# Best way to remove and clean heat exchanger Perkins 4.236



## edwmama (Jun 15, 2008)

A service called heatexchanger Descaler would come to my Cal 46 motorsailer and would clean "descale" my heat exchanger for a fee of $400
I looked around on the web and found that I can get a new heat exchanger for about 4 to 6 hundred dollars.

I am a do-it- yourselfer and am very mechanical. Any recommendations on how best to remove my 1968 Perkins heat exchanger?
What parts would I need? O rings? Any special tools or special things to what out for? Any special precautions?

Is it advisable to fill using a Y valve the heat exchanger with fresh water before turning off engine?

Also what solution besides Muriatic acid would be effective
I am afraid it would dissolve the fine tubes in the exchanger?

I would appreciate a candid reply to:

[email protected]


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## sailingdog (Mar 19, 2006)

While not a Perkins, you may be interested in *Maine Sail's article on cleaning a heat exchanger*.....


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## CalebD (Jan 11, 2008)

Check the link that Sail'ngDog gave you and this one which is just the picture version without the MaineSail narrative: Westerbeke / Universal Marine Heat Exchanger Photo Gallery by Compass Marine at pbase.com
For less then $50 in materials you should be able to clean, re-zinc, paint and re-install your heat exchanger (HX) if you DIY. It depends on how your HX was installed, the size of the zinc and the color paint you want to use on the outside. Replace any hose clamps that seem iffy when you remove the HX for cleaning etc. 
Your HX should resemble the one in both links but the installation and brand of it can vary widely depending upon how it was installed. Pictures always help.


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## poopdeckpappy (Jul 25, 2006)

I haven't done a 4-236, but I've service several others, Volvo, Cummings, yanmars etc,etc. It takes about 90 mins to remove & replace, and the local radiator shop ( long experience in marine systems ) cost between 75-165.00 bucks ( depending on size ) to clean, braze, install seals & zinc, test and repaint in the OEM color.


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## lancelot9898 (Dec 30, 2008)

I have the Perkins 4-108 and the heat exchanger design is probably different, but I've found it easy to remove and clean. Over the past 25 years I've probably removed it 3 seperate times and used muraric acid each time. The key is not letting it soak in the acid for a prolong period. I think I used about a three minute soak time and followed it up with a baking soda solution to neutralize the acid. I then rodded each individual tube using gun patches so that all tubes were nice and shiny.


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## RichH (Jul 10, 2000)

Hx Descaling is best done by using products like: RydLyme. No need to remove and partly disassemble the Hx. 
Just pour into a bucket, remove the inlet to the raw pump hose and at the water injection nozzle and stick both (or extensions) into the bucket, draw the RydLyme (or other 'descaler') into the circuit, soak, etc. Descalers are inhibited compounds that dont aggressively attack the base metal of the Hx and exhaust manifold internals ... and are usually eco-friendly so they can be pumped overboard when done. With muriatic/hydrochloric you never know when to stop and leaves the engine/Hx/ex. manifold vulnerable to losing 'base metal'. 

Do websearch: rydlyme + marine .... about $40/gallon.


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## edwmama (Jun 15, 2008)

*Descaling heat exchanger*

Of all the answers I like your the best. I am a little confused
How do I circulate the rydlyme thru the HX? Do I run the engine
For 4 hrs and use the bucket of rydlyme as the raw water? Or do I just soak the HX overnite with the rydlyme? If I decide to run the fluid thru the
Bucket will that harm the exhaust or the cooling system since it is
Not being ejected out thru the exhaust as it normally would under normal
Operating conditions?

Also rydlyme better that baking soda solution?

Edwmama


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## RichH (Jul 10, 2000)

Procedure when using descaling compounds:
1. Drain system side that is to be descaled (typically just the raw water side) ... blow out with pressure air if available. If you cant get 'most' of the raw water out, increase the soak time. 
2. Suck up descaler via engine raw water pump from the bucket .... engine running at idle .... until descaler comes out the hose supplying the water injection nozzle, the Shut down engine, reconnect hoses but keep raw water inlet throughull valve closed. 1 Gallon of descaler is usually sufficient for most small marine diesel engines. 
3. Soak time is 2-4 hours depending on the 'strength' of the descaler being used ... typically 2-4 hours but be sure to follow container instructions. No need to recirculate descaler during 'soak'.
4. With all hoses reconnected (verify) to proper nozzles, valves, etc. .... Start engine to flush out .... then RUN engine at cruising speed rpm and under load so that engine 'heat soaks' at max. operating temp. for about 2 hours to reform protective 'black rust' (ferrous oxide) inside the engine/ex. manifold/ Hx, etc.). Do the 'heat soak' ASAP after descaling, etc. 

Note: if you descale the 'fresh water' circuit, you MUST flush/flush/flush to ensure that ALL the descaling compound is removed. 

Baking soda (sodium bicarbonate) is used to make cookies and to help settle upset stomachs, etc. it is a buffering chemical to control acidity levels and therefore not applicable to 'descaling' or "acid pickling" applications.


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## edwmama (Jun 15, 2008)

Thx much rich H. I will try it. I will soak for 4 hrs and run engine for two .
I guess I meant caustic soda for boiling as other forum replies have recommended ( not baking soda )

Your suggestion seems to be the least invasive and simplest

I will try it and give you a feedback

Thx again

Edwmama


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## RichH (Jul 10, 2000)

Most soak times are ~2 hours for RydLyme. You can pump the Rydlyme back to the 'bucket', open the tube bundle cover on the Hx and simply 'see' if you need more time .... a wee bit of scale deposition left on the tubes can be ignored, all you need to remove/dissolve is the 'thick stuff'. 

Caustic soda (sodium hydroxide or "lye") will have absolutely NO effect on boiler scale (Calcium Carbonate). Sodium hydroxide in treatment of 'water systems' is used to dissolve organic material such as massive bacteria colonies, etc. ... NaOH is quite a dangerous chemical for the non-chemist to use as it can cause very severe and very long to heal 'chemical burns' ... actually it dissolves tissue/skin while generating a lot of heat, etc.


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## edwmama (Jun 15, 2008)

*Heat exchanger descaling*

yes thank you
I did the Rydlyme descaling
It seemed to help
Though I still see a faint white smoke
In my exhaust

At least I know it's not from clogged HX

Thanks again
Edwin
Cal Cruising 46
Marina del Rey CA


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