Need help identifying oil leak on C25XE

[Cavalier342]

Hey guys. Trying to track down the oil leak on my V6 block, I went and bought a new oil pressure switch today, only to find that it's not where I thought it was, and wasn't the source of the leak. I didn't bother fitting it as I lacked a 21mm socket and spanner.




Wherever it's coming from, it's at the back of the block, near or above the alternator.

Can anyone help me shed some light on what this wire is for?





It runs from the top somewhere, to behind the alternator, couldn't feel much when I reached in but suspected it could be a cam sensor or something, I'm confident that the leak is coming from that area as most of the block above is dry. Cam cover gasket looks dry too.

It seems to be leaking onto the alternator, and dripping down the block onto the subframe and a bit on the down pipe. I would have investigated further but something strange and unexpected happened... Rain.... Any help is appreciated

[planetc]

There's not much above the alternator from memory? If it's not coming down from the cam cover then could it be coming from behind the belt cover? Cam seal or crank oil seal throwing upwards? Always possible that it's coming from the back of the oil pump gasket too?

[TurboDan]

You need to jetwash all around that area, give it a proper clean leave it awhile and then run the engine and see if you can see where the oil has come from as it will be much clearer then.

[Cavalier342]

Good luck getting in there! Thanks for the suggestions, looks like it could be a massive job so going to do my best to clean it up when I get a day at it, and go from there.

[btcctroy]

Get the engine steam cleaned it's pretty cheap. The engines are terrible for rocker cover gaskets leaking

[Cavalier342]

My first thought was those gaskets. I'll keep an eye on it for now, thanks for the advice.

[planetc]

Rear cam cover would have been my first suggestion too.

[Envoy CDX]

Clean it up as above.

[iancav6]

I had a similar leak on the 3 litre before I stripped it for rebuild but towards the front.turned out to be a cam seal.
Take the upper cam belt cover off to take a look.

your mystery wire might be the rear knock sensor, does it plug into the loom around the stabiliser bar?

[humbucker]

Rear knock sensor wire, rear cam cover gasket is probably the culprit re the leak. I'm pretty sure we discussed this when you first got the car - poor fitting gaskets or overtightened cam cover bolts are usually the culprits. It's not a difficult job tbh, you just need to take your time with it.

[humbucker]

Part numbers and guide in the HOW2 section.

[Cavalier342]

Rear knock sensor wire, rear cam cover gasket is probably the culprit re the leak. I'm pretty sure we discussed this when you first got the car - poor fitting gaskets or overtightened cam cover bolts are usually the culprits. It's not a difficult job tbh, you just need to take your time with it.

Thanks mate, yes, myself and lowrider dave replaced the gaskets last April/May, but I don't know if we used enough sealant on it... I may try again at some point, I still have parts suppliers saved in my bookmarks so I can find them, cheers. We used a torque wrench upon refitting, so no chance of over-tightening.

[btcctroy]

Did you clean the breather box

[Cavalier342]

You mean by the throttle body? Yes, and all the hoses and pipes. Standard task when servicing an engine.

[btcctroy]

It bolts to the block, the right hand side rear bank

[Cavalier342]

Ye it was clear

[humbucker]

Very little sealant should be used, just a dab in the half moon cutouts on the head. If genuine/quality gaskets are used then the gasket itself should be a good enough fit to seal the cam cover.

[Cavalier342]

Don't think they were genuine but seemed to fit well in the covers. We did apply a bit of sealant to the surface at the back of the block, I ran my finger along the cam cover edge, a hint of oil there but I wouldn't say it's pissing out from there. It's gotta be something else.

[humbucker]

Camshaft seal? Take the cam cover off and have a look - cam cover gaskets should be fine to remove and re-position within the first few months of their life, so don't worry about disturbing them. You can clean up and reapply to the head then, at least you'll eliminate that from the mix anyway.

[iancav6]

Don't think they were genuine but seemed to fit well in the covers. We did apply a bit of sealant to the surface at the back of the block, I ran my finger along the cam cover edge, a hint of oil there but I wouldn't say it's pissing out from there. It's gotta be something else.

I used some pattern ones on my V6,the gaskets didn't fit too well so i siliconed the gasket into the cam cover groove which helped.
To do the cam seals will require removing the front cam caps,these will need a dob of silicone between the cap and head when refitting.

[humbucker]

Green sealant on those iirc and must be put back in the order they were removed i.e. you can't mix and match them across the head

[Cavalier342]

Camshaft seal? Take the cam cover off and have a look - cam cover gaskets should be fine to remove and re-position within the first few months of their life, so don't worry about disturbing them. You can clean up and reapply to the head then, at least you'll eliminate that from the mix anyway.

Been more than a few months now so a new set will be required.

Regarding the cam seals, what is a cam cap? Sorry to sound thick but I don't know what you're talking about. Don't I have to remove the camshaft in order to change the seal?

[humbucker]

Check this post and scroll through the following three or four pages on my old V6 thread. Cam shells/caps are the metal arches that hold the cam down in the head. You can see pics of them removed and the green sealant here:

viewtopic.php?p=27813#p27813

[Cavalier342]

Thanks, so by removing them I can see the seals I presume? Do they just unbolt then?

[planetc]

Seals are behind the cam pulleys Andrei, check for leakage behind the cambelt cover. If there is a leaky one then it's time to learn v6 cambelts too