MErcruiser 140 overheating....help

[petrey10]

I just rebuilt the carb and put the "tune-up kit" on my Mercruiser 140 and was hoping to solve all my problems but now since the engine runs for awhile I have come to find that the engine is overheating in about 15-20 minutes of use. I never noticed anythign strange except for that when I had it full throttle it was only 4000 rpms... I have a 19 pitch prop and I believe it should be higher than this...and also when I had it WOT and I jsut left it there after about 15 seconds the engine would rev even more to about the 4500 rpms....Also the engine leave a small oil trail in hte water, nothing huge but it is noticable.....what do you guys think I should do?

 

[petrey10]

Re: MErcruiser 140 overheating....help

I am trying to purchase a water pump rebuild kit but do not know which kit is for me because all the serial numbers are on parts that are in the lower unit...anybody know which kit is for a 140 mercruiser??

 

[Don S]

Re: MErcruiser 140 overheating....help

A year would sure help.

 

[petrey10]

Re: MErcruiser 140 overheating....help

found the kit... do you guys believe it is the water pump?? I know its hard to do this over the internet but I am just trying to figure this out... what other possiblities could there be?

 

[Haut Medoc]

Re: MErcruiser 140 overheating....help

A year would sure help.

Yep!.....
The impeller is the first thing to check when overheating......

 

[petrey10]

Re: MErcruiser 140 overheating....help

i got my manual and read about the process...sounds like it will take awhile....what are some tips you guys have?? anything else I can check for while I am in there?

 

[Don S]

Re: MErcruiser 140 overheating....help

What YEAR

 

[petrey10]

Re: MErcruiser 140 overheating....help

it is a 1971..

 

[Haut Medoc]

Re: MErcruiser 140 overheating....help

For the oil slick, I think you should drain the drive, examine what comes out for signs of water intrusion & pressure test it.....
Do a compression test on the engine, it may be worn rings.......
Lastly, the impeller is really not that hard to change if you have the manual & read through it.....
If you get stuck, you will have this forum to help......​

 

[Don S]

Re: MErcruiser 140 overheating....help

Don't have a manual link for that year drive, but this will show you the process of replacing the impeller.
http://www.mercstuff.com/waterpumpinst.htm

Are you sure you are seeing engine oil on the water, sure it's not gas or carbon from running real rich? possibly a choke stuck shut?
Could also be a gear lube leak, or trim cylinder or lines leaking. Any indication of milky oil in drive or trim system?

 

[petrey10]

Re: MErcruiser 140 overheating....help

well i wouldn't think it is the trim because it doesn't appear till I run the engine....could be running rich I will check that out....what would be making the WOT not reaching 4600 rpms? MY prop is brand new and is a 19'' pitch

 

[petrey10]

Re: MErcruiser 140 overheating....help

thismay sound real dumb but how in the heck do I change the oil?? where is the drain plug?

 

[sker crunch]

Re: MErcruiser 140 overheating....help

You will need to get a suction pump and suck it out through the dipstick hole. It should have garden hose type threads on the top of it.