84 iron duke

leaks coolant from thermostat housing.
the cap does not seal correctly. new one did not seal.

do i have to replace the thermostat housing???

where can i find one???

if i go to junkyard, what cars am i looking for besides fiero????

is there a different easy fix??

thank you.

Is the sealing surface of your thermostat housing pitted with rust?

By coincidence, today I sanded my thermostat housing because it was weeping from there.

I stuck some sandpaper upside-down on a flat surface (a piece of glass works), and then I sanded the sealing ring of the thermostat housing (I held the thermostat housing in my hand; it was removed from the engine).

I went from 150, to 320, to 600 grit sandpaper.

Depending on the amount of corrosion, only sanding may not be enough. Mine had one really big pit that needed to be welded before sanding.

This is basically the same idea as how some folks sand a cylinder head's mating surface:
https://youtu.be/a8ctywVmzK0?si=PzNuNfCs9QkIN5b7

quote Originally posted by frosTkilos: 84 iron duke leaks coolant from thermostat housing. the cap does not seal correctly. new one did not seal. do i have to replace the thermostat housing??? where can i find one??? if i go to junkyard, what cars am i looking for besides fiero???? is there a different easy fix?? thank you.

I think the problem you're having is that a lot of the newer coolant caps do not have a "full gasket" ... and it causes the thermostat housing to leak profusely through the cap. Let me see if I can find some examples...

You need one like this: https://www.ebay.com/itm/375363085668




Not one like this: https://www.ebay.com/itm/275357048873




Do you see the difference in the size of the gasket? Many of the newer ones have a much smaller gasket for some reason, and they will always end up leaking since the surface contact with the gasket is so small on the new ones. You can buy that (new) old one that I linked to... that'll solve your problem.

quote Originally posted by pmbrunelle: Is the sealing surface of your thermostat housing pitted with rust? By coincidence, today I sanded my thermostat housing because it was weeping from there.

The other thing to check for is to make sure the top of the housing hasn't been bent slightly during "forceful" removal of the thermostat housing cover/cap (ie with a monkey-wrench). Mine was tweaked somewhat, and I had to massage it back into shape before I then also used the sandpaper on a flat surface treatment. You'll know the top of the housing is ready when the sanding on a flat surface reveals a complete shiny ring around the top of the housing.