I have a 1987 GXL that I purchased with a bad engine. I have torn the engine down and completely cleaned every component. Upon examination of the intermediate housing I discovered that it does not have a rectangular hole for the heat riser which I know the 89-91 engines have plugged and the 86-88 don't.

Are there any other tell-tale signs that this engine is a 89-91? Any indentifying numbers or markings? Would it have been possible for an 87 manufactured in 4/87 to have a housing that looks like one from a 89-91? Just leads me to believe that the engine may have been swapped at some point although it didn't look like it when I pulled it. Thx.

 

If you have the short block apart, then you can just look at the rotors. The indentation will be machine finished on the S5 and rougher cast on the S4.

 

Thanks. I should have done a search first on this subject... sorry all. The indents are rough cast and by my search the oil sending unit has fine threads which is also on the S4... which mine has. Looks like it's an S4 but that difference in the heat riser is very strange. Oh well!?!?!

 

if the housings have stamped build location on the top (hiroshima) then they're s4

 

Is there anything to identify the specific year on these motors?