Our Montero just starting leaking oil from the rear of the motor. I took it to the shop and they said that it was a seal for the camshaft. I have only worked on older model muscle car type engines before, but what they said did not make sense. I would think the cam shafts should be installed from the front and that is there the seal should be, not the rear of the heads.

What else could be leaking in the back of the heads? They said it was not the head gasket or valve cover gasket, so I am at a loss. Thanks,

David

Your right and I'm also at a loss to why the camshafts would leak at the rear as they are fully enclosed under the valve covers. The only seal in the rear of the engine is the crankshaft seal. As you would know this is a **** to fix so I hope for your sake they didn't get the two words mixed up (cam & crank).

Jim

On the rear of each head is an oval shaped plate held in place by two bolts. These plates are directly behind the cams. They each have an O ring seal which has failed. I have personally done 3 of these and am sure it is a fairly common fault. It is a task best done when motor is cold, as there is little room between heads and bulkhead.

Learn something new every day! Didn't know that these were there and would have thought they would be unlikely to leak as it is not under high oil pressure.

Maybe the O rings get too hot and warp/melt. If it is a common fault I wouldn't just replace with the same part unless you had some added protection. like a glob of gasket sealant.

Jim

The O rings go hard with age and start to crack. There is a lip which holds a small amount of oil on the inner face, and feeds the leak.
I would also highly recommend using a sealant when O rings replaced.

Good advise. Think I'll try and have a look at mine this weekend even though its a GDI.

Jim

Thank you for the reply. I have been away from my computer so I have not been back to check on the messages. You are right on with the oval covers. Is there any reason that I cannot change them myself? The other mechanic was saying that it requires special tools and the head had to be removed. When I got under it myself it looked like it would be tough do to the limited space, but not impossible. I just want to make sure that there will not be a problem (ie; that those plates hold the camshaft in place, etc.) as long as nothing will drop and it is just an o-ring, it should be pretty straight forward.

Again, thank you for the replies.

Unless the '02 is set up a lot different than my '99 what the mechanic told you was a blatant lie.

I've done this repair on a '95 3.0L and the '99 3.5L. From what I've read it can be done w/o any disassembly of other parts, but I personally believe it's worth the time to remove the intake plenum. That makes both cam plugs very accessible.

You should be able to get the o-rings for about 1.50 per side from your local dealer. It is VERY straightforward.

That is what I needed to hear. It looked pretty straightforward but I wanted to get at least another opinion on it. Thank you for that.

I have a 2001 with the same problem, I had thought this was a big job to da aswell. I took it to my mechanic and they had never done it, nor did they want ot do it. But if you guys say it is pretty simple, I will try it next weekend.

Thanx in advance

your montero only has one "o" ring back there.. on the passenger head. The drivers side head has sealant on it due to the fact that the cam sensor is located there.
the passenger side is the side that will be leaking, and it can be repaired in under an hour. The "o" ring material has been improved so it will not happen again.

mitsu dealer quoted me $440 to fix an oil leak (probably to replace o rings) behind rear camshafts for my 03 montero sport, worth it?

Thanks

PS. If i don't get it repaired, am i just gambling till the engine light goes on?

Well, I doubt the light will come on (unless you don't keep an eye on your oil level) but it's only going to get worse. If it were me, I'd bite the bullet and do it myself within a month or two. I don't know how bad yours is leaking, but I wouldn't want oil dripping onto all over the back of the engine, or my driveway for that matter.

440 sounds like they r doing more than just the cam bore orings (which is what they r called)
find out exactlywhat they r going to do and let us know

The 0 ring seal P# MN176208

The 0 ring seal part # is MN176208 and the most common oil leak comes from the passenger side. I repleced mine when i did the spark plugs, since the intake plenum and the valve covers come off it leaves the 0 rings exposed. I think $400.00 for that is a rip off, the 0 rings are like $2.00 each.

Thanks. my brother and dad, who are more mechanically intelligent than i am, also agree it's a rip off.

When i received the quote, the dealer said it would be at least a 3 hour job, would have to lift the engine, and as a "courtesy" "clean up" engine parts where the oil has soaked/drenched around. Unfortunately it's leaking on both sides of the rear part of the engine, yet it isn't at a point where it's spilling on the ground (or haven't notice). Problems are my cabin is smelling like burnt oil sometimes after i turn off the engine and at night you can see burnt oil smoke (i assume) coming from under the hood.

will look into local mechanic (with a better price...anyone pay a mechanic to have this done? your estimate plz? ) (i can't since i'm not comfortable at all with messing with the engine)

Thanks again.

It shouldn't take more than 2 hrs. Dealers pad these estimates with, what they call, a "rust factor" in case they run into trouble,break bolts, etc.
Only lifting required: a few cold beers once you button it all back up!

In your case, $150-$200 max I'd pay for someone else to do it.

The real question here is, are your spark plugs due for replacement? How many miles on the ones you have, then $250.00 including parts sounds probably about right, since the plenum and valve covers will come off. Then you get the 0 rings replaced without any extra work, pass and drivers side.

yes u never did say what they were going too do for 440...

if they are removing the plenum and changing the valve cover gaskets and the cam bore orings and cleaning it ..that sounds about right...

if they r just doing the cam bore orings ...no ..they only take maybe an hour for them both and half an hour for the one on the right side if u have the cam sensor on the left (which doesnt have an oring)