Volvo Penta V8-430-CE-M Overheating

[nrhansen]

Please help, my V8-430-CE-M overheats only when on the lake. With a gardenhose attached to either flush fitting it does not over heat. The first overheat disintegrated the impeller. I have disassembled and inspected the raw water pump housing and the heat exchanger, installed a new OEM impeller and disconnected and flushed all four hoses connected to the pump and the heat exchanger in both directions. It is not possible to mix up the reattachment of the hoses. I have inspected all four seals in both of the flush fitting caps. When the engine overheats the impeller housing and the heat exchanger get very hot. The coolant reservoir is topped off. When the garden hose is attached to the intake hose of the raw water pump, water runs freely out of the water pickup ports on the front of the outdrive, a DP 232 forward drive.

Should water from a garden hose be able to flow through the back hose of the two that connect to the heat exchanger?

 

[nrhansen]

The water intake ports must be covered with tape when the engine runs on the flush fittings; if not the impeller housing heats up.

I used an old Volva-Penta-type out drive muff connected to the water intake ports on the outdrive and the impeller housing got hot.

 

[nrhansen]

I attached a garden hose to the output end of the pick up hose from the raw water pump and taped off the water pick up ports on the outdrive. Low water pressure blew the tape seal of course so I held it tight with my hands and saw no signs of leaking throughout the full pick up hose system.

I attached a one foot length of clear hose to the input port of the pump and submerged it in a one gallon bucket of water. The pump self primed and emptied the bucket in less than 5 seconds.

 

[ESGWheel]

Others will have to chime in here as I am not familiar with these units but here is my guess: given only in the water but you checked the “full pick-up hose system” is it possible that due to the different positions of the fwd drive when on the trailer vs. in the water a crack opens up in the hose from the drives intake to the transom nipple allowing air to be sucked in? In other words, given all looks good on land and only overheats in water what is the difference in how the drive sits? Can you mock it sitting on the trailer?

 

[nrhansen]

Others will have to chime in here as I am not familiar with these units but here is my guess: given only in the water but you checked the “full pick-up hose system” is it possible that due to the different positions of the fwd drive when on the trailer vs. in the water a crack opens up in the hose from the drives intake to the transom nipple allowing air to be sucked in? In other words, given all looks good on land and only overheats in water what is the difference in how the drive sits? Can you mock it sitting on the trailer?

Thank you for the reply. The drive is in the exact position at the lake over heating and on the hose running normal.

 

[Scott Danforth]

Check for blockage in the power steering cooler

 

[nrhansen]

Thank you I did that and water from my hose runs freely through it. Also the boat runs normal with a hose connected to the engine flush fitting.

 

[ESGWheel]

This is tough one. When faced with ‘cannot figure it out’, I take a breath and go back to basics.

Cleary it used to work fine. What changed? What service, parts, etc. were done, even if it was perhaps days before the issue.

How do you know its overheating? Don’t take that the wrong way, but what is the indication? How do you know it not overheating when running on the hose? Do you run on the hose for say 30 min and all is normal but when in the water idling for 30 min it overheats? In other words, provide as much info on the conditions as you can.

While you have already provided a lot of info in your original posts, for me it’s a little confusing as I am not familiar with your set up. Example: you have a flush hose connection that you hooked up to but you also “taped off the water pick up ports on the outdrive”. On my 5.0 with an SX-M I do not need to tape off the outdrive. Why are you doing that?

And you are 1,000% confident the hoses are connected correctly? Best to triple check. And are you sure the RWP impeller is good? Same idea. What I am suggesting is that frustration can sometimes color what you are looking at. For me, I have (more than once!) swore that I did it correctly only to come back to it the next day and smack my own forehead muttering things best not overheard.

Also suggest posting your year, boat model, etc. in hopes someone with a similar boat will pick up on your issue.

 

[nrhansen]

This is tough one. When faced with ‘cannot figure it out’, I take a breath and go back to basics.

Cleary it used to work fine. What changed? What service, parts, etc. were done, even if it was perhaps days before the issue.

How do you know its overheating? Don’t take that the wrong way, but what is the indication? How do you know it not overheating when running on the hose? Do you run on the hose for say 30 min and all is normal but when in the water idling for 30 min it overheats? In other words, provide as much info on the conditions as you can.

While you have already provided a lot of info in your original posts, for me it’s a little confusing as I am not familiar with your set up. Example: you have a flush hose connection that you hooked up to but you also “taped off the water pick up ports on the outdrive”. On my 5.0 with an SX-M I do not need to tape off the outdrive. Why are you doing that?

And you are 1,000% confident the hoses are connected correctly? Best to triple check. And are you sure the RWP impeller is good? Same idea. What I am suggesting is that frustration can sometimes color what you are looking at. For me, I have (more than once!) swore that I did it correctly only to come back to it the next day and smack my own forehead muttering things best not overheard.

Also suggest posting your year, boat model, etc. in hopes someone with a similar boat will pick up on your issue.

Thank you. I'll cover your suggestions one by one. First no changes or services were done to the boat prior to overheating and melting the impeller the first time. I last used the boat all day and parked it at home the next time out it melted the impeller while going slowly out of the no wake area. I missed the overheat warning at first because I was getting a shallow water warning in the nowise area. Next, I know it is over heating because the impeller housing and the heat exchanger get very hot and quickly the gauge shows the temperature spike. this happens in less than ten minutes on the trailer backed into the lake. On the hose I've run it over 20 minutes and the impeller housing stays cool to the touch as does the heat exchanger at the bottom and gauges stay normal. If I do not tape the inlet ports to the outdrive it will overheat. I've looked multiple times at the hose connections. On the pump they are different sizes and on the heat exchanger the back hose will not reach the front connection. The impeller is new with less than one hour of use. I was certain it was a bad pump but the pump sucks a gallon of water out of a bucket in seconds. Thank you for your help.

 

[nrhansen]

Please help, my V8-430-CE-M overheats only when on the lake. With a gardenhose attached to either flush fitting it does not over heat. The first overheat disintegrated the impeller. I have disassembled and inspected the raw water pump housing and the heat exchanger, installed a new OEM impeller and disconnected and flushed all four hoses connected to the pump and the heat exchanger in both directions. It is not possible to mix up the reattachment of the hoses. I have inspected all four seals in both of the flush fitting caps. When the engine overheats the impeller housing and the heat exchanger get very hot. The coolant reservoir is topped off. When the garden hose is attached to the intake hose of the raw water pump, water runs freely out of the water pickup ports on the front of the outdrive, a DP 232 forward drive.

Should water from a garden hose be able to flow through the back hose of the two that connect to the heat exchanger?

The boat is a 2019 Monterey MX6 Surf with the 430 V8 and forward drive.

 

[ESGWheel]

If I do not tape the inlet ports to the outdrive it will overheat.

Based on this, my best guess is the raw water pump. In brief if you have to block the drive for it to not overheat on the hose, it seems as if the only flow you are getting thru the exchanger is due to the pressure of the hose. I’ll write up more on the why I think this when I have some time.

 

[Grub54891]

Had a customer several years ago that had the same issue. He brought the boat to us and I had a heck of a time figuring it out. Fine on hose, not on lake. I finally told him it could be the pump itself. I even had the clear hose on the output side of the pump, No air bubbles. After replacing the pump, it was fine. The only thing I could come up with was the housing was wore enough that the impeller could not grab enough water to push it through. The housing was clean and smooth as it should be, but who knows why otherwise. What I should have done is measure the inside bore of the new and compared it to the old......

 

[ESGWheel]

Here is the logic I used.

Frist off, is the initial reason for overheating an unknown? This is very odd especially for a boat only a few years old and only used in freshwater. Also, the impeller melting is an oddity as well. I have never heard of them melting, breaking apart yes, but not melting. However, my experience is limited in this area. Pictures of the melted impeller if you still have it would be interesting. And you replaced the impeller yourself? Point is that the RWP seems to be the initial culprit and perhaps remains so.

Now for the other part: these RWPs are a flexible impeller vane type. That means it’s a positive displacement pump and water should not pass from inlet to outlet unless the impeller is not sealing (i.e. its broke or somehow has excessive clearance between the impeller vane and the housing. Thus a ‘non-sealing’ impeller would not pump as expected, leading to overheating. When you hook up the garden hose you have between 40 and 70 PSI of pressure from it. Again, the pump is not pumping as expected but the hose water has enough pressure to get by the impeller but only if you are blocking up the drive’s inlet.

Thus, this logic points to the pump. I get that it sucked in a bucket of water and cannot account for that. But here is a statement: Everything appears to be up to snuff but it overheats, therefore something is wrong. Don’t shoot me for this oversimplification, but I am back to what I do when nothing is wrong but still does not work. My recommendation: pull the pump apart and post lots of pictures.

 

[nrhansen]

Grub54891 and ESGWheel thank you both. That does make sense that it is the pump. I was certain it would not suck water from that bucket and disheartened when it did. Nonetheless, the boat was on Lake Powell for a week in early June during heavy run off. Suspended silts and other fines could have worn the pump housing down but keeping it smooth. Lake Powell is from top to bottom a lake in sand stone. Melting of the impeller may not be accurate but it was hot and and smoking and disintegrated with parts from tiny to large. I flushed some out of the oil cooler and found some in the heat exchanger. I wonder if any pieces could have gotten past the heat exchanger.

 

[nrhansen]

I am about to the point of spending $700 just to see if a new pump and impeller make everything right again.

 

[ESGWheel]

Its certainly worth a shot to try. To help keep the costs down, see if this gent has what you need, link. And if it is the pump, post getting the ‘new one’ installed you can send yours to him for a rebuild and thus have a spare.

I was fortunate to be on Lake Powell back in 2008 before all the trouble. Fantastically beautiful.

Good luck and keeps us posted.

 

[nrhansen]

The first video is on the lake the second is on the hose.

 

[ESGWheel]

Vids do not work on PC but did on my phone. The clear hose hooked to the output of pump I assume. What I saw was the 1763 movie file (on lake) showing no water flowing in the clear hose > was splashing around, but not flowing. And the 1758 vid (on hose) shows water flowing but not a full solid stream.

Zooming in on the pump housing it does look damaged. While the dent in the outer edge is probably not relevant there appears to be a non-factory hole, see red circle in pic below.

I am sticking with the RWP is the issue. What is its part number?

 

[Grub54891]

Wondering if there is a airleak somewhere before the pump. Or was it possible that you picked up some debris on the out drive while on the lake. Hope we figure this out. Are the external hoses in good shape?
edit. You posted that^^ while I was responding. Hhhmmm. Never saw one damaged like that.

 

[nrhansen]

Wondering if there is a airleak somewhere before the pump. Or was it possible that you picked up some debris on the out drive while on the lake. Hope we figure this out. Are the external hoses in good shape?
edit. You posted that^^ while I was responding. Hhhmmm. Never saw one damaged like that.

I checked the intake hose again before I started today. I put a lot of tape on the pick up ports on the outdrive and clamped the hose into the pump end of the input hose. I got enough pressure that when I pulled the tape off it sprayed me pretty good. Not a drop inside along the whole length of the input hose. After removing the tape water flowed freely out.