Thermostat question (1 Viewer)

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David*BJ70

David*BJ70

Looking forward to reach the end of the world
Joined
Jan 13, 2004
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Location
Montréal, Canada
I just change my thermostate. I think I know the answer but... tell me your opinion.

So I ride on the Highway and I always look at my thermometer. It is fine but climb slowly... slowly climb just under the red zone (I still can see the last white range) .. and then drop to the middle.

I suppose the time when it drop is the time when the thermostat open ? Is it normal ?

Never see that before. The old one was a 82C thermostat, but the new one is a OEM from toyota with 88C. Is that difference (on the thermometer) came from the thermostat difference ? (82 - 88)

If I whant to put a mech temp sensor, where do I have to look ? What kind ? I have to put a new thermometer ?

Thank
 
David,

What is the thermostat behaviour during normal city driving? Does climb slowly towards the red and then comes down to about the middle or it stays pretty much in the middle? What it sound like is either 2 things:
1. You have air trapped in the system
2. You radiator needs to be cleaned or rodded out.

Alex
 
Yes it climb slowly just under the red and then comes down to about the middle.

I have a new rad
I have a new water pump and gasket
I have a new thermostat and gasket
I have a new elbow gasket (the one on the engine block)

Maybe air in the system... How can I remove the air....

Actualy, I run the engine without the rad cap until the themostat open (I belive it open) then I fill the coolant fluid until no more can go in the system...
 
run the engine with the front of the truck higher than the rear-like idling with the front wheel up on the pavement. idle it until the thermostat opens, and then some more-the air should 'burp' right out.
also, keep the reservoir refilled, with time the air will come out and take in fluid from the reservoir. it might take a few days...
Jan
 
if it only does this when the engine is warming up to operating tempurature the first time then it is just the thermostate, this normal. i would not worry... but then that is me...
 
Put a aftermarket gauge on there. Stock are not very accurate and tend to spike for no reason.

There is another npt port on the thermostat. I used a couple of brass fittings and T'd into the block on the passenger side.
 
what is the PSI recommed for the radiator cap for a 1985 BJ70 ?
 
I have also occassionally noticed the same thing when I changed my thermostat to a new OEM one. Mind you, my temp gauge doesn't go that high, but it does go quite a bit above the normal operating range for a few seconds before coming back down the first time it warms up. Almost like it's lazy to open the first time. My temp gauge usually sits below the halfway point in normal driving. This doesn't happen every time though, and I seem to notice it more when it's colder out.
 
mine behaves precisely as Stone's. Usually a bit below the middle, but the first time it warms up it goes a bit above the middle, then drops down-and it is brandnew.
 
Mine does the same thing, spikes for a minute when it first warms up, then levels out just below the half-way mark, and stays there for the rest of the day. Both the old FJ40's used to do this too. As long as it doesn't actually overheat, or consume coolant (look for grey slimy crap under your oil filler cap), I wouldn't worry too much. There is a test kit for the coolant, mix it and it will turn blue if there is any oil in it, this indicates a cracked head or block, or a bad head gasket.
 
13psi should be fine for rad cap in PQ. I used to use a 16psi when I lived in BC as I was frequently at pretty high altitudes.
 
Would the thermostat in the 13B-T be the same as the 3B? The local dealer ordered one in for me for the 3B and this thing is huge,do not want to take everything apart and find out I am stuck with the wrong part,if possible a part number and picture would be appreciated.
Thanks James...
 
Chang-kuao-lo said:
13psi should be fine for rad cap in PQ. I used to use a 16psi when I lived in BC as I was frequently at pretty high altitudes.
Click to expand...


13... this is what I have right now.... ANYWAY, I have question about this... See it in a new thread call : COOLING FLUID ALWAYS GO OUT FROM ENGINE.
 
First off, sorry David for hijacking your thread.
Thanks guys,looked at the 4wheelauto site this morning and was hoping it was just a picture of unrelated thermostat,mine definatly does not look like that,big brass thing,about 70mm(2 3/4") in diameter and 50mm (2")high, the gasket they got for me is about 50% that size.Oh well back to the dealer on monday..
James..
 
Hey james the oem # for your thermostat is

#90916-03103

Cheers
 
Thanks silvercrusher ,my part has a different #.90916-03052...
James..
 
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