Volvo 4.3 gl overheating

[Gray87]

Okay so a little back ground. I have a 2003 Volvo penta 4.3 GL in a Crownline. I winterized it last fall by just pulling the plugs from the block (2), manifolds (2) and by removing all the lower hoses including the two from the raw water pump. I pulled it out two weeks ago changed engine oil and filters, hooked up the hose to the flush out fitting that is y piped into the raw water pump and ran it in the driveway to running temp. Everything was good.

I dropped it on the lake last week and trolled around with the kids while my wife parked the truck. Picked her up at the dock, went to 3/4 throttle and back down to 1/2 throttle once planed out, trim all the way down. Once out of the bay I throttled it up and it started loosing power. I looked at gauges and water temp was 240°f. I immediately moved throttle to neutral and looked to the back of the boat. Smoke coming from the engine bay and shut off the key. Opened the top and the bellows had melted off and was obviously extremely hot. Coasted to shore and got towed back to the dock.

Now at home. I removed the bench and everything around the engine removed the raw water pump expecting to see it missing all the fins or the splines wore out but it’s perfect. No issues at all with it. I started it for 3 seconds, mainly to see if it would start because it wouldn’t restart on the water after I shut it down. Fired right up sounds smooth. I removed the rubber bellows and turndown elbows to assess the damage and I have a few questions.

Why are there no flapper/shutter valve in the lower exhaust like I’ve seen on pictures?

If the raw water pump seems fine could it be the regular water pump and it didn’t show up in the driveway because water pressure from the garden hose was doing all the work?

Do I need to worry about the head gaskets?

Thanks in advance I have so many more questions

 

[itsathepete]

Is there an oil or ps fluid heat exchanger in the freshwater inlet hose? If you didn't drain this or fill with antifreeze it could have cracked and the impeller is sucking air

 

[itsathepete]

Also could be a blockage in water inlet hose. If it only overheated at high throttle it may just not be getting enough water.
Take inlet hose off seawater pump and backflush to outdrive and check for leaks and make sure it flows freely

 

[CapnNemo]

I recently had a (much less severe) overheating issue with my 5.0 GL, which I posted on this form, and received a lot of good information and advice. You might want to check that out.

Since the risers got very hot, I don't think your problem is related to the engine circulation pump. When the thermostat is closed, I believe the raw water pump pumps water into the thermostat housing and out to the manifolds, bypassing the engine. So if the circulation pump is the only problem, your manifolds and risers would be cooling fine. Were the risers on both sides hot? Maybe one or both have plugged water channels.

 

[Gray87]

I pulled both risers last night and they were both cleaner then I thought they would be, like really clean. I’m going to re-gasket the risers, put on new bellows and test it in the drive way again but with muffs. And see what gets hot with a temp gun. I haven’t had issues with this boat ever and the main water pump looks to be original so I’m replacing that as well as the thermostat before the test run.

 

[Gray87]

Also I’m going to back flush and there is a heat exchanger for the power steering but it’s at such an angle that I don’t think any water could have been left in it.

 

[Scott06]

Did u swap inlet and outlet hoses in raw water pump When getting the boat ready

 

[Gray87]

That’s a thought, but they are molded hoses and zip tied together. I’ll have to check though.

 

[stouchton]

I had a blocked nipple on the thermostat housing (actually an eel - figure that one out). I did the real obvious thing and simply removed both manifold feed hoses at the thermostat housing and fired her up - she was in the water of course. Real obvious that flow on one side was restricted.

If you did this and did not get flow you would know you have a problem pulling water up from the outdrive or your raw water pump has failed.

As to the power steering cooler - my marina likes to back fill with antifreeze but I normally just blow air thru the line. There is at least one place water gets trapped - might be in the hose connected to the transom mount?