Excessive crankcase pressure, plenum pressurised too.

[cuh8er]

Hi,
I am posting this on behalf of a friend who has an overheating Toyota Hilux.

My question is this.
There is EXCESSIVE pressure in the crankcase/rocker cover area. Also, the plenum has pressures well exceeding what I would expect to see.

With the engine running, we pulled off the hose that goes between the rocker cover, and plenum chamber. Block either opening with your finger and after a few seconds, the pressure builds to the point where it's hard to hold your finger over the opening.

The car is plagued with an overheating problem. Everything has been done to try to rectify this including-
New radiator.
New water pump
New hoses.
New radiator cap.
New temp sender.
New injectors.
Flushed block (forwards and backwards).
Had the head off and checked. It's ok.

Just wondering if the overheating has anything to do with the excessive crankase pressure?

Car runs ok, no significant loss in power or fuel economy. Having said that, it's been like this since he's owned it, so no numbers exist to compare power/economy too.

Thanks in advance everyone.

 

[Red Rattler]

It doesn't sound to good but we need more info, is it turbo or not (3L, 5L). Have you looked at the fan hub. Is it real easy to turn by hand? Is the fan on the right way? However if the blowby is high it will most likely be a broken ring.

 

[cuh8er]

Thanks Red,
Forgot to mention he changed the clutch fan for a Spal thermo fan.

Engine is non turbo, 2.8L diesel (pretty sure it's 2.8L, it's a 1994 model anyway).

Unless there is something i'm missing, the blowby is real high. But I can't see how it's finding it's way into the inlet plenum.

 

[Red Rattler]

Somethings not right with it. How sooty(thick) is the oil? How it stains your fingers is a good indication of how bad it is. With a broken top ring you should expect to see a high amount of carbon in the oil. I recently rebuilt a 2.8 for spiting oil out of the filler cap. When rebuilding it I found a bent con rod and the previous owner thought he could do a 30/70 diesel petrol mix this caused all the ring to melt into the pistons. Have you tried to fit a Murphy gauge to it to make sure your not chasing something that's not there.