GU Intercooler

Thats how I think but my dealer says that there is a crack in the intercooler and this is where the oil leak is coming from. I thought there was only air but I think if there is oil around the intercooler then the engine is on its way out. It is only 9000k's old (the engine that is). If i need to replace this item then it gets added to the list and there would be hardly anything that hasn't been replaced.

Perhaps you are getting excessive blow buy or a Turbo oil seal may be shagged

Yep, most 4.2TD Patrols (before the TD6 intercooled) can be found to have a sign of oil under the large pressure valve immediately above the inlet manifold. That valve has been plugged up on my rig now; was done when Denco fitted the bigger turbo and increased the boost to 15psi.

I have read several times that the 3L intercooler is subject to oil leaks.......that whole intake system is subjected to boost pressures of "up to" 30 psi at various times. This is supposed to only be for very short periods of time when the VVT is working it's hardest. However, my theory is that various electronic "gizmos" (eg: EGR valve + MAS) are conspiring together to feed false info to the controller of the VVT and it ends up pushing those exaggerated pressures when it ain't supposed to be. The result is leaking intercooler (at best), blown-off intake hoses and ultimately blown pistons.

Well, that's my theory anyway..........

Roachie

Sorry, just realised I used the term VVT a couple of times. I meant to refer to the Variable Vain Turbo......but realise VVT actually means "Varaible Valve Timing"

Roachie,
I've had a blown piston and cracked piston, 9000kms ago. Now I have a cracked intercooler and oil leak. Initially I thought it was a rear main seal as this was the area of the leak but I did not have a real good look (lost interest and it is now under warranty). Could these pressures that you speak of crack the intercooler? I noticed the oil on the concrete in the shed and crawled under and it seemed excessive. I didn't start it to trace it, just took it down and said fix it.

Been an interesting exercise owning a Gu 3-0! Very character building.

I'm thinkin of dropping the Gu off at the Toyota dealer!

AJB,
What Roachie said is mostly true. One of the problems, I think, is that Nissan techs don't check or adjust boost levels, even when they replace the turbo because they are setup on a bench from the factory. Each and every car has it's own characteristics and some of these can affect the boost levels.
I wound my boost down slightly to try to achieve some reliability after fitting a boost gauge and seeing the levels they go to. Mine will now peak at 18psi instead of 25plus with no noticable loss of power. Hopefully this will reduce the risk of a split intercooler or worst.

Thanks for all the info. I'll find out more tomorrow. Wont loose any more sleep on it as it's only a car!

Chaz, how did you wind the boost down on ZD30? I've been tempted to fit a blowoff valve.

David

Hi David,
You can’t fit a blowoff valve to a ZD30, but the boost level is easy enough to control by adjusting the grub screw that stops the VNC (Variable Nozzle Controller) from travelling all the way around. This is the small grub screw and lock nut behind the VNC actuator in the centre of the turbo.
Simply undo the VNC actuator and remove it out of the way and then undo the locknut (5/16AF) and wind the grubs crew down (clockwise about 1/3 to ½ a turn). I think the grub screw is a 2mm or 2.5mm allen key.
It would pay to have a boost gauge fitted to see the difference, but this will lower the peak boost levels without any noticeable power loss through the normal driving ranges.
This Link explains it a bit better, but you'll have to translate the page from French to English.

Well I have been through a bit if crap with the ownership of this vehicle but I still have my sense of humour (it's a little bit dryer these days) and the exercise has been interesting. Expensive but interesting. Got the quote today for a new intercooler, $950. It's feels like going outside and lighting a fire with hundred dollar notes as kindling! What do you do. A Nissan is worth nothing and a busted one less!

What area are you from AJB?
My understanding is one of the frequent posters on this site makes intercoolers, but I think he is from Melb?? Maybe if you are from that area, one of the Victorians could get in touch with him to give you an unbiased opinion??
I know how you feel regarding your truck, I have felt this way many times with my 4.2 but for some reason (maybe madness setting in???) I keep spending money and fixing what should have been right when I first paid for it.

Other than the broken bits the rest of the truck is good LOL!!! (That's my sense of humour....and you reckon yours is dry!!)

Best of luck,
Trevor.

Trev, I'm from Vic but don't hold that against me. You know there are some really good people here in Vic and I know both of them! Anyway I am getting an intercooler from a wreck for $220 so I have saved a bit. Hope it is OK but will test it first and send it back if it is buggered. I thought I'd have a good chance of getting one of a wreck as there'd be heaps of owners smashing their GU's out of frustration!
Our problem with the money we continue to spend on these vehicles is similar to one of my dogs actions in chasing its tail. We never get to the end. Now I have gone so far I can't go back. The funny thing is I hardly drive the thing now. I've only done about 9000k'sin 10 months! I went over to SA and NSW for a couple of weeks so that did about 4500.
Other than my broken bits the GU is good also but christ is there some debris behind me!

AJB, I think I'm probably the guy that Trevor is talking about. I've built a few intercoolers in the past mainly for the ricer brigade but I wouldn't mind having a look at your leaking intercooler to get some sort of idea of what seems to be happening with the cores to fail like they are.
From my understanding the intercooler tubes are failing as they go through the header plate assembly, if so, this is a problem also with some aluminium radiators as well. The only way to fix it is to cut off both endtanks and isolate the offending tubes but as the I/coolers are so small you are effectively lessening the volume of air your intercooler can cool.
Another possibility is to cut off the endtanks and get a custom core built to suit but I don't know just how much PWR will charge for a new core. If they are like their custom radiator cores then they certainly won't be cheap.
Where are you in Melbourne? When you've got the other I/cooler on your car I would like to see the one that failed.
I work in Carrum Downs and live in Berwick.
Regards Andrew.

Andrew
I am in Gippsland and travel to Melbourne occasionally. I was planning to have the leaking one looked at so your the man. Where do I take it ?

Andrew,

You certainly were the man I was referring to and thanks for responding.

As for AJB coming from Vic, I won't hold that against you until you decide to come and try to take over our beautiful state up here like the rest of your brethren!!! LOL.

Cheers to you both and good luck with what you find.
Trevor.

AJB, my home phone number is 03 9769 5196 and my work number is 03 9775 0558. My work address is D&F racing products, Factory 13, 27-29 Aster Avenue, Carrum Downs, VIC, 3201. We are specialist Tig welders and fabricators for the motorsport industry.
Give me a call anytime, if I can help I'll be only to happy to oblige.
Regards Andrew.