Looking at the front of the engine the LEFT Front & RIGHT Rear have compression. The 2 without are Left Rear & RIGHT Front
0 bar <--> 6 bar
6 bar < --> 0 bar
The battery I was using was weak & therefore not turning over the engine very fast, i reckon that's why the 2 are showing 6 bar, would have expected nearer to 10bar
Could it be something simple, such as lack of oil in the hydraulic tappets [ if they have Hyd tappets ] or will it more likely be badly seated or bent valves?
The 2 heads had been removed & re-fitted by another person, from whom I bought this engine.
Comp tests must be done on a hot engine (drive it around a while), then after with all plugs out, wide open throttle.
A wet test should always be done.
This means squirting about a teaspoon of oil into the cylinders via the plug hole (in turn of course..) and repeating the comp test; that is a great way to 'wet-up' the rings and make them seal (better/properly!). Thus a wet test really can indicate whether rings or valves are the problem. If the wet test gives much higher values than the 'dry' then the rings are worn out.
Brit, thanks for the advise, kinda hard to get it warm when the engine lying on the ground, removed form a car...... i'm looking for possible reasons why there is no compression. could it be a re-assembly error? bad timing?
from the symptoms described does it give any indication as to what may be wrong?
Is the timing correct? Give us more details as those you are providing are very little to diagnose something. For example what have you done to the engine before that , for example new rings or gasket , timing etc...
all i did was I bought an engine which another person had replaced the 2 head gaskets on. he claimed it was running but mis-firing due to a faulty coil pack
Before usng this engine I decided to do a compression test, to find 2 of 4 cylinder are without compression.
As for strippig it etc, yes I have the tools & skill required to do so. Its just I'm not familiar with the boxer engine. i was hoping some-one might say if Cyl A & Cyl B have no compression its means =???
It'll be a few weeks before I'll look at it in any detail. Thanks for all the replies.
To clarify, the engine is NOT fitted in a car at present, its under a work bench.
BTW its a '92 1.7 16V engine from an Alfa33 P4, i assume Hydraulic tappets? or if they are mechanical what is the measurement for the clearance gap
If there is no compression at all then something is drastically wrong.
First thing that comes to mind is that those valves are not opening/closing properly (seating badly or damaged seat), hence the compression issue. That will run horribly on 2 pistons if it runs at all.
Check the timing - if that looks ok take the heads off.
Take the heads off and turn the cams by hand to see how the valves lift. Looks like a rebuild - do it yourself this time!
At that rate Id pull the heads anyway and give it a good look over. I assume its history is unknown as it came as parts so its worth splitting it and having a root around before you put it into a shell. It sounds to me like the pistons and valves may have met at some stage.
Just looking at the cylinders which have compression (1 and 4) and those that don't (2 and 3), I would say that something is 180° out of phase somewhere - did the correct camshaft go on the right cylinder head? Hydraulic cam housings are pretty symmetrical looking?
Thanks for all the replies & suggestions. I won't get a chance to look at this until the kids are back in school. I'm hoping its just a few sticky tappets. its been 2 years since the head were re-fitted
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