Engine: T5/R Oil leak, not from the usual suspects

[Juular]

After rebuilding my T5 I still have a small oil leak that I'm struggling to trace, and I'm wondering if I'm missing something daft.

Oil is leaking from somewhere top to mid-engine, transmission end down the back (bulkhead) side.

Oil only escapes when actually moving. I could idle the car for an hour and nothing would drip. As soon as I drive off oil runs down the back of the engine.

Here are the things I've eliminated:

Crank seals - dry at both ends
Cam seals - I replaced both as they were leaking, now dry.
PCV - This was cleaned and renewed while the head was off. Oil filler provides suction.
Cam cover - dry as a bone all round
Sump - it's soaking, but I cleaned it and covered it temporarily with duct tape. It appears that the leak is not from the pan but running down onto it.
Turbo oil feeds - totally dry.
Oil cooler - I deleted mine.

The only clue I have is that the upper nearside exhaust manifold stud seems quite wet. Can oil actually leak out from the manifold studs?

[JohnM 855 T5R]

When you rebuilt the engine, did you use the proper anaerobic sealant between the top of the cylinder head and the cam cover? This sealant (and its specification) is critical and must be applied by roller to the top of the cylinder head evenly to the Volvo specified thickness and the mating surfaces must be scrupulously clean. There is a Volvo procedure covering this.
Any old sealant won't do and nor will any old roller and even the tiniest variation or break in the sealant coverage inevitably leads to leaks. As you say you think it's coming from top to mid engine at the back and as you have eliminated all the usual suspects, I'd be tempted to suspect that sealant joint.

Regards
John

[Juular]

While I didn't use the anaerobic stuff, I am almost certain this isn't the problem as all around the mating surfaces are 100% bone dry. In fact there is no oil above the exhaust manifold level whatsoever now that I've done the cam seals.

I've been running with the spark cover off too - specifically to keep an eye on the cam cover for oil pooling around the plugs etc. I'm pretty sure it's not that.

[Baffler]

Turbo oil return pipe seal, where it enters the block, can be easily overlooked as it appears visibly dry on inspection but once under load starts to chuck out oil at varying angles. Seal and gasket kit available for a several sheckles.

[JohnM 855 T5R]

Originally Posted by Juular

While I didn't use the anaerobic stuff, I am almost certain this isn't the problem as all around the mating surfaces are 100% bone dry. In fact there is no oil above the exhaust manifold level whatsoever now that I've done the cam seals.

I've been running with the spark cover off too - specifically to keep an eye on the cam cover for oil pooling around the plugs etc. I'm pretty sure it's not that.

If you didn't use the correct anaerobic sealant and the right roller, that's a lot of potential trouble. Silicone sealants are an absolute no no. They break down, but worse still, they tend to "squish" into the oilways that feed the cam bearings when you torque the cam cover down. The proper sealant thickness is literally not much more than a few microns.
Truly, you need to do it right with anaerobic. Hear speaks a man of wisdom - I found that a previous owner had used the wrong (silicone based) sealant on my T-5R when trying to track down a troublesome leak (back of the engine, high up, transmission side). I took it to my Volvo independent that I've used for years to fix it. They lifted the cam cover and lo and behold - wrong sealant that had almost gummed up the oilways. Luckily, there was enough oil feed getting throung so no bearing or cam damage. On lifting the cam cover the first words were "bloody amateurs". They see this problem frequently with DIY and it inevitably ends badly.

Regards
John

[Juular]

Ok, so I had a good look tonight. I'm certain the leak is coming from this manifold stud.



When I took the nut off there was oil on the threads and under the washer.

With the engine running there is an occasional puff of burning oil from right there.

I assume this stud must go into an oilway?

I'm going to try extracting it, sealing it and refitting it.

I didn't use rtv on the cam cover. I have the anaerobic sealant on order but it is taking forever to arrive so I used a substitute flange sealant rolled on using a foam roller. There's no overspill and I'm fairly certain it isn't leaking but I will redo it in the future.

[JohnM 855 T5R]

I don't think the stud is supposed to go through

John

[Luxobarge]

Looks like you're right - I'd do the same, take the stud out, put some sealer in and re-fit, and see how it goes. Probably best to do a really good clean of that area while you're doing the job, so you can easily see for sure if that's fixed it.

[Juular]

So that stud was properly dripping with oil.



Threadlocked, and a bit of rtv on the outside for good measure.



Someone also mentioned that one of the long sump bolts next to the transmisison can leak if not sealed. One of mine was in fact soaking, so that was sealed too.

I've yet to take it a run, will let you know how it goes.

[Pupbelly]

Strange. I'd be interested to know just where that is going and why a stud is entering an oilway.
Hopefully you've sussed it now. Maybe someone who's had a head off will be able to offer some guidance.