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The mkiv Supra Owners Club

Another 'heaters not hot' thread


Jam127

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Ok so iv looked at all the possibilities, iv checked linkage in passenger footwell all is good. What iv found is on pipe is hot going into the bulkhead - the one on the right looking at the car and the other is cold.. This means a blockage??

Just lookingn for a second opinion before trying to flush it

 

Thanks

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Was it warm previously? I'm having a similar issue but I think mine is related to the drive arm not opening & closing (wiring fault). The linkage is connected but when I move from cold to hot, it doesn't budge. I'll hopefully be investigating it over the weekend. I can't think of any reason for the valve to be jammed shut so I'm going to disconnect the linkage and see if the valve is free. If it is, then it's into the wiring (fun).

 

Check from underneath with the fans on. Turn the temperature to cool then over to hot after a few seconds. If you see the valve move then you're OK at that end.

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Was it warm previously? I'm having a similar issue but I think mine is related to the drive arm not opening & closing (wiring fault). The linkage is connected but when I move from cold to hot, it doesn't budge. I'll hopefully be investigating it over the weekend. I can't think of any reason for the valve to be jammed shut so I'm going to disconnect the linkage and see if the valve is free. If it is, then it's into the wiring (fun).

 

Check from underneath with the fans on. Turn the temperature to cool then over to hot after a few seconds. If you see the valve move then you're OK at that end.

 

Control arms are prone to falling off. Will probably be that Scott.

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Iv been under the footwell and all is good and moving there so i know its not that at fault.. Iv just a new engine built and fitted and its not been hot since that but was fine before so has to be air somewhere. Gona start simple by parking on a steep hill and letting it heat up with cap off first if no luck then il fill matrix from bulkhead with coolant maybe flush il see when it comes to it :) il post on here again tommorow with my results!

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Ok so iv had both pipes off and water runs through no problem. Heaters are a little hotter but wouldnt say great, just the one hose is hot not both. Also the bottom rad hose isnt hot but the top one is

 

You need to allow your car to heat up fully before bleeding it. The reason the bottom one isn't hot is because the thermostat is closed. This won't open until the engine is up to temp. Get your car on a steep hill facing upwards, take off the rad cap and let it heat up fully until both the upper and lower pipes are hot. While it's heating up, give the matrix pipes a squeeze periodically to push through any air.

 

While all this is going on have the heater on hot and full.

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I had it running on a hill last night for ages. Iv let it idle for 25mins today with the cap off heaters on, they are better but not roasting hot id say pretty warm at most. Chris im not sure what thermostat is in it but when running it likes to sit between 79 and 83 deg, well so my commander tells me. Iv filled the expansion tank, what am i looking for regarding that?

 

Thanks again guys

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Never had an air lock in any of mine either although they always tend to blow cold after a refill until I take it for a blast (from warm) and drive in 2nd up to around 5 or 6k revs then let off the throttle while it "engine brakes" back down to around 2k..... Usually feel the heat kick in then.

I would also mention that after 20 years of being driven around without flushing then the fine particles build up to form a hard mass that needs attacking with something other than a gentle flow of water to clear.

 

Should mention that mine is an auto hence the holding it in 2nd.....Or follow the same procedure in Drive but with the overdrive off.

Edited by trebor69 (see edit history)
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Seems to be fine now guys.. Was giving all the pipes a good squeeze with a top up everytime and that seemed to have done the trick. Chris its ran at that temp ever since iv had it and iv had no problems i start to get worried if it reaches 85 sitting idling lol

 

Thanks for everyones input :)!

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It should be around 85 idling though, this is a good thing. I think the running temp of the engine is around 90+ degrees. Think mine idles bang on 90 once warm. As Chris says, if you don't have a thermostat in there then it'll do exactly what you are experiencing regarding cooler running temps. This isn't a good thing bud.

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Hard to see if anyone would try running without a thermostat ? In the colder weather the engine needs to warm up as quickly as possible, oil especially, and goes without saying a good heater output. The thermostat also acts as a flow controller and optimises the degree of cavitation and surface errosion and ecconomy etc, inside the engine etc.

Also complete combustion and everything supporting the engine relies on the design optimum running temperature, if you are above this to any degree, or, below it, you will eventually have problems.

I have cars and a boat with big twin diesel engines and i know from experience that the engine thermostats are a very important piece of kit.

Finally, if you live in the south were the water is quite hard, (high PH value), and you have been using a water based coolant, then you can expect on an old car where the heater element and the cooling radiator will be well calcified with dissolved salts, the salts are a good insulator and increase the pressure drop across them, and reduce the coolant flow, so overheating of the engine's cooling system and with the heater element, little heat being extracted from the element.

I bought my daughter a 1.7 tdi vauxhall from Essex some time back, it was 6 yers old and had 75k on the clock, good little bus, but the heater was very poor, after trying all the usual stuff, thermostat, air locks, etc, i changed the heater matrix, problem solved, out of interest i cut open the old matrix and was amazed at the 80% restriction caused by calcification etc.

I have just spent £40 on Toyota "Forlife" coolant 10 litres,now called 4life, this avoids all what i have said, for 10 years. herbiemercman.

Edited by herbiemercman
added extra text. (see edit history)
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