496 mag slowly heating up

[Hagan]

Trouble is on the horizon. Have a 99 baja outlaw sst with a 7.4 L 496 mag merc with an alpha 1 out drive. Bought two years ago with a new impeller at that time. Ran 170 last year. Have taken it out twice this year. Ran 175 on the first trip. Got up to 180 on the second. Cooled down at idle the first time. Not so quickly the second time. I did notice one riser is running hotter than the other. Anyone have any idea where to start?

 

[Bondo]

Re: 496 mag slowly heating up

Trouble is on the horizon. Have a 99 baja outlaw sst with a 7.4 L 496 mag merc with an alpha 1 out drive. Bought two years ago with a new impeller at that time. Ran 170 last year. Have taken it out twice this year. Ran 175 on the first trip. Got up to 180 on the second. Cooled down at idle the first time. Not so quickly the second time. I did notice one riser is running hotter than the other. Anyone have any idea where to start?

Ayuh,.... That's an odd combination,....

Change the Impeller,... that's Always the 1st thing to do in Any overheat situation,...

 

[emilsr]

Re: 496 mag slowly heating up

Ayuh,.... That's an odd combination,....
.

That's what I was thinking; probably handles funny with a 7.4 on one side and a 496mag on the other.

 

[Hagan]

Re: 496 mag slowly heating up

Changed impeller today. It was complete and looked impeccable. So, I'm guessing no blockage anywhere either. What now? Bondo, I may be missing something but one engine. 496 mag 7.4 L engine. As always any help is appreciated.

 

[Hagan]

Re: 496 mag slowly heating up

Sorry, emilsr, one engine.

 

[Hagan]

Re: 496 mag slowly heating up

May have sucked up sand in shallows of the river. Was going to flush it out today but not sure where to begin with this. Again, any help would be appreciated.

 

[emilsr]

Re: 496 mag slowly heating up

Sorry, emilsr, one engine.

Where I was going with that is there is a 7.4L (454 cu in) and a 496 mag (8100 in GM vernacular, or 8.1 liters). 2 very different engines. You also mentioned that you have an Alpha drive which was briefly used behind the 7.4 in the late 80's but never behind the 496. A '99 model Baja would have come with a Bravo behind a big block.

I was just confused. Bond-o's advice is correct for either motor (or either drive) though. Carry on. :usa2:

 

[Hagan]

Re: 496 mag slowly heating up

It is a bravo 1*red face*. Anyway flushed it out but didn't remove any blue plugs where sediment might b built up(info from what I read on other threads). Any ideas where they r and what to possibly check next?

 

[Bondo]

Re: 496 mag slowly heating up

It is a bravo 1*red face*. Anyway flushed it out but didn't remove any blue plugs where sediment might b built up(info from what I read on other threads). Any ideas where they r and what to possibly check next?

Ayuh,...Where do ya go boatin',..?? Sweetwater, or Brine,..??

If yer gettin' any blockage, I'd think the riser/ manifold junction would be suspect,...
Especially if yer boatin' in Brine,...