Author Topic: White powdery residue around the thermostat housing  (Read 1452 times)

TA301

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White powdery residue around the thermostat housing
« on: July 21, 2024, 05:16:05 PM »
This has me baffled. Never seen anything like it.

5th T/A

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Re: White powdery residue around the thermostat housing
« Reply #1 on: July 21, 2024, 07:46:27 PM »
On my iPad the photo is not very clear, making it harder to determine what I am looking at.

A couple questions, what does the coolant look like when you remove the radiator cap. Is the level low? I wouldn’t be surprised if you have a coolant leak and old coolant causing corrosion. Old coolant can turn acidic. You can borrow a coolant pressure tester from most auto parts stores to help isolate the leak source, for free or a minimal rental fee. There is a test you can perform on the coolant determine if it’s bad, requiring a DVM and taking voltage readings of the coolant in the radiator. Lots of examples online, here is one >

https://www.familyhandyman.com/project/coolant-testing-with-a-multimeter?_cmp=stf

https://www.youtube.com/watch?v=sxQ2zHHZfoI

You can also use PH strips to test acidity, available at most auto parts stores.

« Last Edit: July 21, 2024, 08:42:07 PM by 5th T/A »
1980 T/A with a Pontiac 461

Gone but not forgotten;
1973 T/A 455
1975 T/A 400
1978 T/A W72
1982 T/A cross fire injected

Two wheel toys;
2014 Harley Ultra Classic Limited
2013 Honda CB1100
2010 Yamaha Vmax
1982 Yamaha Seca 750

apfstg

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Re: White powdery residue around the thermostat housing
« Reply #2 on: July 22, 2024, 04:38:59 AM »
That’s hard water in my opinion
A radiator shop owner told me once to use distilled water to mix with antifreeze instead of tap water and I’ve always done that since

roadking77

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Re: White powdery residue around the thermostat housing
« Reply #3 on: July 22, 2024, 06:36:51 AM »
To me water is water :shock: When I filled my radiator for the first time I read and was told to use distilled water, so thats what I did. I think apfstg is on to something and also I would imagine something is leaking. I would second 5th ta recommendation of using a pressure test. I just got one from Auto Zone. It was free but required a $200 deposit.
Finished!
77 T/A - I will Call this one DONE!
79 TATA 4sp-Next Project?
79 TATA - Lost to Fire!
86 Grand Prix - Sold
85 T/A - Sold
85 Fiero - Sold
82 Firebird - Sold
'38-CZ 250
'39-BSA Gold Star
'49-Triumph 350
'52-Ariel Red Hunter
'66-BSA Lightning
'01-HD RoadKing

tinpusher

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Re: White powdery residue around the thermostat housing
« Reply #4 on: July 22, 2024, 08:49:20 AM »
I think it’s a combination of several things. As mentioned before, distilled water should be use to keep the mineral content removed from the coolant system. Dissimilar metal’s, aluminum thermostat housing, cast iron manifold and a metal thermostat sandwiched between the two. The gasket is probably saturated causing moisture to combine with metals and oxygen causing that corrosion.  I have seen it on my car , especially when it’s not run for several months….. I don’t use distilled water either.
I’m thinking that the engine temperature helps keep the gasket from becoming saturated and if not run for a while, it gets saturated and wicks…. Just my opinion, not necessarily a “leak”

Re: White powdery residue around the thermostat housing
« Reply #4 on: July 22, 2024, 08:49:20 AM »

langss

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Re: White powdery residue around the thermostat housing
« Reply #5 on: July 22, 2024, 04:10:08 PM »
I started using Distilled Water years ago on the advice of the radiator shop owner that simply said the water here in California is HARD. That's not exactly what he said, but this is a family friendly forum. So that's what I use. I just replaced the Radiator in my 92 Camaro and at less than $2.00 a gallon, it was the cheapest thing I put in that car. The tap water here is heavy with Calcium and Lime. It shows up on the shower head and the toilet. I don't even let the dog drink it. He gets bottled water from Costco

Re: White powdery residue around the thermostat housing
« Reply #5 on: July 22, 2024, 04:10:08 PM »
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