GU Overheating

Submitted: Monday, May 14, 2007 at 14:53
ThreadID: 45462 Views:4052 Replies:9 FollowUps:6
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I havea 2000 Nissan TD 42 Ute that is overheating under load (towing)
So far have had radiator cleaned (tanks off & rodded out) , engine flushed, new fan assembly fitted, new lower radiator hose fitted (with internal spring)
Still overheating ANY IDEAS ??

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Reply By: Member - Roachie (SA) - Monday, May 14, 2007 at 15:04

Monday, May 14, 2007 at 15:04

I know how you're feeling. My last truck (also a 4.2TD, 2000 model) nearly drove me to drink. That was until I worked out that it doesn't matter if the temp gauge goes up to nearly the "HOT" zone.

If you do a search of the archives you'll find many posts by me from a couple of years ago on this subject.

In the end I fitted a VDO temp gauge, with the sender unit fitted in the top radiator hose. The hottest that ever got to was 118oC. I drove it with that temp showing and the air conditioner on (see below) for about 2 hours at highway speed and with no ill effects.

If you want the temp gauge to drop back down to normal, the short answer is you must reduce your speed and take it a bit easier.

NOTE: Air conditioner will shut off shortly after the temp gauge starts to rise. If you want to avoid this, you can unplug the electrical plug on the passenger's side of the radiator, just below the air cleaner box.

I take no responsibility for any consequences of the foregoing statements...;-))


AnswerID: 239937

Follow Up By: Ron George - Monday, May 14, 2007 at 15:39

Monday, May 14, 2007 at 15:39
Greg, Roachie makes a very valid point, & I should have mentioned it in my previous post, (must have had "Junior moment") before you do any thing else fit a good quality temp gauge to find out where you`re really at temp wise other wise you might be chasing your tail. Cheers Ron.
FollowupID: 500917

Follow Up By: Gregrash - Tuesday, May 15, 2007 at 10:49

Tuesday, May 15, 2007 at 10:49
Thanks for the help guys
Problem found - water pump impellor worn down to resemble a lid off a tin can
can,t believe it wasn't running hotter
FollowupID: 501073

Reply By: Ron George - Monday, May 14, 2007 at 15:18

Monday, May 14, 2007 at 15:18
Greg, when you say new fan assembly I take it you mean the viscous coupling????
These problems are a process of elimination & you`ve covered most, next I would test the thermostat, failing that throw a new one at it, making sure you have the right temp rating for your motor, if you`re still experiencing probs, I`d be looking at the water pump, there could be excessive impeller clearance, the vanes on the impeller could be a bit worn, or, & it can happen, the impeller may have come loose on the drive shaft... Good luck mate. Cheers Ron.
AnswerID: 239939

Reply By: Dingo77 - Monday, May 14, 2007 at 15:19

Monday, May 14, 2007 at 15:19
the thermostat is pretty important to the whole cooling system, maybe its worth a look at. My gauge sits at just below half, I at first I was worried but soon found out that it was normal.
AnswerID: 239940

Reply By: Max - Sydney - Monday, May 14, 2007 at 16:00

Monday, May 14, 2007 at 16:00

Cost Effective Maintenance reckon if your engine is all sludged up it can lead to overheating.

Have a look at their web site and see what they say. Personally I have not had overheating problems but in the past couple of years have kept my engine oil (Landcruiser 1HZ) a lot less sooty and running smoother by a "maintenance dose" every couple of oil changes, following the major clean up dose when I first used it.

Just a thought
AnswerID: 239944

Reply By: Member - Stephen M (NSW) - Monday, May 14, 2007 at 17:12

Monday, May 14, 2007 at 17:12
Hi Greg, I was reading an article on the 3.0L patrols and 4.2 T/D through the week when I was up north. Now this seems to be a common problem with the 4.2 when towing mainly. They said (now I'm only saying what I read before anyone shoots me) they said the main heating issue with the 4.2t/d is the radiator is far to small to cope with the addition of the turbo from the factory to the 4.2. Apparantly they never increased the size of the radiator after deciding to manufacture the t/d and more or less said we need to turbo the old 4.2 so whack one on. They say by getting a larger radiator manufactured and fitted will solve the main heating issue when towing. Now in saying that I'm sure there are blokes/woman who have already done this here on this forum and still have the overheating issue. Maybe some one who has done this and still having the problem will clarify it for me. Remember thats only what I have read. I dont own one but My mate has one but has never towed behind it and our other friends have just sold there patrol but was 4.5 petrol and never had a problem and they did a lot of towing heavy loads included. Seems to be only an issue with the 4.2 diesel. Regards Steve M
AnswerID: 239955

Follow Up By: Member - Duncs - Monday, May 14, 2007 at 20:53

Monday, May 14, 2007 at 20:53
Stephen & Greg,

I think you will find that Roachie put a bigger radiator in his and the problem persisted.

The long and the short of it is that the 4.2 is an old motor which has ahd significant development done on it to get the most out of it. The thing that most people in the know seem to be saying is that the water galleries are just not big enough.

The simple solution is to slow down on those hot days.

In Jan 2006 I drove a 4.2TD GU Patrol with 5 people, gear for 5 weeks away, and a camper trailer fully loaded out the back, from Broken Hill to Ballina. When we passed through Coonabarabran at 1030am it was 42 C. I had to watch my speed while travelling up to Narrabri and I had an overheating issue through the mountains of Mt Kaputar NP, so I slowed down and it went away.

This trip was done in one day 1545km in 16 hours and 10 min which includes all stops for food, fuel and leg stretching. Maybe the 4.2 has an overheating problem but it still covers the ground when you ask it to.

FollowupID: 500979

Reply By: Member - stefan P (NSW) - Monday, May 14, 2007 at 17:19

Monday, May 14, 2007 at 17:19
To state the obvious, your cap is holding pressure isn't it??

Cheers Stefan
AnswerID: 239957

Follow Up By: Gregrash - Tuesday, May 15, 2007 at 07:43

Tuesday, May 15, 2007 at 07:43
Forgot to mention themostat & cap have both been replaced

FollowupID: 501052

Reply By: Waynepd (NSW) - Monday, May 14, 2007 at 22:03

Monday, May 14, 2007 at 22:03
Hi Greg welcome to the hot 4.2 club.

I have considered using the
Aussie Desert Cooler
This company has a 3 pass replacement radiator. I spoke with Norm by phone and he recommended i make sure there isn't an airflow problem due to driving lights, hi-mount winches etc before i go spending $800 or so on a radiator.
AnswerID: 240043

Reply By: Steve T - Monday, May 14, 2007 at 22:55

Monday, May 14, 2007 at 22:55
Check that the RadiatorThermo Fan relay hasn't been taken or stolen, I finally tracked it down as I had the same problems as everyone else. After getting hot on Stockton Beach I had time to ponder while it cooled down, I thought to myself I have never heard the Thermo Fan cut it and wondering how bloody hot does it have to get before it does. So I followed the circuit thinking the fan motor may not be working, I lift the relay box cover and to my shock find the relay missing. I swapped it for another relay (CORN LAMP) and whammo the fan kicks in, the temp drops almost straight away. I flogged it for the rest of the day and on the way home up the big hills with the a/c on and the needle didn't move. So next day go to Nissan to get a new one, $137rrp, I almost fell over. So I guess some one else went to Nissan to get a relay, found out the price, saw our "soon to be" Patrol in the Yard for sale, take it for a drive, take the relay, and save $137. Why else would it be missing, surely the previous owner would have replaced a faulty relay and not have the over heating problems. Since the relay was installed the temp hasn't moved, except when towing the camper trailer up the big long hills under load, but when it does warm up it is only slightly and takes alot longer to move. By the way it is a 98 GU Patrol 4.2 with DTS turbo. I hope this helps someone and is not the answer to the overheating problem, just one part of the puzzle. Steve
AnswerID: 240059

Follow Up By: Member - Roachie (SA) - Monday, May 14, 2007 at 23:23

Monday, May 14, 2007 at 23:23
But the 4.2 doesn't have a "thermo fan" AFAIK...... Just the viscous hub (mechanical, not electrical) and the air conditioner fan.....which does cut in if temp gets to a certain level. Is this what you are referring to?
FollowupID: 501022

Follow Up By: Steve T - Tuesday, May 15, 2007 at 17:27

Tuesday, May 15, 2007 at 17:27
Look on the relay cover "Rad Fan", yes the a/c one, it's all part of the cooling system. Steve
FollowupID: 501132

Reply By: Flash - Monday, May 14, 2007 at 23:35

Monday, May 14, 2007 at 23:35
"Redline Water Wetter" and the lowest percentage of Glycol you can get away with (depending on expected winter temps) will make a BIG difference. (More glycol makes the engine run HOTTER, as it carries less heat away than straight water.)
I have an elderly turboed TD42 with NO overheating issues with the help of the above.
AnswerID: 240069

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