4.3GL Sudden Overheating

[oldmanoftheski]

Hi everyone. I have a Seaswirl 175 bowrider running a Volvo Penta 4.3GL FEPS, engine No. 40120286013869053. It suddenly overheated one afternoon whilst waterskiing. I had noticed it was running slightly warmer than usual, (Usually ran very cool which I now know was due to impeller vanes stuck in thermostat housing) I took it home and checked the impeller which was good but found a vane in the outlet of the raw water pump. Further inspection found the thermostat housing bypass holes blocked by more pieces of rubber which I removed. I checked the thermostat with a thermometer and hot water it was OK. I back flushed all the hoses and leg, no more rubber. I then ran it on muffs and in a large tub, with some of the smaller hoses replaced with clear as per overheat diagnostics article found in other posts. Everything worked OK. The engine sat on about 160f or so and all seamed well. Took the boat out again and it ran hot in about five minutes, this time the alarm went off. I plan on removing the risers next chance I get to check corrosion and blockages. I plan on also changing the circ pump as it has a slight amount of bearing play while every thing is apart.

Is there any thing else i should check???? Scratching my head.

 

[ENSIGN]

Re: 4.3GL Sudden Overheating

Check the inside of the seawater pump for any grooves or score marks.A common mistake when serviceing these pumps is to just through a impeller in there when in fact the housing is worn from all the sand and debris.

 

[Bondo]

Re: 4.3GL Sudden Overheating

I took it home and checked the impeller which was good but

Ayuh,... Impellers are throw-away parts that aren't Checked, but are Changed...

Make sure the housing is Ok, 'n replace the impeller...

 

[oldmanoftheski]

Re: 4.3GL Sudden Overheating

I will also replace the impeller. When I inspected it the vanes sprang back ok. I realise they are a service Item and have to be replaced every season. I had expected that it had failed due the suddeness of the overheat and was surprised when it hadnt. The pieces that I found were from another one that had failed prior to my ownership of the boat. Thank you guys for your input.

 

[Don S]

Re: 4.3GL Sudden Overheating

Fix the obvious problems like your circ pump, and check the manifolds and risers for blockage and see how it works.

 

[quintonwatts]

Re: 4.3GL Sudden Overheating

Careful when replacing the impellar. I put an OEM part into mine and as it was a 1mm short I ended up with an overheat as it didn't push enough water through. Often things can look OK on bellows as the mains/outside water pressure helps force water through whereas when you put the boat back in the water the everything has to be working OK for it to pull the water through properly.

 

[oldmanoftheski]

Re: 4.3GL Sudden Overheating

Righto guys, actually had a chance to do some work on the boat this afternoon. I have removed the impeller looks abit more stuffed than last time I looked at it, (maybe I know more from reading all these posts)so its getting chucked. Removed the risers as Don S suggested. Risers are in excellent condition with no real corrosion as are the manifolds. I did notice a small amount of corrosion on the outside where the bolts go through the risers to the manifold, which would possibly indicate a small amount of leakage???? Left hand one was VERY easy to remove and the gasket may have be leaking. The right one a little harder to remove. Both gaskets seemed to fall apart so both may have been leaking exhaust gas under under load into the cooling system. All spark plugs are normal colour. I have to wait for some parts to arrive before it can go back together and test. Thanks for your input guys. I will update as time permits

I did find an interesting Volvo Penta parts list on the net which seems to have up to date part numbers for the basic service items for all V/P engines and drives. The link is below for those that are interested.:joyous:

http://www.volvopenta.com/SiteCollectionDocuments/VPC/Market sites/China/船机发动机零件速查手册.pdf

 

[oldmanoftheski]

Re: 4.3GL Sudden Overheating

Finally got a chance to water test today. Work and weather have beaten me till now. So I changed the circ pump, Impeller and riser gaskets and all is well. Engine sits on the right operating temp and runs better than before. Even repeated loading and unloading the throttle would not make the gauge move more than a couple of degrees. I did test the thermostat again and found it was not in spec so chuked a new one in. So which was the culprit?? I would say a combination of all but mainly the Impeller. Thanks for your input guys. I am now a happy boater again.