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New Manifolds, one has low flow

Docksidemarineservices said:
The gaskets are incorrect.

Between the manifold and the 3" riser you should have the gasket with 4 large holes. Part Number 860232


Between the Riser and the elbow you should have a restrictor gasket with 2 large holes...Part number 860233
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IGNORE THIS I gave you incorrect information.

Mercruiser Service Bulletin No. 99-10

All gaskets are to be non restricted on your application.



Is this boat being tested in the water?

Is this an inboard or a sterndrive?
 
freebeerisgood said:
I did do that just about an hour ago, it has flow. I also pulled the elbows and re inspected, no blockage at all.



I mentioned that I have low flow out of one of the hoses that enter the manifolds, hence my reason for believing its in the exchanger. Thermostat isn't in play here, its freshwater cooled. I don't think I'm anything too difficult, how do you mean?
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If you have a fool proof 100% accurate way to visually inspect exhaust elbows for blockage, you'd get the nobel prize in marine repair.

Due to how the raw water outlets on HEs are derived physically, the only way to accurately judge the flow is to partially restrict the flow from both sides at the same time and then judge the flow. Often outlets are at different heights and different flow paths and with zero back pressure and or low flow rates, i.e. @ idle, one or the other of the outlets will flow more water.
 
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Docksidemarineservices said:
IGNORE THIS I gave you incorrect information.

Mercruiser Service Bulletin No. 99-10

All gaskets are to be non restricted on your application.



Is this boat being tested in the water?

Is this an inboard or a sterndrive?
Click to expand...

All the new gaskets intalled are non restrictive

Sterndrive. The boat is being tested on the trailer. I will likely back it in the water once it is back together and see it the Port manifold overheats.
 
If you have a fool proof 100% accurate way to visually inspect exhaust elbows for blockage, you'd get the nobel prize in marine repair.
Click to expand...
Actually, you can get a weenie teenie borescope for your iPhone for small coin. Like $15.
 
freebeerisgood said:
All the new gaskets intalled are non restrictive

Sterndrive. The boat is being tested on the trailer. I will likely back it in the water once it is back together and see it the Port manifold overheats.
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All right. Testing on a hose in not what you should be doing. Chances are everything is working fine.

The only thing you need to check is the water fitting through your transom assembly and make sure it is clear.

If it is not corroded shut, put the boat in the water and it will probably be fine.
 
Docksidemarineservices said:
All right. Testing on a hose in not what you should be doing. Chances are everything is working fine.

The only thing you need to check is the water fitting through your transom assembly and make sure it is clear.

If it is not corroded shut, put the boat in the water and it will probably be fine.
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I've been out of the country for work, but I finally had a chance to get it in the water today. It checks fine in the water. While on plane I can see both exhaust ports are flowing water evenly, and the manifolds are similar temperature. No issues that I can see.

I still don't understand why all of the raw water is coming out of one manifold when running on the trailer, its never done that since I have owned it from new and its making it basically impossible to idle it for more than a few minutes, as the Port manifolds is way too hot. If I add a little back pressure to the starboard hose by clamping it partially shut while idling, it flows to the port better. To me, it seems like the one restrictive gasket might help that, although I read through 99-10 service bulletin and it says to use non restrictive on both gaskets with 3inch risers.
 
freebeerisgood said:
I've been out of the country for work, but I finally had a chance to get it in the water today. It checks fine in the water. While on plane I can see both exhaust ports are flowing water evenly, and the manifolds are similar temperature. No issues that I can see.

I still don't understand why all of the raw water is coming out of one manifold when running on the trailer, its never done that since I have owned it from new and its making it basically impossible to idle it for more than a few minutes, as the Port manifolds is way too hot. If I add a little back pressure to the starboard hose by clamping it partially shut while idling, it flows to the port better. To me, it seems like the one restrictive gasket might help that, although I read through 99-10 service bulletin and it says to use non restrictive on both gaskets with 3inch risers.
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Because the Raw water pump needs more water than a hose can provide.
 
Docksidemarineservices said:
Because the Raw water pump needs more water than a hose can provide.
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i totally understand that but it doesn't make sense
1- Its never had this issue in 15 years or more, same house, same ear muffs ect.
2- It changed as soon as I put new manifolds on the boat, one week flow from both sides was good with the hose, next week (new manifolds) its not.

Either way Im more than ok to run it like this I'd just rather be able to flush it without one side overheating.
 
As an aside... My engine is intentionally setup for thru hull, not thru drive water inlet. I have a T valve for a hose fitting and when I run the engine "on the hard", I stick the hose from the raw water port into a 5 gal pail with a free running hose also in the pail. I wait for the pail to fill to the top before I start my engine. At 650 RPM, the garden hose ( at full bore) supplies just a bit more water than the engine takes... however at 800+ RPM (cold enriched RPM), the engine takes more water than the hose can supply, and the water level in the pail has to be carefully monitored to prevent the raw water pump from running dry.
 
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I still don't understand why all of the raw water is coming out of one manifold when running on the trailer,
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Ayuh,.... Probably as simple as the hull not bein' level,....
 
what was the cause? I have the same issue. Poor flow coming out of the heat exchanger on port. Port is too hot to keep hand on it for more than 3 seconds
 
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