Overheating issues on R5

[knuckles529]

Long time listener, first time caller here

I just bought a 2017 R5 Surf a month ago. It has the Volvo V8 380 (S/N A752846) . Only 45 hours. I've put about 10 hours on it since I got it. Dealer performed oil change, coolant changes, replaced impeller etc and had no *known* issues when I got it.

Last weekend pulling out of the slip I got the overheat siren of death. It got up to the low 200s, I killed the engine. Let it cool off then putted back to slip about 50 yards out. I heard a winding noise too but didn't know what it was

Knowing very little about stern drives I was hoping y'all could help me. I have not put the boat in any shallow water or beached it. I cracked open the raw sea pump and it was dry. I replaced impeller with OEM volvo and lubed it up nicely ( the previous one looked to be in good shape but wanted to rule this out ). I also flushed the lines using the hose connector for about 5 min with engine off. Water came out of the outdrive as expected and appeared to be clean. I cranked the engine back up and sure enough after 10 minutes it started over heating while idle (~800 rpm). I thought maybe my hose at dock didn't have enough pressure. Lowered lift and dropped it in water. Same problem. Although this time I could see visible cloudiness leaving the drive (see picture). Both times the winding noise appears to come from fuel pump (my best guess) when the engine breaches the 180+ temp mark.

At this point I suspect there may be a clog in the heat exchanger. How would I go about flushing the coils? Is it as simple as taking top off (this is the cylinder shaped ones), disconnecting hose to sea water pump and running water through?

Any other ideas? I've heard the sea water pumps were faulty during these years so I have a complete new assembly on order. Also have a new t-stat to replace while I'm monkeying with heat exchanger.

Here's a pic of the boat when I first got her.

[AsLan7]

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Hey K529. Welcome to the Cobaltchat forum. So glad you found us!

My first thoughts turn to the visible cloudiness you mention coming from the outdrive as seen in your picture. That shouldn’t be there. It's clogged for sure. Are you able to spray the hose on jet setting up and into the outdrive intakes? You need to clear that sand bag up there. You inhaled something pulling out of the slip via those intakes.

Thanks for the pics and let's get her fixed. Again welcome aboard mate!

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[greenhut]

I pulled up some sand and overheated my 380. Don't think you want to open the heat exchanger, but flushing it fixed my issue. See thread below, but instead of what I did, you can reverse the input and output hoses going to the heat exchanger (at least on my slightly newer square shaped one), and then backflush with a hose. Alternatively I did this:

viewtopic.php?f=34&t=4153

[AsLan7]

I pulled up some sand and overheated my 380. Don't think you want to open the heat exchanger, but flushing it fixed my issue. See thread below, but instead of what I did, you can reverse the input and output hoses going to the heat exchanger (at least on my slightly newer square shaped one), and then backflush with a hose. Alternatively I did this:

viewtopic.php?f=34&t=4153

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Ahh...forgot about your thread GH. Nice job with that post. Hopefully K529 can get that sand out one way or another.

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[Big Block Power]

That steam im thinking is just hot exhaust with no water. Not good. You could have fried that new impeller already also. That wine is the fuel pump. They are water cooled. They don't like heat and that can shorten there life in a hurry. A whinning volvo pump is the death of them. So keep a eye on that. Yes follow greenhuts thread.
Also if you aren't getting water to the impeller I would back flush that inlet hose.

[knuckles529]

I ended up back flushing both hoses from the raw water sea pump. One side flushed the heat exchanger and the other side the intake and oil cooler. Both were slightly dirty but nothing too alarming.

The real culprit here was the sea pump. Apparently this model is faulty and they've since replaced it with a new model. I purchased a rebuilt one off eBay for $300 and slapped it on, easy peasy. It's slightly shorter than the original FWIW. Honestly I could have pulled a warranty claim but my dealer is back logged 2-3 weeks and it was an easy & relatively cheap job for me.

She's running 152-158 degrees without issue. Even got her up over 50mph, it was topping out around 48 before. Also, ironically its cooler at higher RPM (more water flow?) Anyway I'm happy to have the boat ready for the weekend!!

Pic for proof!!

[AsLan7]

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Thanks for the update k529.
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[Big Block Power]

With all of the 380s on this forum and if it was a issue surprised no one else has had a issue with it? Did you take any pictures and maybe post what you got? Compare the too. Show what's wrong with the original one.

[greenhut]

I ended up back flushing both hoses from the raw water sea pump. One side flushed the heat exchanger and the other side the intake and oil cooler. Both were slightly dirty but nothing too alarming.

The real culprit here was the sea pump. Apparently this model is faulty and they've since replaced it with a new model. I purchased a rebuilt one off eBay for $300 and slapped it on, easy peasy. It's slightly shorter than the original FWIW. Honestly I could have pulled a warranty claim but my dealer is back logged 2-3 weeks and it was an easy & relatively cheap job for me.

She's running 152-158 degrees without issue. Even got her up over 50mph, it was topping out around 48 before. Also, ironically its cooler at higher RPM (more water flow?) Anyway I'm happy to have the boat ready for the weekend!!

Pic for proof!!

Wonder what failed in the original pump?

Appears we are neighbors - from the Garmin, that is Lake Lanier!