Overheating

[DaveLeonard]

I have a 98 Capri with a 3.0 Mercruiser. It overheats. I changed the impeller and thermostat. I ran it on the trailer with the earmuff on. Water came out the prop, I think that is what should happen. I also seems to overheat faster with the prop engaged vice just reving the eng (in water, not on trailer)

Any thoughts???

 

[Howard Sterndrive]

Re: Overheating

if you putt around at idle does it overheat? or just running on plane at higher rpm?

if the latter, impeller housing probably sucking exhaust- Gen II alphas like to do that. tricky to get that impeller housing sealed completely

 

[cr2k]

Re: Overheating

Can you hold your hand on the exhaust when warmed up? Temp gauges on boats are known for bad reading. Get an IR temp gun and aim at the base of the thermo housing where it mates with the block.

 

[Rocky_Road]

Re: Overheating

I have a 98 Capri with a 3.0 Mercruiser. It overheats. I changed the impeller and thermostat. I ran it on the trailer with the earmuff on. Water came out the prop, I think that is what should happen. I also seems to overheat faster with the prop engaged vice just reving the eng (in water, not on trailer)

Any thoughts???

What are we talking about in degrees?

Most 3.0L's run just above 175....

Happy boating!

 

[DaveLeonard]

Re: Overheating

It is not a bad reading, it's hot. it will het 250 deg and smoke. Idle and high RPM both overheats. I can drive around with just enough RPM to keep in moving and it will overheat. The sucking exhaust issue amy be right. I just replaced the exhaust bellows(rubber hose from outdrive to the eng.). How do I check/fix it?

 

[flashback]

Re: Overheating

Did your old impeller come out in one piece? if not, you may have a chunk of impeller blocking the water flow........

 

[DaveLeonard]

Re: Overheating

The old impeller looked fine to me. Also the hoses on both sides of the thermostat feel hot.

 

[triggmarine]

Re: Overheating

check the water hose on the port side of the drive to make sure it is not rotted. it may not over heat on the hose and at idle but on plane it could leak

 

[Volphin]

Re: Overheating

Do a compression test and make sure you have not cracked the head or blown a head gasket.

HTH

V

 

[Bt Doctur]

Re: Overheating

when was the riser changed out

 

[DarrinT]

Re: Overheating

Cracked the head on a Mercruiser 140 (3 L) after changing the impeller and the engine still overheated. The bits of the old impeller were hiding in the bottom of the outdrive water intake where I didn't think to look.(bonehead) Those four small bits of rubber would intermittently clog the intake causing an occasional overheat condition until finally they jigsawed themselves together to totally clog the outlet pipe from the pump and being in the wilds of Georgian Bay with the kids at the time I badly overheated her and wrecked the head to get back to shore.

 

[averagejoe71]

Re: Overheating

when was the riser changed out

Was having the same problem. Pulled my riser elbow off and looked terrible, clogged pretty good. Have it ordered, think I will wait till winter to do the manifold, it doesnt look near as bad as the elbow. Same problem, new impeller and thermostat, overheated still. Only costs you a few dollars for a new gasket to pull the elbow off and take a look in the water jacket. If your not sure how it works, the water goes around the exhaust on that elbow and meet at the first boot into the first pipe down from the elbow. When you changed your impeller how did the coupling look that couples the tube to the impeller housing? Mine was burnt and the boat shop guy told me that is a tell tell sign of it clogged, not enough water cooling the exhaust before it gets down to the drive, also the bellows burnt/blown open.

 

[DaveLeonard]

Re: Overheating

After reading the last fewpost, I guess I am puller the riser in the morning.