Mercruiser 140 overheating in neutral

[nick.martin]

Hello all, I am the new owner of an 86 Dixie with a Mercruiser 140 I/O. I have spent several hours getting to know this new boat on the water with my family. This seems to be a strong running little engine. It has impressed me more then my previous OMC 4.3L.
I have found that at idle in neutral the engine starts to overheat. The temperature climbs to +200*f and pegs my gauge. If I keep the idle up around 1500rpm in neutral, the engine temperature remains steady at about 160-180*F. Is this due to a failure of the outdrive foot pump or possibly a failing circulating pump? Thanks for your help in advance. I do not want to break down on the water.

 

[carcraze]

Re: Mercruiser 140 overheating in neutral

Could be a few different possibilities but the circulating pumps do not go bad all that often, by the symptoms if you are unsure the last tinme the impeller in the outdrive was changed that would a good place to start.

 

[Bondo]

Re: Mercruiser 140 overheating in neutral

Is this due to a failure of the outdrive foot pump

Ayuh,... Replacing the Impeller is always the 1st thing to do in an Overheat situation....

 

[nick.martin]

Re: Mercruiser 140 overheating in neutral

o.k. sounds like I will be replacing the outdrive impeller. I have a Mercruiser manual, but how difficult is it really? I am very mechanically astute but have never done this. How long would you think it should take? Does the outdrive need to be removed and fluid need to be drained for this?

 

[Galaxyman]

Re: Mercruiser 140 overheating in neutral

o.k. sounds like I will be replacing the outdrive impeller. I have a Mercruiser manual, but how difficult is it really? I am very mechanically astute but have never done this. How long would you think it should take? Does the outdrive need to be removed and fluid need to be drained for this?

Do a search on this forum for this as several people have taken the time to submit step by step instructions. It is not hard and should only take an evening to do. Just remember to go ahead and install the upper and lower section of the waterpump with the new impeller. You do need to drop the lower section of your drive so get some lower gear oil to replace when you remove this. Wish you the best. BK