Engine trouble

[Freddievan]

My daughters van broke down at the weekend. I think it has a Golf engine in it. When it reaches a level on revs the power dips and white smoke comes out of exhaust. Any ideas with that poor level of info?

[Robsey]

Very little to go on, but white smoke from the exhaust would hint to me, a blown head gasket.
Or at least a breach of the cooling system into the induction / exhaust system.

Is it only revs related?
That would be very odd to my simple fault diagnostic knowledge.
Is it not more like when the engine reaches a certain temperature? which would be more indicative and easier to fathom out

[Freddievan]

Very little to go on, but white smoke from the exhaust would hint to me, a blown head gasket.
Or at least a breach of the cooling system into the induction / exhaust system.

Is it only revs related?
That would be very odd to my simple fault diagnostic knowledge.
Is it not more like when the engine reaches a certain temperature? which would be more indicative and easier to fathom out

Yes, I thought it was a long shot.  It's a T25 with a Golf engine, is what she was told when she bought it. I went to pick her up when it broke down.  They pulled up because the engine suddenly had a dip in compression when reaching higher revs.  I started the engine and it was ok but when I rev'ed it, it dipped and blew smoke out of the exhaust.  I'm guessing it would have cooled by the time I'd got to them.  My immediate thought when she phoned was gasket but I was perplexed when the engine actually started and ticked over.

[ajsimmo]

Could be that the head gasket is capable of containing a certain pressure. When revved the combustion chamber pressure rises greatly, passing that limit and leaking. When revs drop, pressures drop and normal combustion resumes. Rare, but possible.

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