Another Mi16 Oil Leak

[S@m 156]

Hey Guys,

I seem to have an oil leak on my 1.9 mi16 that is baffling me somewhat. Basically, the engine doesnt leak until its up to temp, then you get the lovely smell of oil in the cabin and if you give it any kind of revs you get a nice plume of smoke in there aswell. I checked underneath and there was oil on back of the engine, the underside of the downpipe and the subframe was dripping. So i thought "Thats got to be the cam cover gasket!" as you would. Resealed that (twice now) and no change. So i got the car up on some ramps yesterday, had a good look up the back of the engine. Now, i can see wetness (oil) around each of the bottom row of exhaust manifold studs. When i had the engine running on the ramps i could see what appeared to be oil seeping slowly from one of them. The top half of the manifold is dry, the rocker cover doesnt seem to be the culprit. In fact, all of the manifold is dry apart from a nice half moon shape of wetness around each of the bolts in the bottom row. Is it possible for oil to leak from these? Basically, i am lost now on this one. Aside from taking the studs out and loctite-ing them i dont know what to do. Although i thought the exhaust stud holes were blind anyway. All ideas are much appreciated.

 

Sam

Edited March 2, 2011 by Sam306

[Anthony 1,003]

I had a similar issue with a 1.9 Mi16 that I was swapping an exhaust manifold on for a friend, although in that case I'm pretty sure that it was coolant rather than oil that was leaking out of one of the lower exhaust studs when the engine was run.

 

Given that it was only a fairly minor leak and there was no will to remove/replace the head, we put some high-temperature RTV in the stud hole and after leaving it a few minutes to begin to set, wound the stud back in and left it to fully set before filling with coolant or running the engine. It appears to have been fine since, although in truth the car hasn't done a huge amount of miles.

 

I'm not sure what the underlying cause of the leak was, be it a hairline crack, damaged casting where someone had previously wound a stud in too far, or perhaps alloy that's gone porous. Whilst that was coolant rather than oil, if the leak is definitely coming from the stud holes, a similar "fix" may work for you.

 

It does seem odd for all of the lower exhaust studs to be weeping though, especially when most of the oil on the exhaust side of the head isn't under pressure AFAIK and I'm not sure that there's any oilways near the lower studs anyway. Are you sure it's definitely fresh oil coming from those studs, and not old oil that's previously leaked from elsewhere? Hot oil leaking in an engine bay has a habit of ending up far from the original leak point in my experience and can thus be a pain locating where the underlying leak is.

[S@m 156]

Just had the car on the ramps again, with the engine running. Could see a slow drip from one of the studs (and thats with the oil cold). Have replaced two now, with sealant and new bolts/washers. Will see if that makes a difference. The top row of studs are definetly bone dry, its only 4 out of 5 of the bottom row that are wet. The one closest to the timing end in the bottom row is bone dry aswell. Seems to be falling onto the driveshaft and being thrown all over the place! Underside of the whole car is nicely rust proofed now i suppose!!! ANy more ideas are much appreciated.

 

Anyway, thanks again.

Sam.

[S@m 156]

Ok, that didn't work! Now i have clouds of smoke when i go near full throttle (but none otherwise). Coolant level isnt dropping at all. Oil level is plummeting at an incredible rate. Entire underside of the car is coated in oil now. Going to try sealing the remaining manifold bolts. Any other ideas at all guys? I am lost.

[davev 1]

sealing manifold bolts will not help the matter, as there shouldn't be any oil getting into the exhaust ports in the first place.

 

youd be better off trying to find the reason why you are getting oil there first, and sorting that.

 

but either way its does not sound like an easy/simple fix if you are losing oil at an alarming rate and smoking like a trooper.

 

at best id be hoping for blocked breathers, but to be honest it sounds more like valve stem seals, piston rings.