Thermostat -140 Mercruiser 1973 missing (?)

[Jim Robbins]

Hi, I was checking out my first I/O, it's a 1973 GM, 4 Cyl. , 140 H.P
Mercruiser (181 Cu.In.). After using for the 09 season
I found out that there was no thermostat installed in the cooling system.
How can I find what is the proper thermostat for my motor ?
(140 degs. to 152 degs. ? not sure) ? How do I find out the part numbers for my motor? (only at a Marine shop?)
Can I use car parts for my motor ie; distributor cap, rotor, condenser, points, etc. ?

I do have a manual and a second on order. The 1st. manual did not have the details I want. Thank-you for your time!

 

[havasuboatman]

Re: Thermostat -140 Mercruiser 1973 missing (?)

Go to the adults only section above. you will find a link that you can use to download your service manual for free. If they go back that far.
You can find out your part numbers by going to any Merc. dealer with the engine serial number.
I am a Merc. tech. I therefore cannot reccomend you use automotive parts in your boat. Some automotive parts greatly increase the chances of fire in a boats closed engine compartment.

 

[ziggy]

Re: Thermostat -140 Mercruiser 1973 missing (?)

If they go back that far.

it seems like they do. #1 would be the one to get. sometimes ya see book versions on ebay too. got mine from there.
if yer engine is raw water cooled, it'll likely use the 140* tstat. (no heat exchanger)
if yer engine is fresh water cooled, it'll likely use a 160* tstat. (w/ heat exchanger)
the service manual will tell you exactly which one to use. go by the book, it has the facts in it for your engine and drive.
tstat range is usually stamped number on tstat, + 20*.

don't use car parts on your boat. it's a bad idea. boats have engines that live in an enclosed area. so all peripherals bolted to the engines have safety features to prevent a loose spark which could ignite stray fuel fumes that could congregate in the bilge if ya have a fuel leak of some kind. fuel fumes + a spark = a bomb.

if possible, use oem parts. they are the proper ones and will likely work proper from install. aftermarket may or may not.

an example of a slight difference. (this is comparing oem part to aftermarket marine part, i would think that there could be even more differences between oem and auto parts)

these are the dist. cap for my 165 L6. the mercruiser cap is on the left.
most notable is the lack of beef around the 6 individual contacts . the mercruiser cap was notably heavier. the cap on the right is an aftermarket alleged marine duty cap for my engine. the differences were enough for me to not use the aftermarket cap. there was a major difference in price. but there was a major difference is quality of the part too.
use marine rated parts. you'll be happy ya did.
here's a place you can look up some oem part numbers. http://mercruiserparts.com/ item #37 from this link is your tstat for a '73 140hp. http://www.mercruiserparts.com/Show...=1586&bnbr=60&bdesc=EXHAUST+MANIFOLD+ASSEMBLY
this would be for your engine. confirm proper list by serial number. http://www.mercruiserparts.com/selectSerailRange.asp?doc_nbr=140+++++GM+181+I/L4+1972-1978
there are others too.

 

[Bondo]

Re: Thermostat -140 Mercruiser 1973 missing (?)

Can I use car parts for my motor ie; distributor cap, rotor, condenser, points, etc. ?

Nope,... The igintion systems used on marine motors, have Never been used in Cars...
The parts from an automotive igintion won't fit...