GQ Head Cracks?

[PowerSlide Racing]

So I finally got myself a GQ (93 model) after 12 months of wanting, I picked one up for only $2k but knowing it wasn't running due to a head problem. I figured for that price even possibly having to fit a 2nd hand motor its still a cheap GQ
I was told it split a hose and ran hot and possibly had a cracked head or damaged gasket. The oil is milky.
Upon disassembly it is clear cylinders 3 and 4 have taken in coolant and this corresponds with marks on the head and damage to the gasket. What I dont know yet is where the water is getting into the oil. I cant see any obvious cracks but I dont know where I should be looking or even if they would be visible?
The head itself is only 12 months old so is not corroded. I'm hoping to get it going with minimal expense as the motor has done 320 000 and will have had a fair bit more taken of its life now.

[BigRAWesty]

Any sign of coolent in head? If not could be a possible cracked block..

Kallen Westbrook
Owner of
Westy's Accessories

[kevin07]

if your head is cracked there will be white color in your exhuast ports

[nissannewby]

Won't be so much a cracked block but could be a cracked liner. It will be hard to see a cracked head as to get that much mixing it will going back into the oil anything that comes through the ports will be burnt. Was there any fluid in the pots you said were at fault? Getting a head crack tested is pretty cheap these days.

[dom14]

Any sign of coolent in head? If not could be a possible cracked block..

Kallen Westbrook
Owner of
Westy's Accessories

Cracked blocks are rare. I think chances are it's the head as most of the time.

[dom14]

Here is the thing mate.
Usually you can find it by carefully examining the head, block and the gasket.

In anyway, would have it pressure tested by taking it to machine shop. You need to take take the cam shaft off to do that, but it's worth the trouble. Looks like you've done that already.

You can take a chance and clean it up and put it back with a new gasket. But, I wouldn't. It is not uncommon to have cracks inside where you can't see them at all. If the machine shop guy finds cracks, then get him to test it whether it's worth welding and machining it. Make sure you get hold of the manual and check whether it's been machined previously upto the limit. Over machining can stuff up the bottom end. But, you can get a thicker head gasket to fix that problem(to reduce the compression), but I wouldn't do that.
Recondition head is around $600. Pressure test should be just over $50. You should be able to get it pressure tested, then if there are any cracks, get it welded and machined for around $250, depend on where the cracks are.
I would put a change over recondition head. But, you gota make sure the bottom end is not heavily worn out. But, if it's an RB30, I would say it should be good for the kms it's done. Mine has done over 300k and still got good compression.
You need a torque wrench. Some guys do that with the feeling, but that comes with experience though.

Haynes manual got all the information you need to do a 'head job'.

You can download it here, or let me know your email, I can email.

Be careful when you tighten the head bolts. If you see any of them badly rusted, you may want to replace. 'cos if they breaks, then you end with a whole lot of headaches. Also, if you decide to put the head back on without any tests or machining, make sure to be careful when scrape off the old gasket bits from the head.
The alluminium head can easily get scratched by scrapers, then you won't have any choice but machining it.

If it's TB or TD42, it's good practice to adjust the valve clearance before putting the rocker cover on..

[dom14]

Not sure where you are.
In Melbourne, "All Head Services" have really good deals on reconditioned heads. They deliver for free as well(last time I checked)

[nissannewby]

Here is the thing mate.
Usually you can find it by carefully examining the head, block and the gasket.

In anyway, would have it pressure tested by taking it to machine shop. You need to take take the cam shaft off to do that, but it's worth the trouble. Looks like you've done that already.

You can take a chance and clean it up and put it back with a new gasket. But, I wouldn't. It is not uncommon to have cracks inside where you can't see them at all. If the machine shop guy finds cracks, then get him to test it whether it's worth welding and machining it. Make sure you get hold of the manual and check whether it's been machined previously upto the limit. Over machining can stuff up the bottom end. But, you can get a thicker head gasket to fix that problem(to reduce the compression), but I wouldn't do that.
Recondition head is around $600. Pressure test should be just over $50. You should be able to get it pressure tested, then if there are any cracks, get it welded and machined for around $250, depend on where the cracks are.
I would put a change over recondition head. But, you gota make sure the bottom end is not heavily worn out. But, if it's an RB30, I would say it should be good for the kms it's done. Mine has done over 300k and still got good compression.
You need a torque wrench. Some guys do that with the feeling, but that comes with experience though.

Haynes manual got all the information you need to do a 'head job'.

You can download it here, or let me know your email, I can email.

Be careful when you tighten the head bolts. If you see any of them badly rusted, you may want to replace. 'cos if they breaks, then you end with a whole lot of headaches. Also, if you decide to put the head back on without any tests or machining, make sure to be careful when scrape off the old gasket bits from the head.
The alluminium head can easily get scratched by scrapers, then you won't have any choice but machining it.

It it's TB or TD42, it's good practice to adjust the valve clearance before putting the rocker cover on..

Im pretty sure these aren't a overhead cam engine.

[PowerSlide Racing]

Cheers, i dropped it off to get tested this morning they said $165 to test it, face it and check the valve seats. I'm reasonably confident it will turn out to be just the gasket that failed. They also quoted me about $200 for new gaskets and head bolts, I dont know if thats good or not I havn't checked anywhere else yet? They also said the bolts are angular torqued, does this require a special tool? I have a very good torque wrench and have rebuilt a few motors before but have never come across angular torquing.

[nissannewby]

Those prices sound pretty fair mate.

With angular torqueing you well have an initial figure say 60nm then they will go say 60 degrees on all then another 120 degrees on them. You can do this by simply marking the bolts and your socket with a pen. For example if you have a hex bolt each point is 60 degrees so you mark a start point and a finish point and turn it that far.