Any mechanics around?

atrixblue.-MFR-.

chrisw wrote: »

No, Strider was correct, although rather than air pockets, they are pockets of water vapour. These will form in the system even without air once the water reaches its boiling point and the uneven heating warps the head causing the gasket to fail.

water vapor is heated to create steam! so how you have water vapor at boiling point separately when the vapor would be heated to create steam would be illogical science to me.


yes as you say you need no air to create vapor pockets but once the pockets are opened up it starts heating the vapor to create steam the process never stops so builds pressure until heat is withdrawn, the only way to relieve pressure is for it to find a way to escape at a weak point in its contained space and blow it out. if the head doesn't warp due to cooking itself, the pressure will find its way out through the head gasket or pipe or rad cap or expansion bottle pressure release cap, if the pocket is trapped, within the engine, it will find the weakest point to which to blow out.

colino

This is developing into a race to the bottom for those that have no clue about MOTs, basic science and how engines work!

Marktheshark

colino wrote: »

This is developing into a race to the bottom for those that have no clue about MOTs, basic science and how engines work!

Thats how it started, by a couple of idiots leaving an engine running with a water leak.
And now, it wont start.
No matter how far they tow it shouting at it...:mad:

lost_the_plot

The car is still there but they have stopped work on it. It is getting picked up either later today or tomorrow. The garage wont take payment so do any of you know what I should ask for to prove th work they have done on the car?

Marktheshark

Just get it out of there, if they don't want paying, then they obviously know what they have done.
Worry about implications later.
When the new garage gets it just stick to telling them what the known facts are, they left it running with a water leak and it stopped running whilst left running and wont run.

AdrianC

I'd love to hear how bump-starting a car can cause the timing chain or belt to jump. Seriously...

When you start an engine with the starter motor, it turns the flywheel and spins the engine.
When you bump start an engine, the clutch turns the flywheel, and spins the engine.

If a timing chain is going to jump teeth, it's purely and simply because it's worn and stretched.

The reason that bump starting is advised against is that it can cause heavy clutch and engine mount loads. No more, no less. Jump-starting is advised against because of voltage spikes harming ECUs.

There's either some serious idiots at this garage, or there's some serious chinese whispers going on.

If leaving idling idling for half an hour caused serious failures, then the car had issues and was near to dying anyway.

Marktheshark

AdrianC wrote: »

If leaving idling idling for half an hour caused serious failures, then the car had issues and was near to dying anyway.

Yes it did it was called a water leak from a bust radiator , they left it running hoping a bottle of snake oil would stop the leak.

lost_the_plot

AdrianC wrote: »

I'd love to hear how bump-starting a car can cause the timing chain or belt to jump. Seriously...

When you start an engine with the starter motor, it turns the flywheel and spins the engine.
When you bump start an engine, the clutch turns the flywheel, and spins the engine.

If a timing chain is going to jump teeth, it's purely and simply because it's worn and stretched.

The reason that bump starting is advised against is that it can cause heavy clutch and engine mount loads. No more, no less. Jump-starting is advised against because of voltage spikes harming ECUs.

There's either some serious idiots at this garage, or there's some serious chinese whispers going on.

If leaving idling idling for half an hour caused serious failures, then the car had issues and was near to dying anyway.

The car has been owned by my mum for the last 3 years and has full service history. It has always been reliable, sounds and drives smooth. My mum is in her 50's and is a very sensible driver. The car is only used to drive to and from work mon to Fri which is a 20minute drive and a local trip to the add a once a week. Even though there's a possibility it could have had engine trouble I doubt it very much.

AdrianC

Marktheshark wrote: »

Yes it did it was called a water leak from a bust radiator , they left it running hoping a bottle of snake oil would stop the leak.

Assuming they checked that the bodgegoop was holding, and didn't let it run dry, that would not have caused any further issues.

atrixblue.-MFR-.

AdrianC wrote: »

I'd love to hear how bump-starting a car can cause the timing chain or belt to jump. Seriously...

When you start an engine with the starter motor, it turns the flywheel and spins the engine.
When you bump start an engine, the clutch turns the flywheel, and spins the engine.

If a timing chain is going to jump teeth, it's purely and simply because it's worn and stretched.

The reason that bump starting is advised against is that it can cause heavy clutch and engine mount loads. No more, no less. Jump-starting is advised against because of voltage spikes harming ECUs.

There's either some serious idiots at this garage, or there's some serious chinese whispers going on.

If leaving idling idling for half an hour caused serious failures, then the car had issues and was near to dying anyway.

Under bump starting conditions the hydraulic tensioners can let go of tension causing the belt to slip or chain to jump. as allot of modern cars are fitted with hydraulic chain tensioners especially GM products bumping can cause the hydraulic tensioner to fail to provide adequate tension under the load forces of bump starting or the tensioner to fail completely. As the timing chains guides are mainly plastic in these cars they can also crack split or snap under bump starting conditions.