Offroad-Express

Got a 95 Pajero with a 4m40 engine and its got an oil leak.
Now this oil leak is coming out the inlet manifold and leaking down the side of the block, It wont do it when its idling it only leaks out under boost/load. Even running it at 3000revs on my hoist it wont leak it needs load on.
What can cause this?

Compression and leak down is really good, motor doesn't breath a lot from the rocker cover breather.
Any ideas would be appreciated.

Oil pressure switch on the 4m41 is a known to fail and leak oil out of it but that's on the other side of the block, I don't know where it is on the 4M40.

How bad is the leak?
May have a slight leak in the intake gasket allowing it to weep out oil
(blow by) under boost situations,

Guess 2: maybe it's leaking higher up and tracking around and down on to the manifold

The only thing higher is the rocker cover gasket and its dry as a bone. Its definitely coming out the intake manifold and it leaks a lot of oil to the point it drips onto exhaust manifold and smoke comes out the bonnet. Its not a weep.

At this point I'm thinking the oil pressure is to high and pressurising the turbo and leaking into the turbo inlet and making its way through the intercooler an into the inlet manifold.

But what I want to know is why the sudden oil pressure increase? what could cause a sudden pressure hike?

bad seals in the compressor housing side of the turbo will give you the same results, i would imagine the sudden rise in pressure high enough to force oil through the turbo seals would also give you an awesome smoke screen as it leaked in to the exhaust housing and other intresting symptoms

Check the intake pipes (intercooler) for excessive oil (pre and post engine breather) to rule out turbo,

My guess would be slight leak in manifold gasket combined with mass amounts of oil (blow by or turbo seals) in the intake and boost pressure then allowing it to escape the slight leak in manifold.

ClassicCruiserSpares wrote:But what I want to know is why the sudden oil pressure increase? what could cause a sudden pressure hike?

Im not familiar with the motor but does it have a bypass/relief pressure valve in the oil pump? could be stuck and causing over pressure but usually unlikely as most of them are pretty simple ball and spring design.

Other guesses are excessive blow by forcing oil out the breather into the intake, could try a temp catch can to exclude this (coke bottle is cheap and plentiful)

Or pull apart the inter cooler piping and see how much oil is in there to see if its the turbo causing it, seals could be on the way out

trucked wrote:

ClassicCruiserSpares wrote:But what I want to know is why the sudden oil pressure increase? what could cause a sudden pressure hike?

Im not familiar with the motor but does it have a bypass/relief pressure valve in the oil pump? could be stuck and causing over pressure but usually unlikely as most of them are pretty simple ball and spring design.

Other guesses are excessive blow by forcing oil out the breather into the intake, could try a temp catch can to exclude this (coke bottle is cheap and plentiful)

Or pull apart the inter cooler piping and see how much oil is in there to see if its the turbo causing it, seals could be on the way out

Yes they do have bybass/relief valve and your right they are very basic ball and spring, I checked these also and they are fine.
It doesn't have bugger all blow by into the intake, I tested that also.
Intercooler piping is coated in oil but I has turbo care here in christchuch check over the turbo and it is good as gold.
They also mentioned that the motor is over pressurising.

Could a blocked/faulty or incorrect oil filter cause higher oil pressure?

Got me stumped, Good luck think ill stick to Transmission's

I assume this engine is the 2.8 turbo engine?

and only leaks from the intake manifold under pressure correct?.....

one of three things.

Oil seal on the intake side of the turbo.
Oil Air separator is no longer separating the oily air from the crank case
Piston ring/s are damaged excessively worn and over whelming the oil/air separator.

Crash bandicoot wrote:I assume this engine is the 2.8 turbo engine?

and only leaks from the intake manifold under pressure correct?.....

one of three things.

Oil seal on the intake side of the turbo.
Oil Air separator is no longer separating the oily air from the crank case
Piston ring/s are damaged excessively worn and over whelming the oil/air separator.

Yes 2.8 turbo,
If the piston/ rings were that bad it wouldn't have good compression and leak down.

Were is this oil/air separator you speak of?

And oil can leak out of the intake side of the turbo due to high oil pressure but what can cause the high oil pressure?

ClassicCruiserSpares wrote:Could a blocked/faulty or incorrect oil filter cause higher oil pressure?

Anything clogging up the oil galleries, filter or cooler could increase pressure.

There is a chance of this happening but would be pretty slim i would of thought.

Some filters do have internal bypasses in them and anti drain back valves, but i would of thought a blocked filter would be bypassed by the engines oil bypass valves so there is not excessive pressure.

trucked wrote:

ClassicCruiserSpares wrote:Could a blocked/faulty or incorrect oil filter cause higher oil pressure?

Anything clogging up the oil galleries, filter or cooler could increase pressure.

There is a chance of this happening but would be pretty slim i would of thought.

Some filters do have internal bypasses in them and anti drain back valves, but i would of thought a blocked filter would be bypassed by the engines oil bypass valves so there is not excessive pressure.

Now theres an idea, never thought of the oil cooler in the front, that could be blocked?
Theres something odd going on here, I was certain it was the turbo but the experts say its not. They said it would have to have buggered bearings and a lot of play and there would be oil in the exhaust side also which there isn't.

ClassicCruiserSpares wrote:

Crash bandicoot wrote:I assume this engine is the 2.8 turbo engine?

and only leaks from the intake manifold under pressure correct?.....

one of three things.

Oil seal on the intake side of the turbo.
Oil Air separator is no longer separating the oily air from the crank case
Piston ring/s are damaged excessively worn and over whelming the oil/air separator.

Yes 2.8 turbo,
If the piston/ rings were that bad it wouldn't have good compression and leak down.

Were is this oil/air separator you speak of?

And oil can leak out of the intake side of the turbo due to high oil pressure but what can cause the high oil pressure?

the turbo doesn't need high oil pressure to leak ... just a worn seal.

From your description in first post it seems theres one, maybe two problems.
First problem is a leaking intake manifold gasket. (It don't matter how much oil and pressure was in it, if it didn't leak it wouldn't leak...).
Its not good to have an intake leak, I suggest that gets fixed either way.
Second problem is oil inside the manifold. It will come from only two places, either turbo seal leaking, or engine blowby. To confirm, best bet would be to clean out intake (intercooler and piping etc), extend tappet cover breather down to low on chassis, blank off preturbo pipe (so it doesn't suck unfiltered air) and drive it around for a week or so. If intake piping gets wet, its turbo seal. If not, check chassis near where breather exited and you'll probably find oil wet. This could be 3 things; piston rings poor seal, turbo seal bad (leaking boost into sump), oil seperator (inside tappet cover) drains blocked/gunked up etc.
The blowby could also be quite normal, but after heaps of kms its started to pool up and now inlet manifolds got a leak it can get out easy leaving stain.

You could try clean it and run it up on hoist in 5thgear (4x4 has more load), so you can get it onto boost (even use brake, but don't overheat them) Not as good as a road test, but you may be able to spy it as someone else drives it.
I very highly doubt too high oil pressure would cause the problem, it should easily cope with 100psi+ without any issues.

Bypass valve spring opens at 390 +- 29kpa or 56psi
Regulator valve spring opens at 490kpa or 71psi

Oil pump relief is on the pressure side of the pump therefore if the filter or cooler whatever may be blocked doesn't matter as it will relief at the given psi and bypass said blockage to avoid blowing up cooler or filter. From what ive just googled this has happened to many people. Another thing besides the oil pump that determines oil pressure is bearing clearance, big ends, mains and camshaft but even then I'd imagine that the pump would relief off at the given pressure.

As for your leak my guess is either turbo inlet seal or as said above about oil separated blocked causing excess blow by, turbo leaking boost into sump and a relief valve that's sticking shut or blocked gallery directly after the relief valve.

Just my three cents

This is where I got the specs from
http://www.mitsubishi-motors.kiev.ua/Ma ... .pdf#page6

I've just reading through this fourm and I seem to be having the same issues with my 96 Pajero 2.8T. Just wondering if this issue was ever solved and if so how? Or does anyone have any further information on the issue and how to fix it??

Cheers