Burping Yanmar 2GM20

Sinbad

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May 7, 2012
4
Hunter H-356 Grand Rivers
I recently changed the antifreeze in Gypsy's 2GM20 and had a bit of trouble with the overheat alarm telling me that something was now not quite right. Following lots of good (and some not-so-good) tips on the internet, I heated some water and confirmed the thermostat and sensor switch were OK but I was at a loss beyond that. I had seen an earlier thread on changing the antifreeze where a couple guys mentioned burping and guy #3 thought they were goofy. Initially I thought burping was a little far-fetched, but it turned out to be exactly what I needed to do. I had been adding the A/F into the heat exchanger. This traps air in the thermostat housing until the thermostat opens, as mentioned by guy #3. The trouble is that the thermostat is surrounded by air and fails to open before the sensor switch trips and the engine cries out for help. I suppose the thermostat might eventually start to open if things got hot enough, but I did not want to take that chance. Topping off the thermostat housing is what I ended up doing, but loosening the hose to the water heater should also do the trick. I am a believer in "burping" and wanted to thank S. Sauer and Gary Y. for mentioning it. Sail on, Ken
 
Jan 4, 2006
6,444
Hunter 310 West Vancouver, B.C.
One of the big mistakes early on was ensuring that I got ALL of the antifreeze out of the hoses and heat exchanger coil (in the hot water tank) by blowing the antifreeze out using compressed air. Big mistake. Suffered loss of prime on the pump, overheating, repeated low antifreeze in the reservoir again and again. Finally smartened up and now drain and add antifreeze every other year to the engine only and leave the rest behind in the system. Quick and easy. This refreshes enough to ensure the chemical levels (lubricants, antioxidants, etc, etc) are always up to scratch.

The air vent (shown below) quickly vents all air from the engine (as you add antifreeze) and you're ready to go with no problems.

Vent.JPG
 
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Tom u

.
May 3, 2015
5
Hunter 28.5 Athens
Hi Sinbad,
I have same Yanmar in my 28.5. I think have the burping issue as my engine has overheated last year since I changed the circulation pump. After I changed the pump I continue to get overheating alarm. I tried running engine with coolant cap off and even loosen hose coming out of thermostat and tighten belts. You mentioned topping off AF at thermostat housing - do you mean you filled AF with thermostat removed? Not sure I understood the solution. Thanks for any help.
 
Jun 3, 2010
177
Hunter 27-3 Erie
Ralph, I have often looked at that same fitting on my Yanmar and wondered what it was for. Another mystery solved, thanks for sharing.
 
Jan 17, 2013
439
Catalina 310 St. Simons Island, GA
Ralph,
Is that your original engine? How many hours and how does it stay so clean? I have the same engine, same year with 1,000 hours but it does not look like that...
bob
 
Oct 30, 2011
542
klidescope 30t norfolk
I use 3/4 heater hose you buy from auto parts store and hose adapter from hardware store disconnect 1 hose feed to hot water heater install heater hose put in 5 gal bucket adapt hose to dock water hose start motor open fresh water and let her rip first 5 gal has anti freeze mix in it rest run in bilge till clear water runs out then close up drain 1 gal water add anti freeze
 
Jan 4, 2006
6,444
Hunter 310 West Vancouver, B.C.
Is that your original engine? How many hours and how does it stay so clean?
That's the original engine with about 2,000 hrs. Afraid I'm a bit OCD as far as the engine goes, not to mention the rest of the boat. Just follow up on any oil leaks and have a heart attack over water leaks.

I wasn't too clear on filling the reservoir with AF, but I leave the vent open and let it belch and gurgle while filling the reservoir. I've never had an overheating problem however, I will add more 50/50 antifreeze for the next 2-3 outings as the bubbles are collected in the reservoir. After that, good for two years until the next drain and fill.
 
Jan 17, 2013
439
Catalina 310 St. Simons Island, GA
Ralph,
Not to beat a dead horse but what do you use to clean your engine and keep it free of rust? Here is my original 1999 with 1,000 hours. Runs perfect but has soot and some rust.
20170225_083649.jpg
 
Jan 4, 2006
6,444
Hunter 310 West Vancouver, B.C.
Not to beat a dead horse but what do you use to clean your engine and keep it free of rust?
One thing I am OCD about is that my packing gland (not mechanical seal) runs dry. There is no water anywhere in the bilges.

https://forums.sailboatowners.com/i...y-need-to-leak.136282/&highlight=need to leak

Being in Georgia, I think you may also see humidity conditions above and beyond what get here in the colder climates. If, some day, you have absolutely nothing to do on you boat (about the same time hell freezes over) you could steel wool a few of your rust spots, spray paint with Yanmar paint, and then coat the surfaces with a synthetic grease like Super Lube to hold the corrosion at bay.
 

19thol

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May 2, 2014
111
Hunter 30 St.Petersburg, Fl
You guys are making me so jealous with all that engine access!!
 
Oct 6, 2007
1,023
Hunter H30 1982 Chicago IL
You guys are making me so jealous with all that engine access!!
I was thinking the same thing.
This is probably more typical of the access many of us deal with, though I've be told by a few people that the access to my 2GM is pretty good compared to others. It was declared by a power boater friend from the south to be "....a clean little critter".
A single drop of oil on the blue appear towels under the engine sends me looking for the source, so I'm up there on the OCD scale too. The raw water strainer on the left (with the missing bowl) is being replaced this spring with a bronze Groco model. Purchased from this site by the way.
IMG_7727.JPG
 
Last edited:
Oct 6, 2007
1,023
Hunter H30 1982 Chicago IL
Dallience, I like the fuel shutoff at the filter. Very convenient for filter changes.
Very observant of you. Have one at the tank too -- just in case. Also, the Racor was originally behind the engine; hard to reach and dangerously close to where the stuffing box drips into the bilge. I moved it forward when I replaced the engine compartment insulation a few years ago.
 
Oct 6, 2007
1,023
Hunter H30 1982 Chicago IL
Hi Dalliance,

Where did you get your engine insulation?
Sailor_Jeff,

I bought it at West Marine. FREE shipping to the store for pick-up. Other sites may have had a slightly lower price, but the shipping cost tipped the balance. It is surprisingly heavy -- 1" thick, two layers of foam (absorption layer and an isolation layer) with a flexible pvc layer between (that's where the weight is), mylar foil on the outside and peel & stick adhesive on the back. Comes with foil tape & mechanical fasteners too.

One helpful hint: Get some large pieces of corrugated cardboard to cut and fit as templates before cutting the insulation.
 
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