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Water flow issue 2002 8.1Gi-b

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Silverbullet555

New member
2002 8.1gi-b
450 hours
Raw water cooled
No flappers

Port side manifolds run 20-30 degrees hotter than starboard. This happens if bost is level or not; in the water or on the muffs.
I know some will say this is normal, but this a new issue and when something new comes along then something changed.
Engine does not overheat. Issue is in the flow that goes to the manifolds and risers.
Problem arose 2 years ago. I was sick last year so I didn't work on it.
Compression test is fine.
Leakdown test is fine

Compression
170, 175, 170, 175, 170, 175, 170, 170

Leakdown
20%, 13%, 13%, 5%, 10%, 10%, 7%, 6%

Manifolds and risers have been checked
Oil cooler has been backflushed
Raw water pump replaced.
Used clear hose to observe water flow. Noticed water flow to port side much less than starboard. Put equal length hoses in the system and swapped sides. The low flow switches sides as does the higher temps.

To me this indicates the issue is NOT in the cooling system after the thermostat housing. It has to be somewhere upstream of that. Possibly the thermostat housing though I have visually checked it. The other possibility is that there is some kind of blockage which is simply reducing the flow and pressure enough that one side is getting starved
 
Silverbullet555 said:
2002 8.1gi-b
450 hours
Raw water cooled
No flappers

Port side manifolds run 20-30 degrees hotter than starboard. This happens if bost is level or not; in the water or on the muffs.
I know some will say this is normal, but this a new issue and when something new comes along then something changed.
Engine does not overheat. Issue is in the flow that goes to the manifolds and risers.
Problem arose 2 years ago. I was sick last year so I didn't work on it.
Compression test is fine.
Leakdown test is fine


Compression
170, 175, 170, 175, 170, 175, 170, 170

Leakdown
20%, 13%, 13%, 5%, 10%, 10%, 7%, 6%

Manifolds and risers have been checked
Oil cooler has been backflushed
Raw water pump replaced.

..... All the above, while good are not related to your problem...

Used clear hose to observe water flow. Noticed water flow to port side much less than starboard. Put equal length hoses in the system and swapped sides. The low flow switches sides as does the higher temps.

To me this indicates the issue is NOT in the cooling system after the thermostat housing. It has to be somewhere upstream of that. Possibly the thermostat housing though I have visually checked it. The other possibility is that there is some kind of blockage which is simply reducing the flow and pressure enough that one side is getting starved...
Click to expand...

Correct in that the low flow is upstream of the hose attachment point to the T'stat. What work got done 2 yrs ago before problem started???? Are there salt deposits in the T'stat housing? Is it the correct T'stat? Is it installed correctly???

 
sandkicker said:
Correct in that the low flow is upstream of the hose attachment point to the T'stat. What work got done 2 yrs ago before problem started???? Are there salt deposits in the T'stat housing? Is it the correct T'stat? Is it installed correctly???

Click to expand...

All of that was listed to eliminate or reduce questions about what had been done. Some were based on slight potential causes of reduced flow.

In late 2015 I switched from VP 30wt oil to Mobil 1 synthetic due to VP eliminating that oil. That would have no impact on this issue. I rebuilt the raw water pump in 2015. To eliminate that as a potential problem, I replaced the pump a few weeks ago. The thermostat is the correct one and installed correctly. I have ordered a new housing to see if erosion or buildup has caused a change in the path of perhaps made it easier for water to flow out one port or the other. I'll change the thermostat again at that time. In the meantime, I'll triple check that it is installed in the correct orientation.

Thank you for the reply.
 
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