Volvo 130 C overheating problem

Rocket Robinson

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Joined
Aug 12, 2013
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2
I've read several previous threads on this, and it's been an problem that I have dealt with previously. The enigine is a Volvo 130 C (1985, Chev 350) inboard/outboard with San Juan fresh water cooling. It generally runs at 160 degrees, but this past weekend went up to 175 degrees while planning at 2300 RPM's. Should not do this. I changed out the raw water impeller (the old one was about 6 years old, but didn't appear in poor condition) and have ordered a new thermostat (140, like the old one), but don't have a lot of hope this will fix it. The fresh water pump does not leak or squeek, no loss of antifreeze. My questions:

1) Is there a way to eliminate the possibility that it is sucking in air at the raw water intake while planning? I read that the fitting on the outdrive can become corroded and suck air. The boat is 26' long and it's costly to pull it. If I was to simply run the engine at 2300 RPM in neutral would that tell me anything? The fitting would be under water, but there would be no load on the engine. (am awaiting the new thermostat to fire it up again).

2) I have removed and done the coat-hanger clean and water jet on the manifolds, the last time being about 4 years ago (ps: at that time I installed a T-valve in the hose just past the raw water pump that allows me to flush out the seawater from the system when back at the dock). Do I have to remove the manifolds to wire-clean them, or can I do that through the end caps? Is there a way I can tell if it's the manifolds / risers that are plugged up?

Thanks for any help! Mark
 

captmello

Captain
Joined
Jun 30, 2008
Messages
3,826
Re: Volvo 130 C overheating problem

Welcome!

It the system is leaking air at the intake fitting, It will typically overheat while on plane, then quickly cool down when you bring the boat off plane.

I would consider backflushing the heat exchanger. I don't believe the coat hanger trick is very effective. A better check of the manifolds would be to pull the risers and inspect the mating surface between the the two. Salt water boats need manifold and riser replacement every few years. Do you have full fresh water cooling, including the manifolds or just partial fresh water, in the block?

BTW, you're model number, 130c is not correct if you have a 350, Post some pics of the engine and fresh water cooling system.
 
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Rocket Robinson

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Joined
Aug 12, 2013
Messages
2
Re: Volvo 130 C overheating problem

Thanks, Captain-

Can't get to the boat for a pic right now but it is a 350 block. It is only partial fresh water, block only, but after every use I do flush the salt water out of the manifolds and risers with a garden hose tapped into the system just beyond the raw water pump outlet. I am hopeing that will extend their life. They are drained at the end of boating season.

Right now the starter (another issue) is being re-built, so I will do further diagnostics once it's back on. I can certainly try backflushing the heat exchanger, too, that should not be too difficult (I have the flow diagram for the San Juan fresh-water cooling system.

And again, thanks, great resource. Also an aside to those with this issue: some ten years ago I had an overheating problem and replaced manifolds, risers, raw water pump, thermostat, all to no avail. One day while underway I had my wife take the helm and went below in the engine compartment to find that the hose that brings the salt water into the boat to the raw water pump intake was flattened, like sucking on a straw with your finger over the end. When the engine was shut off, I couldn't squeeze it down, but underway, wow. Replaced it and problem solved.
 
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