Engine overheating, 3.0 140 mercruiser

[jedimaster]

Ok, so I changed the water pump impellor and it seemed to be working as I could see water squirting out at where the rams mount to when I ran it in a bucket, however, when I got it out on the lake it started to overheat. I followed the manual and it seemed to go together as it should. I am going to take the lower unit off again and make sure the impellor isn't broken or something. Now the old water impellor got chewed up pretty bad, not much left of it, would the debris have gotten sucked into something and jamming up the pipes? Is there a way I can test for obstructions? Also I don't have a water preasure gauge but I tried squeezinfg the various water tubes and none of them seemed to be very firm although I could feel a little bit of sloshing around in them. Should they be as firm as a car engines Pipes? And does it need to be primed with water or anything?

 

[tommays]

Re: Engine overheating, 3.0 140 mercruiser

You need to find the old parts they could be blocking the water flow from the new pump

when the drive is off you can backwash the water supply hose from the motor to the drive to push out any parts stuck there

You can also check the thermostat as things will get jamed up there also


Tommays

 

[jedimaster]

Re: Engine overheating, 3.0 140 mercruiser

How hard should the hoses be to the touch when the water pump is functioning properly? Do you know of a water pump flow diagram to show the direction of flow for all the hoses?

 

[jedimaster]

Re: Engine overheating, 3.0 140 mercruiser

Ok, I took off all the hoses and removed the thermostat housing, and no debris. I took off the two water intake plates and nothing jammed up inside. Took off the lower unit and nothing in there, now I am at a loss. Where else should I look?

 

[Bondo]

Re: Engine overheating, 3.0 140 mercruiser

In the Hose that runs from the Transom to the T-stat Housing,.... The In-coming water from the Outdrive to the Motor.........

Hook it to a garden hose,+ Flush it Out............
Backwards, from the Motor to the Outdrive of course.......

 

[jedimaster]

Re: Engine overheating, 3.0 140 mercruiser

Should I have the lower unit off when doing this?

 

[Cptkid570]

Re: Engine overheating, 3.0 140 mercruiser

Also look between the impellor and the outside of the drive (where the water sucks into the outdrive - where the muffs go on).. One time, I had an impellor disintigrate and big piece of rubber actually fell down into the drive where the water comes in and it was sticking into the impellor where it was trying to suck water in (not push water out).

Also check your thermostat.

 

[Bondo]

Re: Engine overheating, 3.0 140 mercruiser

Should I have the lower unit off when doing this?

Ayuh.......

 

[jedimaster]

Re: Engine overheating, 3.0 140 mercruiser

Thermostat seems to be moving properly, I noticed when I put the garden hose on the motor side(with the drive off), That a black rubber hose seemed to leak pretty heavily, it runs right between both bellows on the port side about an inch in diameter. Is that the hose that goes to the transom from the water pump? Water came out without any noticable obstruction and nothing came shooting out I had the drive in a big bucket.
I think maybe I had a combination of leaky hose and blown impellor, I changed the impellor but now the hose must be leaking bad enough to cause lack of water flow.
I shoulda pulled the hose off the thermostat housing while I had the boat in the water to see if anything was even comming up.

 

[jedimaster]

Re: Engine overheating, 3.0 140 mercruiser

I guess my next question is.
How difficult is it to pull the upper unit to replace the bellows and water hose?
Will I need to use the alligment tool?
Any special tools needed to pull it off and replace the above mentioned parts?

 

[jedimaster]

Re: Engine overheating, 3.0 140 mercruiser

Also is it possible to replace the water hose without pulling the drive?

 

[tommays]

Re: Engine overheating, 3.0 140 mercruiser

Its a pretty BIG job which requires pulling everything apart

I would have to wonder about the condition of your other rubber parts if the hose has failed

If doing one its best to do everthing all at once its such a PITA to get in there

http://www.boatfix.com/merc/Servmanl/6/6covr3.pdf

http://www.boatfix.com/merc/Servmanl/6/6A4R3.PDF

This is if you have a older alpha drive

Tommays

 

[jedimaster]

Re: Engine overheating, 3.0 140 mercruiser

Yah thats why I was hoping I could bodge it together for a few more runs, as the season is nearly done, likely only a few more runs on the lake, and do the whole thing over the winter. maybe I should just try some of that self sealing silicone tape, I used it on a radiator once when it blew a hole in it. It last 2000 km's on a car before it finally let go again, I finished the trip though.

 

[tommays]

Re: Engine overheating, 3.0 140 mercruiser

Thats about as BAD and idea as i can think of :devil:


Tommays

 

[jedimaster]

Re: Engine overheating, 3.0 140 mercruiser

I know I know. I wonder ho much back preasure there is. I can get the one side off maybe just slip a hose in there just big enough to be a tight fit and synch her back up for another jaunt across the lake. Maybe I could just hook up the bilge pump to it. and stick it in the live well. hmm I know I know all bad ideas. but hey they beat duct tape.

 

[jedimaster]

Re: Engine overheating, 3.0 140 mercruiser

Ok I found another website that walks through the changing of the gimbal, bellows and water hose. Sounds a bit of a pain but not too bad. When I pull the drive off of the bellhousing and put it back on does it need any kind of allignment or can I just take it off and slide it back on?

Here is the instruction set I found.

http://www.outdrives.com/merc/mdtips03.html

 

[jedimaster]

Re: Engine overheating, 3.0 140 mercruiser

Ok I am gonna stop posting on this thread as I have started to pull the unit apart to change everything.