Overheating KAD 42 again!

Hi and thanks for the reply, I had a spare raw water pump that i used. When the boat was on the hard for 7/8 months I neglected to remove the impellers, on start up one of the shaft seals let go. I bought spares from Keypart and re fitted it, all to the port engine which is fine. I replaced the seals , the bearings were ok and with a new impeller I fitted this to the starboard engine. This was after the impeller broke up on that engine , I initially just fitted a new impeller but recent posts advised that if the cover plate was at all scored or grooves in the pump body etc then the pump might not pick up on suction very well, so I fitted the refurbished one at the same time as I did the heat exchanger. I did not change any cams though as I was using what I understand to be the original bits of kit . I think the raw water side is working fine I think the FW side is the problem ?
 
Hi all just thought i would let you know I did a combustion gas check on the engine today and what a relief , it seems that if the test is correct then it's not a cracked head or blown head gasket! I made up the test jar with the test fluid which was a blue colour, if it turns yellow / green then it indicates combustion gasses in the coolant. Thankfully it never changed at all. I changed both stats before warming up the engine for the test , it did not get as high
as the last time . Around 165o or so.need to check out the circulation pump now as other than a blockage cannot not site what's left to look at ?
 
Keithleask said:
Hi all just thought i would let you know I did a combustion gas check on the engine today and what a relief , it seems that if the test is correct then it's not a cracked head or blown head gasket! I made up the test jar with the test fluid which was a blue colour, if it turns yellow / green then it indicates combustion gasses in the coolant. Thankfully it never changed at all. I changed both stats before warming up the engine for the test , it did not get as high
as the last time . Around 165o or so.need to check out the circulation pump now as other than a blockage cannot not site what's left to look at ?
Click to expand...

I've not time to read the whole thread so.

Have you checked the exhaust elbow?
Have you cleaned all the cooler tube stacks?
Have you carried out a sea trial with a laser gun to test for hot spots, measured the inlet and outlet temp of the sea water?
Measured the inlet and outlet temp of the fresh water at the heat exchanger inlet and outlet from the exhaust manifold and the fresh water pump inlet?
Carried out a pressure test on the sea water pump flow?

Seems you have been looking for your answer for some time so gather data from your problem rather than keep taking everything apart in the hope you find something.

Have you had any kind of Volvo pro engineer on board ?
Lastly I have changed a few early kad series fresh water pumps as the plastic impeller has fallen off , but when this happens the engine overheats in a matter of minutes not under load.
Come back with info, where is the boat?
 
Paul hi, was hoping you might pop in to the discussion, sorely needed! The exhaust elbows ( both port and starboard) were replaced with new ones last autumn,( the original ones had holes in them that had been filled with metal filler)only a few hours on them since fitting, so I can't think they can be the problem? I removed the heat exchanger and cleaned it and carefully rodded all the tubes, several blockages but cleared them then flushed it through. I took the after cooler top off and checked every tube, no blockages all clear.
I have not checked the temps on a sea trial, as it's the starboard engine which has the power steering I was hoping to try and sort it on the pontoon as getting in and out of the lock ( Chatham) on one engine with limited steering is notveasy ! Ditto re the pressure test on the pump, not done ! I have tried a few engineers locally to try and sort the issue but to be honest it's like drawing teeth to try and get someone to come and check it out, I have lost count of the e mails and phone messages I have left for " reliable " engineers who do not even have the courtesy to say sorry I'm too busy or you're too far away so I am battling on as best I can . I checked with Keypart on Friday re the circulating pump and the were saying the pumps have bronze impellers though I know the earlier models did have plastic ones but from your notes above if the impeller had failed I would have had an overheat well before the hour or so I had the engine running.
I think I need to get a trial done with temp gun and log wants going on, really appreciate your comments Paul, thanks,
 
Keithleask said:
Paul hi, was hoping you might pop in to the discussion, sorely needed! The exhaust elbows ( both port and starboard) were replaced with new ones last autumn,( the original ones had holes in them that had been filled with metal filler)only a few hours on them since fitting, so I can't think they can be the problem? I removed the heat exchanger and cleaned it and carefully rodded all the tubes, several blockages but cleared them then flushed it through. I took the after cooler top off and checked every tube, no blockages all clear.
I have not checked the temps on a sea trial, as it's the starboard engine which has the power steering I was hoping to try and sort it on the pontoon as getting in and out of the lock ( Chatham) on one engine with limited steering is notveasy ! Ditto re the pressure test on the pump, not done ! I have tried a few engineers locally to try and sort the issue but to be honest it's like drawing teeth to try and get someone to come and check it out, I have lost count of the e mails and phone messages I have left for " reliable " engineers who do not even have the courtesy to say sorry I'm too busy or you're too far away so I am battling on as best I can . I checked with Keypart on Friday re the circulating pump and the were saying the pumps have bronze impellers though I know the earlier models did have plastic ones but from your notes above if the impeller had failed I would have had an overheat well before the hour or so I had the engine running.
I think I need to get a trial done with temp gun and log wants going on, really appreciate your comments Paul, thanks,
Click to expand...

Right so it's sterndrive?

Remove steering cooler and all hoses from drive to bottom of Sea water pump, lay pipe in bilge and allow sea water to flood in, does it flow quickly with a full diameter of water the same bore as the pipe, if not you have a restriction .

Does it overheat Only when on the plane? If so only lower part of drive is in the water allowing air to be sucked in where the centre housing of the drive meets the lower housing it's a common issue, there is a seal there which fails, or the plastic elbow gasket at the top of mid section.
Loads to go at now.
 
Paul , yes Stern drive. Never got on the plane , overheated just poodling about. Your points about the raw water pipe to the pump though are really good! When the impeller broke up several weeks ago I freed off the raw water hose from the drive to the pump, there is a manifold in line with a couple of small hoses from it, when I pulled off the hose from the manifold only a dribble ( perhaps slightly more ) came from the manifold. If I am understanding correctly I should have had a full bore of sea water in? In fact today I fitted a Volvo Neutra salt system which stated on their installation notes that when you connect into the raw water feed to the pump the boat needs to be out of the water because the sea water would flood in. Because I never had a flood when I cleared the impeller bits I wondered why this was an instruction? I fitted the Neutra kit and never had much of an inrush of sea water! Do you think from what I have said that it points to a severe restriction ? The sea water filter does fill up though ? It appears that I might have a restriction ?
 
Keithleask said:
Paul , yes Stern drive. Never got on the plane , overheated just poodling about. Your points about the raw water pipe to the pump though are really good! When the impeller broke up several weeks ago I freed off the raw water hose from the drive to the pump, there is a manifold in line with a couple of small hoses from it, when I pulled off the hose from the manifold only a dribble ( perhaps slightly more ) came from the manifold. If I am understanding correctly I should have had a full bore of sea water in? In fact today I fitted a Volvo Neutra salt system which stated on their installation notes that when you connect into the raw water feed to the pump the boat needs to be out of the water because the sea water would flood in. Because I never had a flood when I cleared the impeller bits I wondered why this was an instruction? I fitted the Neutra kit and never had much of an inrush of sea water! Do you think from what I have said that it points to a severe restriction ? The sea water filter does fill up though ? It appears that I might have a restriction ?
Click to expand...

Look at the top of the drive area , is the water elbow under water? They usually are. If you took the hose off the steering oil cooler water will pour in if the elbow is under water as it siphons through. Impeller blades end up in this hose when it fails. When you start the engine after fitting a new one they get sucked into the cam on the pump blocking the intake.
So you need to check the intake flow, don't worry about water ingress but do t take the elbow off the transom shield on the inside that could be fatal! . This sounds like the reason why your impeller failed due to lack of water and seal failure.
Don't run it much until the water intake is restored.
 
Did you check the water pickup on the drive? If it's broken the impellerpump sucks air when you pick up speed because that part is then no longer under water... as the speed drops, the stern of the boat drop's back in the water and the pump gets water again...
 
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