Low compression on replacement engine.

[Hammy66]

I've bought a replacement engine and had it fitted to my 308 petrol a few weeks ago, but the garage can't get it to fire.
I'm exploring the route of getting jmkent to bring his box of tricks to analyse it and possibly get the keys recoded.
The reason I've started another thread is that the garage that fitted the engine have said today that there is low compression on 2 cylinders and I'd like any opinions on whether this is likely to mean that the engine won't fire at all?
The engine is 2 years old and has covered 11,000 miles.
It's costing a fortune so far, plus it has been at the garage for 5 weeks and I don't know who to believe any more.
Any suggestions?

[Hammy66]

Forgot to say;- the engine was 'bare' and they have fitted all ancillaries from my original engine to it..

[jmkent]

I've just done a Google for low compression..... at least I now know what it means

From reading various websites, all of which seem to say the same reasons for low compression (worn valves, camshafts, head gasket, etc). There is talk of dry testing and wet testing, and that they may have lost the oil seal in the cylinders.... has the garage done a wet test too? They obviously can only do a cold test as the engine won't start.

After the reading, I doubt that it would prevent the engine from starting altogether.... more like just run bad or have a power loss, unless there is no compression and in which case its some major work required. On an engine with just 11k, I would very much doubt it.

[danthevan]

Yep, it would if it was low enough

4 strokes of the engine:
Induction (suck)
Compression (squeeze)
Ignition (bang)
Exhaust (blow)

If it ain't squeezing, it ain't gonna bang

If it has only done 11k miles (sounds more like 111k if compression is low) then i'd be very wary of the bloke who sold it to you.

Being on 2 cylinders, it's quite possible the head gasket has blown between the 2 cyclinders. Losing 2 cylinders on an "11k" engine is very rare for anything else.

Could it be that the mechanics don't actually know what they're doing and have blamed it on the donor engine?

btw, ask them for the compression figures across the 4 cylinders

[Hammy66]

Thanks for that, Dan.
I think the fact that he has taken 5 weeks to get to this and now he seems happy for me to tow the car away when I've paid him suggests that the mechanic is out of his depth..

[danthevan]

Anyone who actually knows the basics of an engine should have checked the compression within a couple of hours of it not starting.
Trouble with "mechanics" nowadays is if they can't plug it in to a computer to be told what's wrong, then they don't know what to do.
Air, fuel, spark and compression is all an engine needs to run. Check those 4 and then plug it into the computer!

[davidireland]

Originally Posted by danthevan

Anyone who actually knows the basics of an engine should have checked the compression within a couple of hours of it not starting.
Trouble with "mechanics" nowadays is if they can't plug it in to a computer to be told what's wrong, then they don't know what to do.
Air, fuel, spark and compression is all an engine needs to run. Check those 4 and then plug it into the computer!

What engine, diesel, petrol?

[Hammy66]

1.6 vti petrol

[davidireland]

What are fault codes?

[Hammy66]

No fault codes, according to the garage that have the car atm..
Check my other thread:- '308 1.6 vti', David.