1999 Evinrude 8hp 4 strokes Cooling problem

[PierreL]

Hi all,

First I'd like to apologize for my poor english as I don't practice it a lot here in France.
So, my problem is that I got a 1999 Evinrude 8hp 4 stroke (E8RL4EEM) and the first time I used it (salt water), it was running fine but overheated and stalled. I don't know anything about outboard engines but since then I try to read and understand as much as I can.
I unmounted almost everything except the head. I cleaned everything, changed the waterpump, the thermostat, a bunch of seals, the gearcase oil, motor oil etc...
Before going out using this boat I'd like to be sure that it's cooling fine and I don't understand how works the thermostat.
From what I've seen after unmounting the engine is that the water comes from the water pump, goes to the head via the exhaust part, goes to the pee hose (funny, the french word is the direct translation) and to the engine. It goes out of the thermostat via a hose right in the middle engine section with the exhaust.

My questions are:
How could I check that my cooling system is working properly now?
(the flow getting out of the pee hose pretty strong now so I guess the water pump is good now)
If, engine running, I remove the hose coming out of the thermostat (the one going in the middle section) there's water flowing all the time (engine cold and also after 15min) is it normal?
What is the water circulation in this engine?

Thanks for reading,
Pierre.

 

[Mas]

Re: 1999 Evinrude 8hp 4 strokes Cooling problem

At operating temps, you should be able to hold your hand on the head for a couple of seconds after the motor has warmed up. If it burns, you're still too hot.

If you are just idling in a bucket, it may not warm up fully. It sounds like the motor is cooling fine now since repairs...if it isn't warming up?

How long were you running the motor when it first overheated and at what speed?

Did you notice if the tell-tale was peeing when it was overheating? It is possible that some debris (seaweed?) may have clogged the water intake and prevented cooling.

MAS

 

[PierreL]

Re: 1999 Evinrude 8hp 4 strokes Cooling problem

Thanks for your answer Mas,

When the motor overheated I was running it at low speed (just to take my 20ft sailboat out of the harbour) for about 15 min.
The tell-tale was peeing but a really little stream.
When I took of the thermostat, it was a block of salt. So I think almost everything was wrong when I got the motor.
Now, I can believe that the water pump is doing fine (tell-tale is peeing strong), but I'd like to check the thermostat and the rest of the cooling system.
If I blow some air in the thermostat hose, motor cold, would the air run trough the thermostat or not.

Thanks,
Pierre.

 

[Mas]

Re: 1999 Evinrude 8hp 4 strokes Cooling problem

If your thermostat was a "block of salt", I would not run it until I also removed the head and inspected/cleaned all the cooling passages, and least make sure that the cooling passages are clear!. If the motor is run in salt water and overheats, some of the water meant to cool the motor evaporates and leaves salt crystals behind...further reducing its cooling ability by clogging up the passages.

Being that the thermostat was a block of salt, so possibly is the cylinder cooling passages...unless the thermostat was faulty and prevented water from entering the cooling passages around the cylinder in the first place. Either way, I would not feel comfortable going out on the boat without knowing the exact health of my motor! You do not want to get stranded!

I "burned up" a small 2 hp a couple of summers ago due to the same issues. My particular motor by design did not have a tell-tale, so there wasn't an easy way to monitor cooling. I was having a fun day putting around when my motor began smoking....not good.

During the "autopsy," I discovered the water passages around the cylinders were completely clogged with salt and probably aluminum salt deposits. No cooling was happening.

I was not the original owner of the motor and religiously flushed the motor every time it ran in salt water...I had no idea of the problems!

I was able to "rebuild" the motor and clean all the passages with a dremel tool very effectively. The motor runs very well now!

It doesn't sound like you knew the previous history of the motor well, and likely the maintenance was lacking. A small motor should be flushed in fresh water every time it's run if salt water. Not doing so will only reduce the life of the motor!

I hope this helps,

MAS

 

[PierreL]

Re: 1999 Evinrude 8hp 4 strokes Cooling problem

Hi Mas,

Sure this helped!
But I'm kind of stuck now, I already moved the motor back on the boat and the place where I was able to work is around 150 miles far from the boat and my place.
When I took the motor apart I blew some air in the head and let the intake manifold soak in soapy water (hope that's enough), anyway, I will let it run on freshwater for at least 30min hoping it'going to clean the cooling system.
But I think the cooling is fine from now, I can run the motor for 10-15min and keep my hand on the head. I see the water flow changing behind the thermostat so I gess it works.
My main concern now is that when I let it run to check the cooling, I progressively increase the rpm, and near the half way the motor starts to shake and slows down, if I accelerate or slow down, that's fine but if I let the rpm constant at half-gas it wants to stall.
It does not seem to be an over heating problem as I can really let my hand on the head without being burnt.
I was thinking of a carburation problem or a Low Oil Pressure Warning.
Any Ideas?

 

[Mas]

Re: 1999 Evinrude 8hp 4 strokes Cooling problem

I would do a compression check on each cylinder to make sure the mechanics of the powerhead are OK. Then I would remove one spark plug lead while the motor is idling and see if it changes the RPMs. If it does, you know that cylinder is firing...then replace and do the other. If the RPMs don't not change, that cylinder is not firing properly.

If compression is good, and spark is good, then you've a fuel problem and should look to adjust...or possibly rebuild the carb. It sounds like you're "dragging a piston" by the way you described the shaking. Also, pull the plugs to see if they are clean & dry or wet from fuel.

Any idea when the motor was last tuned up? New plugs, checked timing etc?

MAS

 

[PierreL]

Re: 1999 Evinrude 8hp 4 strokes Cooling problem

Hi Mas,

Thanks for following up on this post.
Unfortunately, I don't have the equipment to perform a compression check. Maybe later...
I went back once again on the boat at lunch time to run the motor.
I was a little bit low on oil, wich is not surprising with the transport in my car, so I filled it up.
I tried the unplug of the spark plug trick and both cylinders fire, so firing is good, I'll put some new plugs anyway.
The motor idles very fine except at one rpm rate but it's not that serious. I think I'm too worried about that stuff.
It seems to be only a carburator tune-up.
I'll keep you informed as soon as I have some news.
Thanks again.
Pierre.

 

[Mas]

Re: 1999 Evinrude 8hp 4 strokes Cooling problem

Also, make sure that the throttle plate in the carb throat opens up & closes smoothly as you increase/decrease RPMs. At idle, the plate should be all the way closed.

MAS