overcooling without blockoff plate

[luky7]

Hello everyone!

I just bought a boat with a motor 351W silverline. I change the impeller and check termostat to be sure and I noticed that the engine temperature is always very low and never exceeds 100 degrees and which causes a miss at full throttle for lack of heat I think .. .. because the engine will idle very well ? ? throttle

I saw a piece on shemas named (separation plate or block off plate) and when I change the gaskets the last time there were none? I'd like to know if the water cooling too quickly get out of the system when these plates are missing between the manifold and riser?

 

[04fxdwgi]

Re: overcooling without blockoff plate

Hello everyone!

I just bought a boat with a motor 351W silverline. I change the impeller and check termostat to be sure and I noticed that the engine temperature is always very low and never exceeds 100 degrees and which causes a miss at full throttle for lack of heat I think .. .. because the engine will idle very well ? ? throttle

I saw a piece on shemas named (separation plate or block off plate) and when I change the gaskets the last time there were none? I'd like to know if the water cooling too quickly get out of the system when these plates are missing between the manifold and riser?

Bringing the engine up to and maintaining operating temp is strictly a function of the thermostat, provided there is enough water flow to keep it cool. If the engine is not reaching operating temp, then check the stat to see it it's hanging open. They are cheap and I would suggest putting in a new one.

Is this engine raw water cooled or closed cooling (anti-freeze in engine w/ a heat exchanger)? If raw water cooled, don't block off the passages between the manifold and riser, as you will have no water flow. If it's a "full system" closed cooling, meaning the manifold and engine are cooled by anti-freeze, then yes, the 2 must be seperated. If it is a 1/2 system (only block cooled by antifreeze and manifold is cooled by raw water) then do not block off passages between manifiold and riser (same as raw water cooled).

 

[luky7]

Re: overcooling without blockoff plate

thank you for responding!

sorry for the lack of info on my post but I'll do better, here's my shemas of my engine with the separation plate.



my thermostat is open to 150 degrees for the test. the cooling system is raw water and I can see the water inlet manifolds without blockoff plate then water when hot water arrives engine as it divides up into the riser and the manifold instead of recirculated into the engine til the water is a good temparature to open the thermostat because presently it is as if I was driving without a thermostat .. and i good waterflow for output.

what do you think?

and sry for my english .. not my first language!

 

[04fxdwgi]

Re: overcooling without blockoff plate

thank you for responding!

sorry for the lack of info on my post but I'll do better, here's my shemas of my engine with the separation plate.

View attachment 165835

my thermostat is open to 150 degrees for the test. the cooling system is raw water and I can see the water inlet manifolds without blockoff plate then water when hot water arrives engine as it divides up into the riser and the manifold instead of recirculated into the engine til the water is a good temparature to open the thermostat because presently it is as if I was driving without a thermostat .. and i good waterflow for output.

what do you think?

and sry for my english .. not my first language!

I think I understand what you are saying, but not 100% sure. If the thermostat is the correct one, is installed and working correctly, the engine should come up to the rated temp of the thermostat. Have seen many of them hang open if they were overheated, even once. The thermostat should be closed until engine hits the rated temperature. If it's open, engine will never heat up due to overcooling. PS: The part you are calling "Block-off Plate", is a seperator / restrictor gasket (and sometimes a stainless steel plate) between the manifold and riser. Doesn't actually block off anything, just restricts the flow a little bit and must be installed correctly.

 

[muc]

Re: overcooling without blockoff plate

Yes you need that plate and a gasket on both sides of it. Sounds like that is your problem.

 

[luky7]

Re: overcooling without blockoff plate

Yes you need that plate and a gasket on both sides of it. Sounds like that is your problem.

Thanks guys very apreciate ur help !!!

MC-20-60207 Stainless steel block off plate (with
vent hole) for use with MerCruiser
riser #?s 60426, 76351 and 76771. Requires (2) gaskets part # MC47-27-
99777. Used in pre-heating plumbing systems.