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The problem

I have a leak in the upper half of this thermostat housing on this T5 engine of a Volvo between parts 28 and 27 of the diagram below. I disassembled things today and found a metal gasket (part 26) which got a little deformed and bent upon disassembly. I went to look for a replacement gasket but found it to be discontinued. They instead sell the entire two part housing kit which has a gasket of its own which are both still for sale. In the sale page there's part 26 which is the gasket I am seeking but which has no corresponding part number on the website: https://usparts.volvocars.com/a/Volvo__XC90/__5702956/Coolant-pump--thermostat-and-cable/GR-365311.html.

Volvo GR365311 exploded parts view for Coolant Pump, Thermostat And Cable

Here's an image of the full two part housing kit, the seam that I trace with the orange lines is where the gasket is found, the leak is dribbling somewhere on the bottom on the opposite bottom corner from where the blue arrow points.

annotated thermostat kit 31293700

Here's a photo of the upper half removed from the block and with the gasket visible and bent and showing some metal corrosion as well as fragments of its gasket material that got brittle and fractured off.

upper thermostat housing with bent gasket

Here's a photo of the bottom half still attached to the block and with gasket material broken off and left behind.

bottom thermostat housing still installed on the block

What are my options

I'm trying to consider what my options are to eliminate the leak. I'm considering mating the two halves directly with this Permatex Water Pump & Thermostat Housing Gasket Maker 22071 after thoroughly cleaning and polishing them both with a 3M Roloc Bristle Disc followed by some brake cleaner spraying. Tube of Permatex Water Pump & Thermostat Housing Gasket Maker 22071

I'm also soaking the metal gasket in gasket remover and have been scraping and abrading the old gasket material away hoping to straighten it out polish and clean it and apply the above gasket maker and sandwich the housing pieces back to how they were and effectively refurbish the metal gasket since I can no longer purchase one. Is there any added benefit to doing that? I'm hoping it may create a more enduring seal but maybe it would just be a waste of time? Are these metal gaskets better than gasket maker or are they just time savers at the factory to get a seal established very quickly as opposed to fiddling around with gasket maker and wasting factory time during assembly?

metal gasket soaking in gasket remover to refurbish it

metal gasket close up for condition--both sides visible

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4 Answers 4

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I think I would replace that with a home made gasket using a sheet of waterproof gasket paper. Gasket paper is readily available from many places and is often used as an OEM gasket in places like this.

The worry I would have with reusing that metal gasket is that you bent it in a couple of places. This may cause ‘weak’ spots in the seal.

There are videos on YouTube showing easy ways to cut your own gasket with simple tools, for example -

enter image description here

https://www.youtube.com/watch?v=0pf15CtvvrY

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  • Indeed there’s now a little crease/lip where the bend occurred trying to flex the unit off. I should have got a wooden dowel or block or something to press against the outer half and tap it with a hammer from above to get a clean break and separation.
    – jxramos
    Sep 1, 2023 at 16:26
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Gaskets aren't meant for re-use, they deform to fit a shape and once removed they won't necessarily fit into the same space again. By polishing your gasket you are removing material, making it thinner, maybe too thin to fit. Also, you are likely to get an uneven surface and you could get leaks either way. The recommended solution would be to use the instant gasket, RTV silicone can work in medium-high pressure applications and is what I'd recommend.

You could also use a thin bead of RTV on both sides of the gasket to ensure a good seal, I see little value in that over just using all RTV.

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I wouldn't use a rotary tool to remove the gasket material, but a scraper.

Use it gently, as one could make scratches, that would make the new gasket ineffective.

Use RTV, but sparingly. Globs of RTV tend to get loose and block something important in the coolant circuit.

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    Yah the rotary tool with a wire wheel seems a bit aggressive I agree. I was using a combination of a scraper and the 3M Rolloc Bristle wheel which does a good job acting on the part and leaves the surface intact. This is interspersed with gasket remover soaking in between.
    – jxramos
    Sep 1, 2023 at 16:22
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This is an uncertain finding regarding the durability and success, but searching for that gasket I found this hit where someone pretty much did the same thing I was contemplating and actually refurbished the gasket allegedly. We can see them polishing the gasket with a rotary tool in the image below...

Gasket of split Volvo V70 thermostat housing

This gasket is not sold anywhere (to my knowledge) so I cleaned the sealant chips of off it to reuse with liquid gasket https://imgur.com/gallery/KUN7C

Volvo GR365311 exploded parts view for Coolant Pump, Thermostat And Cable

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