No compression at no 4 cylinder.

Right, I've recently changed the head gasket, replaced coolant flanges, changed the cam belt, tensioner, vacuum pipes (thanks Crazyquiff!) the dizzy, sparks and battery. Timed it all up today, spun the engine by hand 3 times - all good. Tried starting it with the key - wont start.
Checked the compression - no.1 - 150ish, no.2 - 150ish, no.3 - 150ish, no.4 - 0. Double

Any ideas on what could cause this? I've searched the forum and found alot points to valve clearance but Ive got hydraulic tappets and was under the impression they are self adjusting?
My mate mentioned a valve might not be seated properly, can anyone suggest an easy way of checking this or do I have to take the head off again?
When I turn the key and have the compression tester in no.4 spark plug it does sound completely different from testing the other 3, but I guess it would anyway if there is no compression…

Please help! Any advice is greatly appreaciated!  :mrgreen:

I take it it was running fine before you did the head gasket ?

I think you're pretty much going to have to remove the head again. It might just be worth removing the cam cover and pushing down on the tappets, to see if there's any difference in the feel of the valves going up and down against the springs. It might be much easier (suggesting a broken spring) or much harder (sticky valve in guide?). The other thing it might be, is you've somehow snagged the new head gasket and its damaged, blowing out to the side of the block or something.

You could take it to a garage and ask them to do a cylinder leakdown test, this will show where the cylinder is leaking. It will be blowing into either: inlet manifold (inlet valve), exhaust (exhaust valve), cooling system (head gasket), or oil system (valve stem seals or rings). Or to outside the engine.

Here is something else that could have happened but not very common. On the big block engine you can fit the head gasket on up side down, thats what my Dad done to a 1600cc MK2 (same engine) It would not start or fire or anything! He got a friend of his at a garage to have a look and he fitted a new gasket and all was fine!   That was almost 10 years ago and we are still making fun of him for it!    

Well Ive taken the head back off today and checked it over. I found a couple of things which need looking at some more. Firstly that the inlet valve was very stiff and I ended up having to tap it out with a hammer. Secondly theres a deep enough scratch on the surface of the head that you can feel it with your finger which wasn't there before!
I'm gonna get the head skimmed but don't know what to do about the valve. Is there any way of making it smoother cos the guide it sits in looks like it's part of the head?:dontknow: Or could the valve just be catching on the stem seal instead? Im gonna replace the seals (again lol!) on both valves to be safe anyway…

Look closely at the valve stem, if its not smooth you could smooth it off with a file and emery paper, etc. If it is, then the valve stem seal must be notched or distorted. They can be replaced, but you need a press and the appropriate fittings to push them in and out. In other words.....leave it to an engine reconditioner!