Overheating at the beach...

[bschotty]

Hi everyone,
So I managed to get away up Teewah beach in QLD this weekend to try out my '89 GQ in the soft stuff.
All in all it performed great, had the tire pressure down low and floated on top of even the really soft stuff no problem.
I run on LPG and I'm always keeping a close eye on the temp gauge. For most of the trip it was fine, sits at about half way. Twice, however, it suddently spiked up to the upper limit of the guage. I pulled off to the side of the beach and cranked the heat (leaving it running) to try and cool things down but it still continued to climb... I then turned the car off and sat around for about 15 minutes to let things cool off with the bonnet open. 15 minutes later I was on my way again and things sat fine at about half way on the temperature gauge for about another 20 minutes then it all started again.
The big thing i did notice was that it overheated only when we were going slow, which is normal I guess as we're in the soft stuff working hard and there isn't the wind present to cool things down.
My big concern is that it continued to get hotter even when idling and then engine not under any load at all...
I'm just wondering if this is a normal? If not, what I might need to do to correct it... maybe a second electric fan? (the wiring is already in place so i'm thinking maybe a previous owner had one...)

A few details about the truck:
- It's a 1989 GQ. 4.2L Petrol (although I mostly run it on LPG). 5 Speed Manual. 2" lift running on 33" MT Baja ATZ's. Tires were at 16psi today.
- I've owned it for four months.
- I've never had the temp gauge go over half way when operating at speed (even climbing a big hill to maleny each day), it only seemed to do it when we were travelling at less than 30km/h today.
- The radiator is less than 2 years old and all the hoses look to be in good condition.
- There is a very small winch on the front bullbar (4000lb) which may interfere slightly with airflow (shouldn't be much), I will be taking that off this week, it came with the truck and is pretty useless. Otherwise no driving lights or other interferences.
- Under the hood I can see the big clutch fan which was working fine when idling and also a small electric fan in front of the radiator (I assume a second fan would be mounted beside this one with a switch to operate inside the truck?)

The beach was in pretty rough shape today with soft torn up sand for a couple of long stretches. Plenty of bogged vehicles around (had to lend out my MaxTrax more than a couple of times but luckily didn't have to use them myself).
It was 26 degrees at the beach (not sweltering heat).

Just looking for ideas. We're planning a big trip to Fraser early next year so this was a great test run.

All in all it was a great day and can't wait to get back up there!

All input would be greatly appreciated.

Thanks!

- Ben

[happygu]

Ben,

Did it actually boil, or just get hot?

Is your radiator clean and clear - can you see through the core?

Was it OK once you were off the beach again?

Mic

[my third 256]

change the themostat mine did the sane
after changing every thing back to normal
use the nissan thermostat dont go aftermarket

[stets]

First and foremost, check your viscous fan hub, if this spins more than a few blades by hand when the engine is off, it needs replacing. Best to change the water pump at the same time as vibrations can cause things to run a foul. Once a thermostat has been cooked, it is best to change that too. Flush the radiator and entire block, getting very hot loosens corrosion flakes which tend to block radiator cores. Change your engine oil and pressure test your engine and cooling system. Aluminum heads warp easy and you may have done hidden damage.

My bet is the fan hub has worn out with age as most do


Tap,tap,tapping in your head

[macca]

Mine did the same, our mechanic removed the two nuts on the radiator top so he could seperate the radiator from the Air Condition core.
Had a look with a torch.
It was full of leaves a mud and crud, cleaned it out and sweet as.

Also I had a tail wind when travelling along the beach, so it got hot quite quickly, headed into the wind and temps normal!!!!

[MQ MAD]

Leaving it idle or turning of when hot doesnt make it go cooler, it can actually increase the temp
Id go for a radiator flush out , called rodding out, thatll cost about $100,plus labour costs,new thermostat,new cap, and a full flush out
IF you had a cooling issue, high revs,low speed,you would have cooked it pritty fast

If the temp guage goes up and down in general driving, thats good, means the thermostat is doin its job

[bschotty]

It just got hot, not all the way to the top of the gauge but close...
It was overheating as I came off the beach and when I was idling when inflating my tyres back up.
As soon as we started driving on the road again it cooled right down within a few minutes.

[bschotty]

I found a small leak in one of the radiator tanks today, not a biggie, just a small drip. It looks like I'll be taking the radiator in for a repair job so I'll swap out the thermostat and everything will get a good flush then. Hopefully that helps.
One thing I did notice is that the electric fan in front of the radiator looks really small compared to the size of the radiator... I'll take a photo tomorrow and post it. I was speaking to a friend of mine today that was having a similar problem on the beach and put in an aftermarket fan (biggest he could find).
The radiator itself is really clean, no debris. Also the coolant level looks good (despite the small drip).
I'll put some pictures up tomorrow to give a better idea of what things look like.

thanks everyone. i appreciate the help.

- Ben

[the ferret]

Sounds like the fan has spat the dummy, can you hear it cut in as she warms up?
Cheers, the ferret.

[bschotty]

First and foremost, check your viscous fan hub, if this spins more than a few blades by hand when the engine is off, it needs replacing. Best to change the water pump at the same time as vibrations can cause things to run a foul. Once a thermostat has been cooked, it is best to change that too. Flush the radiator and entire block, getting very hot loosens corrosion flakes which tend to block radiator cores. Change your engine oil and pressure test your engine and cooling system. Aluminum heads warp easy and you may have done hidden damage.

My bet is the fan hub has worn out with age as most do


Tap,tap,tapping in your head

Didn't have a chance to check the fan hub today, got home pretty late but I'll check it tomorrow for sure. Thanks for the advice.

[MQ MAD]

If its still got the plastic tanks on the radiator, good luck finding them,so could be a new radiator ....
Be interested why someone added an electric fan, the stock clutch fan system are quite adequate to do the job and flow alot more air than most electric fans, so maybe there was a cooling issue that wasnt adressed correctly
Im running EF Ford twin thermos in my MK shorty project, not for effeciency but the huge body lift
IF you go that way and do a full thermo fan set up, its not hard and doesnt cost much
Fans $30, and coupla hours to do