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88c vs 180f?; thermostat specs
Topic Started: Jun 15 2009, 11:13 PM (1,057 Views)
redpepe


i've been resuscitating a 326k engine and had replaced all the cooling components before the rebuild. since i'm only adding breakin miles at the moment, i have gone back to examine the final cooling issues i've noticed.

i looked at the thermostat i'd removed and discovered it was different from the one i replaced it with .... ahh hindsight! the original is 88 degrees centigrade and the new one is 180 degrees f. the few threads i've read here seem to recommend the 180f tstat. the haynes manual says 180 degrees. my parts person's catalogs say 180. i went to chevy today and the 88c is the original specification. this translates to 190 degrees f. this is for the manual transmission, 1991. the automatic specs call for a 92c tstat. ..... almost 198 degrees f.

i'm sure there are lots of opinions. i'll be returning to the 88c and trying to match the previous performance and system balance.

at the moment i'm thinking that the new after market radiator is poorly designed and made. i'll do some more tests but it does not appear to be able to keep up with prolonged engine heat under harder loads ... even in cool weather and no ac. this was never a problem previously. i do still have the original radiator and have done some r+r and may put it back in for comparison. i've already reinstalled the old fan switch and it's much closer to the original performance range than the apparently poorly calibrated new one.
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Dallas


depends. all will work. in the summer time I use the colder one (180) and in winter if im feeling up to it ill change it to the hotter one. I dont even buy new ones because if I swap it out I just keep it safe in the shop and use it next time
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wikityler
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Some say...

From what I gather reading the FSM there are two temperature options for these cars. The metal portion of the rad fan temperature switch it will be etched with a number, such as 95C. This indicates temperature range 'A' and is to be matched with the lower temperature thermostat.
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redpepe


i suspect you're right about the 'matching' .... and i'll check the numbers on the switches thanks. there wouldn't be any original match for the 180 though ..... quite a bit lower than either original option 88c + 92c.

i am running the 180 now and yesterday's driving showed the swings through the whole range on the gauge. even with normal driving the gauge showed about 190 which means that the wide open tstat can't manage / maintain the heat on slightly warm days. what will it do in 110 degree conditions?

pulling the 'grapevine' again, this time a hotter day and i kept the ac on, showed that the system could not really keep up with the heat produced .... even with the fan on. at the moment, all indications still point to the radiator as lacking in adequate reserve capacity.

we all seem to intuitively think that keeping an engine cooler is better but there is an optimum design and operating temperature and i'll keep trying to match the original.
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wikityler
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Some say...

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mwebb
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FOG

you may want to look at the spaces around the radiator before you replace it -
we have had cars that were missing shroud parts that overheated just because the air flowed around the radiator instead of through the radiator , my 1996 1.0 liter has huge gaps on both sides as original there is no way it will have the same heat transfer as a system that directs all the air through the radiator


i am going to seal mine up with some aluminum flashing ,but we have used foam weatherstrip type stuff that is used to seal AC condensers in home installations with some success and we have carved up the thick plastic foam floor pads used for standing on concrete as purchased at the big hardware chains , to close up the gaps ,
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