Roachie- Help!!!!! GU overheating.

G'day Austravel,

I can't help and I know it is a serious matter BUT you do realise that in making this request you will need deep pockets and a tremendous amount of thick hide. I'm sure Roachie will come good and you will have anought gadgets in the old truck to make anyone proud. I hope you have a good relationship with your bank manager (sorry Bill and Austravel couldn't help myself).

Kind regards

Roachie will be here shortly :o)

was hot yesterday...how did roachie get on...does his still get hot or has it been fixed?

G'Day Austravel. .not sure if it halps and you've probably considered it but.just in case FWIW.. I had a 2.8 TD which had similar probs.. all was great.. could load it to the hilt with no apparent probs until one day.. at 110.. hit a hil land bang.. temp guage worked it's way up pretty quick.. then cooled back to norm once on down hill/flat again..
After several attempted radiator flushes etc using all kinds of "radiator cleaning agents" etc.. no better, then bit the bulet and had the radiator removed and opened it up... and sure enough the radiator was 3/4 blocked...
Not sure how accurate the following statement from the mechanic was but perhaps others could commetn but his explanation was:" Nissan was known to have a particulalry fine radiator and hence blocked with the smallest amount of build up.. "
Considering my 2.8 was loaded up with roof racks, all the gear one takes on a long trip steel bar and winch and spotties to further reduce the intake.. once the radiator "reassembly" it never looked back.. temp guage never evn crept slightly above the "norm"... so FWIW have you considered opening the radiator and/or at least a professional flush out?

Sort of thought this would be the case after reading the trials of Roachie's. Will look at getting the radiator removed and stripped but mainly what to see what really is hot. Just because the gauge gets to "H" under extreme load is that really to high???? Didn't run rough, no steam or major coolant loss etc, etc. Not sure, might have to fit a proper temp gauge to see what it is in deg C. Problem I have is not knowing anyone with a similar motor and doing what I do as in the same as I did on that particular day.

G'day Austravel,

Okay; where do I start??? hahaha

The first thing I'd like to say is that mine (and yours by the sound of it), has never actually over-heated (ie: never got to the point where it has boiled and caused me to stop and fix something).

However, it has got right up to almost being in the RED zone at times. The things I've already done (and which were probably a waste of time/money in retrospect) are:

1. New PWR double-sized radiator with free-flowing tubes (so they say)
2. New fan hub
3. New thermostat
4. Cut hole in bonnet and put scoop above turbo
5. Fitted new turbo recently (I thought this MAY have reduced heat a bit as the OE turbo is water-cooled and the new Schwitzer is not), but that wasn't the primary reason for upgrading.
6. Tried removing Lightforce 240s and putting them on top of the bullbar
7. Tried driving with the plastic air-dam underneath the radiator removed
8. Tried various types of anti-freeze/boil stuff
9. Stuck 2 bottles of chit in the radiator that are supposed to seal up any tiny cracks in the head if there are any (can't remember the name of it, but I got it from Repco and it was recommended by somebody on here).
10. Have fitted a VDO water temp gauge with sender unit mounted in top radiator hose
11. Have fitted a EGT gauge to see if there is any relationship between exhaust temps and water temps (there really is no relationship apart from if the engine is running for prolonged periods at high speed....anything over about 105k/h, both temps do go up).
12. New radiator cap
13. New radiator hoses
14. Added a 10" Davies Craig fan in front of air-cond condenser which I can manually turn on....maybe I should upgarde this to a 12" or 14" jobbie?

The only thing that I haven't done yet, and which someone on here suggested I should do (can't remember who it was, but he was a bit smug about how he did things;-)) is to change the impeller in the water pump. The bloke who talked about it said he could fix my problems really easy by fitting a new impeller which would stop cavitation of the water. He would not elaborate, even though a few of us asked him for more info :-((.

I've also thought that maybe I might take the winch off this summer as well as the driving lights and see if the extra air flow assists.

We have had a few quite warm days lately, but I haven't had to go too far and not with the camper on anyway.

One thing to keep in mind is that when the Nissan's gauge goes up to around the 3/4 mark, your truck is not over-heating at that point. According to my VDO gauge, the temp in the top hose at that time is around 110oC and it seems as though the concensous of opinion is that up to about 120oC is okay when say, going up a hill....but you wouldn't want to see it up at 120oC all day. I haven't yet gotten the VDO gauge to go to 120oC and so I try not to worry too much. I rely more on the VDO gauge these days (even though the Nissan gauge is still functional). I also tend to drive and change gears according to the EGT gauge as much as anything else.

It has been said on this forum before that the 4.2 motor does not have anywhere near the size water galleries that the Toyota 4.2 motor has. As such, you have this huge mass of motor that has smallish "veins" running through it trying to collect the heat and take it through to the radiator for cooling purposes.

Another thought which I've had recently is to instal another temp sender unit in the intake where the water from the bottom radiator hose is about to re-enter the motor. Having changed turbos, I now have a "blank" bolt where the banjo bolt used to be that had water going to or from the old turbo. I could take this plug out and have it drilled and tapped to take a VDO sender, which I could then take to my gauge via a switch. That way I could switch between top and bottom radiator hoses and see how much cooling the radiator is actually achieving. This is the same thing I have done with my EGT gauge; have a thermocouple above and below the turbo so I can swap between pre-turbo and post-turbo EGTs.

I don't suppose this helps you, other than to say that you don't really have to worry too much as long as your Nissan gauge isn't going too far past 3/4 of the way.

Cheers

Roachie

The first thing that would solve alot of Roachies problems would be to reduce the weight of the vehicle, it's gotta be at least 500kg's heavier than it should with the shoo roo...etc etc (sorry mate, but it's true). Secondly, if your running bigger tyres, higher suspension anything aftermarket, expect fuel economy to drop and the vehicle to work harder. A patrol is like driving a brick into the wind, especially the GQ's.
Thirdly, any mods mechanically steered away from specs are going to change the characteristics of any vehicle. 3 inch systems apparently help vent the gas, upping the boost and increasing fuel increases power and torque but then we fit VDO guages to ensure we 'drive to the conditions'. Don't get me wrong, I'm Mr powerup and cannot stand driving a standard diesel, but it comes down to finding the right mechanic to do the work. Ensure the cooling system is maintained is number 1, if you've down powerup work, ensure it's not fueled up too much just to provide that extra 10 pounds of torque etc. My mate owns a 2002 GU TD with 135,000 on the clock and had the same guy I've used over and over again to powerup vehicles to provide a bit of extra zip. No worries about heat at all, and that includes a very recent trip to the tip towing an aussie swag with boat, kitchen etc etc.

At the end of the day, unfortunately, you can only shut the air con down, wind down the windows and tick along at a speed that keeps the temp reasonable, annd enjoy the ride (unless you have the TD6). Still a tough truck that will give you hundreds of thousands of k's of joy.

Cheers

Chris.

Obviously there is a problem in the older models with heat because Nissan did replace the smaller radiator with the new 4.8 jobbie, it's huge and I never had a problem with the guage moving ever, even under heavy loads.

Hello all,

Sorry if this sounds patronising.... but, mabey you should concentrate more on the obvious. My 2.8 was doing the same thing a couple of years back. I flushed radiator, changed hoses, and filled 100% of radiator with very exy coolant.
My brother lives in top end WA and fills radiators in all of his vehicles with 100% coolant, because he rarely has a day through the year under 35 deg. His 8yr old boy came to stay with us last year in Blue Mountains NSW, and hadn't ever seen a wool jumper!
I did the same with coolant and have not had a problem since.
Also check thermostatic fan, to see if it is cutting in.

Hope this helps.

Steve

Having read all the threads I can on the issue of Heat Buildup on 4.2TD patrols ( i have a 2000 GUII 4.2TD) my biggest issue wiht this is that my Temp guage gets to 1/2 way and the AirCON shuts off.. Is this what everyone else experiences? although I note Austravels comments seem to indicate that this is not an issue for him.

I have dual factory thermo's (2nd one came from a very early 4500 petrol) doesnt seem to make as big a diff on the diesel as it did on the petrol - supporting the idea of poor coolant capillaries within the block..

I had to recore my radiator at 90,000kms (replaced Al with Cu) - now 160,000kms and thinking of flow checking it again.