Cam Seal Oil Leak!!

[Chris]

Hi all, I’ve got a 99′ Mitsubishi Magna 3.5L V6, the Aussie equivalent of the Diamante. My PCV valve got blocked and as a result, I had oil spewing from all the upper seals in the engine. I’ve changed the o-rings at the distributor and the thrust case (they were already in need of a change anyway), and of course the PCV valve. Now, and only once the engine has heated up, it leaks from only the rear bank cam seal. I’ve had the timing belt and seals done 5,000 clicks ago, so they’re more or less brand new. It used to leak from the front bank cam seal as well, but it no longer does this after the new valve was put in.

My question is, is there some other problem that is causing the rear bank leak, or would I just need to change the seals (went out and got genuine seals)? I’ve got a new blow-by hose on there, and the breather hose looks fine. I’m assuming that the oil leaks because of pressure built up in the rear bank, but is there something else I am missing, or is it just that the oil seal is damaged? I don’t want to put the genuine seals on and then find that the problem still exists, not cheap, those seals. Ohh and also, the car runs on LPG so the breather hose is connected to the gas mixer thing where the LPG is pumped to mix with the intake air before entering the throttle body (apologies, I can’t remember what it’s called). Might that have an effect on the pressure inside the rear bank (assuming I am right about the pressure causing the leak, that is)?

Cheers,
Chris

Topic

[EricTheCarGuy]

Not being able to see the issue for ourselves it would be almost impossible to tell you what you’re up against. However I do cover how to find and fix leaks in this article. The information in here might be helpful to you.

http://www.ericthecarguy.com/faq/finding-and-fixing-leaks

Good luck and keep us posted.

[Chris]

Hi Eric, thanks for the comeback. I will try and upload a video of the problem, on the off chance that someone else may have the same problem in future.

Well, basically, shortly after the temp gauge goes up to operating temperatures, oil starts pouring out of the rear bank cam seal. It literally looks like it’s pissing out of that seal, colour and all. It used to come out the front bank’s seal as well, but after changing the faulty PCV, this no longer occurs. Am I right, or at least, on the right track that the issue is not a damaged cam seal, but excess pressure in the rear bank that’s forcing oil through?

I have read the article, thanks man, especially the part on the PCV system. I will go check the hoses for blockages first.

[Lorrin Barth]

I can’t see how the pressure would be any different anywhere under the valve covers or in the crankcase. It is all connected space.

A turbocharged car has a PCV valve that is also a one-way check. That way if the manifold is pressurized it doesn’t pressurize the crankcase. A turbocharged car also has a second vent hose that can vent the crankcase when the PCV valve is closed.

So, I’m not sure how your engine is vented, how many hoses we are talking about or if the intake is pressurized. Pressure in the crankcase will blow oil through the weakest seal or blow out the dip stick.

[Chris]

Hi barneyb, I am unsure how exactly the pcv system in my car works, I was looking it up on my car club’s forum and I’ve only found tests to do to see if anything is blocked.

Alright, so, there’s:

1) A breather hose runs from the top of the valve cover and is attached to the housing that the LPG is pumped to before the intake (I’ve got the older mixer system), right before the throttle body. This is at the back of the engine.

2) A blow-by hose that runs from the front to rear valve cover, also at the back of the engine.

3) Lastly, there’s the PCV hose at the front of the engine, connected to the front bank.

Here is a badly illustrated picture. Note, this is not my engine.

The red arrows are just the general direction the hoses run.

The thing that is confusing me is how the air travels around the engine. I’m thinking (or guessing really) fresh air enters the valve cover via the breather hose at the rear bank, goes through the crankcase, carrying the blow-by up to the front bank where the PCV valve is, and is sent into the lower intake manifold from there. So at low rpms, the vacuum in the intake manifold is high, causing low flow of blow-by gases, and at high rpms, there is pressure in the intake manifold and this causes high flow of blow-by gases. I am assuming that the blow-by hose is for engine loads too high for the PCV valve to handle the volume of blow-by produced, thereby sending it back to the rear bank and out through the breather hose to enter the engine via the throttle body.

If this is correct, I can see now, why there wouldn’t a difference in pressure throughout the engine. But then, that leaves me at square one again. Why does it start leaking only after it has reached “operational temperatures”?

[EricTheCarGuy]

What comes to mind is installation or the parts that were used. If you have a leak that’s that bad and the seals were replaced not that long ago, that would be the #1 suspect in my opinion. You might have to go in there and replace the seals again. While you’re there examine the cam shaft. If it has a groove worn in by the seal, try repositioning the seal so that it doesn’t make contact in the same place. Good deeper in instead of shallow. You don’t want it falling out.

Keep us posted.

[Chris]

Alright, thanks Eric, I will. It may take a while though, exams and stuff coming up, so the car stuff has to be put on hold.

[Chris]

Hi Eric, sorry it took so long, just got back from overseas to deal with the problem.

Turns out, we were both right. I checked the PCV valve and the new one had become sludged up as well. The hose had traces of sludge, but it’s all clear now. Anyway, I sprayed a little intake cleaner into the lower intake manifold and put a new valve on. That brought the leak down to a trickle, as opposed to it pissing out. Replaced the seals and all seems good now.

Thanks so much man, you’ve already saved me a couple of thousands with you videos and advice!

[Author]

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