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Temp gauge remains on cold and no heat in cabin

1998 KZJ95 Chris

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Joined
Jan 23, 2018
Messages
5
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cyprus
Hi all,

I have a 1998 Prado KZJ95 that has some cooling/heating issues. The temperature gauge does not move during normal driving, remaining on or below the 'C' line at the bottom. It only begins to move when the vehicle is under extreme load, i.e driving up a mountain, but even then it never gets much past a 1/4 of the way up the gauge.
I also do not get any heat in the cabin through the climate control. With an engine that is staying freezing cold (according to the gauge) I'm not surprised but when you get out of the car it smells warm/hot, but still no hot air from the blowers.

Any tips and tricks of things to check please? I have a new thermostat ready to fit, just need to get some coolant to replace what I lose when I take the old one out. How about the location and orientation of the thermostat and the temp sender so i can check that this is actually telling the gauge to move as it should.

Thanks in advance, the truck has covered 318000 KM by the way
 
Hi Chris welcome aboard. Nothing like having heat in the cold winter months. Unfortunately been there so I feel for you. Not having a Prado model not able to help you personally but our other enthusiast members I'm sure will come along soon.

Hope you get a simply quick fix.

All the best

Dervis
 
*UPDATE*

After a bit more diagnostics, engine physically feels like its warming up and stat seems to be opening as I could visibly see the flow start through the top of the rad cap. Temp gauge however didn't move from below the cold line!

As for the heating, after reading somewhere else about the valve on the bulkhead behind the engine, I disconnected the operating cable and the valve moves freely by hand but the cable doesn't move when temperature dial is adjusted through its range. When we opened the valve, heat began to come through the vents as the engine warmed up.

Next step I think is to change the stat, just because I bought one anyway, replace temp sensor and see if that fixes the gauge issue and trace the fault back to the control knob on the climate control to see why the valve is opened automatically.......

Good times
 
Looks like you’ve just about got it all covered with the above logic, Chris.

Welcome aboard BTW :thumbup:
 
It wouldn't surprise me if when you come to fit the new stat, the old one is actually missing. The stat restricts the flow of water allowing the engine to heat up. If it's missing the water just goes round and round. Obviously if it used to work and now doesn't, then it's probably not this. I don't know how long you've owned it.
 
Thanks for the replies guys, always good to get your theories checked :)

I've only owned it since December and, as far as I know, it's been like this since I got it. The other thing I noticed is the viscous fan, it seems to be "'on" constantly. This would also contribute to slow warm up, especially if the stat is not working/missing. Has anyone got got any idea on how fast its supposed to spin when cold and how I could check (without putting my hands anywhere near it, as suggested somewhere else I've looked!) I have no idea if its ever been serviced, or if it even needs servicing but the truck has 300000+km on the clock, so it probably wouldn't hurt. I imagine the silicone oil breaks down eventually making it less efficient?

Not too sure where I would find any of the oil in Cyprus though.

Thanks again
 
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Chris I’m not sure where your based here but if your available to drive over to the northern part of Nicosia my cousin who does my repairs and servicing can have a look at it for you. He sells the best oil and may be an opportunity to lay you mind to rest.

His an Landcruiser enthusiast.

Thanks
 
I have no idea if its ever been serviced, or if it even needs servicing but the truck has 300000+km on the clock, so it probably wouldn't hurt. I imagine the silicone oil breaks down eventually making it less efficient?

Refilling the fan hub is something people do, usually because of concerns to keep the cooling system in tip-top condition. Obviously you have the opposite issue, but you may want to service it anyway

I think it's hard to tell if the viscous fan is working properly. It always turns, but it has a series of stages that govern how fast it turns which are dependent on its own thermostat

There's actually quite a bit of good info on how to refill the silicone fluid out there (recent thread from another forum) and I found it a straightforward job when I did it three years ago. According to my notes, I used 10000cst oil, which I got off Ebay (it's used in radio-controlled cars) and I added c.40cl after draining the original fluid.
 
*UPDATE*

Thermostat replaced (old one was present but had failed open and was looking pretty tired). The temp gauge now responds as expected and hovers around the 3 o'clock position during normal driving, I will keep monitoring for now and look at an aftermarket gauge and sensor if required. Any suggestions?

Re-filled the coolant with genuine Toyota long life red stuff after reading other recommendations about the additives and keeping the transmission oil pipes free of corrosion (that and when I went searching, all the car shops were shut apart from Toyota!)

I have also trace the cabin heating problem to a snapped cable, the motor operates as it should when I turn the temperature dial on the climate control, but rather than push/pull the cable through its housing it folded in half where the solid middle had snapped. I'll pick up a new one from Toyota on Monday.

Next jobs are a full service, once I've picked up a trans filter, replace/repair the cracked and broken center armrest and drink holder lid, and maybe a home restoration project on the alloys as they look a little tired. Was thinking of a Hammerite job and see how it turns out.
 
Good to hear this is sorted. Engine temps, either too hot or cold, can be tricky, there are so many factors. Always best to start with the cheapest and work towards the most expensive cures.

Thanks for posting the feedback.:thumbup:
 
I would use acid etch primer on your alloys after a good but fine blast clean, followed by a good top coat. Hammerite is good on rusted steel but I'm pretty sure it's not the best for ally.
I made a note of the following when I had ideas of doing it myself. There's probably a vid on youtoob.

1, acid etch primer

2, filler primer, fill holes and sand smooth

3, possibly another coat of primer

4, top coat
 
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