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iron-b

My 1989 evinrude 200hp is giving me an overheating alarm only when I try to plane the boat at high speed. I can troll all day with no trouble. It has a new water pump kit,and the telltale is pissing pretty good. the thermostats look a little questionable so they will be replaced, what else could this be, I need help I want to fish,but don't dare until thiss problem is resolved. I haven't taken the water channel covers off the heads yet,but don't know if I should because I get good flow from the telltale. also the only two constant alarms according to the manual are fuel flow restriction and overheating. silly question but could bad fuel flow cause overheating??? HELP!

dbaker

I have the same issue on one motor.... I run merc's.

I have yet to get into it but I did change out the stats with no improvment.

I think I've got a bolckage someplace... I haven't done a water pump in a while so I will go after that next..... it's driving me nuts.

it won't overheat at the dock so I've got to get it down the river to open it up only to find out I've got to head back in.... Keep me posted.
I'll post anything I find out

Greene

On the old rudes and johnsons, the water coming out of the tell-tale doesn't go through the cooling system first. So it's really just a test of whether the water pump is working or not.

Now as to the problem. Replace the tstats since they are old and "questionable", but I doubt they are the cause be the tstats would have open and closed many times during your long idling periods.

It could be the pressure relief valve (sometimes known as a poppit valve). The system consistest of a poppit valve, spring, and grommet. When the water pressure gets high enough at higher RPMs, the water pressure overcomes the spring and water is dumped out of the block directly into the exhaust. If the poppit doesn't open, then you'll overheat at higher RPMs. Just in case others are watching, a poppit that doesn't close fully will cause overheating at idle speeds.

Your overheat problem could also be caused by swollen water deflectors, located under the water jacket head. I'd start with the tstat and poppit because the odds are in your favor for breaking some bolts when trying to remove the heads on a 1989 motor. Becareful removing the bolts for tstat and poppit valve housing as well.

Good luck
andy

jpinheiro33

If it isnt too hot when touch you it (and it says your overheating) isnt overheating definitely a wiring or gauge/sender problem.

jpinheiro33

If it is hot your problem may also be that when you or whoever installed the waterpump you didnt install the copper tube off the waterpump housing correctly there is a rubber peice on the waterpump housing that the tube goes into that sometimes gets kinked so to speak and restricts flow. Ask me how i know

JackSpina

THE SENSOR ON THE HEAD MAY GIVE YOU FALSE INDICATIONS

82hydrasport

dbaker did you figured your problem out yet? i had this same problem on my motor. i could idle all i wanted but when i got the motor up to cruising rpm's 3500- around 4800 the motor would overheat. i did find if i ran wide open it wouldn't overheat. i tried changing everything in the cooling system and it didn't work. come to find out it was a bad head gasket.

Scup

I am not a mechanic, but I do remember reading about a procedure for checking the temperature of an engine head independently of any electronic indicator. There are wax crayons available that can be purchased for just about any temperature range of interest. The way they work is you make a mark on the head at a point, or points, with the crayon for which the maximum temperature is to be determined. Run the engine and observe the wax mark. If the wax melts, it has reached the temperature indicated on the crayon.

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iron-b

I found the problem was a stuck thermostat on the port head, i removed and replaced voila! thanks for the advice guys.

dbaker

Thats kind of what I'm thinking.. head gasket.

I'm going to swap out the poppit first... cheep part easy fix and I can do it the water. I hope for some weather on Friday to get it done.

If that doesn't do it I will have to pull the boat. then I'll do the water pump, pull the heads check for cracks and do the gaskets.

Keep you posted