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Exhaust elbow gasket

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pursuit2460

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I have been searching and even asked Mercury for the answer to this question. Like I said I have been searching and reading and the answers are all either open or restricted, but no concrete answer it seems. I have a FWC 2000 5.7 TBI B3 L635326. It has Barr manifolds/elbows with the restricted gasket. When I went to boats.net to look up the part numbers so I could replace everything, it gives me an open gasket part number. I call a Merc dealer and he wasn't to sure and said, replace with what it has. I email Merc and asked for confirmation and they directed me to Service Bulletin 99-10. I have read the SB and it also says I should use the open since I have FWC with 1 hose going to the bottom of the Exhaust manifold. I know that I should follow what Merc has on their SB but some people/mechanics on the forums seem to do the opposite.
 
Most FWC factory systems use a full system,meaning the manifolds are included in the cooling.so the manifold is sealed off from the riser
 
To understand your interpritation of FWC, answer this question,

Does your cooling system have a heat exchanger and does the system use antifreeze/water and is there is radiator cap on the exchanger.

For future reference,

RAW WATER COOLED = NO HEAT EXCHANGER

CLOSED COOLING = HEAT EXCHANGER

Using FWC vs RWC is confusing so most in the business use Raw or Closed. That way there is NO confusion.


If raw water is flowing through the exhaust manifolds you do not have a closed cooling system.
 
I have a heat exchanger and use anti freeze. The only part of my system that doesn’t have antifreeze is the exhaust manifold. I also have raw water flowing through my exhaust manifolds. But I see the confusion and understand what you mean.
 
On your, engine block only FWC system, there are two options... cold manifolds and warm. Cold uses the "open gasket", while warm uses the restricted flow gasket. Replace with what you have, i.e. restricted.
 
I have never seen a closed cooling system where raw water flows through the exhaust manifolds. Not to say that it doesnt exist.

what gaskets were between manifold and elbow? Open or "restricted"? (Restricted = Complete block off so NO water/liquid passes to elbow)?
 
sandkicker said:
On your, engine block only FWC system, there are two options... cold manifolds and warm. Cold uses the "open gasket", while warm uses the restricted flow gasket. Replace with what you have, i.e. restricted.
Click to expand...
Problem is that according to the Mercury Service Bulletin 99-10, my engine takes the open. It did have the restricted ones but the manifold/elbow were replaced already so who knows if it was the wrong gasket.
 
kghost said:
I have never seen a closed cooling system where raw water flows through the exhaust manifolds. Not to say that it doesnt exist.

what gaskets were between manifold and elbow? Open or "restricted"? (Restricted = Complete block off so NO water/liquid passes to elbow)?
Click to expand...
Yup, it exists. Look on boats.net for my year and serial and look at the closed cooling system. The raw water exits the heat exchanger on both side to 90* elbows on the bottom of each exhaust manifold. So as for your gasket question, there are 3 gaskets. Completely blocked off, restricted, which has 2 large openings and the other 2 openings have a small hole and open, all 4 sections open. Mine had restricted gasket. But according to the Mercury SB 99-10, I should be using the open.
 
Next question,
Do the elbows have a raw water (cold) to the elbow with individual hose?
If so, then restricted is correct.
If not raw cold water to elbow then use fully open gasket.

So, when elbows have there own cold water supply (which is what keeps exhaust cool so rubber exhausts connections dont melt) then a restricted gasket slows water flow thru manifold.

If No cold water to elbow, and only flow is up thru manifold then I would say full open gaskets so exhaust stays as cool as possible.
 
kghost said:
Next question,
Do the elbows have a raw water (cold) to the elbow with individual hose?
If so, then restricted is correct.
If not raw cold water to elbow then use fully open gasket.

So, when elbows have there own cold water supply (which is what keeps exhaust cool so rubber exhausts connections dont melt) then a restricted gasket slows water flow thru manifold.

If No cold water to elbow, and only flow is up thru manifold then I would say full open gaskets so exhaust stays as cool as possible.
Click to expand...
My elbows have no hoses coming into them. The water exists the heat exchanger and enters the bottom of the exhaust manifold and up through the elbow and out the exhaust. I had noticed before I removed everything and was flushing it out this weekend that the leaking elbow was hotter than the other one. When I did remove the elbow there was buildup on the restricted side of the gasket. Mind you I had just cleaned the manifold about 5-6 months prior and installed new gaskets. So it would make sense that you need more water flow through the elbow to keep it cool, that’s where the open gasket come in.
 
pursuit2460 said:
Yup, it exists. Look on boats.net for my year and serial and look at the closed cooling system. The raw water exits the heat exchanger on both side to 90* elbows on the bottom of each exhaust manifold. So as for your gasket question, there are 3 gaskets. Completely blocked off, restricted, which has 2 large openings and the other 2 openings have a small hole and open, all 4 sections open. Mine had restricted gasket. But according to the Mercury SB 99-10, I should be using the open.
Click to expand...
Block only FWC, with raw water in the exhaust manifolds is standard for Volvo... and the "budget" option of many aftermarket FWC systems for MERCS... and some other marinizers, which is apparently what persuit2460 has. Re: persuit's confusion on the gasket and what MERC calls for.... you don't have a standard MERC system. Likely FWC was a factory option and they installed the Barr budget kit, i.e. a smaller heat exchanger supporting only the block wth raw water to the manifolds.... Refer to a BARR manual for part numbers ....
 
pursuit2460 said:
Yup, it exists. Look on boats.net for my year and serial and look at the closed cooling system. The raw water exits the heat exchanger on both side to 90* elbows on the bottom of each exhaust manifold. So as for your gasket question, there are 3 gaskets. Completely blocked off, restricted, which has 2 large openings and the other 2 openings have a small hole and open, all 4 sections open. Mine had restricted gasket. But according to the Mercury SB 99-10, I should be using the open.
Click to expand...
Ayuh,.... Then that's what I would do,.....
 
sandkicker said:
Block only FWC, with raw water in the exhaust manifolds is standard for Volvo... and the "budget" option of many aftermarket FWC systems for MERCS... and some other marinizers, which is apparently what persuit2460 has. Re: persuit's confusion on the gasket and what MERC calls for.... you don't have a standard MERC system. Likely FWC was a factory option and they installed the Barr budget kit, i.e. a smaller heat exchanger supporting only the block wth raw water to the manifolds.... Refer to a BARR manual for part numbers ....
Click to expand...
I am not the original owner, I bought it from the original owner though. At some point the OW did put Barr manifolds/elbows. Boat is a 2000 Pursuit 2460 Denali. All the Denalis I looked at, that did have a closed cooling system, had the exact same system I have. All hose have OEM numbers on them and match Boats.net part#. Even Boats.net shows the OEM system and it doesn't supply antifreeze to the exhaust manifold. Either way, everything is on order and I got the open gaskets.
 
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