1999 7.4 Volvo GI mpi cooling hoses

[Dave-R]

Hello all; I have bought a boat that the cooling hoses were all removed .
They were all obvious except the two from the crank pump. I have tried to
find a drawing showing the flow path to no avail. When running, the temp creeps up
to 180@ and I shut it off. Impeller looks good, new 140@ thermostat.
Before I keep troubleshooting, I want to make sure things are hooked up
correctly. 1999 Volvo 7.4 GI MPI. Thanks. Dave-R

 

[Bondo]

Re: 1999 7.4 Volvo GI mpi cooling hoses

Hello all; I have bought a boat that the cooling hoses were all removed .
They were all obvious except the two from the crank pump. I have tried to
find a drawing showing the flow path to no avail. When running, the temp creeps up
to 180@ and I shut it off. Impeller looks good, new 140@ thermostat.
Before I keep troubleshooting, I want to make sure things are hooked up
correctly. 1999 Volvo 7.4 GI MPI. Thanks. Dave-R

Ayuh,.... The Raw water pump,..??

1 hose is the in-comin' from the sea strainer or drive, 'n the other goes to the t-stat housin', the out-goin' line,...

If it ain't pumpin' out raw water, switch 'em,...

 

[Dave-R]

Re: 1999 7.4 Volvo GI mpi cooling hoses

Thanks Bondo: I took both hoses off and turned the water on. Found the Supply hose.
Then I took the pump off, and figured out how it pumped. Still did not improve much.
I then took the muffs off and bent them tight to the drive, and tried again.
This time no overheating. She stayed at about 140deg.and ran just fine.
I am a little worried though, the manifolds and risers looked really good,
the raw water pump and impeller were new. When I pulled some of the hoses
off, there wasn't a lot of flow or pressure. I have had a lot of different drives , but never
had problems with the muffs. Do you think the raw water supply from the drive could be partially
blocked. Thanks.

 

[dypcdiver]

Re: 1999 7.4 Volvo GI mpi cooling hoses

I cannot find a 7.4 Gi MPI on any of the sites, can you supply a bit more info. I'll have a guess. It sounds to me like you may have a problem with your raw water pump and that tightening the muffs allows water pressure to be forced through the pump. I know you say it is new, but I would still be interested to pull the out put hose off (ie. the one that goes to the thermostat housing) and start her up with the muffs on and make sure you have a good and pressurised flow. If all that is good then I'd move to the thermostat housing, check that the 2 outlets to the hoses that supply the manifolds are clear of corrosion. If they are then also check that the elbows that are screwed into the manifolds are clear and that the holes into the manifold are also clear, debris can lodge in these. If they are good leave the hoses off and with every thing else connected start her up and check that you have a good flow coming out of both hoses. If that fails then it is back to the thermostat housing and check for old vanes blocking any of the internal passages in the housing. If the correct thermostat is installed she should run at 160 F.

 

[payitforward]

Re: 1999 7.4 Volvo GI mpi cooling hoses

I had the same issue....... change the water hoses on the back of your engine attached to the fuel Reservoir.