Bleeding a Yanmar 3GM 30 (F) - is it always necessary??

Jan 10, 2018
260
Beneteau 331 Halifax
Hi all,

In the courses I have taken, they always said to bleed after changing the primary and secondary fuel filters. I read on another site that if you are only doing this (working on the low pressure side of the fuel system) you do not have to. In fact, the mechanic I had working on the engine last year confirmed this - and he was very well trained.

When I changed these filters today, I filled them both with clean diesel and then ran the engine for 20 minutes after. In particular I ran the engine after I changed the first, changed the second, and ran again, all over 20 minutes each.

No problems that I could see.

Is this OK, or will air get into the injectors??

Thanks!

Mike Casey
Halifax, Nova Scotia
 
Mar 20, 2016
594
Beneteau 351 WYC Whitby
I have a perkins M30 and have never bled the system after both filter changes, and like you said if you don't touch the high side ,I pretty sure your good to go. After 20 minutes it would have stalled long before if air was present and I never even pre- filled my filters
 
Jan 10, 2018
260
Beneteau 331 Halifax
Thank you. I even had it at 2,100 RPM for 10 minutes, in addition to 10 minutes at 1,500, so it must be OK.
 

DougM

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Jul 24, 2005
2,242
Beneteau 323 Manistee, MI
I have a 2GM20F Yanmar and have changed primary and secondary filters. The first time I did it, being new to diesels, it did not occur to me that bleeding ( other than my knuckles) would be needed. The engine started up and ran without a problem. Since then I have read several threads about filter changing/ bleeding, yet have not seen the need in my case, and 14 years of filter changing later, I still don’t bleed the system. I guess I must just be lucky.
 
Jan 7, 2011
4,727
Oday 322 East Chicago, IN
I have a 2GM20F Yanmar and have changed primary and secondary filters. The first time I did it, being new to diesels, it did not occur to me that bleeding ( other than my knuckles) would be needed. The engine started up and ran without a problem. Since then I have read several threads about filter changing/ bleeding, yet have not seen the need in my case, and 14 years of filter changing later, I still don’t bleed the system. I guess I must just be lucky.
+1.

If you are careful, you don’t need to bleed. I ran mine IN GEAR to make sure I had a load on the engine.

Greg
 
May 24, 2004
7,129
CC 30 South Florida
It varies from engine to engine and to how high the fuel tank sits above the engine. If the engine started and is running well then you are good to go, but if sputters a little and wont clear then there might be some air trapped.
 
Jul 27, 2011
4,990
Bavaria 38E Alamitos Bay
After changing filters w/o bleeding, the diesel usually “coughs” after a minute or two of running, whereupon I throttle up some. If it doesn’t sputter out, I’m good to go. Job finished.:dancing:
 
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Jan 10, 2018
260
Beneteau 331 Halifax
All interesting comments, thank you. Before this boat I had an Island Packet. I am still a member of the owners group. Several very knowledgeable people on that site also say no ned to bleed.

Today we went for a sail - probably the last of the year. No problems whatsoever, and we ran it for a while at 2,500.
 
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Jan 7, 2014
395
Beneteau 45F5 51551 Port Jefferson
My Perkins needs bleeding at the injectors, my universal didn't need anything. I guess it depends on the engine.
 
Feb 2, 2006
464
Hunter Legend 35 Kingston
I have a 3GM30F, and I've had it both ways.

First, I don't bleed unless it needs it, so after doing filter changes, I will try to start the engine. If it goes, then it's critical to run it for a while preferably under a bit of load as it may take a while for trapped air to cause a problem. If it doesn't go, or sputters out, then time to bleed.

Sometimes (maybe most times) I have to bleed the air out, and other times the engine started and cleared the air out on it's own. It could be that I'm not doing my filter changes as well as I could be and let in more air in the process.

Chris