Temperature of exhaust risers

[High Bidder]

I got my boat out today(1993 5.0 OMC IO) and installed my spare outdrive to test it. It ran great after I changed the outdrive water pump housing.( lesson learned, when installing a new impeller also use a new housing). The risers were cold until the thermostat opened and then they got pretty warm, too hot to keep your hand on it. How hot should they get? Last year I borrowed an infared heat gauge they registered about 170 degrees. Is that about correct? I had replaced one riser that ran hotter last year and removed and cleaned the other one. The engine temp stayed between 165 and 160 degrees so the T stat is working.

Thanks

High Bidder

[BullGator]

The risers will be slightly warmer than engine temperature. As the hot (160-180) water rises up through the thermostat housing, it is directed to the manifolds. There it is heated slightly more by the exhaust. So they typically end up about 180-190 degrees. (Assuming in good shape, minimal scale inside) This has been my experience with Mercruiser and Volvo-Penta setups.....would imagine its basically the same for your OMC.

[High Bidder]

Thanks, I just wanted to be sure they weren't getting too hot. I appreciate your response.

High Bidder