Overheating Problems

[bengerman]

thanks guys,
always up for learning something new about my old girl

hoping i´ll have the new seals in the morning
although everythings already been replaced bit over a month ago, have ordered not only the axle seal but spindle seal and grease seal as well.
$60 is cheap peace of mind

let you know how i go

have also been experiencing a bit of an overheating problem, especially when i´m running a/c
planning a bit of a radical fix which involves a nibbler and my bonnet... :D

anyone else dealt with overheating issues?

maybe this isn´t the right place to ask this q?

[patch697]

No but AB will move or copy it into where it will get a good response so don't sweat it mate....

Define over heating to us as the gauge in the patrols run up pretty hi with little increase in temps.....

[AB]

Where you are the dust might have blocked up the radiator too, clean that for starters and as Paul mentioned bit more info will help us.

[Finly Owner]

Finly has new radiator, real coolant and has not been showing any heat rise. Check level of coolant last week and found level down but can't find obvious reason yet. Heater has been on in cold mornings. Suspect heater hose has small seaping leak. So I suggest check your heater hoses if you are losing water, causing a rise in temp.

[bengerman]

...replied in wrong area on fri sorry, have copied it here...so anyway:

okey doke, well here´s a recent example for you...
heading up to isa a few weeks back and have probably bit over half a ton of tools and gear in my 89 safari wagon. (non turbo td42 5spd)
ambient temps hit 36 deg and temp gauge sits on bout half at say 100kph
switch on a/c and temp climbs to within a couple of mm of hot mark on gauge..steady
switch off a/c temp comes down again after a few minutes of steady driving.
if i add a hill, higher speed of say 110kph or accelerating, climbs quickly

have so far, fitted new 3xcore copper radiator (actually ran warmer after that), new clutch, thermostat, water pump was ok bout 6 months ago, have flushed system completely, cleaned a/c condenser core and running correct amount of coolant.

re, inaccurate gauge, my system is 24v factory so unsure how similar or not from 12v units
also, as mine´s an early jap model, there´s no factory electric thermo on the front

in a nutshell, from everything i´ve read and heard, the overheating problems in most gq´s appears to be able to be fixed by drastically increasing the airflow through the cores.
so my plan is to locate where the air is thrown up from the clutch fan and make some holes in the bonnet.
have had some factory jap cars with this setup and seemed to work quite well

if it doesn´t work i´ll turn it into a feature lol

guess this is how one fixes things in the bush when off the shelf thermo fans etc... aren´t available

[bengerman]

re your comment AB, good suggestion, but had thought of that one.
used commercial refrigeration coil cleaner (mild acid in a can) to thoroughly wash both ac condenser and radiator

so finished cutting hole in bonnet on friday arv
300 wide
80 deep

with bonnet closed, the clutch fan pumps the air straight up out of there just at idle

expect ambient temps back around 34+ in the area tomorrow, so will test her out on a drive then

see how we go

[AB]

Let us know how you go too mate.

It's good to hear back on what worked didn't work.

[locks]

Ive got some friends up in the mines with GU utes and they mention that they constantly need flush out their radiators and gerny them clean with the red dust otherwise they heat up constantly.

[Finly Owner]

I'm confused. If you use air con/ heater it should help cool as it is actually going through another small radiator and fan cooler. It doesn't make a big difference but should be slightly noticeable. Unless theres a leak or blockage. Did you say you have teh correct thermostat and and temperature sender unit. I to am unsure of what components can be 12/24 volt use. But I think temp senders should be voltage specific as to guage. when hot is the radiator boiling/ expanding the water?

[YNOT]

I'm confused. If you use air con/ heater it should help cool as it is actually going through another small radiator and fan cooler. It doesn't make a big difference but should be slightly noticeable.

Using the heater can help pull engine temps down a bit, but using the A/C will have the opposite effect as the heat from the condensor gets blown over the radiator.

Bengerman, make sure the radiator is sealed off on the sides, so ALL air entering the front of the vehicle has to go through the radiator. Also make sure all parts of the fan shroud are fitted, as well as the 45 degree stone guard under the radiator. All of these things effect air flow through the radiator.
Also don't trust the factory gauge, fit an aftermarket gauge and sender. If you talk to someone like VDO, they may have what you need in 24volt (to suit trucks).

Another thing to try (might be a bit late now with your bonnet mods) is spacing up the back of the bonnet so air can exit there in the low pressure area at the base of the windscreen.

Tony

[bengerman]

hey locks,
yes you´re right, the dust is quite bad up here.
have already thoroughly cleaned both the radiator (which is brand new, like 1x month old) and the air con condenser, so, no dust, bugs or anything

and finly:
just to clarify...it does not get hotter when i use the heater
it gets hotter when i:
the ambient temp is quite high...early 30´s and higher
i use the air conditioning (which causes the condenser in front of the radiator to heat up...and my model does not have a thermo fan fitted factory)
i drive at speeds 100kph or over on bitumen
or 80kph or over on dirt
or am carrying or towing a load
or climbing hills
or any combination of any of these

the thermostat is the lowest factory temp option which i think is 77 or 79 deg from memory
temp send unit is factory, never been changed and seems to operate normally, bever had a problem with it

have not seen radiator boiling water yet

essentially it just appears to be getting uncomfortably hot, relatively quickly

i guess it´s just more noticeable up here, because its hotter, more load on the vehicle etc...


anyway, test drive didn´t happen today...

[bengerman]

thanks for your suggestions ynot,

radiator sides are sealed, shroud is complete, stone guard is fitted

will look into finding a 24v aftermarket temp gauge... makes sense


re your bonnet comments,
i know other gq owners who have tried lifting the back of the bonnet, in each of their cases, their vehicle ran hotter
reason we came up up with is that air over the top of the bonnet is at high pressure when it hits the windscreen creating an air dam preventing air from escaping from under the bonnet.
as opposed to the air at the front of the bonnet,
air hits the front of the car and gets deflected up, creating low pressure at the front of the bonnet

please feel free to pick holes through the theory :-)

[Alicetroll]

I have a similar problem in my 2.8 GU. I have recently cleaned the radiator, replaced the oil-cooler, thermostat, radiator and heater hoses (because of an oil cooler failure). At speeds over 100 kms the temp gauge heads up towards the top of the scale. it normally sits just below half.
does anyone else have this problem or a solution. (besides replacing the wiz-bang 2.8)

[Chops]

The Clutch Fans have a tendency to fail, especially in warmer climates. Its overlooked by many people, because as long as its spinning you don't even think of it. They are filled with oil, and one of the issues is the fan looks like its spinning fast, but when the engine revs, the clutch doesn't lock-up the fan, so the pulley spins faster, but the fan doesn't.

If you can spin the fan on the clutch rather easily, most likely your clutch fan is stuffed. In that case you only need to replace the clutch, not the fan itself.

[Adlarplant]

Ive had a problem with my td42 running warm from new in a 02gu and occasionally running hot steps ive taken so far raised the rear of the bonnet 5/8 of an inch (some help) removed lh sensor from radiator so ac doesnt cut out when it gets warm (theory is it keeps thermo fan working) some help replaced thermostats up and down the range (like a dog chasing its tail) little to no help removed spotlights and bullbar (driving at night was interesting) not much help to cooling replaced radiator with 4 core unit some help i finished up removing the water pump and checking it against another unit and found the impeller had worked its way aprox 3 mm up the shaft being an open backed pump it was therefore not pumping efficiently and causing cavitation since then i replace the water pump every 75000k or 6 months and ive had no more issues

[Alicetroll]

"If you can spin the fan on the clutch rather easily, most likely your clutch fan is stuffed. In that case you only need to replace the clutch, not the fan itself."

I can rotate the fan by hand. there does seem to be some resistance when the engine is cold. I haven't tried it while the engine is hot though. how much resistance should there be in the clutch?

[the ferret]

Mate, if the fan is working correctly, you will hear it roar when it kicks in.

[Alicetroll]

Mate, if the fan is working correctly, you will hear it roar when it kicks in.

Thanks ferret but my troll has a thermo-dynamic clutch on the radiator fan rather than a thermostat controlled electric one. As the fluid in the clutch gets hotter it gets thicker and transfers more torque to the fan so there is no roar :( the good thing with old tech is that it is eaiser to trouble-shoot.

[the ferret]

Nah, thats what I mean, your fan should make a roaring sound when the fluid does its job, have a look and see if there is any fluid leakage at the front of the fan hub, where the coil is.
It only holds a small amount, so any leak can affect it's operation. You can re fill some types, Toyota sell it cheers.

[Alicetroll]

Thanks Ferret. It seems that the fan in my troll has not been working for some time then as I don't recall it being all that loud. I went for a drive out to the airport today to get the car a bit warm and turned the fan over by hand when i got out there. It was as easy to turn with the engine hot as when it is cold. I'll have a closer look at it tomorrow.
Is there an after market mod to replace the clutch with a direct drive or electric fan? this one has failed before and cost the previous owner a new head.

[the ferret]

Depending on the model of fan, you can pull them apart and replace the liquid inside I believe, havn't done it, dunno what its called, but you can get it from Toyota,
makes it like new again, I'm not keen on electric fans, where you are you need good airflow most of the time eh, you will need two vials I am told. I'm sure someone on here has done it and may be able to throw more light on the subject cheers.

[Gantos]

I'm not sure what model Nissan you have but I have a 1988 GQ 4.2L petrol model with carburettor that had an overheating problem that had everyone baffled. Overheating problems are the worst kind and difficult to solve sometimes, the GQ 4.2L seems to have more than its fair share of overheating complaints.
In my case, apart from the engine getting too hot especially when the air conditioner was used , it was noticeable that the water cooling system was unusually pressurised which everyone diagnosed as a blown head gasket or warped head or the head going soft, common in Nissan GQ's I was told.
None of these turned out to be the cause and the cause was actually the two carburettor water heating hoses that were original and had never been replaced because they are almost inaccessible underneath the carburettor. One hose comes off the back of the water pump housing and the other comes in up higher, one hose was breathing in air when the vehicle was traveling at speed but not leaking water, it was acting as a one way valve. A traveling air pocket(s) was formed in the head and presumably causing hot spots or interfering with the thermostat.
Once both hoses were replaced, and this was a difficult job, the overheating problem was solved.

Hope this response helps someone else with a similar problem, I was at my wits end and looking at removing the head.

[AB]

Lucky find then Gantos and welcome to the forum mate.

Don't forget to introduce yourself to the community when you get a chance too.

[Mrowka]

Seems to me that cutting new holes in the bonnet and adding new fans are examples of "bandage" type solutions. Like a bandage on a wound, they fix symptoms but do nothing for the underlying problem.

In this case, you are fixing the overheating but not what is causing the overheating.

[gf0012-aust]

re your bonnet comments,
i know other gq owners who have tried lifting the back of the bonnet, in each of their cases, their vehicle ran hotter
reason we came up up with is that air over the top of the bonnet is at high pressure when it hits the windscreen creating an air dam preventing air from escaping from under the bonnet.
as opposed to the air at the front of the bonnet, air hits the front of the car and gets deflected up, creating low pressure at the front of the bonnet



I used to have a range rover with a 351cleveland and C4 tranny. I vented the engine bay heat out the sides via a couple of inlet ducts made from an old chin spoiler - it worked a treat as the engine bay used to get stinking hot.

instead of going for a lifted bonnet at rear and cop the boundary layer issues at the windscreen it might be better to duct to the sides like I did. (eg like the old pontiact trans-ams and current discos.)