86 X - thermostat housing to head gasket

C

cstorry

Low Mileage
Hi all,

I'm putting the head back on my X after upgrading the cam.

I now realize that the thermostat housing to head gasket I have must be for an older model as it is not quite the same as the one that came off the car (it doesn't have the same cutout shape nor the extra hole). Though the 3 mounting holes perfectly line up. The old one doesn't really look re-usable.

I checked a couple suppliers and no stock. Can I use the old one or should I make my own (thick paper stuff from local auto parts store) ? Can I just cover over the extra hole - it doesn't seem to go anywhere ?

Any suggestions ?
Thanks
Chuck
 
Make one

It's easy. Just make up a pattern by "pressing" a thin sheet of white paper up against the surface edges. Go to your auto parts supplier and get the real gasket making sheets and cut one out using your pattern. I use leather punches for making up the holes, (works very nice) and had to make up this exact gasket this week. Seems the factory replacement was indeed different than the original surface.

Good luck!
 
Uh-Oh! RED ALERT!

Need some uber-experienced XHeads to debunk/confirm this one.:eek:

Going from memory.....

I seem to remember a recent post where this is discussed in the context of putting a carbed heads into a previously FI car, or maybe it was vice-versa.

I think the poster said that when you see coolant running out of the exhaust manifold, you know there was a mismatch and the wrong stat manifold to head gasket was used, because there's a extra coolant passage on the carbed head that is not used on the FI stat manifold.

Of course this would not apply if you are reinstalling the head that came out of the car in the first place....are you?
 
Wrong side Dan...

He's talking about the thermostat housing, not the exhaust manifold. :)
 
I knew I should have taken pics : )

The head that is going back on is the one that was on the car before the cam swap but this doesn't mean it is the original head (though I have no reason to think it is not).

The water passage opening in the side of the head is a sort of triangular shape. The thermostat housing (and old gasket) has the same outer shape but there is a hole in the housing that seems to go nowhere and the gasket has a cut-out for this hole though the cutout and hole do not have a mate in the head. The hole appears to line up with the single large triangular-ish opening in the head so the purpose of the extra hole in the housing and gasket mystifies me.

I have a new gasket which is apparently for a pre-FI car and the three mounting holes line up perfectly but there is no provision for this 4th mystery hole. Also the cut-out would need to be slightly modified to line up with the cut-out in the thermostat housing.

The last thing I want is water running out the tailpipe so want to get this right but would rather use the new pre-FI gasket than to cut my own if it can be made to work.

Thanks
Chuck
 
cstorry said:
Hi all,

I'm putting the head back on my X after upgrading the cam.

I now realize that the thermostat housing to head gasket I have must be for an older model as it is not quite the same as the one that came off the car (it doesn't have the same cutout shape nor the extra hole). Though the 3 mounting holes perfectly line up. The old one doesn't really look re-usable.

I checked a couple suppliers and no stock. Can I use the old one or should I make my own (thick paper stuff from local auto parts store) ? Can I just cover over the extra hole - it doesn't seem to go anywhere ?

Any suggestions ?
Thanks
Chuck
Click to expand...

Can't even tell you how many cars have been towed to me with a blown head gasket when this gasket was the problem.

This is the most common gasket worldwide. http://www.fiatplus.com/thermostat-to-head-gasket-pr-285548.html
This is what your european, fuel injected, or 4 port air injection car should have .

This gasket is very rare, it is used only on 1977-80 carbureted North American cars with the single air injection port. http://www.fiatplus.com/1977-80-thermostat-hsng-gasket-pr-285440.html
Install the wrong gasket in this application, and coolant will come out your tail pipe, and the oil gets all white & creamy. Since it's made of the same material as your head gasket your not going to be able to just cut it out from gasket material.
 
Okay, here is the story......

There are two styles of thermostat housing to head gaskets.

This one fits 77-80 models.
http://www.fiatplus.com/1977-80-thermostat-hsng-gasket-pr-285440.html

And this one fits 74-76 and 81-88 models
http://www.fiatplus.com/thermostat-to-head-gasket-pr-285548.html

The reason for the odd shape for the 77-80 model gasket is the the provision that Fiat made for exhaust port air injection during those model years. In earlier X's and 128's there was an external manifold that connected to four ports in the head for air injection. During 77-80 model years, there was a long drilling made through the length of the head to connect up to the exhaust ports. This allowed a single connection for the air pump.

The hole was drilled from the left side of the head under the area where the thermostat housing bolts. If you use the 74-76, 81-88 gasket in these heads, the coolant system is hooked directly to the exhaust port. Hence, seeing coolant out the tail pipe.

Bottom line: This port must be blocked in all cases. It pays to use the correct gasket for the head that you are using.

Thanks to Chris Obert for use of his website to illustrate.

Ciao,
 
Doh - Why didn't I check C Obert !

Sorry Chris - completely opposite end of the country puts you out of mind but I'll bet UPS is just as fast from California.

Anyways I see on Fiatplus webpage that the thermostat housing to head gasket is the same for everything but 77-80 carb cars.
http://www.fiatplus.com/thermostat-to-head-gasket-pr-285548.html

This suggests to me that I don't need that extra hole. I may just trim the new gasket I have so that it fits the cutout on my head.

Chuck
 
Thanks

Thanks Chris and others - sorted

I'm just re-acquainting myself with X ownership (and experts/parts suppliers).

Chris
Been a while since I checked out your site. I like the selection of pics I get at the top of the page - I keep refreshing the page just to see new ones : )

Chuck
 
Excellent Write-up

This is the exact part I'm referring to.
I got the same gasket as described and had to fab one up to match the shape of the port. I'm now thinking about the material of my gasket, is it correct.
The one removed was just like the photo Anthony said was wrong.
I made one to the correct shape, but now I'm thinking about re-making ...

Good discussion.
 
This brings up a question...

Obviously, the later model gasket DOES NOT block the hole.

Would there be a disadvantage of blocking this hole in the later model?
In other words, can the early model gasket, "the hole blocker" be used in later model X's? Does this affect cooling?
 
cstorry said:
Thanks Chris and others - sorted

I'm just re-acquainting myself with X ownership (and experts/parts suppliers).

Chris
Been a while since I checked out your site. I like the selection of pics I get at the top of the page - I keep refreshing the page just to see new ones : )

Chuck
Click to expand...

Send in more pictures! We need more cars up there.

BTW, if you make your own gasket for the head that needs the 'special" gasket, make sure you think about how to support the back side...
 
Alternatively...

That hole can be drilled/pipe taper reamed and threaded with a 1/4" pipe tap deep enough to accept a flush pipe plug.

This fix can be more reliable than a gasket.

It's one of the quirks from the smog pump era when FIAT decided the tubular smog injector manifold continued to fail and replaced it with a gun drilled passage. Later EFI heads and EU version heads without smog pump don't have this quirk.
 
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