7.4 Volvo Overheating

[alindquist]

Hey guys, I have a 1999 7.4 Volvo GI (serial number 4110176452) that is overheating on me. I have changed the impeller & thermostat. I'm running the boat on the hose at my house. I have pulled the intake hose and I'm getting water to the seawater pump, I have pull the output hose and the seawater pump seems to be flowing water out at a good rate. I pulled the next hose toward the back of the engine and I'm not getting water to that location. I then back flushed that hose to make sure there was no debris and there wasn't. What next? This doesn't make any sense to me. I can't find any leaks.
Thanks,
Aaron

 

[bruceb58]

Re: 7.4 Volvo Overheating

Pull the hoses going to the manifolds to see what the flow is like is there. If the flow is good there then the next step is to pull the risers to see if there is blockage in there.

 

[alindquist]

Re: 7.4 Volvo Overheating

Water is not getting to the Thermostat housing, I did disconnect the hoses that run to the Manifolds and flushed them out. There was no blockage. Manifolds and risers were replaced in the spring.

 

[bruceb58]

Re: 7.4 Volvo Overheating

I believe the power steering cooler is between the pump and the thermostat. May want to checj that it is clear.

 

[alindquist]

Re: 7.4 Volvo Overheating

Any idea how much water should be coming out of the sea water pump when at idle? Seems like there is plenty of water coming out but it is not reaching the power steering cooler (it's either the power steering cooler or the fuel cooler). I did back flush that hose and it was clear.

 

[parrisw]

Re: 7.4 Volvo Overheating

Is it pumping its own water from a big bucket? Or do you have the hose attached to the leg? Since the water pressure from the hose, you won't be able to tell properly if its pumping on its own ok.

 

[alindquist]

Re: 7.4 Volvo Overheating

It's pumping off the hose with the muffs, I have flushed the with the muffs after everytime I use it and never had a problem. Should I use a big bucket or garbage can?

 

[parrisw]

Re: 7.4 Volvo Overheating

It's pumping off the hose with the muffs, I have flushed the with the muffs after everytime I use it and never had a problem. Should I use a big bucket or garbage can?

Ya, the thing is you'll never know if the water pump is working ok on its own with the hose on it since the water pressure from the hose forces everything up. But if its overheating with the hose, something is definitely wrong.