Member
New aluminium thermostat housing has a 4mm (0.16 inch) hole between the two chambers.
I thought on the OEM housing the hole was smaller. I think it's for bleeding.
Technically hot water could go straight through the hole to the other chamber and back into the engine without going through the radiator. I suppose if the hole is small it doesn't matter. I'm now unsure if the 4mm (0.16 inch) hole of the aluminium part could be too big and cause problems. When I remove the OEM plastic part I'll update here how the hole sized compare.
Anyone ever installed one of the aluminium housing with a similar sized hole and can tell if something happened in relation to coolant temp or not?
Last edited by importbanana; 01-07-2022 at 11:10 AM.
Member
You are correct, it is an air bleed hole. It is not a problem. We all have one. It will be fine.
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With aluminum housing I would be concerned that the surface of the housing is perfectly flat.
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shade tree mechanic
Moderator
I installed a aluminium housing in 2016, a cheapo set from *bay made/sold by Uro with thermostat. For the price nothing to complain. I have a small electric grinder rotary tool and accessories kit and cleaned the surface a bit inside the housing where some spots were rough. For the contact surface I did a sandpaper treatment, used a tiny bit of RTV for the surface. No problem since then.
As for the gasket size there is a long thread here https://www.bimmerforums.com/forum/s...recommendation
Shogun tricks and tips for the E32 series are HERE!
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LOL!!! People!! No RTV required, nor recommended!!Originally Posted by shogun
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shade tree mechanic
Moderator
no RTV: Meanwhile I know, but 6 years ago not, anyway, the bit of RTV did not do any damage and the housing still works and no leaks
Shogun tricks and tips for the E32 series are HERE!
Member
Some of the cheap aluminum housings seem to be a little warped and/or porous or the seal groove is not bored to the correct depth. RTV helps and it is easier to put on at first than later.
Member
The hole might serve as an air bleed but the main purpose is to prevent or limit cavitation while the thermostat is closed.
See ya later,
tony
'98 M3, '92 Dinan3, '05 R1100S BCR, '07 R1200S, Aprilia T
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