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The mkiv Supra Owners Club

Bloody heater!


slugger1
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I've been having a few issues with the heater recently and thought I would try and solve it last week. A common problem appears to be an air lock in the system so I left the engine running with the rad cap off to see if I could remove the air lock that way.

 

Whilst running the engine for a while (up to normal running temp) I felt the pipes either side of the matrix and both were cold! I was a little surprised at this because most air locks are located in the matrix itself (correct me if I am wrong). Could it be that maybe the thermostat is faulty or there is another problem elsewhere? I have searched the forums for answers but not come across one like this yet.

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Is the whole of your radiator warm/hot ?

 

You have an expansion tank i assume and its approx half

full of coolant.

 

You can try raising the rpm to around 2k with the rad cap

off as this sometimes helps to get any air out the system.

 

Do this with the heater on max hot

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When bleeding the air out of the cooling system, wait until the thermostat has opened and try giving all the hoses a good squeeze (including the heater pipes that go through the bulkhead).

 

Sometimes air gets stuck in the system if the jiggle pin on the stat is in the wrong position (should be at the top)

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Pop a matrix pipe off. Put a hose pipe up one end and see if water flows out of the other. If it doesn't, there's a blockage. If it does, refit the pipe, run it up with the cap off and see if it warms up inside.

 

I had a Toyota Emina the other day that wouldn't bleed up despite trying pretty much everything including revving it whilst stationary to 3k. The only thing I could do was "Kamakaze" run it up the road and it pushed the air lock out. (Not recommended unless you're a professional, and about to hang yourself!)

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Thanks for the replies. I have run the car and revved it to 2000rpm as suggested. I think I will give it a proper go at the weekend weather permitting! Just a question about the thermostat though, is it the small unit attached to a couple of metal pipes by the side of the radiator?

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Follow the bottom rad hose to the engine, that is where the thermostat is located

 

Look at the PDF on page CO-6

 

Cheers. What was it that I described earlier then? It has a small cap on it with a metal pin underneath. I think the cap has the letter 'H' on it iirc.

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There is absolutely NO issue with either the N/A or the TT engines in the JZA80 suffering air locks in the heater or in the cooling system. In all the years i have worked on them not ONCE have I had ANY issue with bleeding air from the rad, the engine or the heater system. Now, the MKI and MKII MR2's are a different matter, and do require a specific routine.

 

As Dnk says, fit a new genuine thermostat for a start. Pattern `stats (for any engine) tend to have more than their share of issues.

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There is absolutely NO issue with either the N/A or the TT engines in the JZA80 suffering air locks in the heater or in the cooling system. In all the years i have worked on them not ONCE have I had ANY issue with bleeding air from the rad, the engine or the heater system. Now, the MKI and MKII MR2's are a different matter, and do require a specific routine.

 

As Dnk says, fit a new genuine thermostat for a start. Pattern `stats (for any engine) tend to have more than their share of issues.

 

Ok will try that first. Anyone got a spare knocking around?

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Had a conversation with a mate at work about this issue (he knows quite a lot about engines etc) and he said there is a possibility that the heater control valve might not be opening correctly which might explain why there is no heat either side of the matrix. Does this sound like a possibility?

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