GU Overheating

Greg,

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...;-))

Cheers

Roachie

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.

Greg,
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.

Greg

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

Have a look at their web site www.costeffective.com.au/ 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
Max

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

To state the obvious, your cap is holding pressure isn't it??

Cheers Stefan

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.

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

"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.
Cheers