200 Merc heating up at Idle and slower speeds

[rhinomerc422]

I have a '89, 200xri. I took it out for the first time this season yesterday. When it is idling or or going any less than WOT it is heating up rather quickly. I replaced the impeller last season mid way through. The tell tale seems to be spitting fine all the way through the rpm spectrum. Took the T-stats off today and checked them in boiling water, they seemed fine. I just need a starting point. Should I replace the impeller again just to be safe? What else should I be checking? Any suggestions would be awesome. Thanks!

 

[Barnacle_Bill]

Re: 200 Merc heating up at Idle and slower speeds

Yes, you need to pull the L/U and check the impeller and woodruff key it slides on. Also check for any obstructions while you have it down. Tell tale should be doing more than just spitting.

 

[gss036]

Re: 200 Merc heating up at Idle and slower speeds

I agree with the above post and I would suggest that you take a look at the poppet valve while you are working on the engine. The poppet usually has nothing to do with low rpm overheating, but still take a look just to be safe. If it is stuck completely open then the water flow might be enough to let the water bypass the heads and flow out the exhaust. A water pressure guage would be nice to check the pressure.

 

[rhinomerc422]

Re: 200 Merc heating up at Idle and slower speeds

I have a pressure guage it reads about 15 lbs at WOT and 2 at idle. Thank you for your replies so far!

 

[vaboatdoc]

Re: 200 Merc heating up at Idle and slower speeds

id drop the l/u and check the gaskets under the upper and and lower water pump housings. ive seen several of those overheating not because of the impeller but because of the gaskets being blown out. if you replace those make sure to use the magical peanut butter!!

 

[rhinomerc422]

Re: 200 Merc heating up at Idle and slower speeds

Peanut butter?? do tell! Ok...I just got to the impeller. It seems fine, No wear. and still has elasticity. Is eying it a good indicator? Gaskets maybe? Or just replace the entire pump? housing and all?