Nissan Patrol GQ - Heating Issues - I can't find the cause.

Hi, travelling to Alice from Sunshine Coast in Nissan Patrol GQ (1989), I had to turn back at Blackall because engine running too hot, (near the top of the temp gauge), so I turned round and drove back home slowly - a very slow drive home to keep the temperature down. - the heat climbs up steadily and is hard to bring down, I had to put on the heater from time to time to help cool the engine.

• flushed the radiator with radiator flush and the water was very dirty, ( I last flushed it out about 4 months ago), and flushed again twice after it heated up.
• I took out the thermostat can cut our the spring mechanism and put it back so that I don't get too much water going through the engine - still hot.
• I noticed the clutch fan does not engage, - I replaced the clutch fan with brand new Clutch Fan which cost $190 - new fan does not engage either ????
• I washed out the radiator with garden hose and put in fresh coolant, - the engine is still heating up,
• took out the radiator, the grill / fins are in poor condition and crumbling, - but water flows freely through using garden hose pipe.
• I last replaced the water pump about 5 years ago, - so expect this is still woking well?
• I took off all the hoses and cleaned out all the crunchy bits that stick to sides, - I plan to replace all hoses next, but the current hoses are in good condition.

I don't know what else to check other than buy a brand new radiator which I'm currently looking to do next, - any suggestions?

• I don't any water in the oil
• I don't have any oil in the water
• The engine is running normally

Today I used an infra red heat sensor on the thermostat housing is 102 degree, block 104 degree, the lower part of the radiator is about 70 or 80 degrees.

Thanks Roly

Could be anything but sounds like crud has built up in the system and it needs a proper flush , not sure what engine you have but timing tune etc can affect some motors , thermostat could also be playing up I had one that opened up 9 out of ten times and would stick shut on the tenth .
If the radiator fins are damaged , if you have big spotties covering the air flow ( I even removed the oversize "Nissan" badge and noticed the difference , is it manual or auto , were you towing with aircon on and outside temps were high , if you were towing are the brakes set right .
So many things to consider .

G'day Roly, quite strange that your new clutch fan is also not engaging. Maybe return it or use the search function on here as I remember reading blokes using Toyota hub oil with great success apparently. If it were me I'd turf that radiator, hoses and thermostat for peace of mind with such a long adventure ahead of you. Not sure how to test water pumps, hopefully someone here can help you there too. Good luck mate, hope you can get back on the road soon!

Let us know what engine this too mate...

Had very similar issues on my 1990 GQ TD42 after being in Loveday 4x4 Adventures in SA. Driving back to Vic it was similar to yours, scary and long 10 hour drive.

The original radiator had enough, fins just fell apart and a new radiator solved everything for me.

Yes, thanks for the encouragement MB, - yeah brand new clutch fan out the box, grumpy cause I can get a clutch fan on EBAY for about $80 and I paid $190 - what's the world coming to?

I am not sure how a clutch fan works, perhaps it needs to get hot first ( to make it engage ? )

I was looking on youtube and noticed that some people wash out the engine with muriatic acid ( hydrochloric acid for pools) - I was thinking of doing this to before replacing the hoses, water pump, clamps and fan belts, this will make sure the engine head is perfectly clean? what do you think?

Clutch fans are a viscous coupling hub that do require heat to gradually engage until full lock when required. In regards chemicals, don't know and weary, best to drop in here mate as they can flush systems with their gear ready always https://natrad.com.au/ I believe they are Australia wide.

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Originally Posted by Rolsta

snip...
I am not sure how a clutch fan works, perhaps it needs to get hot first ( to make it engage ? )

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Yes they do indeed need to be hot to fully engage.

For the first few seconds from cold on initial start up and when hot they should shift an immense amount of air.

If you stop the engine from hot the fan should stop immediately, if cool to normal it should freewheel a teensy bit, max of couple of revs.
If it freewheels too much the clutch is shot

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Originally Posted by the evil twin

Yes they do indeed need to be hot to fully engage.

For the first few seconds from cold on initial start up and when hot they should shift an immense amount of air.

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Exactly what ET said.
I'm toying with the oil quantity in the viscous clutch. on my right now. Since I've put a larger fan on.

The fan moves a lot of air when very cold. And then generally eases up ..kind of like the eye of the storm .
And then gradually the clutch grabs firmer as the hot air from radiator heat's it up.
http://www.nissanpatrol.com.au/forum...017/09/148.jpghttp://www.nissanpatrol.com.au/forum...017/09/149.jpg

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Just google viscous coupling in YouTube. Some great videos explaining exactly how they work.

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Thanks for the feed back, I learned a lot about Viscous fans. - - appreciated -

First things first, -

• I'll replace the radiator, I plan to do this early next week - any suggestions for a good radiator ( price is fairly important to me )
• While I'd doing that I will replace the hoses and put on flat clamps instead of the wire type clamps
• While I'm doing that I will replace the belts - noticed that the belts are all Bosch so I will stick with Bosch unless advised otherwise

Any thoughts about washing the engine out with Hydrochloric Acid ?? - or can you advise a better way of flushing out my engine out,

Another Question - Why can't I just fit a fixed fan? that always turns, - Why are there so many points of failure in a car / truck

• When you thermostat fails - it always fails to a closed positition
• When the clutch fan / viscous fan fails - it fails to a none working position
• ...

• Why don't they make a bypass tap so that if your thermostat fails you can manually over ride?
• Why don't the make an oil tap so it's easy to drain you sump oil? - like my radiator has - so easy

It's like a bank, have you ever had a bank problem work in you favour? - no never - same with cars !

Don't you think t's time we made more simple cars and things?

Thanks for all the advice and help- really appreciate your feed back

Car makers would never sell parts mate that's why but like your thinking and agree totally with what you've said .

i had my thermostat seize open. you can get taps for your sump, but i wouldn't. try a cooling system flush like liquid intelligence stuff ( used it it works) dayco / gates made decent belts

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Originally Posted by Rolsta

Any thoughts about washing the engine out with Hydrochloric Acid ?? - or can you advise a better way of flushing out my engine out,

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Yes, many thoughts. Don't do it unless interested in putting a new engine in soon after.
Even avoid chemicals where you can. Reverse flushing with pressure is fine, and a radiator flush chemical from an autopart shop may be necessary depending on how much rust.
Get hold of the repair manual from here and start reading it for the relevant areas so you understand these topics better.
The repair manual's meant for DIY'ers.

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Another Question - Why can't I just fit a fixed fan? that always turns,

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It's a temperature control/power saving mechanism.

https://en.wikipedia.org/wiki/Fan_clutch

When cold, you don't want the fan to turn at full blow. Electric fans in modern cars are used for that purpose(fans only come on when necessary). Older cars use viscous fan clutch with built in thermostatic trigger.
Fan that turns all the time at full blow is not good, particularly when the engine's cold running. There is less force transferred to the
fan via viscous hub when cold and more force when hot.

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- Why are there so many points of failure in a car / truck

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That a philosophical question. Bertrand Russel may know the answer to that. ;)

...on second thought, some of them may be intentional to sell parts. :)

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When you thermostat fails - it always fails to a closed positition

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No, it doesn't. It can get 'stuck' open as well, or open too much in response to the temperature of the water.
I have two spare thermostats that open too early, stay open too much for a given coolant temperature, effectively
causing the coolant temperature to stay 'too cold' all the time. Not a good thing for the engine, but not as bad as
running too hot. Too cold cause excessive engine internals wear and poor fuel economy.

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When the clutch fan / viscous fan fails - it fails to a none working position

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More like the silicon "gel" inside the viscous hub loses it's viscosity properties(in relation to temperature) over the years and less and less force is transferred from the water pump axle to the fan via the viscous hub, causing the fan the run slower and slower when the engine's hot and eventually the fan may not run at all, but nobody waits for that point 'cos you'll notice the overheating engine, diagnose and resolve the issue before that. Degeneration of the viscous hub is usually gradual.

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Why don't they make a bypass tap so that if your thermostat fails you can manually over ride?

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That's idiot proofing I would say. The engine lasts it's natural lifespan when run at the optimal temperature. There always will be an idiot that would use a tap improperly and cause the engine run "too cold" and end the engine's life prematurely. All the thermostats(or most of them) have a small valve on it that opens up when a permanently shut thermostat valve causes the water to trap inside the engine and overheat,. The small valve allows the overheated water/steam to escape but it only helps with buying some time and saving engine block.

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Why don't the make an oil tap so it's easy to drain you sump oil? - like my radiator has - so easy

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Good idea if you want somebody to sneak under your vehicle and loosen the tap so you can lose oil on the highway and lose the engine. Engine oil is too critical for the health of the engine to allow an easy mechanism to drain the oil.