1990 bighorn engine issues

[willyr]

hello everyone. Im new to 4x4ing while I've had a few 4x4s in the past and spent a fair bit of time off road with hunting and tramping, never has the 4x4 driving been the main activity. I recently got hold of a 1990 bighorn lwb but straight away the cam belt broke. Two broken rockers and the two corresponding push rods bent so replaced them and got her running again but smokes like a bugger on start up until it gets hot then comes right but perhaps slightly down on power. When i start it in the morning it take maybe 30 secs of turning over to get it to fire and start up. When it dose get running it is ok at idol but from 1000 rpm to 2500rpm it smokes real bad but above and below its all good. She's a bit down on compression on 2 cylinders so next step is to take the head off (been holding off on taking the head off because I'm on a tight budget and head gasket is just another expense). Thinking damaged valves or rings? Any ideas on what i should be looking for or ideas on what could possibly be the issue?
Really looking forward to getting it going right getting involved in the local club and perhaps building a nice 4x4. I think this forum is awesome and looking forward to hearing from anyone.
Cheers.
Willy Roundhill.

[geeves]

Are they the same cylinders you had broken pushrods and rockers in? Did you check the rest of the push rods?
Is the timing correct?
Did you check all tappet clearances?
Bent valves are a possibility but I would of expected a bigger loss of compression as bent valves tend to stick slightly open.
Rings unlikely if it was running ok before the belt broke but piston damage is possible but once again they are very robust. If it had a pistonleak cranckcase blow by would be high.

[turnturn]

Unlikely, but possible, a bent conrod(s).

[nb422]

I'd put my money on valves, my engine is 200psi(520psi in 1 and 2 vs 320psi in 3 and 4) down in two cylinders due to valve damage, as i purchased it with a broken cambelt, misses at idle when cold, smokes like a dog when cold, and as it is now getting worse it is beginning to miss under high load

[willyr]

Well running through things with my mechanic mate and think the heads all good ill take it for a good thrash at some stage and check tappet clearances after that. It did have a bent valve so repaired and leak tested and they seam to be sealing ok. It is still running a bit rough on start up and when cold but when it warms up its a honey. Now correct me if I'm wrong but is the hose running into the air intake system along the top of the injectors a breather of some sort from the crank? I took that off and blocked it with my hand and after a matter of seconds oil comes up the dipstick like a fountain. So what is likely to cause this or is this normal? Damaged rings?
Cheers.
Willy Roundhill

[geeves]

It is a breather and most of these engines produce some fuming

[willyr]

So it's normal to have enough pressure to force oil up the dip stick and fountain out the top when blocked?

[geeves]

It does sound a little excessive but that is an extreme test
If you take the oil cap off how much smoke is there?
I looked at a pajero a while ago and taking this hose off the fuming was so bad the hose whistled. That engine was still running ok.

[isuzurob]

Its normal as you are blocking the only vent for the engine, dont worry about it, 1 of mine had 3/4 hose off the rocket cover as use to blow the dipstick out when driving it hard, it lasted 6years before it gave up

[willyr]

Ok Cheers lads. I started it up with another mechanic mate around to listen today and he thinks perhaps there might be a very small air leek in the line to injector pump. I'll replace the line tomorrow and see how I get on. He doesn't think it a compression problem by the sound of it.

[geeves]

leak in that hose will make funny noises and reduce power

[willyr]

I've checked the fuel lines and they seam fine. Although before a start the truck I pump the hand prime pump and it's always soft and starts beter if I do pump the hand prime pump but is still a bugger to start and takes a while before it will rev up. It spits and sputters and dies a few times with my foot flat or even taking it easy as you would with an old petrol trying not to flood it and it makes no difference. When it dose get going it smokes real bad at 2000 rpm even when it warms up but it seams to be only when it sits still. When it's in gear and driving it seams to not smoke. The smoke is white not black. Any one have any thing for me to cheek? Or is it a case of tough luck I've got a f#cked motor and just drive it till it stops?
Cheers.
Willy Roundhill.

[geeves]

If the hand pump is going soft there is an air leak somewhere
Likely causes are fuel filter seal hoses or injector pump seals. Air in the injectors can stop them spraying right explaining the smoke.
Check the filter first. The pump seal most likely to cause this without leaking diesel is the front seal which is a cheap enough seal but the timing cover has to come off along with belts and pulleys

[willyr]

ok just got out and pumped the hand pump and I can hear a leek somewhere so now to find the leek. is soapy water a good idea?

[willyr]

right tried soapy water and cant find the leek so might be time to take the injector pump off? if it is that front seal Geeves would i be able to here the leek?

[geeves]

No
A tiny leak will only need to cause a few bubbles before causing issues.
What I normally suggest is getting a length of clear pvc hose and put this between the filter and pump then watch it when its sat overnight. If there are bubbles in the hose the problem is in the filter. If not move it to the fuel return and you should see bubbles which will prove it to the pump. To do the pump properly is over 1k but this seal and the other 2 doddgy seals are cheap even if hard to get at

[willyr]

Cool Cheers I'll get something to suit tomorrow.