My Volvo 2003 is fresh water cooled via a heat exchanger and sea water. The heat exchanger is corroded and blocked beyond repair. New ones are way to expensive $2000 and I don't think worthwhile on motor nearing end of life.
I'm wondering why not toss out the heat exchanger and rely on sea water cooling until I can get a new motor. I believe some Volvo 2003s were salt water cooled.
Is my theory flawed?

Trek a new motor would require a new heat exchanger anyway so would not now be as good of a time as any ? I guess you will re motor with as similar motor as possible, to simplify fitting ? Is not the existing unit rebuildable ? Of course unless if you are thinking to go electric ? On direct raw water cooling all things being equal it will work, possibly need to change engine thermostat, how is the transmission cooled ? Is it a separate exchanger or does it piggy back off the main exchange ?

I would suggest a check in the back of the Afloat magazine first for parts. The other alternative is to make your own. I would avoid raw water cooling at all costs. These blocks are just industrial engine blocks and meant for freshwater cooling.

Thanks Woko and Ramona. One good thing is the motor starts instantly and has good compression. But its very rusty and the seals every where are terrible.

I read that the history of the 2003 engine was it was originally a Peugot car motor. Volvo was getting hammered in the small boat engine market so hastily bought the design and made it into a re-badged boat motor. That explains why theres hundreds out there, but they are not very marine.

Select to expand quote

Na, should be no problem. Just make sure you fit the anode. And a new thermostat. Most were sold with raw water cooling. forums.ybw.com/index.php?threads/volvo-2000-series-raw-water-cooling.354841/
www.parts4engines.com/volvo-penta-2003-water-pipe-seal-fuel-washer-kit/ will get you the rubber seals to stop most leaks.

Select to expand quote

Trek said..
Thanks Woko and Ramona. One good thing is the motor starts instantly and has good compression. But its very rusty and the seals every where are terrible.

I read that the history of the 2003 engine was it was originally a Peugot car motor. Volvo was getting hammered in the small boat engine market so hastily bought the design and made it into a re-badged boat motor. That explains why theres hundreds out there, but they are not very marine.

I thought they were Japanese built Perkins for Volvo.

Select to expand quote

Ramona said..

Trek said..
Thanks Woko and Ramona. One good thing is the motor starts instantly and has good compression. But its very rusty and the seals every where are terrible.

I read that the history of the 2003 engine was it was originally a Peugot car motor. Volvo was getting hammered in the small boat engine market so hastily bought the design and made it into a re-badged boat motor. That explains why theres hundreds out there, but they are not very marine.

I thought they were Japanese built Perkins for Volvo.

Now that's a good question. I just did lots of Googling. One place says VP 2003 was designed and manufactured by Volvo and VP 2030 was a
fixed up version Japanese Perkins. But I read elsewhere VP and Peugeot have had a manufacturing partnership for marinised engines. After the Googling rebuilding it looks better option than scrapping and re-engining.

The VP 2000 series has versions with one, two, and three cylinders. They are all much the same at the forward end. Hence unlikely to be a car engine derivative. 9hp, or even 28hp pretty slow car.:-)

Select to expand quote

Yara said..
The VP 2000 series has versions with one, two, and three cylinders. They are all much the same at the forward end. Hence unlikely to be a car engine derivative. 9hp, or even 28hp pretty slow car.:-)

True!!

Problem is fixed. The heat exchanger looked very awkward to get off so I tested other things in the cooling loop. Found faulty thermostat, removed it and all good.

The problem wasn't fixed as I thought. Cruising at a moderate speed engine was hot, but later running at full speed into a southerly it still over heated. So I checked out price of new heat exchanger ($1600), new circulation pump ($2600) + miscellaneous added up to $5K. You can get 100 cartons of beer for that, so no way.

After looking at pictures of the Volvo Penta 2003 Raw Water cooled version on the internet worked out the re-plumbing and implemented it, including adding zinc anode.

I tested it by putting a bilge pump in a bucket of water and feeding its output through the engine cooling system to make sure it circulated and exited according to theory first.

Now there is visually more water pumping through judging from exhaust outlet. Cruising at a moderate speed engine the engine is slightly warm not hot. (I thought hot was normal, it wasn't). Running flat out for extended duration the engine is only slightly warmer. I can place my hand on the head and leave it there.

I'm writing this for anyone else with the same problem. The conversion of the engine to raw water cooling was successful and according to the ancient info I have the lifetime of the engine should be fine as long as anode is periodically checked/replaced. Especially since up until now the cooling system was internal loop and coolant based so in prime condition although old.

i have 2003 raw...not worried about rust, engine runs cool...and yep anodes need attention regularily, my issue at moment is under propped....different story