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MD2030 Heat Exchanger Clean and Coolant Drain Tap

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Category: General
Forum Name: Chit Chat
Forum Description: Talk about anything to do with your boat
Printed Date: 06 June 2023 at 08:17
Software Version: Web Wiz Forums 12.06 -

Topic: MD2030 Heat Exchanger Clean and Coolant Drain Tap
Posted By: Brightside
Subject: MD2030 Heat Exchanger Clean and Coolant Drain Tap
Date Posted: 14 February 2010 at 09:12
Volvo MD2030D 2002 Engine Hours 800.
Hi All.
To add to the Volvo manual, which is your guide, here are some notes on my 2-month project to clean the heat exchanger, which may assist you. With the tools and knowledge I have now it would be a job for two day with 72 hours in between for sealant to cure. Sorry for the disjointed style of posting but my PC is very old.

The Need to Clean the Heat Exchanger.
Summer 09, I noticed the saloon felt hotter than usual with the engine running. After 6 hours at 2600 rpm we had to increase revs to 3200 rpm, 5 mins later the engine over temperature alarm sounded, I reduced the revs to 2000 and the alarm quickly cleared.

Reduced Heat Exchanger Efficiency.
The postings on the Internet refer to scale building up saltwater side (inside) of the tubes being the main cause of reduced efficiency. In my case the insides of the tubes were OK, with 5 of the 34 tubes being partially blocked, the cause of the reduced efficiency was sludge on the coolant (antifreeze/fresh water mix) side of the tubes. There was a 1mm coating over the tubes with solid sludge at the ends and within the tube matrix. Unfortunately this does not show up well on the attached photo. I removed this sludge with a paint brush, running water and a soak in a mild mix of limescale remover and again lots of running water to flush it clean.


Posted By: Brightside
Date Posted: 14 February 2010 at 09:14
Heat Exchanger Intro.
The heat exchanger is held in position two the rubber boots, one front and one rear (these are black but covered in green paint). These rubber boots also keep the salt water and coolant separated. You need to drain the coolant from the engine block before removing the two clamps on both boots.

Posted By: Brightside
Date Posted: 14 February 2010 at 09:17
Draining the Coolant.
On my engine Volvo did not fit a coolant drain tap but fitted a plug with a 17mm square head that needs a 17mm 8 point socket to remove it using a long lever. The rounding you can see on the square head is due to an unsuccessful attempt to undo the nut by hammering on a 12 point socket (as used on normal 6 sided nuts). Upon removing the plug the coolant gushes out and I used a washing machine grey hose (correct size and flexibility), with some tape wound around the end to improve sealing, to drain it into a 5 litre container, lifting the floor boards in front of the engine meant gravity assisted me.


Posted By: Brightside
Date Posted: 14 February 2010 at 09:19
Fitting a Drain Tap.
A " to " BSPT Taper adaptor was screwed into the engine block using a 28mm socket (which is a non standard size). A " BSPT Tapered drain cock was then screwed into the adaptor but the spout must not exceed 24mm from the centreline or it will hit the oil filter case. In my case I had to cut down the length of the spout. All the threads were sealed with Locite 572, which takes 72 hours to set fully (available from Screwfix). I was told 572 perform better than PTFE tape or old-fashioned plumbers thread sealant. Fortunately the drain tap thread pinched up in the nose down position.

Posted By: Brightside
Date Posted: 14 February 2010 at 09:22
Removing The Heat Exchanger Matrix.
The most important thing is to close the seawater intake valve on the saildrive leg !!!!
With the Coolant drained from the engine block, undo the 4 clamps, plus a fifth on the exhaust elbow, pull the 2 boots off carefully and carefully pull the heat exchanger matrix forward. Be ready to catch some seawater and coolant.

Exhaust Elbow.
Check the hole is not blocked or restricted by scale.

Reinstalling the Heat Exchanger Matrix.
It is very important to check fore and aft position of the matrix to ensure that the clamps are positioned on the solid ends of the matrix.

Posted By: Brightside
Date Posted: 14 February 2010 at 09:22
Flushing the Engine Block.
I found using a fresh water hose with a trigger nozzle kept the water flow easily under control. Not much rust coloured water came out using a clear hose on the new drain tap.

Antifreeze Coolant Mix.
I used 50:50 but used De-ionised water rather than tap water.

I hope this has been of help to others.

Posted By: iliohale
Date Posted: 20 February 2010 at 16:40


Thanks for this, it is very helpful and great job in providing a step by step.


iliohale, Hanse 341
San Francisco, CA USA

Posted By: Astolfo
Date Posted: 30 July 2014 at 16:18
Do you mind telling me what and where those blue hoses coming out of the engine block go to?

Posted By: H8jer
Date Posted: 30 July 2014 at 18:08

We got the same two hoses on our md2020.

They are bi-turbocharged perfomance enhancers....

No really - they are for heating the hotwater tank.

Hanse 370#487 30HP 3-cabin

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