Hi guys, I need a little help.
I've just finished changing the HG on my mates XH ute. Its running a hybrid engine, and I used a AU HG on it. While it was off we dropped it down and had it machined to make sure it was completely flat.

Anyway I've put it all back together, Checked the timing chain marks, everything lines up, Cranked it over by hand about 7-8 time to make sure everything was fine. Then jumped in and cranked 3-4 times for about 2 seconds, just to get some oil circulating before I tried to start it.
On the 4th time, it started it spin allot quicker, like it had little compression.
I tried again for a second and the same thing.

I then cranked it over by hand, and it has defiantly lost allot of compression.

I've rechecked the timing chain marks and everything is lined up correctly, the chain is tight and the valves appear to be opening and shutting at the right time.

I really don’t think that the valves have hit the pistons as I would of heard them, and also would of felt them as I cranked it over the first time.

I've done over a dozen head gaskets and never had a problem, and I cant think what the hell could be causing this..

Any help or ideas would be much appreciated.

were the valve seats ok? all torqued down properly I can only assume. the head is not hanging on anything?

I didn’t get the Valve seats checked, but I would imaging they were ok, as there was no problem before. The head was torqued down right. I've check all around the edges and it looks like it sitting dead flat...

Its weird how it was ok, and then lost the compression…

sounds like a tooth has been missed on the chain somewhere.. for it to loose comp like that, either gained a tooth or dropped a tooth or 2.. no comp everything else checked, rocker cover off, bring cyl 1 to TDC and make sure nothing is open. I think if you find 1 cyl like that you will find em all like that.

Well, we got it all sorted out. It ended up been that the lash adjusters had pumped up and were holding the valves open a little. After running it for a 30 seconds it was all back to normal.

Wasted an extra hour or so double checking things for nonthing, but hey its better to be safe then sorry..

Thanks for the help.