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Slimvest
Samba Member
Joined: March 20, 2014
Posts: 431
Location: Portland, OR
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 Posted: Thu Mar 25, 2021 8:58 am Post subject: Re: Temp gauge creep - Thermostat? |
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Took some IR Temp readings in the engine bay after a drive around town and the fan cycled a couple times idling in the driveway. Range from 160F on the driver side of the block to 200F at the coolant exit on the passenger head. 180 on the aluminum t'stat housing. Then my battery on the temp gun got too low. I lost the laser pointer and started seeing temps as high as 360F.
Test inconclusive. 9V battery on the shopping list.
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'87 GL w/ Reimo top |
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Slimvest
Samba Member
Joined: March 20, 2014
Posts: 431
Location: Portland, OR
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| Posted: Thu Apr 01, 2021 9:42 am Post subject: Re: Temp gauge creep - Thermostat? |
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A few variables seemed to be the culprit here.
1) Bad "flush" job done by the mechanic that did the water pump a couple years back lead to some funky coolant and/or sludge building up in the radiator. Coolant was switched from red to blue Pentosin at the time. The two coolants in the system may not have liked each other.
2) T'stat had a "Made in West Germany" stamp on it and may have also been on it's last legs not opening fully. NOS part used when motor was rebuilt in '14. I'm replacing it with a Wahler 87deg. Tried a new Mahle and it ran hotter.
3) Radiator is bad after 85k miles. Inconsistent temps across the radiator. Maybe accelerated because of issue #1? South African Behr is the new one.
Blue cap:
Temp sensor on radiator:
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'87 GL w/ Reimo top
Last edited by Slimvest on Thu Apr 01, 2021 2:57 pm; edited 1 time in total |
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4Gears4Tires
Samba Member
Joined: October 08, 2018
Posts: 3019
Location: MD
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| Posted: Thu Apr 01, 2021 2:02 pm Post subject: Re: Temp gauge creep - Thermostat? |
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I think you probably need to pressure test your coolant system to make sure that coolant cap isn't milkshake of death. I would be draining and filling your coolant system with distilled water until that water ran clear.
What does your oil dipstick look like?
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'87 Syncro
Ferric Oxyhydroxide Superleggera Edition |
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Slimvest
Samba Member
Joined: March 20, 2014
Posts: 431
Location: Portland, OR
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| Posted: Thu Apr 01, 2021 2:31 pm Post subject: Re: Temp gauge creep - Thermostat? |
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I think you probably need to pressure test your coolant system to make sure that coolant cap isn't milkshake of death. I would be draining and filling your coolant system with distilled water until that water ran clear.
What does your oil dipstick look like? |
I'm replacing the blue cap. Oil dipstick is clean, has always looked that way, and compression is all over 150psi. Oil cap doesn't show any milkshake death either.
I also pressure tested my system prior to starting all this work and found no leaks and the cap functioned as it should (seemingly). I like the distilled water flushing idea, but the system is all full and sealed up now with fresh coolant. With fresh coolant and radiator, hoping most of the gunk is out with the idea that I may need to flush it again after a few thousand miles. Hoping the new-ish heater core isn't full of crud too.
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'87 GL w/ Reimo top |
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MarkWard
Samba Member
Joined: February 09, 2005
Posts: 17114
Location: Retired South Florida
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| Posted: Thu Apr 01, 2021 4:01 pm Post subject: Re: Temp gauge creep - Thermostat? |
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Add a bottle or 2 of Shout and drive it through multiple heat cycles. Then drain and flush till clear water is returning to the thermostat housing. Then add coolant, and bleed. Verify fan cycles on and off. The Shout does a great job of cleaning the cooling system out.
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