GU 4.2 Overheating

Submitted: Tuesday, Jan 27, 2009 at 09:04
ThreadID: 65450 Views:3211 Replies:7 FollowUps:13
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Hi guys,

I seem to have an overheating problem with my 4.2 TD and noticed this on the weekend when coming back from the country, sitting on 110km, no air con running and temp gauge was on 3/4. outside temp probably around 30deg. I have never had a problem with this until the last 12 months.
It does have a bull bar, lights, winch, 35 inch tyres, etc.
I understand the GU's have an overheating issue, so was wondering whether it would be worthwhile replacing the radiator with a PWR and whether you think this will fix the problem?

thanks for any advice / info.
Brett
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Reply By: Lotzi - Tuesday, Jan 27, 2009 at 09:38

Tuesday, Jan 27, 2009 at 09:38
G'day Brett

Lot of things to check before going to the expense of a PWR radiator.
Condition of the radiator hoses, are they sucking in when increase of revs.
With radiator cap (condition) removed, start and warm the engine up, can you see good coolant flow, if not ... or thermostat or could be inside of radiator hose coming in/loose.
Has the surface of the radiator been hosed clean?... from the engine bay out.
When the motor was running warm, did you turn the heaters on to increase water flow to see if there was a temp dropped.
Have yo had the engine flushed and changed coolant?
At the end of the day 110 k's at 30 deg with 35 in tyres, the vehicle is pushing a lot of air and working, did you back off to 90/100 k's to see if the temp came down. Also were you towing a trailer.
Brett, these are some of the things I would check/do first..
Good luck
Lotzi

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Reply By: Leroy - Tuesday, Jan 27, 2009 at 12:21

Tuesday, Jan 27, 2009 at 12:21
Do a search on viscous coupling as others in the past have replaced the goop with good results in their patrol

Leroy
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Follow Up By: Lotzi - Tuesday, Jan 27, 2009 at 12:50

Tuesday, Jan 27, 2009 at 12:50
That's an important one.
Lotzi
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Follow Up By: Leroy - Tuesday, Jan 27, 2009 at 13:23

Tuesday, Jan 27, 2009 at 13:23
the fan viscous coupling that is ;)

Leroy
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Reply By: Member - DOZER- Tuesday, Jan 27, 2009 at 13:04

Tuesday, Jan 27, 2009 at 13:04
If it has just started happening, i would be checking for mud in the core....another thing to do next time is turn on the heater full with windows open....if temp goes down, you have a radiator issue...either blocked internally, externally or fan is not connecting.
Andrew
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Follow Up By: Member - DOZER- Tuesday, Jan 27, 2009 at 13:04

Tuesday, Jan 27, 2009 at 13:04
The other thing you should check is the accuracy of your gauge
b4 you bag me out, walk a mile in my shoes, then your a mile away and have my shoes :)

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Reply By: Member - Roachie (SA) - Tuesday, Jan 27, 2009 at 13:15

Tuesday, Jan 27, 2009 at 13:15
If you search the archives you will find numerous posts on this subject from back around 2003/4 which I started and/or contributed to.

The important thing here (and it is always a hard one to swallow) is to remember that the temp gauge is not a good indicator of what the actual water temp is at any given time. I fitted an aftermarket temp gauge (VDO) with the sensor in the top radiator hose. It showed that even when the factory gauge was up around the start of the "H" zone, the temp was "only" 118oC.

Okay, okay, 118oC is getting pretty hot and I wouldn't want to see it get any hotter than that. The factory gauge didn't start moving off the normal position (just below half way) until the real temp got to 105oC..... so, in the space of 13oC, the factory gauge went from "normal" to being close to maximum.

I fitted a PWR radiator, but it was too wide for m eto be able to re-fit the plastic shroud....so the end result was no different. Waste of money in my opinion.

Thermostat is the first thing to check and the viscous hub.

Good luck

Roachie
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Follow Up By: Trevor R (QLD) - Tuesday, Jan 27, 2009 at 21:41

Tuesday, Jan 27, 2009 at 21:41
Roachie,

I seem to recall many of the 03/04 discussions I had with you on this subject and in part, blame you for where I am at now (Don't stress, it's a good thing mate hehehe).

Brett, You have been advised well with most of the responses I have read but there is one other thing I would do to your original fan shroud on the original radiator as well as flushing the radiator out properly. On the passenger's side of the fan shroud, there is a blank void, block this off as it then allows the fan to suck air through this part of the radiator. As it is standard, there is bugger all cooling effect in this part of the radiator. It is a cheap but worthy job to do in my opinion.

I chose to stick with original radiator after speaking with Roachie many years back but I get it flushed out about every 18mths- 2 years as part of my service schedule. Recently I have been hearing of a 4 core replacement radiator from one national radiator mob which by all accounts is a cheaper but very effective alternative to the PWR. Aussie desert coolers in Melb have also been mentioned in a few discussions up my way as providing alternatives to original gear but I do not know anyone with first hand experience in thier products.

If starting work on another 4.2Patrol again, I would add a few VDO gauges so I know exactly what is going on before I went to too much trouble with replacing radiators ect.

Not much you do will change the end result when these things are working hard in hot ambient temps but rest assured they will handle plenty of heat before you sustain major damage. I have 380000km on my first one and it has run "hot" since brand new for long periods so I have stopped worrying too much about it now. My second one does the same thing with 180000 km on it. Each one has been played with to a certain extent but the green one (my first) more so than the second but neither is better at keeping the heat at bay in tough conditions.

Best of luck and kind regards,
Trevor.
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Follow Up By: Member - JohnR (Vic) - Tuesday, Jan 27, 2009 at 22:46

Tuesday, Jan 27, 2009 at 22:46
Roachie, I wondered what you were talking about until we experienced it too. It seems that anything that loads the engine does it.
- large tyres - or oversized
- high speed
- high day time temperatures
- towing or a bigger frontal area
- running the aircon
Nissan comp cars have extra head cooling, I think as the cooling passages aren't as big as they could be - oil and water
Cheers,
Who?
John

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Reply By: brett patrol - Tuesday, Jan 27, 2009 at 13:58

Tuesday, Jan 27, 2009 at 13:58
Thanks for your feedback guys. I will do some more research into it. I cant help but think that a PWR radiator is definately going to make a difference, but will definately have the cheaper items (such as thermostat, viscous fan, blocked radiator, etc) looked at before i go buying a new radiator.
i do plan on doing a trip to central / north-west australia this year, so dont want to have these problems occuring out there.
i will let you know the outcome.

cheers
Brett
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Follow Up By: shirlee - Tuesday, Jan 27, 2009 at 14:14

Tuesday, Jan 27, 2009 at 14:14
Hi Brett , Please take this from experienced bushman , Take out the thermostat and throw it away. and you will see the temp difference immediately.. No worries mate
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Follow Up By: Member - Matt (Perth-WA) - Tuesday, Jan 27, 2009 at 17:56

Tuesday, Jan 27, 2009 at 17:56
Brett whatever you do....dont do this!!!

This has got to be the worst thing you could ever do to the vehicles cooling system. It will only help if the thermostat is buggered...otherwise it will increase your problems.

In a bush fix you can remove the waxpellet plate (middle of the thermostat) but then replace the outer ring back into the housing. The engine will not run at the correct temp when cold but will help a little if the thermostat was the problem.

Definately check the thermostat operation or just chuck in a newy for peace of mind but do all the other checks you have been advised but dont just remove the thermostat.

A restriction to the flow of coolant is very important in the cooling capacity of the system, if the fluid can flow without control..the vehicle will not run at the correct temperature (effecting emmisions performance etc) and could over heat due to the coolant (1) not flowing at the rate to produce the best amount of heat dissapation from the liners and (2) not flowing where the coolant is designed to flow ie by-pass thermostats close off ports before they open the flow to the radiator and as a result the hot coolant just recirculates around the hot engine.

I would do as the others have suggested and the new radiator should be the last resort...you are just masking the problem if you replace the radiator(unless its blocked and thats the only problem) without checking flow, fan, shroud, restrictions etc.

Goodluck

Matt.
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Follow Up By: shirlee - Tuesday, Jan 27, 2009 at 20:37

Tuesday, Jan 27, 2009 at 20:37
Yep thats why you see all the city mechanics in thier pit street turbo charged you beaut state of the art 4x4s, seeking RFDS or the Police or the next poor bugger coming along to help .. then saying ..(On our next trip I will know better ) and believe me I have seen it . Sadly with loss of life..
Ask any real bushman .. Theromostats block your flow in 40 degree heat . But I'll leave it up to the experts in the cities to tell about he outback ..
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Follow Up By: Member - Glenn D (NSW) - Tuesday, Jan 27, 2009 at 21:03

Tuesday, Jan 27, 2009 at 21:03
Good one shirlee ,

Have driven my GU in heaps of 40c heat in the bush ( and in Sydney the last few days LOL ) with a properley functioning cooling system .

Nice to see you resort straight to 'slamming' someone when they dont agree with what you think .

Glenn.
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Follow Up By: shirlee - Tuesday, Jan 27, 2009 at 21:39

Tuesday, Jan 27, 2009 at 21:39
Its not slamming my friend ' Its just a person trying to help some one. A lot of people have died in the bush after taking advise from someone who think they know every thing , Ok you own a GU .. That does not make you an expert about the outback.
Think before you put your knowledge of around Australia treks in the outback in to print.. I see you load the top of wagon up with gear , My friend that says it all ..
END OF DISCUSSION
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Follow Up By: Shaker - Tuesday, Jan 27, 2009 at 23:17

Tuesday, Jan 27, 2009 at 23:17
Removing a thermosat makes most engines run too cool causing excessive wear!

You can buy 'high flow' thermostats for extreme conditions or drill a 1/8" hole in the existing one.
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Follow Up By: Member - Glenn D (NSW) - Tuesday, Jan 27, 2009 at 23:34

Tuesday, Jan 27, 2009 at 23:34
Yes it says I take another spare wheel and spare fuel when travelling in remote areas.

Sorry if you are not able to drive whatever vehicle you have differently with respect to the loads you are carrying.

If the HQ Kinga you have , without a thermostat , handles badly with a roofrack on when driven by an aged bushy know-it- all , well dont travel .

You are quite correct , owning a Gu does not make me an outback expert, which by the way I do not claim to be ,despite having travelled a fair bit , without being rescued or dying !

Glenn,
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Follow Up By: Member - Matt (Perth-WA) - Wednesday, Jan 28, 2009 at 10:27

Wednesday, Jan 28, 2009 at 10:27
Here you go Shiralee....Confucius Say ..... Knowledge was never known to enter the head via an open mouth..

For your interest..oh and by simply living or working in the bush gives you no right to be rude.Image Could Not Be FoundImage Could Not Be FoundImage Could Not Be FoundImage Could Not Be FoundImage Could Not Be FoundImage Could Not Be Found

Use The Correct Thermostat
For today's engines to operate at maximum efficiency in terms of
performance, fuel economy and emission levels it is important for
the engine to get to the correct operating temperature as soon as
possible and ensure that temperature is maintained during all
operating conditions.
In order to do this manufacturers have redesigned their engines to
utilise what is called a reverse poppet or bypass style thermostat.
This style of thermostat has two valves instead of the one valve that
is seen on a non-bypass thermostat. The primary valve operates
exactly the same as the non-bypass thermostat and opens allowing
coolant to flow to the radiator when the engine is at normal operating
temperature. The secondary valve allows coolant to be circulated
back through the engine during its warmup stage. The temperature
of the engine is able to rise more evenly, minimising hot and cold
spots in the engine. The primary valve begins to open and the
secondary valve closes when the engine temperature rises. All
coolant is then directed through the primary valve to the radiator
ensuring that the correct operating temperature is maintained.
A vehicle fitted with a bypass style thermostat must always have
the correct bypass thermostat fitted. Vehicles fitted with non-bypass
thermostats must always be fitted with the correct non-bypass
thermostat. The fitting of an incorrect thermostat will cause the
engine to run differently to how it was designed. Overheating and
subsequent engine damage can be caused by using an incorrect
thermostat.
Correct Bypass Thermostat In
The Correct Application
Figure (1) shows the installation of the correct bypass style
thermostat. When the engine is cold the primary valve is closed
preventing the flow of coolant to the radiator. The secondary valve
is open and directs the flow of coolant back through the engine
allowing it to warm up faster. As the engine warms up the primary
valve begins to open and the secondary valve begins to close. Figure
(2) shows the secondary valve completely closed when the engine
is up to proper operating temperature. The primary valve is then
also completely open allowing full flow of coolant from the engine
to the radiator.
Incorrect Bypass Thermostat
In A Bypass Application
Figure (3) shows the use of an incorrect bypass thermostat in a
bypass application. If the secondary valve is incorrect it may not
close completely and coolant continues to flow through the bypass
port even though the primary valve is fully open. This will cause hot
coolant to return to the engine before it has been cooled. The engine
temperature will be hotter than required and may cause premature
failure of other components in the cooling system.


Non-Bypass Thermostat In A
Bypass Application
In this situation there is no secondary valve that will block off the
bypass port when the engine warms up (Figure 4). This will cause
hot coolant to continue to circulate through the engine without
going to the radiator. The engine will run hotter than required and
may cause a failure of other components in the cooling system.
Correct Non-Bypass Thermostat In
The Correct Application
In engines with no bypass port a non-bypass thermostat must be
used (Figure 5). No coolant flows until the thermostat opens. An
incorrect non-bypass thermostat used in these applications will
normally not physically fit or will be loose in the housing. Correct
opening temperatures must also be used.
Bypass Thermostat In A Non-Bypass
Thermostat Application
This is the worst possible combination as the secondary valve of
the thermostat will hit the bottom of the housing (Figure 6) and
prevent the thermostat from opening, as no coolant whatsoever
will circulate and the engine will overheat and boil. Major engine
damage may be caused as a result of this situation.



There is plenty of information on the net...I see you have access even being so remote and isolated in the bush, so you should have no touble researching about the NEED to restrict some flow in a non-bypass thermostat for effective cooling.

Finally... the origianl post was about fixing a cooling system to operate correctly...not a bush fix that will create more problems than it will solve.

All the best

Matt.



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Reply By: Chambo - Wednesday, Jan 28, 2009 at 14:53

Wednesday, Jan 28, 2009 at 14:53
Hi Brett,

Basically everything has been covered. The 3 main things are the radiator, viscous fand and thermostat. Have the radiator properly cleaned and by this I mean tanks off and not just flushed.
The viscous fans do fail regularly. If you can, have the vehicle put on the dyno and get the operator to load up the engine and put some heat into it. You can then see and certainly hear if the fan cuts in. If not there are only some fans that have the ability to have the silicon or whatever it is replaced. Not all Nissan fans have this capability. They need to have the extra row of nuts so you can pull it apart.
The thermostat is the other. As mentioned you can buy from Bersons or wherever the exteme thermostat as the standard replacement for the original. The radiator cap is also very important the have the correct one for your engine.
I was thinking about the alloy radiator but I believe that if all the original equipment is in good nic then you are just wasting your money as they are not cheap. the viscous fan is not cheap either.
I have a GU4.2TD and it gets hot when towing the camper up long slow hills with the boot into it.
We are doing the Kimberleys this year and the last thing I want is everheating dramas.

Cheers,

Chambo
AnswerID: 346347

Reply By: Member - DOZER- Wednesday, Jan 28, 2009 at 15:26

Wednesday, Jan 28, 2009 at 15:26
The thing to remember hre is it didnt do it until recently, so something has changed. It was hot....and you were powering on.
Before you spend $$ and get frustated, do some testing....get it hot and have a lazer gauge to point at the top radiator tank. whilst there point it all over the core...any cold spot means it is blocked in that area...it would be worth getting your rad cleaned inside and out as a starting position...if it is buggered, get new.
Dont throw the thermistat out, if the rad guy finds the radiator to be clean as buy a new thermistat, if the rad is dirty, keep the old one. Put some new oil in the fan. or install a electric up front. That way you can experiment with the electric once it gets hot again....so as u can see, there is a few options to consider.
Another is to drive slower....or fit a larger safari turbo/3 inch exhaust/larger front mount intercooler to the truck.....performance costs, how fast do u want to go??
Andrew
b4 you bag me out, walk a mile in my shoes, then your a mile away and have my shoes :)

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