overheating

[Dillonracing49]

I have a mer cruiser 3.0 I have replaced the impeller and took the thermostat out and I was on the lake for 6 hours and all of a sudden them temperature gauge went sky high when I’m at lower rpms it doesn’t get hot when I’m at higher rpms it gets hot but not all the time! Does anyone have any clue to what’s going on? Thanks!!?

 

[Bondo]

Ayuh,..... Welcome Aboard,..... Put a t-stat back in it,.....

Did ya find All the pieces of the ole impeller,..??

Lost impeller bits usually hang at the t-stat, but ya took it out,.....

 

[Dillonracing49]

Found out the exhaust manifold was trashed and waiting on new parts to come in I pray my boat will not get hot again!!! Got all new parts on the way! New riser new therm stat everything I hope this works!!

 

[TyeeMan]

If you properly installed your t-stat, you know your new impeller is/was installed properly and you're still getting hot at low and high rpm's, check your water supply hose, the shorter one outside the boat between the out drive and the transom shield. The hose could be kinked causing water starvation.

Or you still have chips and pieces of the old impeller floating around someplace.

Had that same problem on a 3.0L I had some years ago. The dealer I bought it from replaced the water supply hose but didn't know they needed to cut it shorter. So when the outdrive was all the way down or slightly trimmed the engine heated up. It would cool down to the proper temp when the boat was on plane, , probably enough water pressure to force water past the kink.

 

[Dillonracing49]

Well I got my new exhaust manifold here and I don’t know what year my engine is man I don’t know where to find it at I believe it’s a 1996 if I’m not mistaking but the gasket for the manifold is a little different. I’ll have to cut some of the holes out bigger on the gasket I think they might have sent me the wrong gasket man and I will check the line I don’t know where it is exactly but I’ll look

 

[thumpar]

Engine serial number can be looked up to find the year.

 

[Dillonracing49]

where do I find that at,?

 

[thumpar]

Should be on top of the engine. If not there try to find the tag down by the starter.

 

[Dillonracing49]

Everyone I ordered a new exhaust manifold and it came with a drain for the exhaust my old one didn’t have one what do I do???

 

[Bondo]

and it came with a drain for the exhaust my old one didn’t have one what do I do???

Huh,..??..??

 

[TyeeMan]

Are you talking a water drain? It better have a water drain. Buy a plug for it if it didn't come with one, install the plug for when the boat is in use, remove the plug and drain water for winter layup.