MD2040 Volvo PENTA heat exchanger

[landonshaw]

I have the work shop Manuel by Volvo and to remove the heat exchanger seems relatively simple. Anyone have experience?

Out today, no wind so ran the engine. Water alarm went off in bilge and it looks like my raw water that goes thru the engine for cooling is getting into the coolant side. I suspect the heat exchanger is the problem. Any other ideas, possibilities?


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[landonshaw]

By the way, the engine never over heated, it looked like water was coming out of the water over flow hole under the radiator cap.


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[jimbunyard]

Originally Posted by landonshaw

I have the work shop Manuel by Volvo and to remove the heat exchanger seems relatively simple. Anyone have experience?

Out today, no wind so ran the engine. Water alarm went off in bilge and it looks like my raw water that goes thru the engine for cooling is getting into the coolant side. I suspect the heat exchanger is the problem. Any other ideas, possibilities?


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Common problem, can be caused by loose or deteriorated boot clamps on the iron part of the heat exchanger, loose boot clamps on the exchanger bundle, corrosion on either the bundle or the manifold/HE housing, deteriorated boots, or, more difficultily, a clogged exhaust elbow.

The most thorough thing to do is to disassemble everything, clean it, and pressure test the two components separately. I just did this last year on my MD2020, (the H/Es on the 2020 and 2040 are structurally essentially the same). If you're fairly handy with tools and have an air compressor, you can do the same, using various bits of hose, plugs and the existing boots. Some pictures and explanations follow.

Picture 1 just shows the internal culprits. The little bleed hole in the center of the bundle goes up when you reassemble it.

2 shows the bundle, with the boots plugged and attached, and a hose and regulator attached.

3 shows the bundle being tested at 10 psi. No leaks.

4 shows how to make a pattern for a gasket and plate to seal the tstat port.

5 shows the gasket and plate. A flat piece of relatively hard wood would work as well as a block off plate if you use 1/8" or so rubber as a gasket.
I just had the aluminum lying around...

6 shows the housing ready for testing.

7 shows the test in progress. My cap is rated for 7 lbs, so I started at 5 psi and slowly turned the regulator up to 20. Surprisingly, the overflow started at about 8 lbs on my gauge, confirming the cap operated as designed at the proper pressure (or that the cap and the pressure gauge were off by the same amount!) Again, no leaks at 20 psi, so I sandblasted the outside, painted the housing, tested the tstat and put it all back together.

If the tubes in the bundle are really dirty, a .22 caliber rifle brush is just about the right size for mine, a .17 might be needed for some.

A light smear of automotive silicone on the sealing surface between the bundle and its' boot might be good, especially if you're reusing the old boots. Do not use any sealant on the boot to cast iron joint (unless you want to make problems for yourself later).

Good luck with it.

[landonshaw]

Thank you Jim. An excellent presentation.

Did you have any problems getting the heat exchanger tube out?

Before I start to disassemble, I will verify that water is exiting the water outlet. I expect it is not clogged, the engine temp was normal and originally starting the engine water was discharging.


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[jimbunyard]

I've never had a problem pulling the bundle out, but that doesn't mean that that is always the case. A badly neglected engine could have the core stuck but I would imagine some light to moderate hammer work (with a wooden block held between core and hammer of course) and/or some kind of lubricant or corrosion dissolving liquid would free it up fairly quickly...


Regarding the exhaust elbow, it can be partially blocked and the engine will still work fine. Mine certainly did. If it is partially blocked, one telltale sign is that the boots, especially the upstream side, will expand significantly with increased engine rpm, which can force raw water into the freshwater side.

[landonshaw]

Will the heat exchanger come out in either direction? I am going to try to tack it out while it is on the boat and first just test that and the end caps. I will also inspect the exhaust elbow.


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[Cadence]

Originally Posted by landonshaw

I have the work shop Manuel by Volvo and to remove the heat exchanger seems relatively simple. Anyone have experience?

Out today, no wind so ran the engine. Water alarm went off in bilge and it looks like my raw water that goes thru the engine for cooling is getting into the coolant side. I suspect the heat exchanger is the problem. Any other ideas, possibilities?


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I an afraid you guessed right. I have seen it on a GM 4 53 eons ago. I doubt heat exchangers have changed much?

[FULLCIRCLE331]

Have you ever lost a water pump impeller blade, I have a MD2030. If you have, look in the break vacuum valve. At the end of the season I found one missing when I pulled the impeller, I found two blades in mine when I searched for it. The other must have been there when I bought the boat. The blades were blocking water flow but not enough to trip the alarm.

[landonshaw]

Where is the break vacuum valve? I have lost blades before. Now try to change every 100 engine hrs or once a year.


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[FULLCIRCLE331]

My vacuum break value is located on the bulkhead behind and above the engine. Gray plastic upside down U. I have installed a filter between the pump and the valve to catch any possible matter getting past the pump. It usually catches grass.

My vacuum break valve also had the different size nipples, only the 1/4 inch hole was open. I deemed this insufficient, I cut off the small nipple allowing more water flow. Since opening this I have not lost any blades. I think the small opening was causing too much back pressure and breaking the blades.

[landonshaw]

Ok, I never knew the correct name. Check it once a month though to be sure it is clean. Thanks


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[landonshaw]

Jim, I have taken off the HE cap on the front of the engine but having problems with the rear one. Three of the four bolt are off of the steel elbow the leads to the exhaust elbow. I can pull it back to expose the other end of the HE. should I be able to rotate the heat exchanger? Should the heat exchanger SLIDE out? Mine is tight and will not move.




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[jimbunyard]

Both rubber boots and all the hose clamps need to be off to remove the exchanger most easily. It will come out from either end. If you remove the elbow for better access, that's good too, and will enable you to make sure the elbow is truly clean. After removing both boots, try twisting the tube bundle back and forth in the housing before pulling it out, then try gradually pulling it out while rotating it back and forth. A big pair of channel locks might be needed to get things started, but be careful: the bundle is fairly soft. Try the least forceful methods first, but you may need to resort to a hammer and a block of wood and/or some kind of solvent or mild acid to dissolve corrosion, though if there is a corrosion problem it should be evident. I have heard of there sometimes being some kind of seals inside the H/E/manifold housing, that could also be causing the bundle to stick, but I've never seen them and they're not listed in the Volvo service or parts manuals.

Chances are it's just corroded in and just needs to be sufficiently persuaded to come out...

When you put it back together, measure that the tube bundle protrudes equally from both ends of the housing, mark both ends with a sharpie, and then put one boot and clamps on one end at a time, to ensure that you have the maximum 'bite' on both ends of the heat exchanger.

[landonshaw]

Jimbunyard, I am back on fixing my heat exchanger. Had a tropical storm come thru so needed to put the engine back together so incase I had to use it.

So, I took out six bolts behind the heat exchanger housing, loosened to the end of the screw the four bolts holding the thermostat. Shouldn’t I find that the heat exchanger housing should be able to move slightly? I am unable to move it at all. I am afraid that there is another bolt holding it tight somewhere.
Any suggestions from your experience?
Volvo Penta exploded view schematic
http://www.marinepartseurope.com/en/...0-26-4077.aspx

[jimbunyard]

The rust on the studs and bolts are holding the heat exchanger on? Remove the bolts from the housing, and if there's enough room to double lock the studs remove them, or whichever ones you can, too. Then carefully pry the top of the HE away from the block, then push it back toward the block, back and forth until it starts to loosen. 'Carefully' is a relative word, it may take a pretty good effort to get things started.

Conversely, it could just be that the gaskets are stuck pretty good and you're just being overly cautious. A reasonably long screwdriver or thin piece of stiff wood levered between any fairly robust points between the engine and the HE should break it free...

Also, on my MD2020 anyway, the top alternator mount is a bolt hole in the lower right corner of the heat exchanger. That has to come out too (I like to clear everything out of the way when doing something like this, so the alternator would already be off in my case). It is conceivable that there is some other bracket or mount holding some other accessory; double check before you start prying on things.