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Guest Message by DevFuse

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Faulty OEM Thermostat

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3 replies to this topic

#1 markjw


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Posted 19 August 2011 - 12:33 AM

I put a good EJ22 engine into a '91 legacy I picked up a couple months ago. I installed a brand new Subaru OEM thermostat at the same time. About a month ago, I started having overheating problems at high way speeds. The temp would go to about 2/3 rds on the factory gauge. Very consistently, too. Around town, it would stay just under half, always.

The engine showed no other sighs of head gasket failure, except the temp gauge climbing at freeway speeds. I was very hesitant to do a HG job, as it just didn't seem like that was the case. Anyway, I stopped by Shucks today, picked up a cheapo thermostat, installed it, and the overheating is completely gone.

So, I'm on my way to Subaru tomorrow to pickup another factory thermostat. Just wanted to share, even New, factory thermostat's can fail. :banghead:

#2 idosubaru


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Posted 19 August 2011 - 01:49 AM

themoneypit said he had a Subaru OEM tstat fail as well, i think his was immediately after install, sometime last year.

are you sure it wasn't:

an air bubble?

or a partially clogged radiator that got semi-flushed out by the *fluid change* that happens when you replace a thermostat?

you could probably test it in some boiling water, see how far it opens.

#3 Durania


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Posted 19 August 2011 - 07:43 AM

I had a faulty radiator cap do the same thing.

#4 GeneralDisorder


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Posted 19 August 2011 - 11:32 AM

I'm sure it happens - but the failure rate of the OEM thermostat's is very low compared to the aftermarket one's I've used. I've used dozens of OEM thermostat's (made by TAMA Enterprises: http://www.tama-e.co.jp/en/start.html) both from the dealer and from my independant parts supplier that sells the TAMA branded equivilent.....and have seen no out-of-the-box failures.

It is also possible, being that these are just stamped sheet metal parts - that it could have been tweaked in shipping or dropped causing it to bind durring it's opening/closing process and thus stick at less than fully open....

BTW - if anyone can find an online supplier of the TAMA branded units I would love to hear about it. I use a lot of these and would love to buy them in large quantities to possibly save some money on them..... alas I haven't found any suppliers other than my local guys and they are basically within $1 of the dealer wholesale price....


Edited by GeneralDisorder, 19 August 2011 - 11:36 AM.

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