View Full Version : Engine overheating at idle

05-23-2005, 02:13 AM
I have an '87 Prostar and my engine overheats at idle. The risers are super hot to touch....is that normal? Once I start to move the temp drops back to normal. I replaced the impeller, the Thermostat and hoses thinking there may be something caught in there but found nothing and I still have the overheating issue.
I took it in to the local dealer and they are recommending that I replace the manifold and the risers which is going to cost me lots of $$$. Any other areas to trouble shoot? Can the risers and manifold be refurbisher or do they need to be replace. Right now I have my doubts about the full replacement. Ideas would be appreciated.


05-23-2005, 11:05 AM
Manifolds cannot be refurbished. They corrode from the inside ->out.

I highly doubt your manifolds are causing an issue though. I would be check for a retriction very carfully on the inlet side of the cooling system.

05-23-2005, 11:07 AM
Sounds like a raw water intake issue....search for overheating threads

06-20-2005, 10:29 AM
This often happens after a boat eats a rubber impeller, the bits of rubber get in the system a cause clogs. My 89 PS190 did the same, I took the risers off and ran flexible copper wire through the water passages while banging with a rubber mallet, did the same with manifolds but did not remove them from the boat. Temp went back to normal, although I did not find any noticable debris.

Hoosier Bob
06-20-2005, 10:36 AM
I know you said you replaced the impeller but was this recent? Sounds like the impeller if all circulates fine underway. I believe the impeller is all you have at idle. They can get cut up very quickly by debris. also check your scoop under the bottom, mine actually broke apart and sent small brass fragment into the impeller destroying it.
Good luck!

06-20-2005, 11:10 AM
I've run into this issue more than once. The first was a worn impeller, changed it and all worked great. The second time, I had debris (weeds, grass, etc.) at the "screener" which is located by taking off the hose that comes up from the pickup and heads back down into a cylinder looking adapter. This adapter piece has a screen inside of to help prevent debris going through the system. Just take a flathead screwdriver and loosen the hose clamp and pull off to inspect. Hope this helps.

east tx skier
06-20-2005, 11:30 AM
Don't forget to check the screen in the transmission cooler.

06-20-2005, 11:50 AM
You should be able to put your hand on the riser. If it's to hot to touch somethings up. I agree pop the risers off and shine a light in there and see if there is a clog. A riser gasket is only $5.