Over heating Mercruiser 2.5

[mjwmjf]

Hi everyone!

I am in need of some help with my 1988 Mercruiser 2.5 IO.

The motor was over heating while trolling or sitting idle but fine when the RPM's were raised. Someone said that the pick up in the lower unit was bad. I had it replaced and when in my driveway with the rabbit ears on it was GREAT. Never even reached 100 degrees

Now that it's in the water it over heats regardless of how high the RPM's are.

I removed one of the water pump hoses (one of the large hoses) and it was dry. I started the motor with the hose still off no water came out. It was still dry.

I don't know if the water pump in the motor itself now has to be replaced...

I removed the hose coming from the lower end where the pick up was replaced and started the motor and still no water from there.

Does it need the motor pump to actually draw water up?

Can anyone give me some advice as to my next move?

Thank you Very much in advance!

Mike F
Sacandaga Lake
Upstate NY

 

[JoChek219]

Re: Over heating Mercruiser 2.5

were all the pieces still on the old impeller? if not you better find where they are , remove the pieces , and flush out your cooling system.. sounds like something may be blocked

 

[Duke of ....]

Re: Over heating Mercruiser 2.5

I also have an over heating problem but mine is at slower speeds. When I increase the RPM's the heat guage comes down to mid range.

When coming back to the dock at slower speeds it gets close to 190.

I have a I/O 2.5 MerCruiser and the boat had been setting for about three years so that might have alot to do with it.

Should I open the water pump and have a look see?

Thank you for any help you may have.

Duke of ....

 

[chiefalen]

Re: Over heating Mercruiser 2.5

Does the prop turn when you put it in gear motor running? If yes than impeller needs to be checked replaced?

If no that coupler is gone. Need new coupler.

Post your reply well go from there.

I don't want to say to start throwing money at it without know whats wrong.

Simple post back is all we need to the question.

 

[hammond1979]

Re: Over heating Mercruiser 2.5

sounds like the same as mine ,place a new inpeller in it, i am sure this is the issue

Start from the bottom and work your way up

 

[APPALOOSA2]

Re: Over heating Mercruiser 2.5

You need to change the lower unit impeller "water pump". I replace the whole housing.If any of the blades on the impeller are missing try to flush the system.

Lower impeller will never show it bad when using muffs on the engine on land because you have constant water pressure from your hose.

 

[MikeM40]

Re: Over heating Mercruiser 2.5

Most likey the water pump in lower unit or the water pocket in the upper

 

[hammond1979]

Re: Over heating Mercruiser 2.5

$100 bucks its the inpeller