I have a 166 JTDm 20V 2.4.
As it's the same engine as the 156's, I'm asking here
I hope some experienced members can throw some light on this!
Small history: since I bought the car it had small coolant leaks on the hoses, seemed just loosen clips, but eventually I noticed too much pressure on the expansion tank.
On arrival after a long trip (300miles, having a look to the temps every 2 minutes) I stopped at a gas station and took the oportunity to check the coolant... and had almost disappeared! It only had 1inch of depth! Topped it up and that day I drove with the cap slightly loosen to prevent pressure built-up.
Once at home, I added a leak stop additive, and it certainly almost fixed the hoses leaks.
Happy with it, I used the car for few weeks without issues.
But only once, after being parked the whole weekend, tried to start and didn't turn!
I thought, dead battery? Nope, the lights were strong even when I turned the starter on. What the ****?
After several tries it finally started, shaking with very unstable idle and throwing some white smoke.
Could it be just condensation...and the swirl flaps full of soot..and a faulty starter?...hehehe of course not!
Once in the highway, I noticed that I was leaving a giant white cloud trail, totally blocking visibility behind me.
Released the gas and drove very calm until the next exit.
In 2-3 minutes it stopped making smoke, and has never done that again, 3 months has passed since then.
But the pressure is still happening, on cold mornings I remove the coolant cap and it releases some pressure.
After a half hour run, if I turn off the engine and go to the engine bay, I clearly hear the coolant cap slowly releasing the excess pressure built inside.
No oil on water nor reverse. Need to refill 1/3 of the coolant tank once a month or so.
The EGR is blocked at the manifold, the egr cooler could still pressurize the coolant if cracked.
But it can't fill a piston with coolant!
So I was almost convinced of a failing HG, it has to be an extremely small crack on the gasket, I can't think on other source for this problem .
With the cap off the water doesn't "boil", only when revving hard some micro bubbles appear, they look like a slight foam.
But, wait a moment!
Suddenly I remembered that the coolant passes thorough the inlet manifold on 16/20v jtd engines!
Could the manifold gasket break and allow boost pressure to leak into the coolant, and then, when the engine is stopped, leak coolant back into the manifold, thus hydro-locking the engine like it happened before?
Or definitely head gasket problem ?
Sorry for the half Bible! I hope you like reading!
Cheers and sorry for my (probably) awful English