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1987 4.3L OMC Cobra thermostat part number

H

Hava-Don

New member
I need to order a new thermostat for my 4.3L, 1987 OMC Cobra and was hoping someone could the oem part number? The thermostat housing oem number is: 910179. Also wondering if I attempt to de-corrode the housing, is it possible to do so without damaging the surface the thermostat mounts on to?
 
You can buy it right on this site, just look it up under your OMC model number.
Maybe post up a pic of what your stat housing looks like, they can get pretty rusty.
 
I have absolutely no idea what the OMC model number is, but here are a couple pics of the thermostat and its housing. The model number of the housing was posted in my original post. Maybe you can inform me how to determine my OMC part number?

490654561_1965238664003129_6871825168803206944_n.jpg491007443_694524569666656_1612225131496242116_n.jpg
 
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I'm guessing you're in fresh water, that looks pretty good to me!
Most OMC's take the same thermostat, it will be a 160* 'stat.
The OMC model # was on a sticker that was on the 'stat housing,I looked close, the sticker is still there on yours..... They are usually a series of #s and letters, kind of like this:
43 =4.3 V6 engine
followed by a 2 (if 2bbl carb) or a 4 (if 4bbl carb)
Then a G if a General motors engine, or an F if Ford
there will be a few more letters, with a M for manual steering, or a P for power steering, the other letters signify the year I think
You can also buy parts by the year of production:
https://www.marineengine.com/parts/omc-parts/omc-boat-parts.php?year=1987&hp=4.3 here's where the model #s come up but for the stat, it the same for all of them.....it only really makes a difference, if you are looking for carb parts then you have to know if it's 2 or 4bbl, or if you are looking for steering parts, if it has manual or power, but basically all the 4.3s probably came with power steering...
so I picked one....just look at the diagrams and order what you need, I have been buying parts from this site for years, I like it because the service is good and best of all they list aftermarket alternatives for NLA OMC parts.
#56 in the diagram is the 'stat
 
Lou...

Thanks for your patience! After using a lupe on the housing, I was able to distinguish all but one of the characters. It was 432AP?RY. Using deductive reasoning and a bit of filling in missing segments of the character that was under a crease, the model number was 432APARY. That led to this kit: https://www.wholesalemarine.com/sierra-18-3653-thermostat-kit/. I attached a marked-up screen grab of that kit showing what I believe to be the necessary parts, based on the exploded diagram of my engine and all that's attached to it. I am not clear why they include the other parts into this kit? Do you know the purpose of the extra parts?

ps. the boat is in Lake Havasu, AZ...fresh water.
 

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I would order it from this site, marine engine. They are very good and will send you OEM parts. That kit (aftermarket Sierra not OEM) looks like it has the gasket for the V6 and the o ring and the stat, but those other parts look like they are for the 3.0 four cyl.
Make an account here on marine engine and get your parts from them, use OEM when you can find it.
get parts 25, 56 and 57 in the diagram
 
louc said:
I would order it from this site, marine engine. They are very good and will send you OEM parts. That kit (aftermarket Sierra not OEM) looks like it has the gasket for the V6 and the o ring and the stat, but those other parts look like they are for the 3.0 four cyl.
Make an account here on marine engine and get your parts from them, use OEM when you can find it.
get parts 25, 56 and 57 in the diagram
Click to expand...
đź‘Ť
 
The thermostat is not a mandatory component, as when it is cold, it stays closed to warm up the engine faster; and when gets warm it opens up, allows the engine to stay cool. Without the thermostat you will have unrestricted flow to cool the engine, and the only downside is that it will take longer to warm up the engine. In a car, it would take longer for the heater to work, if it is cold out, but that is not a problem in a boat.
If the housing is too rusted, the option is to go without the thermostat, or you may be able to find a new housing in E-Bay, but it doesn't look too bad from your pictures.
 
Running without a t-stat should be a stop gap measure. Do it to get home, not to waste a summer trying to save a dollar.
Your housing doesn't look all that bad to me. It has no moving parts. Hit it with a wire wheel or sand blast it a bit. Re-inspect it; No holes, then reuse it with a new t-stat & gaskets.

Regarding Sierra parts, I've used many over the years with no quality problems. There are sometimes issues with what the catalog says vs what it truely fits.

Marineengine.com usually lists Sierra & CDI interchanges correctly. It seems rude to me to come on this site & then talk about buying elsewhere. Now if the part is NLA, that's a different story.
 
Neal Franson said:
The thermostat is not a mandatory component, as when it is cold, it stays closed to warm up the engine faster; and when gets warm it opens up, allows the engine to stay cool. Without the thermostat you will have unrestricted flow to cool the engine, and the only downside is that it will take longer to warm up the engine. In a car, it would take longer for the heater to work, if it is cold out, but that is not a problem in a boat.
If the housing is too rusted, the option is to go without the thermostat, or you may be able to find a new housing in E-Bay, but it doesn't look too bad from your pictures.
Click to expand...
A more mechanically inclined pal of mine said the same. I ordered the parts anyway. It certainly didn't break the bank!
 
Marine engines run cool vs auto engines so for sure you want a functioning thermostat. Running too cool causes condensation in the motor oil & in some cases depending on choke design (hot air or divorced choke) it can over-rich the fuel mix & cause fuel dilution of the motor oil.
 
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