Thermostat bypass Valves

[Jayrock]

1992 200 Evinrude

What is the exact purpose of these valves? I have searched but cant find a solid answer. They must be necessary for proper cooling, but I would like to know how they do their job, so I can verify that they are working correctly. Thanks guys, Jason

 

[metriccrescentwrench]

Re: Thermostat bypass Valves

Are you talking about the water control valve? At idle and below around 2500 rpm the water control valve is closed, which keeps pressure on the back side of the thermostat diaphragms which in turn keeps the thermostats seated (and they regulate water flow based on temperature). As throttle is increased the water control valve opens which relieves pressure from the back side of the thermostat diaphragms - this lets the thermostats lift off their seat which allows more cooling water to flow.

These engines are supposed to be at around 145 degrees at idle, and 120 or less while under load.

I was having cooling issues because the moron I bought my engine from had removed the water control valve and just plugged the hose that's supposed to go to it. Faztbullit put me onto a fix that involved throwing away the existing thermostat covers, diaphragms, and water control valve (that part was already taken care of), and installing thermostat covers and springs (and gaskets) from the '89 70 HP engine (those parts are still available new). This is much simpler, water pressure builds with increasing engine rpm and lifts the thermostat off the seat - works like a champ.

 

[Jayrock]

Re: Thermostat bypass Valves

I dont have a water control valve. Just the hoses that come off the thermostats that go to as "T" fitting then goes into the upper port rear of the block. I this correct? If differential pressure lifts the thermostat off the seat, running the hoses back to the block would do nothing, same water pressure inside. I would like to make sure the thing is installed and working as intended, so I dont cook my motor. Thanks again, Jason

 

[seahorse5]

Re: Thermostat bypass Valves

I dont have a water control valve. Just the hoses that come off the thermostats that go to as "T" fitting then goes into the upper port rear of the block. I this correct? If differential pressure lifts the thermostat off the seat, running the hoses back to the block would do nothing, same water pressure inside. I would like to make sure the thing is installed and working as intended, so I dont cook my motor. Thanks again, Jason

What is your engine model number?

 

[metriccrescentwrench]

Re: Thermostat bypass Valves

I dont have a water control valve. Just the hoses that come off the thermostats that go to as "T" fitting then goes into the upper port rear of the block. I this correct? If differential pressure lifts the thermostat off the seat, running the hoses back to the block would do nothing, same water pressure inside. I would like to make sure the thing is installed and working as intended, so I dont cook my motor. Thanks again, Jason

That sounds messed up, your engine should have a hose from the port to starboard thermostat cover, then a hose from the starboard thermostat cover to the water control valve (which is activated from the throttle linkage). There's another hose from the lower part of the block to the pressure control valve (that hose supplies pressure below 2000 rpm's to keep the thermostats seated), and finally the outlet from the water control valve has a hose going to the aspirator.

The water control valve is # 37 in this diagram.

http://shop2.evinrude.com/Index.aspx?s1=fb5ds34cnm2t1fsmjbk2jvpjj1&catalog_id=0&siteid=1

Since you're asking about the cooling system I'm guessing you're having cooling issues.


Here's the hose routing diagram from my shop manual:

 

[Jayrock]

Re: Thermostat bypass Valves

I see... My setup is wrong. The thermostat covers are off a newer motor, a 1996 I think. The starboard and port are the same. I am having a small temperature issue. But I am checking all things out before this motor dies. Is there a tried and true way to setup these bypass hoses so they work like a newer 93-96 200 V6? Since the thermostats and covers are of the newer design?

 

[Faztbullet]

Re: Thermostat bypass Valves

Is there a tried and true way to setup these bypass hoses so they work like a newer 93-96 200 V6? Since the thermostats and covers are of the newer design?

No.. as the newer engine is a closed deck block and uses a poppet valve . These newer heads run very little water thru them to build heat quicker and the poppet dumps into t-stat covers as pressure unseats it. Do the mod I gave Metric....thermostat covers and springs (and gaskets) from the '89 70 HP engine and it will be fine....

 

[metriccrescentwrench]

Re: Thermostat bypass Valves

Do the mod I gave Metric....thermostat covers and springs (and gaskets) from the '89 70 HP engine and it will be fine....

Yes. Not much $$ for the parts, it's a much simpler setup, and it works. Can't beat that.

 

[Jayrock]

Re: Thermostat bypass Valves

OK, Thanks all. will look into it.

 

[j_k_bisson]

Re: Thermostat bypass Valves

I waited for this issue to be resolved before Higacking it a bit. I have a 1987 200hp Evinrude looper, does this motor have the same issues? I was planning on replacing/rebuilding the thermostats anyway, will this fix work as well for my motor?

 

[Schtoopid]

Re: Thermostat bypass Valves



That sounds messed up, your engine should have a hose from the port to starboard thermostat cover, then a hose from the starboard thermostat cover to the water control valve (which is activated from the throttle linkage). There's another hose from the lower part of the block to the pressure control valve (that hose supplies pressure below 2000 rpm's to keep the thermostats seated), and finally the outlet from the water control valve has a hose going to the aspirator.

The water control valve is # 37 in this diagram.

http://shop2.evinrude.com/Index.aspx?s1=fb5ds34cnm2t1fsmjbk2jvpjj1&catalog_id=0&siteid=1

Since you're asking about the cooling system I'm guessing you're having cooling issues.


Here's the hose routing diagram from my shop manual:

Don't suppose you could repost that image?
Link is dead.

 

[GA_Boater]

Don't suppose you could repost that image?
Link is dead.

Nope, he doesn't visit the forum anymore. Read the Help Tip on top of the page and start a new thread with what you're looking for.

Closed.