Caurburated 4.3L mercruiser ... do I really need a thermostat??

[Heybuddy]

Ok simple question older 1986 4.3L carbureted engine “B” serial number, do I really need a thermostat to run? Will it help the engine to get to temp sooner? Yes, But is that a make or break issue with a carburetor? Pros? better water flow?/ cons? Cooler engine temp? Just looking for knowledge I’m currently not running one

 

[Lou C]

Yes you do to regulate temperature throughout the engine. The coolant flow was designed with it in mind. What is your resistance to using one? Carb or no carb it does not make a big difference. No thermostat you will be running at 100-120* unless under load which is too cold.

 

[TyeeMan]

I don't think it's a carbureted/non-carbureted thing. It' s running the engine at a constant temperature for performance, quality of fuel burn and probably mostly longevity of the engine.

Yes the engine will come up to proper operating temperature faster with a t-stat. This is probably even a bigger issue if you are boating in cooler water in the spring and fall.

 

[Lou C]

In fact if the engine has an older style Rochester carb with the choke that is heated by the intake manifold with no thermostat it will take forever to open. Even with the thermostat, they tend to open slow but with none you're going to running too rich all the time.

 

[achris]

Engine components like pistons are designed to be operating at a particular temperature... If you run too cold then pistons don't expand to the right size and shape, you accelerate wear. Your oil doesn't get hot enough to boil off contaminants. The choke on the carburettor doesn't open properly, you burn more fuel, which leads to more oil contamination. Without the thermostat, the block and heads heat unevenly, leading to the possibility of head gasket failure. Also, depending on the design of the thermostat housing, some engines depend on the thermostat to direct water flow. Without it, some areas of the engine may actually be getting too hot.

Running without the thermostat is a bad idea.

Chris........

 

[Heybuddy]

Sweet guys! Thanks for all that! I just bought this boat late summer and rebuilt a decent amount on this motor and I got it running. Only been in water once before had to winterize it and it ran fine then but it was real chilly out. I guess I’ll be ordering one before we start the season.

 

[thumpar]

The 4.3l just uses a standard GM type thermostat. Get the one in the temp spec for your engine and you are fine. It will only be a few bucks. Make sure to use a marine gasket. The marine gasket has rivets in it to ground the housing for the temp sender and switch.

 

[jimmbo]

Get the stat from a Marine dealer, it will have the correct temp rating, which is not 180 or higher, even 160 is probably higher than you want to run a Raw Water engine

 

[puddle jumper]

A thermostat will not only make the engine come up to operating temp faster but will also constrict the water flow. By doing this it slows down the water flow so it is more effective in cooling. If your choke is slow to come off.Depending on the style of system you have ; electric you may not have any power to it or it’s set to tight or if you have an older manifold crossover style the manifold crossover may be plugged. Some food for thought.