masi242

My 87 242 has the dreaded 454/alpha combo I have not had any problems yet. But one thing that I can not handle is my temp gauge goes up after a short run. It happens when you come off plane and shift into netural it heads toward 180+, at that point I give it a little gas and it comes down slowly. I talked to my shop and he said this engine combo would benefit from a raw water pump. My impeller and thermostat are new.


They don`t seem to had to install,I will assume I am not the only one with this.Any feed back would be great

Thanks

mark

ThirdBird

You already have a raw water pump. It's located in the lower unit. Sounds like you just need a new impeller.

ThirdBird

Re-read your post - you say your impeller is new. It still sounds like a bad impeller to me. Could it have been run dry for a short time? Doesn't take much time to degrade an impeller.

I still don't get the thing about benefitting from a raw water pump. As I said above, you already have one. Do they mean you should try an engine-mounted pump like a Bravo? If so, there won't be any appreciable flow advantage from that.

??????

selpel

Could it be a restriction in the engine mounted circulate water pump age has maybe clogged the water ports.

ThirdBird

If that were the case, it would heat up speed when more flow is needed.

masi242

Third, That is what I was thinking about a pump mounted to the engine block. I will change the impeller first and go from there. My shop said this was one of the many reasons way the alpha is not a good choice for a BBC.

Thanks

ThirdBird

OK, I got what your saying now. But, I don't believe the raw water supply of an Alpha is any less adequate than that of a Bravo. I think the only reason the pump was ever moved from the drive to the engine-mounted location on a Bravo is that the Bravo is heavier-duty and there was insuficient room in the Bravo case to include a water pump. Could be wrong but that's what I understood. We could post this question over in the Tech/Drives section, I'm sure someone knows.

mopower

Bravos have the pump inside because they shift in the upper so in neutral the vertical shaft is not turning and would cause overheating. Alphas shift in the lower gearcase.

ThirdBird

Aha, thank you.

RaggedEdge

The Alpha is basicaly a crash box, has an ignition interupt switch that cuts out the engine for nano-second when shifted. The water pump is a similiar impeller in a cup deal, and sits in the top of the lower unit case, spun by the vertical shaft.
My 32 Pachanga had a 454 Alpha set up, one converted to counter rotation, and it worked fine for some 550 hours over six years.