Tech Blog: Volvo MD2030 Heat Exchanger

Symptom:
We had been getting a lot of water in the bilge while underway under power.    I know we have a leaky stuffing box (another project) but I never quite believed that could be the cause of all this water.   When running the engine, the bilge pump would expel water for a few seconds about every minute!

On Saturday, while Linda was driving (with no wind), I went down to look for the source. Opening the engine compartment, I could see that water was pouring out of the radiator overflow tube.  Worse, it tasted salty.   Since our engine is not a magical water maker, the obvious reason is that raw water is crossing the boundary of the heat exchanger.  So we've effectively been cooling the engine with salt water all season.  Not good.

I googled around and found a few forum posts talking about this exact problem.   I have never even seen a heat exchanger before but I got some edumakation on them.    In case I couldn't get to it (or more likely it was over my head), we opened a work order with the marina to have it looked at.

Let me try this
I printed the entire PDF of the shop manual for the MD2030 and also a few exploded diagrams I found.   I also read and reread the forum threads on the topic.   Most likely, the seals on one end or the other are not tight or the worst case is that holes have corroded in it and it's leaking.  If it's the latter, the part is about $650 or more.

Step 1:
Get the exchanger out.  Right away, I realized that the cabinetry around our engine was not going to make this simple.  I had to remove the front surface of the engine compartment that has the door in it.   While I was futzing with that, I drained the "coolant" (actually brine) out of the engine.  Also CLOSE THE THRU-HULL for the raw water if you like the boat to stay on top of the water.


To remove it is pretty simple.  Actually the whole thing is pretty simple.   You just undo the hose clamps on either end of the exchanger housing, remove the front boot from the housing and slide the whole unit out.   It's a cylinder  about 2.5" in diameter and about a foot long.

Exchanger housing with the exchanger assembly removed

Step 2:
Look at it and marvel at it's simplicity.  Now look at how disgustingly filthy the thing is and how clogged all the tubes are.   

After the first flushing with the hose.  Yuk

I put it in a bucket and carried it over to the dock.  DON'T DROP IT IN THE WATER.  DO NOT DROP IT IN THE WATER.  It would be very easy to imagine this thing rolling off the dock - splash - $650.

Step 3:
Clean it and figure out if it has a leak.   Blast the crap out of it with as much garden hose pressure as you can get.  Marvel at the crud in it.   At first, I didn't realize you were supposed to be able to SEE through the little tubes in it (I couldn't but you are).

almost like new.  No more debris coming out.

After a few more flushings with no more crap coming out (hey look - you can see through all these tubes!), I tried pouring water slowly though the tubes to see if any was leaking out the fresh water holes.  Nothing!  This is good!  The unit actually looks pretty good now that it's clean.


Step whatever: 
Put it back together.  I took the garden hose in the boat with me and really blasted out as much more crud as I could in the housing.  I also really cleaned the rubber boots that seal the ends of the exchanger.   Slide the exchanger back in the housing and tighten the hose clamps on the boots.

Exchanger housing with the clean exchanger re-inserted

 

Next step:
Refill the engine with actual coolant.  As much as I enjoyed the brine cooling design, I hear good things about this coolant stuff.    Oh and don't forget to close the drain cock when you pour your nice new coolant and fresh water in the engine.

All re-assembled.  ready to fill with actual "coolant"

Did it work?
Fire up the engine.  OPEN the raw water thru-hull first.    Hey it runs.  Hey raw water is flowing out the exhaust.  Hey look NO raw water is flowing out of the radiator overflow tube!    I'll run the engine for a while before I call it a success.    So far so good

I'm thinking now might be a good time to buy various cooling system additives.

A three day weekend in June

Despite busy times at work and other preoccupations, we finally took an actual day off from work to try to go somewhere interesting.

The Plan: Provincetown

We never made it to p-town last year so we decided to go for it.   The wind had other ideas.  We've had a very hot spell for the previous week and most days would offer very hot afternoons with no wind (except when the proverbial thunderstorm rolls by).

Despite the wind, we decided we would go to p-town anyway, dammit even if we had to motor the whole way.   It was about then that I discovered that we have a little engine problem.  The overflow tube on the radiator is spewing a lot of water.  I tasted it and it was a bit salty.  Not good.  Most likely our heat exchanger is allowing the raw water to enter into the fresh water cooling system.   I started googling this on Linda's iPad and found that it is not uncommon for this to happen to Volvos.   We decided we didn't want to beat on the engine for the next 10 hours and be 20 miles off shore.

Little Calf island

Passing Hypocrite Channel

Manchester instead

We turned north toward Manchester-by-the-sea, MA.  This place is special to us not only because it's so beautiful, but because it's where we did our very first ever overnight sail when we were members of Boston Sailing Center a few years ago. We sailed Blue-J a j/24 up there (and stayed in a B&B ).

A nice little spot overlooking Magnolia Harbor

Instead of going directly to Manchester, we went a little higher up the coast and anchored off of Magnolia Beach for lunch and the very first Swim of 2012. This is a great spot to anchor for lunch.  The bottom is mostly sandy but has some patches of grassy areas.  Last time we were there, the Fortress anchor wouldn't grab because we were over some grass.  The water was not so bad.

Finally around dinner time, we got to Manchester harbor and grabbed a guest mooring for the night.   We were tired and relaxed (and hungry)

Chillin' in Manchester

Boats, Trains, Feet
The weather turned sucky the next day in Manchester so we decided to hop the train and go up to Rockport, MA to be tourists.  We went up there.  Walked around, stuck our toes in the water, had coffee, went shoe shopping and took another train back.   By now the weather was looking nice and there was even some breeze.  The guy at the fuel dock in Manchester told us about the public moorings around Misery Island.   We needed to check this out.

Great and Little Misery Islands are part of a reservation.  You can dinghy or kayak (or swim) to shore and find some very nice trails with spectacular views of the ocean, the other islands and harbors.   Now that I'm back on land, I've learned that there was once a resort built here.  And there is a very visible ship-wreck between the islands.   Next time, we're snorkeling for sure.


View Larger Map

Looking at Great Misery Island from our Mooring between the two islands

We found a beautiful spot right between the two islands and did some swimming

A minor mishap
I guess it must be called Misery Island for a reason.   After swimming, I slipped and fell on the deck.  I landed pretty hard on my left hand and bent my wrist back farther than it likes to be.  I didn't think much of it at first.  In fact I played guitar for a while afterwards and didn't notice anything.  But later it started swelling up and aching so I iced it up a bit.

NOAA Radar alerts 
Shortly after the deck falling incident, NOAA started predicting some nasty storms moving our way.   We had plans to meet friends in Salem just across the bay but Linda wisely insisted that we don't try to beat this storm and instead tied up a second mooring line and hunkered down to wait it out.

Scary looking sky coming our way

trying to stay warm and dry while balancing an ice pack on my wrist

The temperature dropped, the wind picked up and the sky looked really scary.   We could hear the thunder getting closer and closer.



After about an hour and a half of this, we finally made a run for Salem.  It was still pretty nasty when we left but the clear skies were moving our way.   By the time we got to Salem, it was calm and beautiful out and we were welcomed with a rainbow!

Safely moored in Salem harbor after the storm

We went out for a fantastic dinner with our friends Phil And Yolande from Prairie Gold.  They came into Salem while the storm was building and waited there for us.   One of the boats near them had it's genoa come unfurled in the wind.

Prairie Gold sitting on her mooring near the day marker

The "race" home
Sunday morning Fujin and Prairie Gold headed back to Boston.  Of course if two boats are starting and ending at the same place, you've got a race on your hands.   We have a few pictures of Prairie Gold behind us (because we left first).  But for most of the way home, we could only see her back end.  I was watching her on radar for a while and guessing how fast she was accelerating away from us!.

PG going Wing-Wing out of Salem South channel

Flying the Jack

Closer

And there she is

And... there she goes

Pretty shot of Prairie Gold against the Boston skyline

(not really) Welcome home
As we started heading down the narrow fairway at Constitution Marina, I notice our slip was not entirely empty.  In fact there was a HUGE fishing boat in it.  So I backed out and Linda called on the VHF.   Oooops sorry, we thought you were coming back tomorrow.  So they gave us another slip assignment on the same row of docks.   On the next attempt, another power boat decided to disembark at the same time.   This time, I did a spin in the fairway and drove out to let him leave.  It's good to know we can spin around in there (never tried it before). On the third attempt, we made it in. 

A repair and a reward sail

The Repair
During all this rain we're having, we noticed some of the stuff in the aft cabin getting wet. Then the other day I spotted the leak - it was a stanchion on the port side near the cockpit. So after work, it was not raining (much) so I thought I'd try to do the re-bedding job. This is probably one of the easiest stanchions to reach the mounting hardware for on the boat. It only required removing one piece of wood trim.

Stanchion removed.  Ready to prepare the surface and the holes

With the vice-grips holding the nuts inside, I removed the screws and lifted the hardware off.   Then I cleaned up the surface with acetone and did the counter-sink trick to the mounting holes (this allows the bedding compound to form an o-ring at the top of the hole).

After preparing everything and applying lots of Life-Caulk,  I re-mounted the hardware  with some nice new fender washers, lock washers and nuts on the inside.   I dried up all the water I could find that leaked in and I'll keep an eye on it.


The Reward
After all that (about 9pm), I decided I needed a sail.  I started thinking of all the reasons I shouldn't go but none of them were very convincing.   It's cold... na.   The wind is pushing me on the dock. nope.   It's raining.  uh huh.  I have work in the morning.  so what?

Boston from the Logan side of the harbor

I was so glad I did it.    It was quite chilly, rainy and very dark out but aside from a couple party boats and ferries, there was no other traffic out there.