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 (http://www.nissanpatrol.com.au/forums/showthread.php?15134-Westy-s-Accessories.-A-small-back-yard-builder.)

[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 (http://www.nissanpatrol.com.au/forums/showthread.php?15134-Westy-s-Accessories.-A-small-back-yard-builder.)

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.

[NP99]

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.

I learn something new every day!

[dom14]

Do the pressure test (only )at first. If there are no leaks, and no warping, there's no need to face it.
So, if it passes the leak test and "warp test", then it's head gasket job. nice and easy.
In that case, total cost should not be over $200, including the head gasket.
shite load of labour though. ;)

angular torque is nicely explained here.

http://www.youtube.com/watch?v=ic_qiTx5B5Y

How to check for warpage:

You need to clean the bottom of the head so nothing is left on it. I use petrol to wipe off all the grime.

Get a feeler gauge and an accurate long steel ruler and place it(on it's edge of course) across the head while trying to push the thinest feeler gauge bits through it. at any stage if it goes in, either in the middle of the head or towards the edges, you may consider resurfacing it. machine shop should be able to do this test more accurately though.
The reason I like to avoid machining the head unnecessarily, is that facing the head, reduces the future number of times the head can be rebuilt and also it increases the compression, which puts extra strain on already worn out piston rings. Some guys put thicker head gaskets to fix that, but they are usually more expensive.
And not to mention some machine shop newbies over machining it, leaving you a motor with high compression, and rings stuff up in no time.
I usually get hold of the vernier caliper and measure the head thickness according to the engine manual, before I machine it.

[dom14]

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

Yes. I may need to see the pictures with glasses on next time. :)

[Alitis007]

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.

Use this tool to torque the head bolts

27182

Your gona hate your 4.2 after the torque sequence, last time i done a head on 1 i thought my arm was gona break off haha. 25 odd head bolts NOT FUN!!

[PowerSlide Racing]

Cool I'll hunt down one of those angle tools. I didnt check the head for flatness before I took it in but if they face it anyway im not fussed. I have read about different thickness head gaskets but not sure if thats mainly to do with diesels? Unless they have to take of a large amount I wouldn't have thought it would matter. Never been a consideration on any motor ive built before gaskets only came in one thickness.

[dom14]

They do have thicker ones, mainly used for turbo converted ones, as I've been told.

[BigRAWesty]

Pretty sure the factory turbo engines came with a slightly thicker gasket to decrease compression, so that's why your here of some blokes running 15+psi and others only running 7..

I'm not 100% on this either so be good if someone can confirm.
A diesel gets its ignition from the compression of the fuel, its gets to a point and self ignites. Now if you have had the head shaved your effectively reaching that critical ignition point sooner so the pistons will be to far BTDC. Pre detonating is what I'm getting at.
So if the guys in the WS are just skimming you may need that thicker gasket to get back to stock compression ratios..
Or it may act like a petty and be off its chops with a good power increase..

Kallen Westbrook
Owner of
Westy's Accessories (http://www.nissanpatrol.com.au/forums/showthread.php?15134-Westy-s-Accessories.-A-small-back-yard-builder.)

[nissannewby]

It's a petrol. I diesel head is near flat and doesn't have a spark plug poking out.

[dom14]

Pretty sure the factory turbo engines came with a slightly thicker gasket to decrease compression, so that's why your here of some blokes running 15+psi and others only running 7..

I'm not 100% on this either so be good if someone can confirm.
A diesel gets its ignition from the compression of the fuel, its gets to a point and self ignites. Now if you have had the head shaved your effectively reaching that critical ignition point sooner so the pistons will be to far BTDC. Pre detonating is what I'm getting at.
So if the guys in the WS are just skimming you may need that thicker gasket to get back to stock compression ratios..
Or it may act like a petty and be off its chops with a good power increase..

Kallen Westbrook
Owner of
Westy's Accessories (http://www.nissanpatrol.com.au/forums/showthread.php?15134-Westy-s-Accessories.-A-small-back-yard-builder.)

And not to mention piston rings giving away after few thousand kilometers of the job.
RB30 s usually have a good bottom end, if it's been looked after. I'm not sure about TB and TDs.
Correct thing to do with any car over 300k is to built the bottom end as well. But, that'd cost whole lot of dough obviously.

I have a question if you guys don't mind(with the OPs permission)
Is it possible to rebuid the bottom end while the head is still attached to the car? For example in a GQ RB30, you can easily remove the oil pan to access the crank. Can the honing and replacing rings, bearings, pistons can be done that way by accessing it from the bottom, without pulling the head or the engine out?!

[dom14]

It's a petrol. I diesel head is near flat and doesn't have a spark plug poking out.

unless they are glow plugs, masquerading as spark plugs. :)

[BigRAWesty]

It's a petrol. I diesel head is near flat and doesn't have a spark plug poking out.

Tooshay.. good pick up.. missed that small detail.. lol
So, skim away, just don't overdo the boost..

Kallen Westbrook
Owner of
Westy's Accessories (http://www.nissanpatrol.com.au/forums/showthread.php?15134-Westy-s-Accessories.-A-small-back-yard-builder.)

[PowerSlide Racing]

Just got the call from the head shop, it pased the pressure test so no cracks but they said it was bent? First time I've heard of that but anyway they straightened it and faced it for $220 so will pick it up tomoro morning. Might have it going by the weekend if i can find gaskets tomoro as well.

[dom14]

Didn't you say you did the warp test and it was fine?! Would be good to avoid facing, if you can.

[Alitis007]

The head warps when the head bolts loose tension then from the heat and pressure of the motor working it bends like a banana. They sound like the job is getting done correctly and by them facing it they mean machining a few thou off (thousandths of an inch)

[Alitis007]

Don't forget to oil the head bolts with 10w30 motor oil, just wet your hand and wipe run your hand across it ( you should have plenty of practice doing that from your early teens lmao ;-p )

[Wine_maker]

Did you check ellipsis of cylinders? It can be problem for high mileage engines.

[BigRAWesty]

Do you check ellipsis of cylinders? It can be problem for high mileage engines.

???? What of the cylinders?

Kallen Westbrook
Owner of
Westy's Accessories (http://www.nissanpatrol.com.au/forums/showthread.php?15134-Westy-s-Accessories.-A-small-back-yard-builder.)

[PowerSlide Racing]

Roundess of the bores, no i didnt check it as i just want to get it going and hit the dirt. I'd rather do a v8 conversion than rebuild the stocker anyway.

[Wine_maker]

Sorry for my English.

[dom14]

Don't forget to oil the head bolts with 10w30 motor oil, just wet your hand and wipe run your hand across it ( you should have plenty of practice doing that from your early teens lmao ;-p )

Or during breakup and rekindling time. :))

[dom14]

Sorry for my English.

Where?! What English?! I thought this is a German forum ;)

[BigRAWesty]

Sorry for my English.

Lol. I figured it was something like that..

Kallen Westbrook
Owner of
Westy's Accessories (http://www.nissanpatrol.com.au/forums/showthread.php?15134-Westy-s-Accessories.-A-small-back-yard-builder.)

[PowerSlide Racing]

Got it all back together over the weekend, torquing those headbolts is quite a workout! After adjusting the tappets it idled properly and a few laps around the block it seems to be running fine. The residual milky oil is a small concern I hope that's all it is and not that the problem isnt solved. I wont really know till its been driven for a week or so. At the moment the oil on the dipstick is milky still.

[Parksy]

I'd drain the oil, chuck some cheap stuff in with oil flush additive and idle it for 30 mins, giving the odd burst of 1500rpm every so often, then drain and chuck some good oil in and a new filter.

[Alitis007]

I'd drain the oil, chuck some cheap stuff in with oil flush additive and idle it for 30 mins, giving the odd burst of 1500rpm every so often, then drain and chuck some good oil in and a new filter.

I wouldn't rev the motor with a flush treatment in it coz you can spin bearings !!

[Parksy]

Chances are when you start a cold engine it will fast idle at around 1500 rpm. So long as no load is placed on the engine there won't be any dramas.

[PowerSlide Racing]

I put in half good oil then half cheap oil after i realised one 5 litre bottle aint enough! I also changed the filter so will wait and see what the oil looks like after a week.

[PowerSlide Racing]

300k's and its clear theres no more water issues. It does have an occasional misfire which I'm certain is ignition related as it happens on gas and petrol. Coil and ballast resistor appear to be recently new (kinda surprised a '93 model car with electronic ignition still has a ballast resistor?) so will try a fresh set of plugs.

[Dales300exc]

And not to mention piston rings giving away after few thousand kilometers of the job.
RB30 s usually have a good bottom end, if it's been looked after. I'm not sure about TB and TDs.
Correct thing to do with any car over 300k is to built the bottom end as well. But, that'd cost whole lot of dough obviously.

I have a question if you guys don't mind(with the OPs permission)
Is it possible to rebuid the bottom end while the head is still attached to the car? For example in a GQ RB30, you can easily remove the oil pan to access the crank. Can the honing and replacing rings, bearings, pistons can be done that way by accessing it from the bottom, without pulling the head or the engine out?!

Simple answer is with the head on. No.

With the head off. Yes.

But any crank machining or bore work would require engine removal.

[Robo]

300k's and its clear theres no more water issues. It does have an occasional misfire which I'm certain is ignition related as it happens on gas and petrol. Coil and ballast resistor appear to be recently new (kinda surprised a '93 model car with electronic ignition still has a ballast resistor?) so will try a fresh set of plugs.

Last year when I replaced the timing gear on sons maverick I replaced the top bearing and seal in the distributor also.
This took alot of the sideways play from dizzy shaft, basically does not miss any more.
He told me a while back his 4x4 mates have commented how well it starts and runs, for a tb42 with points ign with NO electronic ign.
I to am surprised at the results how well it runs for a lpg petrol set up.

I to are about to replace the same parts so I'll give some details when I know more
getting the pin from drive gear is the hard bit as the ends are riveted over, it takes alot of effort to get it out without damage to pin.
doing the work removed 80% off the play so not a bad result.
I'd really like to also replace the bush bearing at bottom, but local bearing shop dose not carry many bush type only needle.
more investigation on that I think, also its a steel type bush not bronze.
cheers

[PowerSlide Racing]

ok, not sure if this is my problem as I've noticed mine only misses when chugging at low rpm particularly in 3rd. My guess is its got a weak spark so misses when its under load at lower rpms.