Coolant in valve cover, could be EGR

[Czechmate]

Hi everyone

Here we are again with yet another lost coolant / EGR cooling issue.


I have only a small amount of coolant disappearing. I have chased this around for a few months now.

I recently started getting a bit of sludge in my catch can (mann hummel provent 200, photos attached). The vehicle was also blowing a bit of blue, oily smelling smoke at idle once warm.
Also i started getting 30-40 ml of water out of my catch can every week or two, instead of 30-40ml of oil every month or two.

I noticed that if i took the catch can filter out the smoke reduced.
I investigated further and found a collapsed inlet spigot on my catch can, so replaced that with another genuine mann hummel provent 200.
I figured perhaps if the catch can was leaking then the crankcase ventilation wasnt being sucked out properly, and oil drawing past the rings was causing the smoke.

But nope still smokey idle, and water and sludge in the catch can.

So last weekend I thought righto lets have a dig.
I replaced engine oil and filter to have a proper look. Oil was fine, filter was normal.
Inspected coolant and expansion tank, all seemed normal except the expansion tank coolant was down maybe 300ml.

Then i pulled the rocker cover off for a look inside.
And found some small puddles of coolant on top of the head. (photos attached)

This d40 had a rebuild about 7 years/80,000 ks ago. That involved a new head, new timing gear, etc etc.
It has run perfect ever since. The vehicle has still only done 155,000 ks total from brand new in 2007.

The interesting thing is that it has never ever got hot, its never overflowed coolant or bubbled, theres never been milkyness or coolant in the oil..


Through a lot of recent forum trawling, ive found that the EGR tubes themselves can be a way for coolant to be introduced into the engine. My d40 is 07 auto STX so it has a cooled EGR across the front.
Ive had my EGR blanked off at the inlet end since day one so the coolant cant have entered into the engine that way.

Does anyone know of the likelihood that coolant could enter into the cylinder head from the (unblocked) exhaust end of the EGR tube?
Ive read that coolant can pool in the egr and enter through the exhaust valves. Im not entirely sure whether this example was with a yd25 in a d40 though..

Im probly clutching at straws here, but I really dont want to take the head off again, and unless its an unlucky failed gasket, head problems seem kindof unlikely...

 

[Old.Tony]

Since your EGR is blocked, you could remove both coolant hoses from the EGR cooler and join them together, then retest. I'm not convinved it's coming from there, though.

Chances of the engine sucking something in the exhaust manifold into the cylinder: slim enough for me to say "nope". Exhaust valve timing begins around BDC of the power stroke (combustion chamber full of burning fuel) and closes towards the top of the piston's rise (this is a 4-stroke diesel, so it doesn't evacuate and compress on the same stroke). Two other reasons this isn't it: what's coming out of the exhaust valves is somewhere between 750C and 900C and it will flash-boil any water/coolant, plus there's no direct path for coolant to move from inside the cylinder (or exhaust manifold) into the camshaft housing. If your turbocharger is operating normally, then everything coming out of the exhaust manifold is behaving normally.

It's really surprising to see the coolant sitting in the top of the engine like that and not have any issues with the sump. You'd think some of it would have made it back down and turned the sump milky!

Is the coolant only present in the cam area at the rear of the motor? There's an oil cooler on the outside of the motor (the oil filter screws into the housing for this) that has coolant actively running through it. It may be the source of the problem. A pressure test of the coolant system (with the camshaft cover off and watching it and the oil cooler for signs) may reveal the culprit.

 

[Czechmate]

Hi again tony

Thanks for your reply.

Yes, the only places i can see coolant is two small pools in the corners at the rear of the head, and a little rim of coolant around one of the head bolts in the centre of the head, one cylinder in from the rear.

I dont think the coolant was there when i removed the rocker cover, it looks as though it seeped in with the cover off and engine not running.


I too am perplexed that theres coolant in the head, but the engine oil is perfectly clean!

All i can think is that its being mainly pushed out the pcv chute into the catch can by the ventilation gases.

It is blowing smoke sometimes though so maybe coolant is making it into the cylinders occasionally too.


I have the full egr delete kit coming from paul at yd25, so when that gets here ill rip the egr tube off and have a suss. As you said though, thats highly unlikely to be the culprit

Time for a coolant pressure test i think