Chronic overheat 1990 150 XP Evinrude

[lizardo]

My 1990 150 XP Evinrude has been giving me a fit for 3 yrs. After about 3 minutes at 3/4 throttle it overheats. I have taken heads off, cleaned the water passages, taken the exhaust cover off, cleaned the passages, replaced the impeller and pump housing, replaced thermostats and bypass valves, flushed it with hose through the water pickup pipe, flushed with saltaway numerous times, replaced voltage regulator -- all this with no improvement. There is a strong tell-tale and the engine shows overheat symptoms when the alarm sounds. The heads are too hot to touch. This engine has always been used in the ocean in Mexico. I need some ideas of what more I could try before I sink it! Thanks for any you might have.

Dan

 

[Dhadley]

Re: Chronic overheat 1990 150 XP Evinrude

Have you changed the deflectors?

 

[ezeke]

Re: Chronic overheat 1990 150 XP Evinrude

Did you replace the water passage deflectors?

Is the water pump vent hole clear?

Water intake screens in good condition?

Is the motor mounted too high so that air can enter the water intake?

 

[SparkieBoat]

Re: Chronic overheat 1990 150 XP Evinrude

also have you checked the motor temp manually to make sure it really is over heating???

 

[ezeke]

Re: Chronic overheat 1990 150 XP Evinrude

If, as he says, the cylinder "heads are too hot to touch", the engine is overheating. You should be able to hold your fingers to the cylinder head for a three count (but no more) any time the engine is running.

 

[SparkieBoat]

Re: Chronic overheat 1990 150 XP Evinrude

I use to know a guy who checked his smoker like that..man he could cook up a storm with that smoker.

 

[lizardo]

Re: Chronic overheat 1990 150 XP Evinrude

Did you replace the water passage deflectors?

Is the water pump vent hole clear?

Water intake screens in good condition?

Is the motor mounted too high so that air can enter the water intake?

Have to admit that I know nothing about deflectors. Need to find more info on that and will check the other items you mentioned.

Thanks

 

[james65]

Re: Chronic overheat 1990 150 XP Evinrude

could be seized up rings on some or several pistons causing friction on cylinder bores thus causing o/heating ?. hows compression? try several d/carbs with sea foam. and see if comp. improves, and o/heat problem.

 

[emdsapmgr]

Re: Chronic overheat 1990 150 XP Evinrude

Would be interesting to connect a 0-30 lb water pressure gauge to the end of the telltale hose and check the pressures both at idle and at full speed. That might help with your assessment of what is going on. Should idle around 6-8 lbs and maybe as high as 18-20 at full throttle. You'll have to pull both heads to check the deflectors. They are cheap, might just plan on replacing all of them when the heads are off. In your original statement, you said you had the heads off an "cleaned the water passages." Did you mean that you had the head covers off and that the heads were cleaned, or were you referring to the passages in the powerhead? If you have not had the head covers off, you need to pull them and inspect.

 

[ENSIGN]

Re: Chronic overheat 1990 150 XP Evinrude

You may have a corroded or cracked water tube.The water pressure gauge is a real good idea,Use a piece of clear hose it may be sucking the exaust. I once had a yamaha that overheated only when making left hand turns.Go figure.I hope this helps,Ted

 

[ezeke]

Re: Chronic overheat 1990 150 XP Evinrude

Have to admit that I know nothing about deflectors. Need to find more info on that and will check the other items you mentioned.

Thanks

Click the thumbnail to see the positions of the starboard water deflectors. In this case the upper two deflectors have caused the flow of water to be blocked on the sides. The water passage deflectors should be replaced and the passages cleaned.

 

[SparkieBoat]

Re: Chronic overheat 1990 150 XP Evinrude

nice pic there Ezek...like they say a pic is worth 1k words.

 

[lizardo]

Re: Chronic overheat 1990 150 XP Evinrude

Actually I believe the deflectors are not present at all. A mechanic a couple of years ago told me he did not think they would contribute to the overheating -- maybe not correct?

Motor mounting doesnt look too high. Intake screens a bit ragged but clear and intake vent hold is clear.

 

[lizardo]

Re: Chronic overheat 1990 150 XP Evinrude

Can you advise how to remove the water tube? Is it a press fit?

 

[lizardo]

Re: Chronic overheat 1990 150 XP Evinrude

could be seized up rings on some or several pistons causing friction on cylinder bores thus causing o/heating ?. hows compression? try several d/carbs with sea foam. and see if comp. improves, and o/heat problem.

I need to do a compression check shortly to see about that possibility

 

[lizardo]

Re: Chronic overheat 1990 150 XP Evinrude

Would be interesting to connect a 0-30 lb water pressure gauge to the end of the telltale hose and check the pressures both at idle and at full speed. That might help with your assessment of what is going on. Should idle around 6-8 lbs and maybe as high as 18-20 at full throttle. You'll have to pull both heads to check the deflectors. They are cheap, might just plan on replacing all of them when the heads are off. In your original statement, you said you had the heads off an "cleaned the water passages." Did you mean that you had the head covers off and that the heads were cleaned, or were you referring to the passages in the powerhead? If you have not had the head covers off, you need to pull them and inspect.

Head covers were off and passages cleaned and inspected. Thanks

 

[lizardo]

Re: Chronic overheat 1990 150 XP Evinrude

That is a great picture. I see exactly where deflectors were but none are present

 

[ezeke]

Re: Chronic overheat 1990 150 XP Evinrude

Actually I believe the deflectors are not present at all. A mechanic a couple of years ago told me he did not think they would contribute to the overheating -- maybe not correct?

Motor mounting doesnt look too high. Intake screens a bit ragged but clear and intake vent hold is clear.

The mechanic is wrong.

The water intake screens are necessary to maintain the correct pressure and more importantly, to prevent small particles from passing into the cooling system which will block the thermostat system and prevent it from functioning.

 

[Dhadley]

Re: Chronic overheat 1990 150 XP Evinrude

Put the deflectors in and go from there. 322411 is the part number. Let us know how it goes. It'll be interesting to see if your mechanic buddy knows more than the engineers. Maybe he does, we'll see.

 

[cajuncook1]

Re: Chronic overheat 1990 150 XP Evinrude

Put the deflectors in and go from there. 322411 is the part number. Let us know how it goes. It'll be interesting to see if your mechanic buddy knows more than the engineers. Maybe he does, we'll see.

Is the purpose of the deflectors to maintain unidirectional flow around all the cylinders and drain out at completion at the other end?? When someone stated that cleaning the water passage ways, does that meaning a manual scraping around the jackets??

Sorry, I have no intentions of hijacking this thread, but since it is somewhat relevant to subject at hand I thought I would ask. It is funny, but none of the service manuals that I have purchase, discuss water deflectors or maintaining patency of the water passage around the heads.

Pardon the interuption Lizardo.