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im having troubles with my 1991 L series overheating, i think its caused by a stuffed thermostat, i really cant find any other fault possible, but lately it heats up beyond half on a small trip (ie 15minutes) it soon cools down again, if you put it in 4wd it goes off the heat scale. what would i be looking to pay for new thermostat?

i purchased a new thermostay yesterday and the price was $16.95

upon removing the old one i discovered that the thermostat fitted was a 180F unit! explains why it was getting so bloody hot! the correct unit should be 170F, also have you checked to see if your radiator is full of scunge?

You can remove your radiator and get a rad specialist to give it a flow test , that will tell you if its choked up .

Cheers A .

subusurfer wrote:im having troubles with my 1991 L series overheating, i think its caused by a stuffed thermostat, i really cant find any other fault possible, but lately it heats up beyond half on a small trip (ie 15minutes) it soon cools down again, if you put it in 4wd it goes off the heat scale. what would i be looking to pay for new thermostat?

21200AA121 $37.09 + LITTLE JOHNNYS TEN PERCENT

IT SAYS HERE THEY ARE A TWO STEP THERMOSTAT

Take the thermostat out and see if you can push it open with your fingers, if you can its stuffed. When you get a new one drill a 3mm hole in the outer edge of the thermostat ring, this gives it a permantent decent bleed hole. I would still get your radiator checked as they have a habit of filling up with mud. Lastly if you can pull off the inlet pipe to the water pump and check to see you still have an impeller.

Personally I hate the thermostat bleed hole idea unless its like the Triden ones with the jiggler valve . These are designed to stay open if there's air in the system but close against water flow . If they're always open (hole) the engine takes noticably longer to warm up and runs cool in cold climates . A thermostat can't regulate temperature in all conditions unless it can stop the water flow to the radiator if need be .

I like the idea of removing the water pumps inlet pipe to inspect the impeller , I suppose you'd need a new O ring to seal it in again ?

Cheers A .

If you have a decent thermometer take your thermo out and heat it up in water on the stove. Depending on the unit I think it should start opening around 65-70 degrees celcius and be full open by around 75. Make sure the thermostat is not resting on the bottom of the saucepan, but raised up a bit. If it opens in this range you have a different problem, and you have saved yourself the money not buying a new thermostat.

I am also not a big fan of the self tapped bleed hole, engines are made to run at a certain temperature, not lower and preferably not higher. If you are worried your car is going to overheat then fix the cause before it happens, rather than relying on a 3mm hole to cool your engine. But this is one of those things that everyone has an opinion on.

definetely get the radiator checked- i reckon it causes the most cooling related problems.

i finally worked it out, there is a switch i think called a thermo switch which wasn't turning the second fan on, i managed to rewire it, replace the coolant and now it seems to be working fine. cheers for all the advice, i reckon a thermostat probably wouldn't be a bad thing to replace as well.

I recently changed mine, although I had the opposite problem to you with the temp guage sitting on cold. When I pulled the old one out it was jammed open...Better than being jammed closed I guess;). Replaced it with a Dayco (I think) from Repco, bout $27.
Good luck

discopotato03 wrote:I like the idea of removing the water pumps inlet pipe to inspect the impeller , I suppose you'd need a new O ring to seal it in again ?

If you're really perdantic about things like that then yes. If not, some high temp silicone around the old O ring does the job - I've done this several times on my L without any problems

Cheers

Bennie