Cooling problems Mercury 115 EFI -02

[Mufflon]

Hello!

Im having some trouble with my Mercury 115 EFI - 02, Im getting a constant beeping after 20-30 seconds when driving above 3000 rpm.
It seems like it has something to do with the temperature

What it've done so far:
Replaced the impeller
Replaced the thermostat (also tried running the engine without and thermostat installed)
Replaced the "pressure control valve"

I have also measured the temperature with an extern thermometer just to make sure it isn't any problems with the sensors - it start showing high temperatures from 1500 rpm and up

is there anyone who got any other ideas that i can try?

 

[sutor623]

Whats your serial #?
What kind of temps are you showing? You said high temps from 1500rpms and up, so what is "high"?
These EFI's typically have 120-140 degree thermostats in them. If your block is significantly higher than this then you are overheating.

The temp warning horn on that engine kicks on at 194degrees. So if your temp gun isnt showing close to that you either have a bad coolant temp sensor or the beeping is another issue.

Warning horn can also mean engine oil pressure switch.

 

[sutor623]

Here's how to test the oil pressure switch:

http://www.boatinfo.no/lib/mercury/manuals/115.html#/104

 

[Mufflon]

Whats your serial #?
What kind of temps are you showing? You said high temps from 1500rpms and up, so what is "high"?
These EFI's typically have 120-140 degree thermostats in them. If your block is significantly higher than this then you are overheating.

The temp warning horn on that engine kicks on at 194degrees. So if your temp gun isnt showing close to that you either have a bad coolant temp sensor or the beeping is another issue.

Warning horn can also mean engine oil pressure switch.

Hello!

Sorry for late reply.

My serial is: OT443300

I got around 60-70 degrees Celcius when driving around 1500-2500 rpm and over 2500 it just keeps going higher untill it starts to beep around 90 degrees C (194 F) So I guess it has something to do with temperature and not oil.

 

[sutor623]

Is your telltale flowing water?
Did your last impeller blow apart or come out while?
Do you run this water in salt?

If you have installed all of the said parts properly then you most certainly have a blockage in the water jacket somewhere. If it's a saltwater motor corrosion has likely built up and you will need to get access inside of the engine to clean it out.

If it will idle without overheating you could try filling a 55 gallon drum with a mix of water and vinegar or a solvent that breaks down calcium/corrosion. Let the engine idle and you will see all kinds of gunk coming out of the engine.

Another thing you can try is dropping the lower unit and hooking a hose up directly to the water tube and seeing what kind of water flow you are getting.

 

[Mufflon]

Is your telltale flowing water?
Did your last impeller blow apart or come out while?
Do you run this water in salt?

If you have installed all of the said parts properly then you most certainly have a blockage in the water jacket somewhere. If it's a saltwater motor corrosion has likely built up and you will need to get access inside of the engine to clean it out.

If it will idle without overheating you could try filling a 55 gallon drum with a mix of water and vinegar or a solvent that breaks down calcium/corrosion. Let the engine idle and you will see all kinds of gunk coming out of the engine.

Another thing you can try is dropping the lower unit and hooking a hose up directly to the water tube and seeing what kind of water flow you are getting.

Telltale is flowing water, yes
the last impeller was actually ok, probably didnt need to be replaced but i did it just to make sure.
the motor is running in salt water,yes

I also talked to a mercury workshop and they said something about an "adapter plate" that is between the engine and the driveshaft, they used this adapter because the engine is actually an yamaha engine and the lower parts is from mercury. There is a gasket somewhere here that sometimes causes this kind of problem - have you heard anything like this before?

I will start working on the engine soon as winter is over here in sweden - and then i will try those tips you gave me here, thanks!

 

[sutor623]

Yea all engines have this exhaust housing or adapter plate.

He and I speak of the same part. The rubber grommet that seals the water tune to the adapter plate and powerhead can go bad. The way to check it is to remove the lower unit and put anhose tightly around the water tube and turn the hose on. If you have water leaking back down the water tube then that grommet has failed . The worst part, to replace it you have to remove the powerhead.

 

[Mufflon]

Hello Again

I've now started to work on the engine again, I did the test with the waterhose in the watertube, And there where som water coming down, see picture

Water was coming from those two marked areas, Does this mean the gasket is bad? I just want to make sure before i start taking the powerhead of.




Thanks in advance

 

[sutor623]

Sorry, havent been on in a while. If that grommet is bad water will be coming down the side of the water hose. Dont push the hose up so far and seal it to the water tube.

Where you are seeing water come down is the exhaust side, and that is normal.