Does anyone know if the thermostat housing from an '88 (S4) can also be used without problems on a '91 (S5)? Are the mounting bolt patterns the same? I want to get rid of this damn plastic one on my '91.

Thanks.

 

I believe that they are the same.

Jarrett

 

I'm 75% sure that you can't w/o swapping front covers. I wanted the same thing.

 

i am pretty sure the S4 top flanged looking piece is held on with 2 bolts, where the S5 is held on with 3.

 

I know that you can swap the S5 pump onto an S4 front cover by taking just a little bit of material off both. All the holes line up. Thinking the reverse swap "should" work no problems. The S4 pump and housing is inferior though. Why would you want to make the swap?

 

Actually, my interest is in the thermostat housing, not the pump housing. The thermostat housing is the component that bolts to the top of the engine and onto which the top radiator hose is clamped.

The S5 thermostat housing is made of some composite which, when subject to the high-heat of the rotary, becomes brittle and likely to fracture. As a matter of fact, if it weren't for JB Weld, I'd be in trouble right now.

Thanks for everyone's responses, but I still haven't been able to get a definitive answer. Does anyone else out there know for sure about this housing compatibility?

 

No. Those do not interchange. One uses two bolts the other uses three. If you want to use the older neck you'll have to change the whole pump housing.

 

The series4 neck is held by 2 bolts while the series5 neck is held on by 3 bolts. You can probably get away with using the series4 water pump housing but I'm not sure if it will bolt up correctly to the series5 front cover.

 

My post is for the waterpump housing. S4 waterpump assembly doesn't *IIRC* bolt up to an S5 Front housing, due to a change in the shape of the front cover.

 

Thanks for your help guys.