JesseT

Sorry for posting to general, but it seems like the standard way to get a reply around here.

My 1.6 cvh turbo engine kept dropping down to 3 cylinders every once in a while at low revs and when cold and started getting worse during the day. However, it was always faultless on boost. All cylinders and all power there. Then I checked the plugs, which were ok. Then I checked the compression and 1,2,4 were at 10bar and #3 at zero/null/zip/nothing. Then I lifted the head off and the head gasket was mint, the piston and bores mint, valves mint. The only fault I found was the #3 inlet lifter was severly pitted. Most of the cam lobe was still there and I was getting still good valve opening when turning by hand.

The question:
Can a too far gone lifter cause it to:
1:collapse totally and not opening the valve at all
2ump it up execcively not to close the valve
3:make it stick and somehow leaving the valve open.
4: something else that explains zero compression.

A low compression I could easily understand, but zero at cranking speed and obviously at revs/boost it suddenly starts working.

xr4x4rs

iTrader: (5)

could be one of them things mate u have mentioned

but could als be more like piston rings cracked

JesseT

Craked pistons rings also would cause a low compression, but not zero. Also there are no marks on the bore at all. Something is not opening/closing the valve.

JesseT

Or it can just be the exhaust lifter pumping up and the worn inlet pointing to the wrong direction...

ON-UJAH

I'd say a lifter has become locked - had this problem before, a new lifter should cure it.

If the head is off, take a look at the oilways to the lifters - it might be worth boring them out if the casting is poor, which I have seen before.
(this probably is not the cause of the problem, but is worth checking)

Only other thing I can think of is a bad valve seat, but you would have noticed that.

Good luck m8, and keep us updated if you decide to drill the oilways out a little.

Edit: It's very cold at the moment, so with poor flow and thick oil, a bad lifter may have caused your problems. What oil are you using?

JesseT

You might have a point there, although it's record warm at the moment. We're even seeing positive degrees every once in a while. The oil is on the thick side for winter being 5wt50. Bloody friday 13th
Anyhow I'll put my "summer-cam" in with its lifters after re-inspeting the oilways and put the engine together. I prepared the engine only a year ago and I cleaned the oilways then.

JesseT

Now I have put the engine back together with an old CVH35 and its lifters and everything is ok. I just have to do a small testrun to get the fuel-map back where it should be after the cam swap. It's bloody cold outsideto build an engine, around -22C, but I'm just happy it's ok. Probably will remain a mystery as to why the compression disappered.