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Fresh water cooling kit


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I put on a fresh water cooling kit on Inmar engine and the coolant flow goes thru the thermostat to the manifolds. This means the manifolds get no coolant flow until the thermostat opens. We see the manifold temperature rising quickly to 190'F and the thermostat temperature is only at 110'F and a long way from opening. So we shut down the engine before overheating of the manifolds.

We are worried the manifolds will overheat while waiting for the thermostat to open. Has anyone else seen this and recommend something? Can the manifolds take a higher temperature? Thanks

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It depends on the coolant system design. Where did you get the kit from and was there directions with it?

If coolant goes to the exhaust manifolds, wouldn't it come out of the back of the boat? oh wait, I guess there are exh. man. passages that get blocked by new gaskets for closed cooling.

Shouldn't there still be a raw water pump that constantly sends water thru the exh. manifolds and out the exhaust?

I'm sure someone will chime in with answers. I have no idea.

I thought coolant or water went through the block and then stopped at the thermostat (keeping it in the block) until the thremostat opens (allowing full circulation).

Edited by JasonK
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Raw water usually cools the exhaust manifolds on an Indmar closed cooling system (half loop)

Did you install a completely closed loop with the catalyic coverters in the exhuast manifolds?

-Chris

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I put on a fresh water cooling kit on Inmar engine and the coolant flow goes thru the thermostat to the manifolds. This means the manifolds get no coolant flow until the thermostat opens. We see the manifold temperature rising quickly to 190'F and the thermostat temperature is only at 110'F and a long way from opening. So we shut down the engine before overheating of the manifolds.

We are worried the manifolds will overheat while waiting for the thermostat to open. Has anyone else seen this and recommend something? Can the manifolds take a higher temperature? Thanks

That temperature is not a problem for the manifolds. They typically run close to 200 degrees even on a raw water cooled engine. Are you sure the manifolds are completely full of coolant? Pull the hoses off the upper fittings on the manifolds and pour coolant in them till they are full. Sometimes those manifolds like to trap an air bubble as the manifolds are actually highrer than the heat exchanger.

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i have fresh water cooling on my BU, and as 99 pointed out, the BU fwc does NOT cool the manifolds. maybe this is different for newer models?

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So where on the manifolds were you feeling heat? General rule of thumb is if the risers are cool (you can touch them comfortably) then you're fine.

-Chris

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  • 3 weeks later...

Vector,

I just installed aFWC from Indmar and have similar questions. It seems on top of the high heat on the Ex manifolds that there is air in the system as the expansion tank is not large enough to handle the variations in temp.

Did you find anything out?

Does anyone know if this is a std. problem?

Thanks

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I put on a fresh water cooling kit on Inmar engine and the coolant flow goes thru the thermostat to the manifolds. This means the manifolds get no coolant flow until the thermostat opens. We see the manifold temperature rising quickly to 190'F and the thermostat temperature is only at 110'F and a long way from opening. So we shut down the engine before overheating of the manifolds.

We are worried the manifolds will overheat while waiting for the thermostat to open. Has anyone else seen this and recommend something? Can the manifolds take a higher temperature? Thanks

That temperature is not a problem for the manifolds. They typically run close to 200 degrees even on a raw water cooled engine. Are you sure the manifolds are completely full of coolant? Pull the hoses off the upper fittings on the manifolds and pour coolant in them till they are full. Sometimes those manifolds like to trap an air bubble as the manifolds are actually highrer than the heat exchanger.

Larry,

I have just had a local mechanic install a closed cooling pkg. He has vacuum charged the cooling system (at about 26") to try to get the air out. The ETX CAT manifold definitiely run hotter (200-220) but we seem to be having a problem with either air in the system or an improper set up. Observations are:

When started cold and the expansion bottle 1/4 full it takes about 5 minutes of idle to get the thermostat to open

The IR gun says that the EX manifolds get to 240 before the thermostat opens and they drop to 210 ish.

Once the manifolds come up to temp the expansion tank is almost full.

When run hard (3000+ RPM) the expansion bottle overflows about 1/2 gallon of fluid into the bilge.

When brought to idle the closed system sucks all of the expansion tank back plus air.

We adapted an expansion bottle that has 3X capacity and we still seem to have a problem.

The engine sensor always stays at 160 +/- 10 degrees

I can hear the coolant boiling in the Ex manifold as the problem becomes greater

We are guessing that there is air trapped in the system and that even a little collects in the EX manifolds this can cause problems which multiply.

Do you have any thoughts?

Thanks

Grant Rogers

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  • 8 years later...

What was the out come of this? I'm having a similar problem installing a fully closed system. The ex manifolds are heating up too quickly..they got to 100c and the thermostat was no where near opening so I shut it down quickly. 

I've since ran it with no thermostat to see how it behaved but am more puzzled the engine didn't get above 125f and the exhausts were around 90c so I'm worries that if the engine temperature increases so will the exhausts?

Any help on this will be massively appreciated.

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@Chazzer:  The cooling systems I have seen all have some sort of bypass circuit that allows at least some fresh water to flow to / through the exhaust manifolds.  I noticed the feedback from Larry @ Indmar implies the full manifold acts as a water tank which per his answer contains enough water to provide adequate cooling (and I would also guess allows the catalyst to heat up quickly) until the thermostat opens to provide the flow needed. 

On some open cooling aftermarket systems, methods to provide water to the exhaust manifolds include a small diameter bypass hose and/or some bleed holes in the thermostat.  Removing the thermostat will allow way too much coolant flow and the engine will not reach operating temperature as the incoming water is always quite cool (as compared to a up to temperature automotive radiator).

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20 hours ago, Chazzer said:

What was the out come of this? I'm having a similar problem installing a fully closed system. The ex manifolds are heating up too quickly..they got to 100c and the thermostat was no where near opening so I shut it down quickly. 

I've since ran it with no thermostat to see how it behaved but am more puzzled the engine didn't get above 125f and the exhausts were around 90c so I'm worries that if the engine temperature increases so will the exhausts?

Any help on this will be massively appreciated.

I think you really need to diagram how you've rigged up the closed cooling conversion for anyone to be able to advise where the problem lies.

This thread is probably the most complete regarding the conversion: 

Although @justgary's conversion was on an earlier motor than yours without cats.

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I have a half loop system but I remember asking about a full loop system.  My dealer said they wouldn't do it because of the very problem you guys say you are having.

However, I did end up talking to someone at BAKES on the phone a couple years ago when I was inquiring again about this and they said the problem has been solved.

I remember vaguely them saying something about putting valves on the coolant elbows at the top of the manifolds to allow the air to escape.

Point being there is a way to make it work with a full loop system.  Perhaps call BAKES for more information.  They are really good guys and can probably tell you what the fix is.

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