Full throttle needed to start Yanmar 2GM20F - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance > Engines > Diesel
 Not a Member? 

Diesel This is a new forum dedicated to diesel engines and their applicable accessories.


Reply
 
LinkBack Thread Tools
  #1  
Old 12-15-2012
Member
 
Join Date: Dec 2012
Posts: 45
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
73Morgan is on a distinguished road
Full throttle needed to start Yanmar 2GM20F

I need some help here. While I have a fairly good shade tree mechanic experience with gasoline engines, this is my first diesel engine.

My starting problem has been getting progressively worst over the years, to the point where now I have to give it full throttle to start the engine. In an effort to resolve this problem the head was rebuilt by a reputable machine shop, and the injectors were rebuilt by my local boat yard.

To start the engine I have to crank it for a while and give it full throttle. When it does start it seems to start on one cylinder, while keeping it in the higher RPM range so it does not stall, after a while the second cylinder kicks in.

While cranking at startup I get occasional kick back. During the start up and until it warms up a little there is a lot of suttee black smoke. During startup and after the engine fully warms up under way there is what the mechanic tells me is a fuel knock. When under way I am able to reach full RPM's.

Now I am being told that the compression is low, and that it might be as simple as frozen piston rings.

At this pint my main question is, if the compression is low why would I be getting fuel knock. As I understand it fuel knock and kick back is a result of early combustion of fuel, and it seems to me that if you had low compression the fuel would ignite later rather than early.

Any help is appreciated.
Reply With Quote Share with Facebook
  #2  
Old 12-16-2012
overbored's Avatar
Senior Member
 
Join Date: Oct 2010
Location: Dana Point, Ca
Posts: 943
Thanks: 1
Thanked 35 Times in 35 Posts
Rep Power: 4
overbored is on a distinguished road
Re: Full throttle needed to start Yanmar 2GM20F

I had the same type problem on my 1GM10, the single cylinder model of the 2GM and it was the injector timing. also I don't rebuild the injectors as they are only $100 each and the cost to rebuild is $125. did your mechanic set the timing to 15 or 25 degrees yours should be 15 and some mechanics don't know that there is a difference in the models of the 2GM series engines
low compression can be valve setting. make sure that the two end valve rockers are held in towards the center of the engine as they will slip outward during setting with the valve cover off and the valve clearance will be to tight when you reinstall the valve cover.
__________________
"FULL TILT" SOVEREL 33
"GOLD RUSH" PRINDLE 16
Reply With Quote Share with Facebook
  #3  
Old 12-16-2012
Senior Member
 
Join Date: Feb 2010
Location: Narragansett Bay
Posts: 8,703
Thanks: 10
Thanked 116 Times in 110 Posts
Rep Power: 6
Minnewaska will become famous soon enough Minnewaska will become famous soon enough
Re: Full throttle needed to start Yanmar 2GM20F

When you push the throttle to full open, you are both introducing more air to accommodate ignition and flooding the cylinder at the same time. The chugging you are referring to as starting on one cylinder sounds like a symptom of poor atomization of the fuel/air mixture. That's how a flooded engine runs at first.

As you said in your other thread, you had the injectors rebuilt, but haven't clarified what that means. All signals are to a fuel/air problem and injectors are usually at the heart of that. They simply wear out. Other causes could be a blockage or poor fuel pump pressure, but less likely. Although, some get ridiculous with the fuel filters they use and assume that lower microns are always better. Not always true, as your system may clog too fast or overwhelm your pump. Have you checked them? What microns do you use? Also, as I mentioned in your other thread, the rebuilt injectors may have been reinstalled incorrectly, with the wrong seats, so the spray pattern would be affected.

Personally, I've had smoking issues and oil burn from low compression, but until its very low, I've not noticed this kind of starting trouble.
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Jeanneau 54DS

In the harsh marine environment, something is always in need of repair. Margaritas fix everything.
Reply With Quote Share with Facebook
  #4  
Old 12-16-2012
Faster's Avatar
Just another Moderator
 
Join Date: Sep 2005
Location: New Westminster, BC
Posts: 14,604
Thanks: 67
Thanked 178 Times in 174 Posts
Rep Power: 10
Faster has a spectacular aura about Faster has a spectacular aura about Faster has a spectacular aura about
Re: Full throttle needed to start Yanmar 2GM20F

I think OB and Minne are on the right track.. while 350 compression may be on the low side I don't think it's low enough to make starting problematic with good fuel delivery. And that means timing and proper atomization.

If you're cranking for excessive time periods try to remember to leave your RW intake closed until the engine catches. Flooding the exhaust system with RWC is never a good thing.

Having to use wide open throttle during starting seems to be SOP for some of these older Yanmars..
__________________
Ron

1984 Fast/Nicholson 345 "FastForward"

".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
Reply With Quote Share with Facebook
  #5  
Old 12-16-2012
Member
 
Join Date: Dec 2012
Posts: 45
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
73Morgan is on a distinguished road
Re: Full throttle needed to start Yanmar 2GM20F

Quote:
Originally Posted by overbored View Post
did your mechanic set the timing to 15 or 25 degrees yours should be 15 and some mechanics don't know that there is a difference in the models of the 2GM series engines
low compression can be valve setting. make sure that the two end valve rockers are held in towards the center of the engine as they will slip outward during setting with the valve cover off and the valve clearance will be to tight when you reinstall the valve cover.
Quote:
Originally Posted by Minnewaska View Post
As you said in your other thread, you had the injectors rebuilt, but haven't clarified what that means. All signals are to a fuel/air problem and injectors are usually at the heart of that. They simply wear out. Other causes could be a blockage or poor fuel pump pressure, but less likely. Although, some get ridiculous with the fuel filters they use and assume that lower microns are always better. Not always true, as your system may clog too fast or overwhelm your pump. Have you checked them? What microns do you use? Also, as I mentioned in your other thread, the rebuilt injectors may have been reinstalled incorrectly, with the wrong seats, so the spray pattern would be affected.
.
There were 3 different mechanics who worked on the engine over the years. Each time I ask around and try to find someone who really knows what they are doing. The last one (No. 4) I had look at it and took the compression, he works exclusively on diesels. But, he said he works on larger engines and he did not sound that familiar with this engine, he also said the timing is fixed at the factory. The injectors were actually rebuilt 4 seasons ago and again this last season. Unfortunately I don't know what that means since i relied on others. No improvements either time. This is why I have to take matters into my own hands. There are to meny people out there who call themselves mechanicks.

The fuel filters I have always changed myself. There is a water separator mounted up stream of the engine, and the filter on the engine. Even though I don't have the numbers on hand I don't believe that is the problem since I get the same numbers every year to replace them, and the engine used to run better.

I will check the valve adjustments, mixing tube, and I will get a brand new set of injectors and seats, worst case scenario I end up with a spare set. Also, it has been suggested in my other thread to change out all the fuel components.
The Fuel Feed Pomp works fine. Personally, I am leaning towards the Fuel Injection Pump or timing.

I don't know how to trouble shoot the Injection Pump. The Yanmar manual is not very helpful when it comes to trouble shooting.
Reply With Quote Share with Facebook
  #6  
Old 12-18-2012
Senior Member
 
Join Date: Sep 2006
Posts: 2,179
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 8
Rockter will become famous soon enough
Re: Full throttle needed to start Yanmar 2GM20F

Full throttle at start-up is normal for my Volvo diesel motor.
Remember though guys, there is no throttle (per se) in a diesel motor in contrast to the throttle gates of a gasoline engine.
For a diesel, full throttle just helps enrich the first few firing strokes.... it squirts more fuel in.
Throttle back the moment it starts.
Reply With Quote Share with Facebook
  #7  
Old 12-18-2012
Senior Member
 
Join Date: Feb 2011
Location: San Francisco Bay area
Posts: 2,136
Thanks: 1
Thanked 30 Times in 30 Posts
Rep Power: 4
MarkSF is on a distinguished road
Re: Full throttle needed to start Yanmar 2GM20F

Am I correct in thinking that the Yanmar doesn't have glow plugs? I'd expect this to result in difficult starting and having to use full throttle to start. Can't understand why they thought it would be OK to not install them.
__________________
1984 Bristol 31.1
Alameda, California, USA
Reply With Quote Share with Facebook
  #8  
Old 12-18-2012
Senior Member
 
Join Date: Feb 2010
Location: Narragansett Bay
Posts: 8,703
Thanks: 10
Thanked 116 Times in 110 Posts
Rep Power: 6
Minnewaska will become famous soon enough Minnewaska will become famous soon enough
Re: Full throttle needed to start Yanmar 2GM20F

Quote:
Originally Posted by MarkSF View Post
Am I correct in thinking that the Yanmar doesn't have glow plugs? I'd expect this to result in difficult starting and having to use full throttle to start. Can't understand why they thought it would be OK to not install them.
I have no glow plugs on my Volvo and it starts right up, in idle, every time. Knock on wood! I had to move it a couple of years back on a 30 deg day in March and it fired up normally after sitting on the hard for months.

The bloody turbo, however, gives me fits.
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Jeanneau 54DS

In the harsh marine environment, something is always in need of repair. Margaritas fix everything.
Reply With Quote Share with Facebook
  #9  
Old 12-18-2012
L124C's Avatar
Senior Member
 
Join Date: Oct 2007
Posts: 1,384
Thanks: 47
Thanked 3 Times in 3 Posts
Rep Power: 7
L124C is on a distinguished road
Re: Full throttle needed to start Yanmar 2GM20F

Quote:
Originally Posted by MarkSF View Post
Am I correct in thinking that the Yanmar doesn't have glow plugs? I'd expect this to result in difficult starting and having to use full throttle to start. Can't understand why they thought it would be OK to not install them.
I have the same motor as the OP. I always do a cold start at 3/4 throttle, throttling back to idle immediately after start, as directed in the manual. It's over 20 years old, does not have glow plugs, and has never had a starting problem (in the moderate SF Bay Area climate). Kicks on the first crank every time! Once warm, it starts immediately from idle position.
Sounds like a good Yanmar mechanic is in order for the OP. If he is in the Bay Area, List Marine will sort it out in short order. I'll bet they will also tell him to cruise at 3000 RPM when it is running properly. Makes for a happy 2GM20!

Last edited by L124C; 12-18-2012 at 06:21 PM.
Reply With Quote Share with Facebook
  #10  
Old 12-18-2012
Member
 
Join Date: Dec 2012
Posts: 45
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
73Morgan is on a distinguished road
Re: Full throttle needed to start Yanmar 2GM20F

Quote:
Originally Posted by MarkSF View Post
Am I correct in thinking that the Yanmar doesn't have glow plugs? I'd expect this to result in difficult starting and having to use full throttle to start. Can't understand why they thought it would be OK to not install them.
Agreed, it does not have glow plugs, and it probably should, it would help if it did. But, about 8 years ago it used to start with almost no throttle. Whatever is going on is not normal.
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Yanmar 2gm20f RPM RobGallagher Diesel 2 06-30-2012 03:24 PM
Yanmar 2GM20F Suave Gear & Maintenance 2 05-16-2011 10:33 AM
Yanmar 2GM20F Work... krozet Diesel 15 04-28-2010 11:41 PM
Yanmar 2GM20F Petar Gear & Maintenance 13 10-02-2009 06:49 PM
Oh... the noise, running full throttle deniseO30 Diesel 2 06-29-2009 11:19 AM


All times are GMT -4. The time now is 09:27 PM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.