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Model year amp overheating problem

T

trailking08

New member
"I have a Mercury 150 Black Ma

"I have a Mercury 150 Black Max outboard on my boat.
I am not sure what year it is, and have not been able to find the S/N # on any of the charts listed in the discussions on this site (S/N 0C198502).
About a year ago I had an new water pump put in at the local dealer. It ran fine before I took it in, but started having problems after I got it back.
It will overheat when at idle, or at low speeds, but cools right back down at high speeds. The problem seemed to be intermittent at first, and seemed to not happen as much at a higher altatude lake I go to, but that could be a coincidence. As they year has gone on, it is now happening everytime i take it out.
It has also started smoking massive amounts of blue smoke when I first start it up, but stops once it warms up.
I took it back to the dealer once I first notice the problem, but they said that since I was getting a steady stream of water out of it that it could not be the water pump or anything they did. They also wanted $90 an hour to diagnose the problem, and I can not affort that right now.
Does anyone have any suggestions on how to diagnose/fix this problem?
Thanks, Mark."
 
"Hi Mark,i get 1989.as to the

"Hi Mark,i get 1989.as to the rest of your problems,depends how mechanically minded you are.compression check,new set of plugs,lower the g/box unit and check the impellor and rubber sealing flanges yourself,check the small drive kek on the impellor,renew the thermostat,mix a fresh batch of fuel,needle valve kit renewal.try those.10.25am sat"
 
"I did a compression test, but

"I did a compression test, but I'm not sure about the results. The compression in 4 of the cylendars was between 95-100psi, but in 2 of them was 120psi. Not sure what it is supposed to be.
Took the thermostats out and checked them, but they were opening much hotter than 143 degrees, and there was a 20 degree difference between the temperature that each one fully opened, so I replaced them.
Found that the fuel pump was leaking, so put new diaphrams and seals in.
I also noticed that little bubles were coming out around the oil injection pump when the motor was running, so I tightened the bolts and it seemed to stop.
While on the trailer, the motor seemed to be running better and did not seem to overheat. The excess smoking also seemed to have stopped.
Feeling good about my accomplishments, I took the boat out to watch the fireworks at the lake.
On the lake, the engine seemed to run better and was not smoking at all, but now, it is overheating unless it is idleing. This is exactly the oposite of what it was doing before, and I am thoroughly confused.
Please help!"
 
"THE OVERHEATING PROBLEM COULD

"THE OVERHEATING PROBLEM COULD STILL BE THE IMPELLER OR THE IMPELLER HOUSING , ALSO IT SOULD BE THE PICKUP TUBE COMING FROM THE TOP OF THE IMPELLER HOUSING. IF YOU HAD BEEN DRY STARTING THE MOTOR ON THE TRAILER NO EAR MUFFS ITS DIFFENTLY THE IMPELLOR"
 
"Thank you for the reply Tim.

"Thank you for the reply Tim.
*Sorry if my postings seem a little long, I am new at this and am trying to make sure I have covered all the bases.

I have used a garden hose and motor attachment each time it was started out of water, so hopefully no further damage has been done.

My plan is to replace the impeller next.
How hard is this to do? I really can not afford to pay the dealer another $150 in labor, esp. when it seems like the problem started after they replaced the impeller last time.

I called about getting the impeller, they told me that there were 3 options 1) just the impeller, 2)an impeller kit that includes a new housing, & 3) impeller, housing, and new base plate. Since I have no water in the lower unit, should I still replace the baseplate?

Do you have any suggestions or tricks on performing this task?

Also, do you think I should be concerned about the difference in compression on the upper 2 cylendars. When I took the spark plugs out, they were covered in a great deal of oil and had a little bit of thick black deposits on them, but looked like brand new after wiping them off. I had also grounded the plugs with a wire and was able to see that each one gave a good spark during starting.

The other thing I am concerned about is that the cylendars did not seem to be holding the pressure. It would hold for a few seconds but then slowly started going down. I am not sure if this is normal or due to a faulty guage, so I am going to try it again with a new gauge this evening.

Any suggestions are welcome.
Thank you again, Mark P."
 
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