Heat exchanger housing corrosion

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shortjohnsilver

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Got the heat exchanger out of my VP 2040 -D after a bit of a battle and found the heat exchanger pretty clear. Peered inside the casing and there’s a lot of corrosion in there on all surfaces. ?

I can get my hand in there and scrape away, but worried all the ‘rubbish’ corrosion sediment will cause issues further down through the system. Is there anything to be done, maybe some sort of treatment that can be applied to remove the corrosion build up that will dissolve the corrosion, so that it can be flushed through and out?

Exhaust elbow also removed and the water entry pretty clear also, although there’s clear carbon build up in the elbow itself. Probably replace that clean up the old and retain as a spare.
 
Add some car radiator flushing stuff from the motor factors, then drain, flush again with fresh water and refill as normal. To prevent future build up, change coolant every other year.
 
Thanks Bobc & robmcg.
Clearly a VP issue that I won’t be able to entirely eliminate!
Yes, I’ll clean away as best I can, whilst I have the heat exchanger out and thoroughly clean through with water. Once I’ve replaced the heat exchanger and exhaust elbow etc, I’ll flush some radiator treatment through as suggested. (How long to leave that in?) Then empty, flush through again and refill with coolant. Whatever I do, should improve the situation and hopefully stop further corrosion and deterioration.
Since owning the boat, eight years now, I have changed the coolant every other year and have always been disappointed at the colour of the old coolant. I’m not sure the previous owner did though!
Anyway thanks.
 
Maybe some slight contamination of the coolant with sea water is occurring.

Check the condition of the rubber end caps and be sure the smaller of the two large clips is making a good seal between the end cap and the tube nest.

Make sure the water injection point into the exhaust bend is not obstructed as that will cause an increased pressure of the seawater.

Dilute the antifreeze with distilled or deionised water, or buy it ready diluted, unless you are in an area where the water supply has a low dissolved solids concentration.

Do not use less than the recommended concentration of antifreeze and consider changing it every year.
 
Is this relevant?

Engine Zincs - myHanse - Hanse Yachts Owners Forum ...
www.myhanse.com › engine-zincs_topic2827

Feb 24, 2009 — It did not have an anode to protect the heat exchanger, but we had to change a ... VP said that they were wrong on not installing anodes originally. ... from the shaft to avoid corrosion instead of using internal (pencil like) anodes. ... http://www.marinedieseldirect.com/repower/specs/volvo/md2040_40hp.pdf

Diesel school - anodes - SaltWaterDiesels.com
saltwaterdiesels.com › diesel-school-anodes

To combat this, many heat exchangers are fitted with a zinc“pencil” anode. You will find it usually under a plug or plate within in the exchanger. The pencil is ...
Missing: VP ‎| Must include: VP
 
 
VicS - Yes I think salt water has got in there and the exhaust elbow was sufficiently blocked - though not entirely to cause a bit of back pressure and force outgoing water via the boot into the HE. Maybe!
I have ordered a replacement elbow in Stainless Steel, also new boots for both ends and new retaining clips.
I’ve cleaned up the HE casing internally as far as I can and that looks a lot better. However, I have an issue with the thermostat now. I have a new replacement ready to go in, but I can’t get the old one out!
It appears that it’s corroded itself in place and it looks as if I’ll have to force it out!
Looking at the schematic it’s not clear however, whether the thermostat sits within the sleeve or whether the sleeve holds the thermostat in place. I don’t want to damage anything forcing them out.
I agree, the engine certainly could have done with some sort of anode protruding within the HE housing, as this perhaps would have gone some way to preventing all of this. May look at retro fitting something.
However, thanks all for suggestions advice. It really has helped.
Si
 
shortjohnsilver said:
I agree, the engine certainly could have done with some sort of anode protruding within the HE housing, as this perhaps would have gone some way to preventing all of this. May look at retro fitting something.
However, thanks all for suggestions advice. It really has helped.
Si
Click to expand...
The freshawater side of the cooling system should not need the protection of an anode. It should be protected by the corrosion inhibitors in the anfifreeze, but it is important that the coolant id not caotaminated with sea water.

If you were to fit an anode what material would it be bearing in mind that zinc anodes are not effective in freshwater
 
VicS my aim is to prevent salt water getting in, so new elbow, new boots and fresh antifreeze - VP pre mixed. And then as you say, won’t need an anode.
Current issue is the thermostat has truly welded itself in there. Got the sleeve out and cleaned back to the thermostat, but it’s solid and immovable. Still compressing though!
God knows how I’m going to get that out, but out it must come! Any suggestions anybody would be welcome. cheers.
 
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