1986 mercruiser 140/alpha one

[bid2ask]

during the winter for maint. i changed the impeller in the drive, new imp./housing/gaskets. i took it out today for the first time this season and she ran great. after about 5 minutes of running it at about 4000 rpm it got hot almost to the h on the temp gauge, i backed off the throttle and made my way back to the dock. i kept it about 2500 rpm and it got cool quick the gauge showed about 1/4 of the way up, last year it stayed consistantly around half. could it be the impeller? i thought i did it right in acordance with the manual. could it be the thermostat?, what should i check out? by the way it runs great on the muffs.

 

[rodbolt]

Re: 1986 mercruiser 140/alpha one

could be the t-stat. could be a clogged riser assy. both can exibit the same symptoms. next time as it heats up place a hand on the riser. should be warm but not hot. and t-stats are cheap and easy to change.

 

[bid2ask]

Re: 1986 mercruiser 140/alpha one

the riser was warm, but the block was hot

 

[rodbolt]

Re: 1986 mercruiser 140/alpha one

then try the t-stat. by the block being hotter than the riser it indicates that cooling water is able to exit the manifold/riser. its just a matter of elimination and remember 1 million gallons an hour into the system is worthless if ya cant get it out.

 

[bid2ask]

Re: 1986 mercruiser 140/alpha one

thanks, i'll replace the t-stat.

 

[bid2ask]

Re: 1986 mercruiser 140/alpha one

i just put the t-stat in hot water and it opened gradualy took about 10 seconds, it was open about 5/16 of an inch, is that normal?

 

[Don S]

Re: 1986 mercruiser 140/alpha one

Just replace the stat. It may just hang now and then.<br />Do you have raw water or fresh water cooling?

 

[bid2ask]

Re: 1986 mercruiser 140/alpha one

don, its raw water cooled

 

[bid2ask]

Re: 1986 mercruiser 140/alpha one

don s. do you have a copy of the procedure to change out the gimbal bearing, and u joint bellows?

 

[Don S]

Re: 1986 mercruiser 140/alpha one

Yea, it's in the service manual.<br />Just run your cursor over the different sections to find the links. They aren't readily visible.<br />Section 4 is what you want.<br /> Mercruiser Alpha Service Manual index. <br /><br />Plus, there is always this one..... Not as good, but usable.<br /><br /> How To

 

[csanna2]

Re: 1986 mercruiser 140/alpha one

Great info Don,<br /><br />I have the same motor,and outdrive

 

[bid2ask]

Re: 1986 mercruiser 140/alpha one

i got all my parts today to replace gimble bearing, all the bellows, and shift cable. there looks like a large seal about the size if the gimble bearing, my manual doesnt show this item, where does it go?