Mercuriser 5.7 1989 circulating pump

[hairchef]

There is a big square nut on top of my circulating pump on my 1989 Mercruiser 5.7. What is it for? Also cound I take it out and feel inside or look inside?

 

[wellcraft-classic210]

Re: Mercuriser 5.7 1989 circulating pump

I thinks the plug is for an automotive application with a heater hose (but not 100% certain)

If you can remove it you can defintley look inside// Not sure how clear the view of the impeller is though. It may be tough to remove if its rusty. Use a thread sealer when you reinstall it.


Are you trying to troubleshoot something?

 

[hairchef]

Re: Mercuriser 5.7 1989 circulating pump

Always. Overheating at rpm's like a lot of posts. New impeller, new thermostat, did the clear hose thing and was fine.So next on list is check cooler,circumating pump and then compression check and please don't be that. Thanks

 

[Bondo]

Re: Mercuriser 5.7 1989 circulating pump

Always. Overheating at rpm's like a lot of posts. New impeller, new thermostat, did the clear hose thing and was fine.So next on list is check cooler,circumating pump and then compression check and please don't be that. Thanks

Ayuh,.... Welcome Aboard,... Water has to be able to get Out, as well as Into yer motor,...

Pull the risers, 'n look for restrictions...

That plug is just a return water port for a heater, or whatever...

 

[hairchef]

Re: Mercuriser 5.7 1989 circulating pump

I'm going to check oil cooler first and then check my thermostat I'm 99percent sure I did it right but no harm in checking. The T stat balls and springs seemed ok from what I know but while have you guys here I'll ask what kind of tension should they have they only have enough to keep them closed very lightly and the hoses are cool when engine is hot so I think they working right. My mechanic says usually fins from old impellers usually flow right through because of amount of presure and the water coming through bell housing is good so I was thinking the oil cooler would be next place and then just keep going. The one thing I hope it is not is head gasket, but I will do pressure test after checking for old fins first. Does this all sound right guys. Thanks alot for all your help I'm just trying to do what I can before it goes beyond me and back to marina. This forum is a great help. Thanks