oil leaking on exhaust

[625]

Hello all, :wave:

Great forum here with a lot of knowledgeable and helpful people!
I've been a lurker for a while and decided to join finally. I used to be a mechanic for almost 10 years, so hopefully I can help some others with their problems.

Ok, to the problem. I have a 94 ATX that is leaking oil onto the exhaust. Other than making a mess of my driveway, it smokes a LOT when I drive it after it sits for more than a day. What is the most common cause of oil leaks on the exhaust? I am about to change the intake gaskets and plug well seals this weekend, but it doesn't look like they are the main culprit. I could have sworn I read something about cam seals, but I can't seem to find anything in a search on this forum. I know shophoenixproject had an excellent how to on replacing the cam seals, but it doesn't seem to be there any more. The power steering pump isn't leaking bad enough to cause this. Any other areas I should check? The bottom of the engine is covered in oil, so it's difficult to see where the main leak is. I know, I know, clean it and then check. I will, but just wanted to know the main leak points of these engines. Thanks in advance.

 

[NiNeTy Fo SHO]

Sounds like the rear main seal is leaking.

Hello and welcome to the forum!

 

[625]

Sorry, I should have stated that most of the oil seems to drip from the front (passenger side) of the engine and gets onto the front cat and front pipe before the right side cat.

 

[SHO#7]

The rear main seal is between the engine and the transmission. It will most likely not make the oil end up on the cats causing it to burn off. On my 93 currently I have a front seal leaking. The one behind the crank pully.

If I had cats it would be leaking right on them. On one of my former SHO's I had the same leak, and it did make a mess all over the top of the cat. Made all kinds of smoke sometimes too.

So, in a nutshell. If you are sure that the rear valve cover is not leaking down, I vote front crank seal. Or maybe a cam seal. Pull the timing cover and look behind the sprokets. That my help point you in a direction.

Mike

 

[625]

:cry: That's what I was afraid of. Do most people replace the cam seals too since the front of the engine is already disassembled? This seems to make sense to me.

 

[SHO#7]

In my case I did not think things through. I was doing my 120k at night in my shop and wanted to get it done. I did not replace my cam seals or front crank seal.

Now, as it always happens, I developed a slight leak from that front seal. However, with a catless pipe, it really does not make any smoke, I just have a few drips of oil hanging around on the pan. Not enough to even make a mess in the garage. Yours sounds like it may need attention a little sooner than mine.

Mike

 

[matt59]

Ditto Mike, The exact same happen to me this week! :banghd:
I am 95% sure it is the Front seal. Clean oil is harder to trace though.

 

[F-22 Raptor SHO]

Hows your cv boot on the passenger side? The front main seal doesnt always result in oil on the cats as much as the cv grease dripping off a torn boot. My front main leaks like the bladder of an 80 year old, but it doesnt get on my cat.

Cam seal is also a culprit which is leaking from higher up.

 

[NoFlipping]

I had the same problem last year. Lots of smoke at stops, etc.. Guy doing an alignment said, "Looks like a power steering leak or a cam seal." Well, the fluid didn't look too red (although it did look a bit like burnt PS fluid), and after monitoring fluids, and a lot of fishing around, I finally tracked down the source. I had a valve cover gasket leak (driver's side that was almost impossible to see) that dripped onto one of the power steering lines which then caused it to drip onto one of the cats nearly on the passenger side. My point? Fluid moves the way it wants, not the way we always expect. Just ask anyone who's tried to figure out where their house's roof is leaking from. Good luck.

 

[625]

Well, I replaced the v.c. gaskets since I needed to replace my wires and the plug well seals were leaking. No change. This past Saturday I replaced the ft. main seal and the two cam seals (started too late to want to deal with the third cam seal that day). The rear (second one back) cam seal was leaking and the ft. main was seeping. The entire p.s. pump was wet, so I'll have to do the cam seal behind the cam sensor soon, then clean everything good. I still get a few drops leaking, but not on the exhaust anymore. It never ends!

 

[SHOblime]

My car recently started doing this as well. I'm pretty sure it's the cam seals or the valve cover gaskets....the rear main seal is NOT in the correct position for this so it's either the cam seal, vgc, or front main if it's dripping low enough. Mine is clearly running down from either the cs or vgc...so I'm gonna go ahead and do a full 120k