Isuzu G-series Twin Cam

I have a mate who has blown the h/g on his G200W.....and has asked me if I could spend the time to swap it over for him.

I have a VRS kit ready to go and have pulled my own twin cam down in the past,all be it over a year ago,but being offered an hourly rate for the job Id like to get it done as quick as possible.....

So who'd like to write up a quick headgasket tutorial

Biggest concerns are the cams and timing chain tensioner etc.

Cheers

Todd.

Surely a search here or elsewhere (HoldenGem, Ozgem) should find info, including the timing.
It's a pretty standard replacement, and usually sufficient to wire the chain to the sprocket (so it doesn't slip a cog) whilst keeping it up so it doesn't slip off the bottom of the crankshaft sprocket.
And for tightening, being alloy I recommend torque it up, let it settle overnight, the re-torque (since the work is NOT to retension alloy heads once run; unlike old cast iron heads that were retensioned after a week of running etc).

rotate to tdc on 1 remove front inspection plate.check bright links line up with dots on sprockets if not rotate 180 till they line up or mark them if you dont have bright links. release the chain tensioner plunger on the side. i think i took the sprockets off the cams and when re-assembled just turned the cams with a set of stiltsons and bolted sprockets back on. when the cams settle they dots will be at a slight angle outwards not straight up but that is normal. then re-tension chain.

When you're trying to run the timing chain over the cam cogs, if there's too much tension, rotate the engine forwards until there isn't (probably want to turn the crank over twice so it lines up again)...

I was putting the head on and the engine rotated backwards a bit without us realising. It put a stack of tension on the chain and uhh, may have... snapped a cam and cam cap+bearing...

Job done.....all went well,in my eyes......until I get a call saying the engine is running rough,not idling and pouring out oil from front of the head.

I had the engine idling ok once I initially started it up,was a bit rough on idle but nothing I would personally worry about,but after shutting it down and being re-started 2 days later Im now told over the phone it wont idle or rev smooth anymore.

I paid particular attention to the cam timing when refitting them,and was happy with both cam marks being as close to 12 oclock as I could get them.......

Now the VRS kit was missing the top timing case seal,where the head sits,so my mate cut a new gasket,made only in paper,be 0.5mm at most! This came to light once the oil leak started and thinking about it obviously theres a issue between headgasket thickness & timing cover gasket thickness once the head was bolted down...

Sooo off with the head again to get the right gasket on there and hopefully running right again.

Would the loss of oil pressure have any effect on the timing chain tensioner and therefore cam timing?

And a new head gasket...

The crank pulls the cams so that part of the chain is always tight.
The tensioner sits in the slack area after the cams, so oil pressure shouldn't make any difference.

i agree...my zz/r rattles like a mother when started, then the oil pressure kicks the tensioner in and all is good (still rattles a bit) but the timing is still good

cheers

FYI - later tensioners have a ratchet. This limits the slackness, hence quieter when starting.
AFAIK they are interchangeable.

I think the G200Ws & blue G180Ws have them, but I'm not sure...