Serious heat exchanger leak (Volvo Penta)

[Michigan_Eric]

The yard launched my boat on April 30. We motored to my slip with the engine cover off to observe any problems and we found one. The raw water intake of the heat exchanger was spurting quite a bit of water. Most of it went into the sump under the engine but a fair amount ended up on the cabin sole. There was still water spurting out of the exhaust, so most of the raw water was still getting through the heat exchanger.

The engine is a Volvo Penta model 2002 DL BT with about 900 hours on it, but I'm pretty confident that it's the original engine for the boat, which was built in 1991. The boat was known to be very lightly used before I bought it last year, so I probably sailed it more in the past year that it had been in the past. I put just under 100 hours on the engine last season.

As part of the cleanup I sponged out the sump under the engine, which had all that water that had leaked out of the heat exchanger. Then I noticed that it had a distinct green tinge to it, the color of the antifreeze in the freshwater cooling loop.

This can only mean that its not just raw water leaking from the heat exchanger, that coolant must be leaking from it too. The fitting with the leak is at the forward end of the heat exchanger where only raw water enters and exits, so I'm afraid that there is internal damage to the heat exchanger allowing coolant to leak into the raw water.

Here's a Y'Tube video of the same type of heat exchanger as mine being rebuilt, you can see that it's your basic heat exchanger:

https://www.youtube.com/watch?v=WbPLA7w2l_g

Based on seeing how the coolant goes in and out of the sides of the barrel, there must be an additional leak in the coolant line. My worst fear is that it's inside the barrel, meaning that the whole thing needs to be replaced in the worst case. Buy your Volvo Penta stock now.

We did winterize the engine when we took the boat out, but I'm afraid now that the coolant mix was weak and it froze over the winter here in Michigan and damaged the heat exchanger. Also, we noticed a small leak from that same fitting at the end of the season, and also a small amount water leaking down the side of the engine cover next to the heat exchanger, so this was a problem already in the making before winter, though freezing would have made it worse.

Any experience with this issue? I'm talking to the yard mechanic who already saw it leaking when the engine ran, and they have a few of Volvo's gold-plated parts on order, but he was not aware of the engine coolant leak, only that raw water was leaking. I'll add a comment when I get his reaction to the news. In the meanwhile, I'd appreciate any advice you can provide.

Thanks.

[jamhass]

I gave up on my VP 2003T heat exchanger and oil cooler and replaced both with simple, inexpensive after-market unit from Lenco.

https://www.lencocoolers.com/

Great company, easy to work with and inexpensive -- especially compared with VP!
I mounted both units off the engine. Biggest issue was the coolant pump connection. This "normally" uses Volvo's favorite square X-section O-rings with nothing to secure the joint except "geometry". Fortunately, the hole is very close to a standard NPT thread -- I forget the size but maybe 1/2-inch. I simply tapped the hole for a threaded hose nipple, and the rest was a piece of cake. Yeah, had to cut/modify some of the pipes and add some hoses, but not a big deal.

[deblen]

Originally Posted by jamhass

I gave up on my VP 2003T heat exchanger and oil cooler and replaced both with simple, inexpensive after-market unit from Lenco.

https://www.lencocoolers.com/

Great company, easy to work with and inexpensive -- especially compared with VP!
I mounted both units off the engine. Biggest issue was the coolant pump connection. This "normally" uses Volvo's favorite square X-section O-rings with nothing to secure the joint except "geometry". Fortunately, the hole is very close to a standard NPT thread -- I forget the size but maybe 1/2-inch. I simply tapped the hole for a threaded hose nipple, and the rest was a piece of cake. Yeah, had to cut/modify some of the pipes and add some hoses, but not a big deal.

Your 2003Turbo cooler was aluminum junk and replacing it with aftermarket(Lenco,whatever) was necessary.


OP's 2002 cooler is fully bronze & copper and is very re-buildable with a new set of rubbers. Of,course,he can replace it with aftermarket if he wishes.

I have done my 2003 (same design as 2002) some 7-8 yrs ago & no problem.
The most difficult part of the job was re-assembling the various copper pipes in the correct order,so that you don't have to force any pipe.



Cheers/Len

[jamhass]

Len:

I cannot agree with you more about the 2003T HX. Seems to me an Al-Cu HX could also serve as a battery! Guess that thought did NOT cross Volvo's management ... or the engineering guy (they cannot have had more then one!)

[deblen]

Originally Posted by Michigan_Eric

The yard launched my boat on April 30. We motored to my slip with the engine cover off to observe any problems and we found one. The raw water intake of the heat exchanger was spurting quite a bit of water. Most of it went into the sump under the engine but a fair amount ended up on the cabin sole. There was still water spurting out of the exhaust, so most of the raw water was still getting through the heat exchanger.

The engine is a Volvo Penta model 2002 DL BT with about 900 hours on it, but I'm pretty confident that it's the original engine for the boat, which was built in 1991. The boat was known to be very lightly used before I bought it last year, so I probably sailed it more in the past year that it had been in the past. I put just under 100 hours on the engine last season.

As part of the cleanup I sponged out the sump under the engine, which had all that water that had leaked out of the heat exchanger. Then I noticed that it had a distinct green tinge to it, the color of the antifreeze in the freshwater cooling loop.

This can only mean that its not just raw water leaking from the heat exchanger, that coolant must be leaking from it too. The fitting with the leak is at the forward end of the heat exchanger where only raw water enters and exits, so I'm afraid that there is internal damage to the heat exchanger allowing coolant to leak into the raw water.

Here's a Y'Tube video of the same type of heat exchanger as mine being rebuilt, you can see that it's your basic heat exchanger:

Based on seeing how the coolant goes in and out of the sides of the barrel, there must be an additional leak in the coolant line. My worst fear is that it's inside the barrel, meaning that the whole thing needs to be replaced in the worst case. Buy your Volvo Penta stock now.

We did winterize the engine when we took the boat out, but I'm afraid now that the coolant mix was weak and it froze over the winter here in Michigan and damaged the heat exchanger. Also, we noticed a small leak from that same fitting at the end of the season, and also a small amount water leaking down the side of the engine cover next to the heat exchanger, so this was a problem already in the making before winter, though freezing would have made it worse.

Any experience with this issue? I'm talking to the yard mechanic who already saw it leaking when the engine ran, and they have a few of Volvo's gold-plated parts on order, but he was not aware of the engine coolant leak, only that raw water was leaking. I'll add a comment when I get his reaction to the news. In the meanwhile, I'd appreciate any advice you can provide.

Thanks.

I rebuilt my 2003 heat exchanger. Not difficult.
Your 2002 is identical to mine,except yours is a bit shorter.
Our HE are all bronze & copper-should last indefinitely,whereas,2003Turbo was aluminum & they dissolved.
Take pic or 2 of the copper piping.Mark it if you want.
Remove HE from engine carefully.Do not force,bend or damage any copper pipes. When you put everything back together,you have to re-assemble in a certain order,in order to avoid forcing pipes.
Remove & discard all square rubber rings from pipe ends.Replace with new.
Clean the pipe ends to shiny copper with sand paper or plumbers brush.Then,grease with a film of vaseline & install new rings on pipe ends.
Clean pipe sockets at pump,HE,etc. to shiny metal with plumbers brush.
When installing a pipe back in it's socket,do so gently & make sure pipe goes in fully to bottom out.


Disassemble HE. You may find the long center bolt corroded.I replaced mine with new SS threaded metric rod & SS nuts-8mm? I think-same as original bolt. There is an improved retainer plate,that holds the 2 end pipes in place.I built one of scrap aluminum-simple.


Clean the tubes with a brush-or take the assembly to an auto radiator shop.


That is about it.
Cheers/Len


https://shop.marinepartsexpress.com/...cs/volvo-penta

[deblen]

Wow! What a nice Youtube video!


Here is an old thread https://www.cruisersforum.com/forums...-227962-3.html


Cheers/Len

[deblen]

This might help if you ever need to psyc out how cooling flows on these 2000 series.


http://coxeng.co.uk/wp-content/uploa...hot-water1.pdf

[Michigan_Eric]

Originally Posted by deblen

This might help if you ever need to psyc out how cooling flows on these 2000 series.


http://coxeng.co.uk/wp-content/uploa...hot-water1.pdf

Thanks for all your helpful advice here. I already have that document and it was helpful in figuring out what the heck all those tubes are for. I mention in another thread https://www.cruisersforum.com/forums...er-285853.html that I'm removing the water heater tank so that had come up in an earlier search.

Another thing on my engine that I had never seen: the tube from the raw water pump goes into an anti-siphon loop under the galley before returning to the heat exchanger. I don't understand why they thought this was necessary. The plumbing for the heat exchanger with the expansion tank and the anti-siphon loop and the hot water heater makes everything a nest of tubes that looks like something from Harry Tuttle's nightmares.

[deblen]

Originally Posted by Michigan_Eric

Thanks for all your helpful advice here. I already have that document and it was helpful in figuring out what the heck all those tubes are for. I mention in another thread https://www.cruisersforum.com/forums...er-285853.html that I'm removing the water heater tank so that had come up in an earlier search.

Another thing on my engine that I had never seen: the tube from the raw water pump goes into an anti-siphon loop under the galley before returning to the heat exchanger. I don't understand why they thought this was necessary. The plumbing for the heat exchanger with the expansion tank and the anti-siphon loop and the hot water heater makes everything a nest of tubes that looks like something from Harry Tuttle's nightmares.

Anti siphon loop/valve:
It is possible that,when you shut engine down,raw water that was flowing from seacock,thru intake filter,raw water pump,HE & out the exhaust-will continue to flow ,due to the common siphon effect.This flow could,in theory,flood your engine thru an open exhaust valve,or flood/sink the boat,if there is a leak in raw water system--and you leave seacock open.

The same can happen with your head,bilge pump, or any other raw supplied boat system.
To prevent a siphon,you can raise a portion of the water ckt. substantially above the raw water supply level-water line on a boat- by making a high loop.
You can improve this by letting air into the top of the loop-this will break the vacuum in the system.
In order to prevent water squirting out of the hole in the top of loop & all over the boat,you can use a T & direct a restricted stream overboard,or you can install a one way (vacuum breaker valve) to let air in & block water out.


Volvo supplies a vacuum breaker valve,but mine was made of aluminum & corroded. I replaced it with a common brass household hot water heater vacuum break valve-10+ yrs ago.
https://www.watts.ca/products/plumbi...f-valves/lfn36



https://www.boatus.com/expert-advice...n-valve-basics



Cheers/Len

[Michigan_Eric]

One more question about the workings of the Volvo heat exchanger that would help me better understand the extent of the problem I am having.

From the cooling system diagram linked in an earlier comment (http://coxeng.co.uk/wp-content/uploa...hot-water1.pdf) it looks like the raw water does a double pass through the HE, through what appear to be multiple tubes, with the fresh water/antifreeze mixture entering at the top near the front, filling the remainder of the space inside the barrel, and then exiting out the rear.

Pretty basic, but the devil is in the details. The crux of the matter, as far as the work required for the repair for my case, is whether a leak in the raw water intake fitting alone would also allow the fresh water/antifreeze mixture to leak out.

From what I've seen here and in the related thread linked in the comments, it loooks like there are separate tubes inside the barrel (not shown in the video I linked in my original post) that fit together with the precision of a Swiss watch (or perhaps a Swedish one). If that's the case, then my fear is that there is also an internal leak that will require a complete rebuild of the HE, not just replacement of the raw water intake fitting.

That, along with a storm front that blew through the harbor, kept me awake for a while last night.

[Michigan_Eric]

So, I think the algae are smarter than me.

I tried to reproduce the green water in the engine sump today by running the engine up to temperature and seeing what came directly out of the heat exchanger leak. I watched the water accumulate in the sump, which I had cleaned as thoroughly as I could given the small clearances, and it all came out clear, or as clear as the raw water in Lake Macatawa at any rate.

When I took the first sample out of the engine sump, on May 3, it had been three days since I had run the engine to bring the boat from the hoist well and then let it die for a while to diagnose the leak. Given the nice warm environment under there, along with some residual diesel from an earlier bleed point leak, I suspect that algae grew in the water before I had the presence of mind to sponge it out. And given the similar hue to Volvo green antifreeze, you might understand why I had to consider a coolant leak as a possibility.

In the meanwhile, the lake water sample I took about three days ago as a "control" has slowly begun to turn green, though not yet the same tinge as what came out of the sump originally.

At any rate, I'm relieved that there is no evidence of a coolant leak in the heat exchanger or anywhere else in the engine.

Science marches on!

[deblen]

Useful explanation of VP 2000 cooling ckt.

https://www.youtube.com/watch?v=R5VWN9O86bM

[deblen]

Originally Posted by Michigan_Eric

One more question about the workings of the Volvo heat exchanger that would help me better understand the extent of the problem I am having.

From the cooling system diagram linked in an earlier comment (http://coxeng.co.uk/wp-content/uploa...hot-water1.pdf) it looks like the raw water does a double pass through the HE, through what appear to be multiple tubes, with the fresh water/antifreeze mixture entering at the top near the front, filling the remainder of the space inside the barrel, and then exiting out the rear.

Pretty basic, but the devil is in the details. The crux of the matter, as far as the work required for the repair for my case, is whether a leak in the raw water intake fitting alone would also allow the fresh water/antifreeze mixture to leak out.

From what I've seen here and in the related thread linked in the comments, it loooks like there are separate tubes inside the barrel (not shown in the video I linked in my original post) that fit together with the precision of a Swiss watch (or perhaps a Swedish one). If that's the case, then my fear is that there is also an internal leak that will require a complete rebuild of the HE, not just replacement of the raw water intake fitting.

That, along with a storm front that blew through the harbor, kept me awake for a while last night.

With reference to video in post # 5


There is a bundle of small tubes inside the HE,that connect to 2 of the 4 HE ports.The Antifreeze-coolant circulate thru these & does not touch the raw cooling water,unless there is a pinhole in a tube,or a weird leak around the end cover big rubber gasket(s).
The raw cooling water uses the remaining 2 ports to fill the space outside the tubes with water & then pass it out to exhaust.
Cheers/Len


A useful tool,when trying to find cooling system faults is an inexpensive auto radiator pressure tester. https://www.amazon.com/radiator-pres...ure+tester+kit

[Michigan_Eric]

A very thorough heat exchanger rebuild video that "the algorithm" presented to me today:

https://www.youtube.com/watch?v=LdoJKivQtlI

[Michigan_Eric]

Originally Posted by deblen

Anti siphon loop/valve:
It is possible that,when you shut engine down,raw water that was flowing from seacock,thru intake filter,raw water pump,HE & out the exhaust-will continue to flow ,due to the common siphon effect.This flow could,in theory,flood your engine thru an open exhaust valve,or flood/sink the boat,if there is a leak in raw water system--and you leave seacock open.

So the Volvo parts arrived, all the way from Sweden, and among them is the standard raw water copper pipe to connect the raw water pump directly to the heat exchanger raw water input. If I use this part it will mean that I will no longer have the anti-siphon loop as part of the raw water supply.

As I already mentioned, I was very surprised to see an anti-siphon loop in the raw water line in the first place. I understand what might happen in the case of a raw water system leak, but it is hard for me to imagine water siphoning once the engine stops, since the raw water pump impeller will be still and block any water from flowing in either direction through the line. Undoubtedly it's extra safe, a belt-and-suspenders solution, but the extra plumbing for the anti-siphon loop also increases the chance of a raw water leak by adding two long rubber hoses and four hose clamps.

According to the video I linked to above from the Sailing Zephyr IV YouTube channel, the elbow fitting that was on the heat exchanger raw-water intake with its flubbery-rubbery hose helped cause the leak in the first place by increasing the motion at the connection due to engine vibration, and my two-banger does vibrate rather vigorously at certain RPMs. So the copper pipe should reduce that tendency.

Because the raw water exits out the exhaust elbow, wouldn't an anti-siphon valve at the top of the exhaust loop also prevent raw water system siphoning?

I also make it my practice to shut off the raw water intake seacock once I have arrived in port, with the engine key hanging from it so I always have to open the seacock to retrieve the key. But when sailing I leave the raw water seacock open and the key in the starter switch. If I were really diligent I suppose I would to the engine key/seacock dance when sailing as well, but you never know when you might need to start the engine in an emergency.