Possible Overheating fault

[Aussie Frontier]

Hi Guys I have an issue with the truck that is somewhat hard to understand .
Up until this week the truck has usually sat at around 89 degrees all day long. This week it has been cruisug up to 93. Now this isnt a big increase but I just happened to see it and it made me curious.
I can drag the temp down almost instantly by simply turning the heat on in the cab . Back down to 89 straight away.
Heater off and it creeps back up
I have checked and radiator is full and I have half a bottle in the overflow so all the levels appear normal.
No visible signs of any leaks and the system doesnt appear to be loosing any fluid.
AC still works and the compressor is clicking in and out. I did notice the fan on the radiator isnt coming on at all.
I cant see any fault codes or anything to give thew slightest hint at whats caused this.
In the cab the fan works on all 4 settings

This has kinda got me stumped

 

[longy509]

mine creeps up to 96 when going up hill goes down pretty much instantly if i back off the throttle a bit this reading is off the scanguage

 

[ljacko78]

if you haven't had the radiator flushed in a while, it could be partially blocked / build up of a white powdery gunk that will just sit thru the radiator.

My D22 had minor temp increase similar to yours for about a month (about 15F above normal), then overheated on a longer trip - turn the heater on full and radiator temps dropped back enough to get to a shop. They pulled radiator apart around found a bucket of the stuff. I had always replaced the fluid and checked levels but never flushed it out solid. Worth considering anyways and hope you fix the prob

 

[JPMC]

Have you done the self diaginostic test for the fan?

 

[Aussie Frontier]

Well Iam just about to swap out the fluids anyway so will check what comes out

JPMC
Still reading through the manual and havent found the elf diag bit yet

 

[LLadnar]

Mate just pull the plug out the fan and run some jump wires to the battery. If it works you know the fans ok and it must be the switch or wiring.
If you park and leave the motor running does it get hot or do the fans cut in?

 

[Aussie Frontier]

Ok just ran the test and the cooling fan is working so it looks like even though the compressor is running and the temp is cold that the system might be low on gas . However not too low. If I disconnect the pressure switch the compressor doesnt run.
So pressure switch appears to be working
Fans appear to be working
Compressor is working although it is short cycling a little

The temp only seems to get highest in top gear at about 100km/h
I will drop the fluid out, flush it and put in new coolant on the weekend
And just for giggles Ill do an ECM reset just on the odd chance its somehow got itself all confused .

The thot plickens

 

[Old.Tony]

Does yours not have a crank-driven fan? My manual shows the VQ engine has one. Think the coupling might be a little shot? Easy to test, get the engine hot, pull over, engine off, pop bonnet, try to turn the fan by hand - it should be really hard to do. If it's easy the coupling's gone and the engine can't turn the fan over hard enough to cool properly.

Other things - sticking thermostat (partly closed) won't let the flow through to the radiator as well as it ought to. Damaged/blocked cores, external gunk (like the shopping bag that stopped the falcon a few years back).

 

[Aussie Frontier]

Tony we must have been thinking the same thing
I drove the truck home and shut it off and I was able to turn the fan easily.
For a start I was worried i had left a rag or something and it stopped spinning but its spinning free enough.
The funny part is that at 100km/h the fan shouldnt make any difference , the air thru the radiator would be faster .
I checked the cores and everything is clean from the outside
The VQ has 2 fans actually. It has the main fan driven from the fan belt and also has the electric fan that will click in at 105 degrees or on all the time with the AC

 

[LLadnar]

I did notice the fan on the radiator isnt coming on at all.

When you said that I thought you must of had thermo fans instead of a clutch fan, do you mean you clutch fan wasn't turning at all while the motor was running?

 

[D40Craig]

My mate's D40 did the same thing on the way back from Fraser earlier this year. Took it to a radiator place in Toowoomba and it turned out that the coolant had turned into a kind of 'sludge' in the bottom tank of the radiator. It looked to be still circulating when looking into the cap, no leaks, bottle full, everything. Had the radiator flushed, new coolant and all good.

 

[Aussie Frontier]

My mate's D40 did the same thing on the way back from Fraser earlier this year. Took it to a radiator place in Toowoomba and it turned out that the coolant had turned into a kind of 'sludge' in the bottom tank of the radiator. It looked to be still circulating when looking into the cap, no leaks, bottle full, everything. Had the radiator flushed, new coolant and all good.

I certainly hope thats going to be it.
I have a flush and new coolant so fingers crossed. I had suspected something like this as the truck had been sitting for 2 weeks and it is due for a coolant change . I sure hope this is it .

Just found the first problem
Looks like the radiator was never fitted with a drain plug

Hate pulling hoses off plastic radiator tanks
Bugga bugga bugga

 

[4 naving]

There all the same Aussie. I had to drop the hose too. check out the computer manual before doing it. I found it hard to get it to fully drain then I read about the bleed valve to drain and fill to purge the air out. it was on the heater line. but thats on yd25. just looks like a cap on the line where a hose has been deleted...

 

[Aussie Frontier]

There all the same Aussie. I had to drop the hose too. check out the computer manual before doing it. I found it hard to get it to fully drain then I read about the bleed valve to drain and fill to purge the air out. it was on the heater line. but thats on yd25. just looks like a cap on the line where a hose has been deleted...

yeah found that in the manual and even after dropping the rad hose and pulling the plug it was still a bugger to drain .I should have pulled the block plugs but didnt.

Anyway I drained it filled it with Nulon Flush and ran it for 20 minutes as per instructions etc etc etc
Filled it all bled it and honestly have no idea if its any better.The temp still fluctuates a few degrees when I drive it and the heater on off deal.

My understanding is the thermostat should be regulating the temp so am starting to think it could be a bad tstat.
But then it could just be that this is the first time I have noticed the temps fluctuating , but I really dont think so

On the other side I honestly have no idea how long the fan hasnt worked with the AC. The compressor still works and puts out cold but maybe not as well as it should.
Pity there is no sight glass on the system. Will have to send it in to get checked and possibly topped up

 

[Aussie Frontier]

Gave the ECU a full reset this morning and then went for a drive and so far no temps over 90 .
I dont know if it was a coolant issue or possibly a reading issue.
I felt the truck was running a bit rough and then found the catch can half full. I emptied the catch can last weekend and the truck was running much smoother.
I think what may have happened was with the catch can half full the air returning back into the manifold was heavy with oil.After emptying it that may have changed the mixture parameters and the ECU was doing something weird.
I didnt see any evidence of any buildup in the radiator so really have no idea
Not keen on trying a thermostat as its a complete unit, housing and tstat, and over $100 to buy from O/S and a huge pain in the butt to do.
I still have to change the oil next weekend and then gearbox and diff oils to complete the full service.

 

[hunter]

Gave the ECU a full reset this morning

Aussie whats the procedure to do a full reset?
Cheers Lyle

 

[Aussie Frontier]

In short disconnect the battery and push the brakes to discharge any residual power
reconnect your battery, reset the stereo and your all set. ( stereo is important so you can listen to ya tunes while warming up the truck lol )

There are a few other ways but disconecting the battery is by far the quickest and easiest.
there is the ECU fuse that you can pull if you can remember which one it is but the battery is a no brainer

 

[hunter]

In short disconnect the battery and push the brakes to discharge any residual power
reconnect your battery, reset the stereo and your all set. ( stereo is important so you can listen to ya tunes while warming up the truck lol )

There are a few other ways but disconecting the battery is by far the quickest and easiest.
there is the ECU fuse that you can pull if you can remember which one it is but the battery is a no brainer

Thanks mate