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Pearson 303 : Yanmar 2GM(F) Core Cleaning Made Easy

Oct 22, 2014
352
Pearson P303 #221 RockPort Maine
Hello Yanmar fresh water cooled fans! I flushed out my engine system and was going to removed the core to have it cleaned. However, I noticed it would be easy-er after inspection to use a GUN Cleaning kit to ream out the pipe's rather the taking out the core. This saved allot of time and expense. So, from the front of the engine i remover the cover changed out gasket and used the 22 pistol gun soft quilt dipped into vinegar and it did a great job. Put the cover back on and started engine running fresh water to remove residue from the cleaning. Total time apox:30 min. I hope this helps someone with a fresh-water-cooled system.

Capt. Rob P303 #221 Yanmar 2GMF:)
 

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Oct 22, 2014
352
Pearson P303 #221 RockPort Maine
Brilliant! The gasket was readily available?
Yes! There are 2 gaskets, the core and cover. NOTE: Do not try to reuse OLD gaskets for it will start to leak! Buy a new set of 4 this gives you 2 spares.

Here is some photo's (left to right) the first one was just removed.. and 2nd 3rd is after cleaning. I used "CLR" and soaked it for 10min then rinse with water. Note the 3rd one has a notch in it. its not a bad cover that's the way its made. The gasket covers over it as seen in pic 1(Left).

Regards, Capt. Rob :)
 

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Jan 28, 2011
40
Pearson 31 MD
Great advice. Thanks! Almost always false economy to try to reuse things like that. I'm also a fan of having spares for parts I've replaced. Usually pretty likely that if you've replaced it once, you'll replace it again.
 
May 20, 2015
5
Pearson 28-2 Annapolis
I know this is an old post, but I'm doing this now. I'm wondering - did you open the back cover of the exchanger to clean it out, or just do the front? seems like any blockage in the pipes will get pushed out the back if I don't take the time to remove it as well. And then that junk might just clog up the pipes again.
 
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Oct 22, 2014
352
Pearson P303 #221 RockPort Maine
I know this is an old post, but I'm doing this now. I'm wondering - did you open the back cover of the exchanger to clean it out, or just do the front? seems like any blockage in the pipes will get pushed out the back if I don't take the time to remove it as well. And then that junk might just clog up the pipes again.
No! leave Back ON! after you clean out with gun cleaner.. pour CLR into veins 2 cups full. let sit while you are putting back the front cap together. let sat 30 min... Start your engine and all the stuff in the back goes out the exhaust. You're Done! Note: I will not harm the environment got that straight from CLR Vendor. it's really like vinegar. Remember use gun clean swabs soaked in CLR first, then the brush.
Regards Capt. Rob
 
Feb 5, 2019
7
Pearson 303 Jacksonville, FL
No! leave Back ON! after you clean out with gun cleaner.. pour CLR into veins 2 cups full. let sit while you are putting back the front cap together. let sat 30 min... Start your engine and all the stuff in the back goes out the exhaust. You're Done! Note: I will not harm the environment got that straight from CLR Vendor. it's really like vinegar. Remember use gun clean swabs soaked in CLR first, then the brush.
Regards Capt. Rob
So, straight CLR, not diluted? FWIW, CLR changed formulation some years back - both are an acid, but the previous formula was not "really like vinegar..."
 
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Oct 22, 2014
352
Pearson P303 #221 RockPort Maine
No, I did not dilute the CLR. I also did this to my outboard motor too!
regards,
 
Feb 22, 2010
39
Oday 322 Delaware River
No! leave Back ON! after you clean out with gun cleaner.. pour CLR into veins 2 cups full. let sit while you are putting back the front cap together. let sat 30 min... Start your engine and all the stuff in the back goes out the exhaust. You're Done! Note: I will not harm the environment got that straight from CLR Vendor. it's really like vinegar. Remember use gun clean swabs soaked in CLR first, then the brush.
Regards Capt. Rob
Hi - sorry to correct you, but the water flow through the heat exchanger flows throughthree times: front to back, then back to front, and finally front to back and out the exhaust elbow. Each pass is 1/3 of the heat exchanger tubes. See the attached diagram from the Yanmar manual. That is why there is that "bent fence" 1/3, 2/3 on the front cap of the heat exchanger. There is a similar one, but different orientation on the rear cap. Note the arrows showing the flow of each 1/3. I agree with the other poster, better to take of both front and rear caps and do the job completely, and replace both gaskets.

Regards
Andre
Screen Shot 02-18-19 at 07.37 PM.JPG
 
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Oct 22, 2014
352
Pearson P303 #221 RockPort Maine
Hi - sorry to correct you, but the water flow through the heat exchanger flows throughthree times: front to back, then back to front, and finally front to back and out the exhaust elbow. Each pass is 1/3 of the heat exchanger tubes. See the attached diagram from the Yanmar manual. That is why there is that "bent fence" 1/3, 2/3 on the front cap of the heat exchanger. There is a similar one, but different orientation on the rear cap. Note the arrows showing the flow of each 1/3. I agree with the other poster, better to take of both front and rear caps and do the job completely and replace both gaskets.

Regards
Andre
View attachment 161490
Andre, Thanks for the input here and the details on flow. Yes given Ideally plenty of time and money you would also remove the core and send it out for cleaning.. However, you really do not have to remove the rear cap that flows out to your exhaust. The CLR breaks up and allows it to flush out particles. Thanks for the input. Best Regards..
 
Apr 12, 2019
13
Hunter 31 Cindy Lou Demopolis,AL
I always say it's hard to argue about good results and if this works it beats taking the heat exchanger out and maybe having a few days down time.James
 
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Dec 19, 2006
5,587
Hunter 36 Punta Gorda
I did this a few months ago but took the front and back caps off and also used
a long thread rod to clean each hole out.
I also take front cap off when ever I need to change impeller to check for anything that gets
in that part of exchanger.
Nick
 
Oct 22, 2014
352
Pearson P303 #221 RockPort Maine
I always say it's hard to argue about good results and if this works it beats taking the heat exchanger out and maybe having a few days downtime.James
Hey! forgot one thing until you get the raw water situation clear I would recommend the following steps before starting the engine in your normal way.
1. SHUT-OFF your seacock for raw water intake.
2. Start your engine
3. OPEN the seacock and check for water going out the exhaust.
this will prevent water from backing up into the exhaust system and causing big damage.
I would also recommend a new raw water impeller. It's a blue one that's called a RUN-DRY! it allows you to run up to 15-20 minutes of running with no or little water flow.
I have been using the Globe Blue Run-Dry™ Impellers for years and I have been very happy with them. I usually check them at the end of the season and they look almost new with a little discoloration.
 
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