My 87 has for the last week giving me some concern about how hot the gauge tells me the water temperature is getting before the thermo opens up. It goes within two lines of the top then opens up and goes to about the thermo rating of 190*. Since I got my radiator replaced and this thermo installed it has been going only about one line obove the thermo temp rating. Today I noticed the gauge fluctuating between roughtly 240* and 190* slowly during driving in about 50* temperatures. Normal?? When I let it idle the water temp actually goes down to normal but then when I drive slowly it slowly climbs up to almost 240* and then goes back toward normal. On fast drives over 45 mph it never climbs up high and sits at about `190*! Any Ideas?? I think it is a bad thermo! Any easy way to test my idea??
Faulty Thermo??
- Thread starter 87gtconv
- Start date
are you using an aftermarket gauge or trying to interpolate the stocker?
sure all the air is out of the system?
if in doubt, i highly recommend the Mr Gasket stats (10 bucks at speed shops). very nice pieces. i wont use a parts store one again, if i can help it.
what i do too (be all careful and all that): cold motor, remove rad cap and run motor (like if burping it). when you start to see water move from pass side to drivers side (stat opening), toss a turkey thermo in the rad cap oriface. note the temps. (DO not use the thermometer for human consumption again, as it has E/G on it now.). i think some folks use their I/R thermometers too.
you can do the pot of boiling water trick on the stat, but i might not bother.
good luck.
sure all the air is out of the system?
if in doubt, i highly recommend the Mr Gasket stats (10 bucks at speed shops). very nice pieces. i wont use a parts store one again, if i can help it.
what i do too (be all careful and all that): cold motor, remove rad cap and run motor (like if burping it). when you start to see water move from pass side to drivers side (stat opening), toss a turkey thermo in the rad cap oriface. note the temps. (DO not use the thermometer for human consumption again, as it has E/G on it now.). i think some folks use their I/R thermometers too.
you can do the pot of boiling water trick on the stat, but i might not bother.
good luck.
ImportEater98
New Member
I agree with Hissing 
Do you have an electric fan? Is it coming on when it should? I had a similar problem in my Explorer, and it was the fan relay hanging up. Your problem, more commonly sounds like a sticky thermostat, and again, as mentioned about, make sure you burp the system. If the water pump cavitates (Gets air in it) it will not pump, not to mention burn up the bearings in it.
I put a MR GASKET thermo in my old mustang and it worked great!
Do you have an electric fan? Is it coming on when it should? I had a similar problem in my Explorer, and it was the fan relay hanging up. Your problem, more commonly sounds like a sticky thermostat, and again, as mentioned about, make sure you burp the system. If the water pump cavitates (Gets air in it) it will not pump, not to mention burn up the bearings in it.
I put a MR GASKET thermo in my old mustang and it worked great!
Thanks, my 87 has a fan clutch driven plastic stock fan using underfrive pullies and an EBrock pump. Think it could be air in the system after a year with no problems? Yes I am using a no name NAPA thermo cause my mechanic did not like my 160* lifetime Saleen thermo. I will try a new Mr Gasket thermo. Yes I am guessing on the temp with my stock temp gauge so the actual temps could be off. I judge from where the thermo has opened up with past good thermos. I know I should get a real gauge!!
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