Corsa No Compression on 3

Can I suggest replacing the valve stem oil seals while you're at it?

If the engine's scrap, they come as part of the head set anyway, and shouldn't take long to change. If the engine's not scrap, at least you won't have to start taking bits off to change the stem seals.

Pete.

Thanks again mrcheerful and Paul. Will give it a try and will let you know

Sorry was meant to say thanks to Pete

Just a quick thought on this, it is possible that the engine will not start because of a simple ignition or fuel system fault and that you have been led astray by a faulty compression tester or incorrect testing procedure.

Does the car have a normal distributor on the end of the cam shaft, if the pin that drives this is broken the plugs will still fire but the timing will be miles out, if it has the coil pack on the end of the cam shaft it could be a faulty crank censor.

And lastly has it actually got any fuel in it and is it being pumped to the injectors.

This is just a suggestion as the comp readings you got should have had a really obvious reason and you have found nothing and the sellers story of it was working fine until it went in for some body work doesn't sound right.

Just a thought anyway.

Let us know if you do find the problem.

Thanks again Paul. Will let you know how it goes

I have put the head back on with new gaskets, bolts etc. The throttle was fully open and the first 3 still have no compression. I have even put my finger over the spark plug holes and there is no air at all on the first 3. I have put soapy water around the edges of the mating face of the head and the engine block and no air appears to be escaping from there. The forth I am getting about 15 bar on. While it was apart I did the petrol test on the inlet and exhaust valves. None leaked. I did the oil test on the piston rings and they seemed ok. I also put my hand over the pots while the engine was turned just to ensure that there was compression. On all of them when the piston was going up a build up of air could be felt on the hand and when the piston was going down it created a vacuum on the hand. I have checked and there is nothing obvious on the head or engine block. Any suggestions would be gratefully appreciated

Then the valves can't be opening. There's nothing else to prevent it working. Turn the engine over with the rocker cover off and see if they are moving. I said at the beginning it was a camshaft problemand the symptoms will be the same if the cam lobes have worn off or the valve lifters aren't working.

Faulty hydraulic followers.

Graham

Have it excorsised.

Fit a bigger flywheel, and enjoy the fuel economy :)

Seriously though. As the pistons seem to be sort-of-sealing, there should be at least some compression, especially as you'd probably feel a fraction of a PSI with your finger in the plug hole. There are only two possible causes, AIUI. Well, they boil down to one. A valve is staying open all the time - maybe not the same one. If it wasn't, then you would at least feel something. Even with no head gasket, I'd expect to feel something.

(probably better ways) Connect a vacuum cleaner on suck to the exhaust. Turn it over slowly by hand.

Do you feel the sucking through the spark plug only when you should?

Repeat, with set to blow on the air inlet.

Otherwise I'm back to the 'made from metal dug up from a viking burial ground hypothesis.'

Thanks for the relpys. I have taken the rocker cover off and it all appears to be pushing the valves down normally. However on close inspection the cam shaft is worn. So I am going to have to replace it anyway. Ian I havn't put the vacuum cleaner on the exhaust yet but I am looking forward to seeing the looks on the neighbours faces when I do. I am sure it will finaly confirm them that I am barking mad. I am considering getting it excorcised

Get the head crack tested. Could be a hairline crack between the inlet and exhaust valve.

I have just tested with the vacuum cleaner. All three exhaust vaves are open all the time when they shouldn't be. Looking for something to test the inlet as my vacuum wont blow. Cheers for that idea Ian. Did get a couple of odd looks with the vacuum up the exhaust. As the petrol test appeared to suggest that the valves wern't leaking is it likely as Graham suggested that the hydraulic followers are faulty. As said before the cam shaft is worn so I will be replaceing that anyway

Is it likely it is just the hydraulic followers?

The chances of all three cylinders crankshaft lobes wearing to the point of no compression at all, when the engine has been running sort-of-normally, is zero.

So, it's at least partially the hydraulic followers. The camshaft may of course be worn, but not to the point of giving zero compression.

Thanks Ian most appreciated. Will give it a try and post back when it is done

Please note - this is a guess - I've never seen this sort of engine, and my most taxing job to date on my car is removing and unsticking the caliper. Actually, I lie, it was changing the heater blower selector knob, after believing the haynes manual, which ended up having to take off the entire fascia.

If you are going to replace the followers then make sure that the oil is getting to them and that the gallery isn't blocked. 2 faults can occur.

The oil isn't released (jacking up) and therefore valves stay partly open - faulty followers.

The oil gallery is (partially)/blocked and not enough oil is supplied to the followers to keep them working - poor valve movement.

Graham

Thanks Graham and Ian. Will check that the oil gallery isn't blocked

Have repalced followes , lifters and cam. Also changed oil and filter. Fault is still the same, no compression on the first 3 and the reading on the forth is fine. However I am going to have it towed in gear just in case the oil is not coming up in the length of time the battery is lasting.