1989 70 hp Evinrude Overheating:

[TwoRivers]

Over the past winter I replaced the water pump and fuel pump on my1989 70.
Both pumps are OEM.
The original fuel pump was a bi passed vro replaced with non vro pump.
Changed all the fuel lines.

Compression is 120 across all cylinders.
Good spark. Motor is peeing strong. I removed tstat and checked in hot water.
Motor starts instantly and runs well at low rpm’s. Get up to or over 4k and shortly the steady overheat horn goes off and motor dies down.
I’m thinking it’s leaking air somewhere?
When the overheat horn goes off I check the top of the motor temperature with a surface thermometer and it’s hot. Around 172.
When I pull the plugs it looks like number 2 cylinder is running lean.
I pulled the main jet from number 2 carb it didn't appear to be dirty but I cleaned it anyways.
At idle when I spray carb cleaner around the #2 carb gasket the motor will stumble. I've ordered new carb gaskets.
I've gone over the fuel lines and none appear to be leaking fuel or air.
I relocated the tell tale to the top of the engine years ago. My new water pump kit included two plastic elbows for the tell tale. One has a larger orifice that the other. The one I've been using appears to be the larger one. Does it matter which one I use? Could it be an issue?
Any ideas how to troubleshoot?
Could it be something other than an air leak?
Thanks in advance for your consideration.

 

[cwella]

The lean #2 plug and carb cleaner test are the biggest clues. It sounds more like a fuel/air issue on #2 than a cooling problem.

I would start with:
• Replace the #2 carb gasket since spraying it affects idle
• Check #2 float height, needle/seat, and all internal carb passages
• Verify the main jet size matches the other carbs
• Inspect reeds if the carb repair does not fix it

The tell tale elbow size is unlikely to cause this; it only shows water flow, not full cooling system performance.

Also check the water pump installation, water tube seals, and cooling passages, but fix the lean condition first. Running lean at 4000+ RPM can quickly damage a 2 stroke.

 

[TwoRivers]

The lean #2 plug and carb cleaner test are the biggest clues. It sounds more like a fuel/air issue on #2 than a cooling problem.

I would start with:
• Replace the #2 carb gasket since spraying it affects idle
• Check #2 float height, needle/seat, and all internal carb passages
• Verify the main jet size matches the other carbs
• Inspect reeds if the carb repair does not fix it

The tell tale elbow size is unlikely to cause this; it only shows water flow, not full cooling system performance.

Also check the water pump installation, water tube seals, and cooling passages, but fix the lean condition first. Running lean at 4000+ RPM can quickly damage a 2 stroke.

Thanks for your reply.
New gaskets came in today. I'll install tomorrow and try to take the boat out for a spin.
What do you think about timing?
My motor calls for 19 degrees BTDC.
Either 1990 or 91 they changed to 17 BTDC.
Was there a SB regarding changing the 1989 model timing?
I agree with you that it's not a cooling issue.

 

[TwoRivers]

Removed the carbs and the intake.
I can see light through the reeds on all three assemblies.
Nothing broken, some more light shines through than others and number two assembly looks to have the biggest gap with a little warp (maybe?)
Also, I'm getting some raw fuel in the airbox?
Questions: Does seeing light through the reed assembly automatically indicate that the reeds need replaced?
Would small gaps with light shining through cause an overheat condition?
thanks

 

[flyingscott]

Is the water pump mod done? The water pump mod was because of Cylinder #2 issues. Do you have a 3 vane or 6 vane pump in it?

 

[Mc Tool]

A bit of light showing thru the reeds is ok ....to a point , if theres a ½ ish mm gap under the tip of the reeds I wouldnt loose any sleep . Big thing is as long as they are not visibly bent ( creased ) or split or any other visible damage they are ok .
A wet inside of the air box isn't unusual , at some point in the rev range there will be a bit of spitting back and its most likely a film of residual oil making it look wet ...again dont loose sleep over it . If , for example you had a broken reed there would be continual spitting back of a lot of fuel ....the damaged reed in one cylinder would be carried by the other two cylinders ....so much so that if it was a single cyl motor it wouldnt run at all .
One thing to check is that the flange surfaces of the carbs are flat ( where they bolt up to the motor ) if someone has over torqued the mounting it can bow those flanges ....not the end of the world ...just reface them with a sheet of medium grit sandpaper on a flat surface.

 

[TwoRivers]

Is the water pump mod done? The water pump mod was because of Cylinder #2 issues. Do you have a 3 vane or 6 vane pump in it?

Thanks for your response.
New OEM water pump installed with 6 vanes. Tell Tale moved to top of engine.
When I had the lower unit and tstat removed I blew compressed air up through the water tube, down the tstat opening and up the tell tale hose.
I ran a zip tie up through the idle relief holes to make sure nothing was blocked.
Everything seemed clear.

 

[TwoRivers]

A bit of light showing thru the reeds is ok ....to a point , if theres a ½ ish mm gap under the tip of the reeds I wouldnt loose any sleep . Big thing is as long as they are not visibly bent ( creased ) or split or any other visible damage they are ok .
A wet inside of the air box isn't unusual , at some point in the rev range there will be a bit of spitting back and its most likely a film of residual oil making it look wet ...again dont loose sleep over it . If , for example you had a broken reed there would be continual spitting back of a lot of fuel ....the damaged reed in one cylinder would be carried by the other two cylinders ....so much so that if it was a single cyl motor it wouldnt run at all .
One thing to check is that the flange surfaces of the carbs are flat ( where they bolt up to the motor ) if someone has over torqued the mounting it can bow those flanges ....not the end of the world ...just reface them with a sheet of medium grit sandpaper on a flat surface.

Thanks for your response.
Thinking about it, I agree with your assessment.
Since I have everything apart, I'll put a new set of reeds in and check the carb flange surfaces.
Not sure where to look next.
I'm thinking head gasket but I did another compression test after the latest overheat and it's holding at 120 on all cylinders.
Has to be pulling air from somewhere?
Motor starts easily, idles and accelerates well.
If I putt around at 3K or lower motor is OK.
Get over 4.5k for a few minutes and horn goes off and motor slows.
(Last time out after going over the entire cooling system, I idle through the no wake zone, then give it full throttle, get up on plane, run at 5K for about 1/4 mile and horn goes off.
I shut it down and came in on kicker motor.)

 

[Mc Tool]

Thanks for your response.
Thinking about it, I agree with your assessment.
Since I have everything apart, I'll put a new set of reeds in and check the carb flange surfaces.
Not sure where to look next.
I'm thinking head gasket but I did another compression test after the latest overheat and it's holding at 120 on all cylinders.
Has to be pulling air from somewhere?
Motor starts easily, idles and accelerates well.
If I putt around at 3K or lower motor is OK.
Get over 4.5k for a few minutes and horn goes off and motor slows.
(Last time out after going over the entire cooling system, I idle through the no wake zone, then give it full throttle, get up on plane, run at 5K for about 1/4 mile and horn goes off.
I shut it down and came in on kicker motor.)

Im wondering if you have a temp sensor getting a bit over excited as well and an intake leak . Screenshot of google search

I dunno for sure but it looks close . 172⁰f is not smokin hot ,its at the upper end of normal . Id remove temp sensor and heat it in a pot of water with a good thermometer and check to see if its still in spec .....its possibly 36 years old so it might be suss.

 

[saltchuckmatt]

Pretty sure that motor has water deflectors inside the water porting around the cylinder walls. Did you inspect those?

 

[TwoRivers]

Im wondering if you have a temp sensor getting a bit over excited as well and an intake leak . Screenshot of google search
View attachment 417974
I dunno for sure but it looks close . 172⁰f is not smokin hot ,its at the upper end of normal . Id remove temp sensor and heat it in a pot of water with a good thermometer and check to see if its still in spec .....its possibly 36 years old so it might be suss.

I'll take your advice and pull the sensor and test it.
As far as the "Pressure Relief Valve" I'm not sure this motor has one. I think the spring and tstat work together to let more water in? I could be mistaken but I've looked at numerous diagrams of the cylinder head and never came across a Pressure Relief Valve? Let me know if you have a location. Model E70ELCEM.
Thanks for your response

 

[TwoRivers]

Pretty sure that motor has water deflectors inside the water porting around the cylinder walls. Did you inspect those?

Looked at numerous diagrams of the cylinder head and no indication of water deflectors. I'd be indebt if you could point me to a diagram.
Model E70ELCEM. Thanks for your response.

 

[Mc Tool]

I'll take your advice and pull the sensor and test it.
As far as the "Pressure Relief Valve" I'm not sure this motor has one. I think the spring and tstat work together to let more water in? I could be mistaken but I've looked at numerous diagrams of the cylinder head and never came across a Pressure Relief Valve? Let me know if you have a location. Model E70ELCEM.
Thanks for your response

I dont know about that relief valve ( could be AI talk for the t/stat) either but saltchuckmatt mentions deflectors in his above post ...might be worth googlin that to see if it sheds any light.
Testing the overheat using ohm meter or beeper to test when it closes circuit ....if nothing else is a nice experiment to see how they work ......if your into that sort of playing around in the w/shop

Edit , I just googled "1989 70hp evinrude water deflectors " and got a good explanation ...which fits your symptoms

 

[racerone]

Deflectors were only used in the crossflow model V-4 !!

 

[TwoRivers]

I dont know about that relief valve ( could be AI talk for the t/stat) either but saltchuckmatt mentions deflectors in his above post ...might be worth googlin that to see if it sheds any light.
Testing the overheat using ohm meter or beeper to test when it closes circuit ....if nothing else is a nice experiment to see how they work ......if your into that sort of playing around in the w/shop

Edit , I just googled "1989 70hp evinrude water deflectors " and got a good explanation ...which fits your symptoms

I really appreciate you trying to help. This issue is consuming my summer and I'm at a point where each one is precious.
This AI stuff is going to get people killed.
So much wrong information, I sure hope you younger smart guys get this AI sorted out before too long.

 

[TwoRivers]

Deflectors were only used in the crossflow model V-4 !!

Appreciate your response R1
If you had to guess, what do you think might be causing the overheating?

 

[Mc Tool]

Deflectors were only used in the crossflow model V-4 !!

Huh!? AI , that would explain why the pic of the kit had two of everything . Check out what it says tho ...could really mess you up

Bastards

 

[TwoRivers]

Huh!? AI , that would explain why the pic of the kit had two of everything . Check out what it says tho ...could really mess you up
View attachment 417975
Bastards

If you get an AI response that you know to be incorrect.
Respond back that "this motor doesn't have Water Passage Deflectors" or whatever.
You'll instantly get a response:
"You are correct, this motor doesn't have WPD's "
Then it will go on to give you more BS.

 

[Mc Tool]

If you get an AI response that you know to be incorrect.
Respond back that "this motor doesn't have Water Passage Deflectors" or whatever.
You'll instantly get a response:
"You are correct, this motor doesn't have WPD's "
Then it will go on to give you more BS.

Yep , reminds me of pothole .......thats one of my neighbours ....everyone tries to avoid him