dude at AFR, but then removed, posted and re fitted at Jurgen's later. It was fine for 1k miles. Definately coming from around the cam wheels as there is fresh oil coming out the join between lower timing belt cover and the coil cover... In answer to your question Chris I didn't seal the caps, it would have been done (hopefully) when the engine was put back together.

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Check it out, you can safely remove the front caps with everything in situ and the cam covers off. Sounds like that's your problem.A lot of people don't seem to know they even should be specifically sealed. (They 100% most definitely should have sealant on them, not too much, just a smidge, it's all in the factory manual).

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The oil is kept in the head by both the camshaft oil seals AND the front cam caps being sealed to the head. they have special grooves milled in them for the sealnt to sit in. The camshaft oil seals can be perfect, but if the front cam caps haven't been properly selaed you will almost certainly get a leak(s). Refer to the workshop manual.

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The oil is kept in the head by both the camshaft oil seals AND the front cam caps being sealed to the head. they have special grooves milled in them for the sealnt to sit in. The camshaft oil seals can be perfect, but if the front cam caps haven't been properly selaed you will almost certainly get a leak(s). Refer to the workshop manual.

 

Ok, cheers Chris. I have the manual on the computer somewhere. Will have a bit of research on it. What sort of sealant should be used on it...?

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