1999 Nissan Patrol St 4.2 Diesel overheating

Here is a cut and paste from a recent post about the same matter...... see the rest of the post: Number 28,798..............

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

If you have been following others overheating problems when towing with the Nissan 4.2, it sounds as if it is a internal water jacket problem in the block, being that they are too small and they do not allowing enough water volume to pass throe the block to remove the heat.

So basically there is nothing that can been done that could be guaranteed to fix the problem short of a new block with a larger water jacket.

Intersted in the cost of the injector replacement and what that was expected to achieve.... ? Sounds like that may have been an expensive factor in the overall recommendation from the mechanical people. Re the advice of others - "may be little you can do, because of flow rates through the block" - that leads me to think that the only avenue you might have is to cool the water better before it gets back into that heated engine block ? There are after market twin core radiators about - all brass and solder re the old fashioned (better lifespan) method of manufacture - greater cooling efficiency - there may be one for your model - it may fit in. If we ponder the factors that slow down water flow (presuming the pump is ok) maybe a higher flow-rate thermostat, if there is such a beast. BOL.

Oz 2,
I have owned 2 GQ's. First one never towed anything other than a box trailer with bikes in it. It clocked over 600,00 Kms without a problem. Still going strong today with new owner.

My present GQ did have the so called "overheating" problem, All fixed now though after many hours testing up bulli pass.

BUT....as much as the 4.2 is a fantastic motor.....the engineers who designed it NEVER did any testing in relation to loads.

From my expierences with it, its not good enough for towing big loads...Sorry to rattle a some apples here guys, but its true. Unless your prepared to spend endless amounts of dollars trying to fix the problem as is in Roachies case (not having ago at u here Roachie ok) But the problem is in the design of the water jackets in the head and block. Also standard radiator is next to useless for engine size.

The only way to fix it is to strip down the motor, open up the water jackets professionally and modify gaskets to suit flow diameter (as stated already).

This is a huge and expensive job to do. Nissan should have fixed this problem way back in around 1994 when by then, they knew they had "overheating" problems. They could have easily designed better water flow through the engine but they decided not to. So here we are, after more than 17 years and nothing was done to fix this problem.

Worst part is, we (the public) pay a very high price when buying a GU expecting it to do the job, but it wont do the job when towing 2500kg up hill. And we pay that price knowing full well, the engine cant tow without getting damn hot.
Very sad but thats just how it is until the 4.2 ends production.
Ange

I have had no direct experience with this but suggest that you try a product called Redline "Waterwetter".
It claims to make the radiator coolant conduct more heat from the block surfaces.
I have heard trhat it is succesful in racing in the US and here, and it is apparently is not a hiclone.
Look up Redline on the net. it is not cheap. Redline is a well known company for expensive oils.
Regards Philip A

Hi Oz 2
Since you're in a bit of a bind, and none of our customers have mentioned it, we have helped several hundred owners of small pre-combustion diesels eliminate overheating problems over the years.

When it is clearly not a cooling system issue, there is an excellent chance our Flushing Oil Concentrate (FOC) will rectify the problem. We have numerous customers who have spent $3000-$4000 on big core ratiators, fans, pumps, thermostats, etc, etc...all to no avail.

If the oil gets filthy quickly, or stains your hands when you change it, you will have a sludge issue, which may be sufficient to cause the overheating. If so, this FOC will correct the problem, by removing what is normally pretty insoluble sludge.

If you would like more information, it might be better to contact me off this thread.

Regards
Brid Walker
COST EFFECTIVE MAINTENANCE
www.costeffective.com.au
sales@costeffective.com.au

Oz 2; You say you don't take it above 2000rpm going up a hill. I know in my one if I let it "lug" too much ( below 2400 towing & loaded ) it'll get real hot real soon. I've found if I drop it down a cog & let it do 2500 - 3200 it seems to pull better & cooler. I normally tow in 4th ( for the gearbox's sake ) but even if I try, 2 horses in the float & all the gear on the back at 100k's - it just doesn't rev enough & gets warm. Drop it into 4th - higher revs/less load & the temperature drops & fairly quickly. I've owned a GQ & a GU, both seem to run hot but if they're nursed a bit they seem to tick over for ever. I agree with the other "postee" who reckons they're fine on their own, just not built properly for big loads. Cheers.....

Just thought I would add my experience towing a caravan when loaded is close
to 3000kg.
My nissan is the 2003 TDI6 model, and haven't had this problem with heat.
Have never seen the original gauge go above half way. Live in Alice Sprigs.
I rev it rather then lug it up hills but I'm sure you have tried that .
The one mode I keep looking at is that plastic expansion/overflow bottle
that is to close to my second battery.
What do you thing of an extra dirtbike rad in that curcuit with an overflow bottle.
I would shift it to a better place?

Yeep i also have a gq 4.2 turbo which gets hot towing the off road caravan it gets to 3/4 on the gauge i have a 3 core radiator hi flow thermostat still the same have learned to live with it.(this is only on hills etc).

Well Oz 2

I guess it's all said above.

Just to say that the biggest point mentioned in a few above is the real fact that the original radiator is under capacity for the truck.

I have done some and most the same to fix overheating on uphill grades. the only result was to fit a 3 row radiator.

After doing so I can now hit the hills towing the van (1950Kg) and the highest the needle gets is just under half.

Good luck
V

i know this doesn,t help OZ2 but does the 3.0 ltr turbo have the same problem ,cause I was planning trip up north towing a offroad camper trailer about 800-900kg loaded and had dicided on a patrol but the overheating concerns me would appreciate your thoughts.thanks

HI All,

I have an 80 series 1HZ diesel with aftermarket Mike Vine turbo which has been fitted since the same day it rolled off the showroom floor (12/90). I have set this truck up for heavy and long distance towing in NT and FNQ and told them this when I asked them to set up the turbo. Remember in 1990 we did not know how long the 1HZ would last either so it was all a bit of a gamble. It now has 285,000km on the clock and doesn't use a drop of oil between changes even after a long heavy towing run.

Part of the Mike Vine installation included a remotely fitted mini radiator tapped off the heater hoses to increase the coolant capacity. This sits behind the bullbar and the air blows through the winch slot.

They also fitted came off a fitting near the oil filter with remote lines and fitted an external oil cooler for the engine oil to run through to keep it cooler. This makes sense because the engine hasn't really overheated until the oil gets too hot to do it's job.

Have fitted a triple core (copper) radiator as I believe the copper disperses heat better than aluminium.
I have also spaced up the hinges at the rear of the bonnet to allow engine bay heat to escape.

This truck has never been hot in it's life and never been above 2/3rd's on the temp guage. This has been towing big caravans, a 2750kg trailer sailer, and often a car trailer loaded to it's limit.

A couple of practical measures could be as follows:

1. I recently posted a thread about A/C turning off when the temp rose. This is nowhere near overheating but from the wise comments from this forum I now understand this to be a safety switch which will do this to protect the motor. So I guess if Nissan do not have this switch it would be wise to make sure your A/C is turned off.

2. Aerodynamics play a big part in labouring of an engine causing overheating. I believe that unless absolutely necessary, in keeping roof racks etc. to a minimum. I know years ago my diesel troppy dropped 4 mpg when I bolted the roof rack on.

3. Again to do with labouring the engine I had a 2.8 diesel hilux that had temp problems when I fitted 33x12.5 tyres because it geared up the final drive too much. As mentioned above I also stay in 4th gear when towing the heavy loads and still sit on 100km/h all day. It does use a bit more fuel though and is probably better to sit on 90km/h if possible. I still run 265's which may help a little.

4. I also run a good quality synthetic oil in the engine as friction causes heat so I will do anything to keep the friction to a minimum.

Finally none of the extra's we had fitted to the cruiser to keep it cool were too expensive. The radiator, oil cooler, extra water cooler probably added $1000 to the whole job but at the end of the day I have a truck that does the job that I have it for very well.

I hope this helps,
Brett

Yeah - Big Woody just reminded me of something else. I used to run Penrite HPR Diesel ( 20W 60 ) in the 4.2. Was told some time ago that oil was too heavy for it. Changed to normal 15W 40 and there was a noticable drop in my engine temp when working. It still gets hot when pulling up big hills etc, but as a whole it runs about 3 needle widths cooler with the "thinner" oil. Cheers....

I have a 60 Series Diesel Cruiser with after market water cooled Turbo. This vehicle would run 3/4 hot if you gave it a bootfull on the highway & go into the red on a long drawn out hill. Took me ages to find the problem, it turned out to be the oil cooler in front of the air con condensor blocking airflow, which was fitted when the Turbo was installed. The 2H diesel has oil galleries inside the block for cooling & can do without the oil cooler. I removed the oil cooler cleaned it out for useing as a mini radiator, fitted it inside the wheel arch where it got airflo from the fan, connected it inline to the waterflow to the Turbo & have never had a cooling problem since. Now runs on a 1/4 ( temp gauge ) on road & never gets past 1/2 even with the air on. When it gets to 1/2 the viscous fan cuts in & drags it back to a 1/4. Try this it works!

Can anyone comment if the Patrol 4.2's in question overheat right from new, or do they get worse with age?

Because if they get worse with time, it is a matter of deteriorating performance of one or more components. If you have to add on additional cooling, or re-engineercoolant passageways in an attempt to correct things, then it is a band aid fix.

If they run hot from new, such additional cooling means is justified. Be interested to hear some first hand comment. Thanks

Hi everyone,

Looks like this is a topic that effects quite a few. What interests me is that only some report to have the problem. If the problem is the restriction in the water galleries then all must have the potential of overheating. If it's the water galleries then I can't see how a bigger radiator or high volume water pump can help. This will simply increase the efficiency of heat transfer but not necessarily increase the overall heat reduction to a level we need. It's the same principle I use in demonstrating heat processes in a solar water prac. Pretty much if the surface area of the water galleries is to small then the problem is transferring enough heat across the interface. If the surface is small to the extreme then even running cold water through will not achieve the effect we need. In my case I've noticed that the engine mass appears to be acting as a thermal tank/heat soak, there is a lag and lead in heat dissipation when the engine is loaded. This tells me that either there is not enough cooling which has been disproved by Roachie, various other members and a turbo specialist I've spoken to. This is by fitting large radiators and high flow water pumps that fail to solve the problem. The other is that there is enough cooling capacity but we can't get the heat to transfer across to the cooling medium fast enough.

The other problem I see with high volume cooling pumps if the case is right with our small galleries is: by increasing flow across an orifice, this being small to large diameter (or vise versa) you get a pressure drop across the restriction. If the pressure drop is large enough you can get flashing of coolant to steam in the low-pressure region. Not saying it's happening but the potential is very real if the flow is high enough or the area reduction is large enough.

Two fixes that have been suggested that may (may, may) have merit if it's the small galleries. One, find a coolant that has a higher heat transfer rate. And two, is to have more cooling via the oil. So an oil cooler, as suggest above. This could work as one of the primary roles of oil is as a heat dissipater. No use using a small radiator it'd need to be big and water-cooled would be much better, especially to those with the larger radiators. Those with an excess capacity for cooling in their radiators could easily use it for the oil cooler. Not sure were we could fit the damn thing as it would need to be a reasonable size.

So far this is just theory on my behalf, maybe experts in this field will say practically it won't work. Be nice to know though and may not be that expensive.

One thing we all have to work out is - what exactly is "overheating" Just because the guage is high doesn't mean it's overheating. Read the owners manual. It has to get up into the "H" bit before you should worry about it. I've had 'em sitting a needle width below "H" for 1200k's without any damage. Just because the air-con. switches off, doesn't mean it's overheating!

It's all objective reasoning. Just what is overheating? Where on the Nissan gauge does the needle show you "overheating"? More to the point, at what stage does the needle position lead you to think it's too hot? Perhaps Roachie could post actual temperature readings, using the new VDO gauge, then co-relate them to the needle position of the Nissan gauge?

Been there done that with a Nissan Patrol. While towing heavy loads (horse float ) up steep hills the only solution I found was to change down a gear and take my foot off the pedal a bit. In one case actually change down into low range and crawl up the hill. Now i have a 79 Land cruiser I don't have the problem !

Solution . . . Perhaps conversion to diesel gas More power , less fuel lower EGT

Good luck

Dunedigger

On behalf of all the 3.0 Litre Diesel owners I have to say this,buy a 3.0 litre they tow better than the 4.2 and do not overheat.
Regards

G'day, I thought I would take time to help you out. I am a diesel mechanic for many years with plenty of experience in most currently produced large and small diesels, and I can tell you your problem IS airflow.
I had a GQ 4.2 diesel with the same problem, and did what you did. I tow plenty of weight when I tow, and long distances. The best temp I recorded @ the themostat housing was 122 degrees towing 1.5t 300 klms on a 46 degree summer day! Mine used to melt the rubber parts of the thermostat while I was trying to get to the guts of the problem. I have always towed in top gear, both in my GQ and now in my 3lt GU after the standard g'box mod was done{ now done 110,000 klms}
I damaged the radiator one bush trip water crossing and fitted a 3 row radiator which made no difference, I also fitted a turbo kit myself and although it pulled like a champion in any circumstance, it still got hot.
I fitted 2 non genuine viscous fan hubs over the time {incl electric fan mods} and still it ran hot climbing hills or pulling weight.
I bit the bullet and replaced the hub with a genuine unit {$340 trade vs $90} and it fixed the problem immediately!!!!!! You see the Davies Craig unit also suits a Nissan powered VL commodore, this is what pricked my ears when I bought the second one. An unleaded engine must run @ 88 degrees or more for the cat conv to work, while the 4.2 diesel themostat is 76 degrees. See the issue????
Nobody wanted to listen to me when I went back to Repco to prove my theory about their hubs NOT suitable for diesels, its all about sales I guess.
You can choose 1 of 2 ways to fix your problem. First obviosly, replace hub with a GENUINE HUB IN A NISSAN MARKED BOX at consideable cost.
I helped a mate 2 weeks ago with his 98 GU 4.2 diesel with identicle problem using a tube {approx 18ml} of silicone which John Deere sell for their viscous hubs. His was a 2 piece bolt together type, and again it cured it immediately!!!
Hence your second option.
I hope I am helpfull to you but please dont bother with different oils, 4th gears, higher revs etc. I never needed to go past 2500 revs after the turbo and with the new hub the temp would rise 1 to 2 needle widths before you could hear the fan cut in and the guage would drop instantaneously!
Please email me if you have any questions on gvcane@optusnet.com.au

Hi, I have been reading this thread with great interest for about a month now and have finally decided to post a reply. I have a 2002 Nissan Patrol ST Turbo ute that was purchased new from Gatton Autos. It is about the fourth or fifth Nissan Patrol we have had and I have had a gutful of its overheating problem. The newer model (2005 Intercooled ST ute) that we also own does not seem to suffer from the same problem but the 2002 model is a complete dog. Admittedly the 2005 model has not been tried as much as the earlier model.

The 2002 model has been to Armstrong Autos here in Toowoomba more times than I have had hot dinners. As I write this, it is in having the gearbox out for the second time - I can handle that - but the thing that is really making me irate is I cannot tow a damm thing without it getting hot!! I have a boat and trailer which combined weighs 1.75 tonne and I cannot tow this up the Toowoomba range without stopping and waiting for the temperature to come back down - regardless of the time of day, the season, revs or gears. We have a 2003 Holden Jackaroo which walks all over the ute in terms of overheating.

Nissan Australia have sent me an internal memo which says that is is normal for the gauge to sit anywhere between the halfway point and high. This is fine but if it is sitting 5mm off high all the way from Hervey Bay back to Toowoomba then there must be damage being done to it somewhere. The fact that the aircon cuts out as soon as the engine gets hot has got to be a problem in QLD in summer!! The head mechanic down at Armstong's has sat in the vehicle with me whilst towing the boat up the range and he was really concerned. This vehicle is still under warranty and I will be asking Nissan - whatever it takes - to fix it. I don't believe in spending $60000-$70000 on a top of the line model which can't even drag a wet hanky. I have a Nissan specialist coming up from Brisbane to look into it further.

I would be interested to hear of any success stories regarding this matter as I will be forwarding this thread to Nissan.

Thanks, Andy.

By the way, this will be the last Nissan we will ever own. I can't wait to get rid of it - maybe an F truck in the new year!