'89 88HP Evinrude Overheating

[FreeBeeTony]

I recently bought a '89 88HP evinrude and have found that the engine overheats. I replaced the impeller and housing. I think the thermostats are bad or the water passages are clogged. The telltale is intermittent (on and off) and there's water coming out where the lower unit meets the rest of the engine. It gives me the impression that the water is not making it up to the top of the engine and is being forced out of the lower unit. Does this sound like the correct diagnosis? I have looked at where the thermostats are located and it looks like the bolts are difficult to get at! I believe this is a cross-flow engine. Is it possible that its just clogged? How can I flush it out if the water doesn't flow? I tried to leave it running to see if it would clear out but it started to get too hot.<br /><br />HELP!!!!!

 

[Dhadley]

Re: '89 88HP Evinrude Overheating

Did you by chance use a Sierra kit?

 

[FreeBeeTony]

Re: '89 88HP Evinrude Overheating

I believe the kit was a Sierra...why?

 

[Dhadley]

Re: '89 88HP Evinrude Overheating

They have had some major issues with their pump kits the last two years. Dont overlook the pump just because its been replaced. It may not be a problem but you may want to get a kit from a J/E dealer and try that. At the worst you will have a spare kit and can use it next time.<br /><br />The thermostats can be serviced but as you said its not real easy. Its not hard but it takes a little patience especially if the bolts are rusted or stuck.<br /><br />You can by pass the thermostats by removing the hoses and putting longer ones on and letting them discharge out over the rear of the motor to test. You will have to restrict the flow to about 1/2 the hose ID. You should have equal water coming out both sides when its under a load and above 2500 RPM. <br /><br />Another thing to look at is the head gaskets and deflectors. If the deflectors are swollen and out of place it can cause an overheat also. A leaking head gasket will allow exhaust into the cooling system and cause an overheat too.<br /><br />Anytime I buy a used motor I like to service the 3 main parts to the cooling system. Pump (complete), head gaskets (including deflectors -- 4 of 322411) and thermoststs (Aqua Power #409 if you can still find any AP stuff) and then go test.<br /><br />Good luck!

 

[FreeBeeTony]

Re: '89 88HP Evinrude Overheating

So........if I bypass the thermostats and water does not come out ok I should take off the heads and check the position of the deflectors......is this right?<br /><br />I have a feeling that the guy I bought the motor from had some work done and it wasn't done correctly. When I replaced the water pump there wasn't a gromet on the water tube and one of the o rings seemed to be in the wrong spot. I am wondering if he had the thermostats replaced by the same person.<br /><br />If the water does come out when bypassing the thermostats I am going to attempt replacing them.<br /><br />Thanks for your help........

 

[DJ]

Re: '89 88HP Evinrude Overheating

FreeBee,<br /><br />That is correct. The thermostats simply stop the water flow FROM the heads. When they open they allow water to be dumped into the exhaust housing. Thus you get flow through the block and heads. When they open you'll see water coming out of the holes at the top of the exhaust housing.<br /><br />I had bad stats on my 90 (same engine). I had two clues. 1. The right cyl. bank would not heat up. 2. There was consistant spray from the holes at the top of the exhaust housing with a cold engine.

 

[FreeBeeTony]

Re: '89 88HP Evinrude Overheating

I bypassed the themostats: Should I see water coming out between the lower unit and the rest of the engine? Even after I bypassed the thermostats there was water coming out of where the lower unit meets the rest of the engine. I would think there wouldn't be much back presure on the pump if the thermostats were bypassed. Water was coming out of the heads but not with as much force as I expected. How can I tell if the water tube is clogged? How long does it take for the thermostats to open? Right now I think I have to replace the thermostats. When the engine is first started and the thermostats are closed, where does the water go? I assume its not backed up to the pump. I have not seen ANY spray out of the holes at the top of the exhaust housing. Should there be water coming out of the prop? I still need help....should I remove the heads? Where should the deflectors be and what do they look like? Any pics? Can I send you pics?