"Not a gasket"

[turf]

ok, then what are you?

i am changing my thermostat and this "not a gasket" was included.

the main hole is smaller thanthermostat opening, but the 3 holes line up with the bolts?

nothing like this was in there. does it belong or not? if so where? it could fit on either side of the lifting bar that is between the tstat and the block.

[Rusty]

It's a template to grind early cylinder heads to fit the tstat and or rubber gasket.

There was a TSB released back in '91, I believe, regarding an "Overheating/No Heat" condition. The casting in some of the earlier cylinder heads caused the thermostat to bind open or closed. The template is a way to find out if you need to remove some casting material from that area or not.

says interwebs

[cadillackid]

I thought the cummins 5.9's are O-ring seal type thermostats like the Navistars are..
-Christopher

[Booyah45828]

They are. Like rusty said, thats a template to grind off any interfering casting flash. I'm surprised they included the template without instructions tbh.

[turf]

thanks for the help!!

it was puzzling, looking at what looks like a gasket, clearly labeled "not a gasket"

i reassembled the thermostat housing without it. the template went to the trash.

[Booyah45828]

Here is the bulletin if you want to read it.

TSB 07-01-91