Yanmar loses power, slows down & kills

[tallyho8]

Tally, I think you're on the right track now. You can always put it in a box and UPS it to a shop ! Ernie

What? The pump or the tractor?

 

[irwin]

Hiya Dudley:

I've been following this thread with concern, everyday I check to see if you've solved it.

Dang it man, hope this problem is resolved soon..I need a happy ending..

 

[AlanB]

What Irwin said..............

Sure hope you get it sorted soon.

 

[tallyho8]

I'm still waiting for the diesel shop to check the pump. Maybe today?

 

[tallyho8]

The diesel shop finally checked my injection pump today and said it is good. Jefferson Diesel Shop Jefferson Diesel Specialist, Inc. Harvey, Louisiana was very busy so they were a little slow checking it but their service was very good. They put new plugs in it so no dirt would get in and even gave me a new copper washer for the inlet and charged me nothing for their service.

Now I am at a total loss as to what the next step will be. I guess I need to get a diesel compression tester and adapter and try to get the compression checked while it is still hot. Does anyone know if this tester will work on my Yanmar or if I have to get a special adapter also. Harbor Freight Tools - Quality Tools at the Lowest Prices

I have still not found a shop within 50 miles that will work on it. Fixing it would be easy but finding out what is wrong with it is driving me crazy. If it was just a head gasket or something similar I could fix it in no time.

 

[BruceR]

You could rent one from Aaron.

Compression Tester * $10 RENTAL *: Yanmar Tractor Parts

Bruce

 

[MJPetersen]

With the possible exception of a valve sticking, compression would get better as the machine warms, not worse and once running the compression would never get so bad that the engine would die! A valve sticking has a very distinctive sound too, try pulling the compression release and you will hear what I am talking about. Your problem HAS to be fuel starvation or air getting into the fuel system. Since you have bypassed most of the fuel system in your tests and have now checked the pump, I believe it is time to turn back to the injectors. Injectors that were sticking when hot could create the kinds of symptoms that you describe. If an injector is not seating properly, then air from compression could flow back into the injector lines. I had this happen on a ford transit engine--the tip of the injector broke and when the engine slowed down it died from air entering the system from the cylinder compression. I know that you had them checked, but I think that i would have them rebuilt or replaced.

Just my opinion in the matter. I empathize with you and have followed the thread with great interest. I really hope that you soon find the problem and get back on its feet.

Mike

 

[tallyho8]

I put the pump back on and naturally it's doing the same thing. I left the exhaust manifold off so I could check the cylinders individually. After it warms up it starts missing and smoking on the front cylinder first. I have a small video of it if anyone can tell anything from the video.http://members.cox.net/tallyho/missing.mpg

 

[mark777]

I have looked and listened to the video a dozen times...even looked away, shut my eyes and can't hear any deviation in the RPM's. The puffs of smoke could be anything from steam to unburnt fuel...

Since you've done all of the difficult diagnosing and fuel injection pump testing, why not pull the head? Everyone seems to have an opinion, some similar and some very defferent...I believe if you pull the head and check for a broken swirl chamber, cracked head, porus valve face or seats or a bad headgasket you'll most probably solve the problem. Obviously, and since the head on any diesel tractor is the first thing to come up to temperature--or overheat, the problems seem to originate from there.

I'm not 100% sure, but if it were my Yanmar, pulling the head would be the next step. And if I were wrong...I would at least have eliminated the valve train, piston tops, rings and gap clearance, head gasket and with a straight edge and feeler gauges, the possibility of warped deck or head. I keep coming back to this, especially since you peformed the remote tank to fuel injection pump experiment which did NOT change anything.

Just MHO and good luck.

Mark

 

[Underwaterdog]

I too have been following this thread daily. I almost told you once to pull your head (the one on the tractor ). I have seen head gaskets or heads expand after they get hot and open a crack. I think that a compression test would show enough variance in the cylinders even when it is not at full op temp that you would know there is a problem. That said, I went back and reread some of the previous post.
Post from jameswms:

Talley check your governor after putting my pump back on it was still shutting down so I had the guy from John Deere come by and he said its definatel the govenor, he put a spring and did something inside with pliers and it runs great now..

Even though he had the injector rebuilt it was still shutting down, and turned out to be an issue with the governor. Could it be that nothing was wrong with his injector pump to start with?
What MJP said about the injector leaking back makes the most sense to me. I wonder if they check for that when they test it. But it may not show up when cold. The injector could have a chip or a crack in it that expands as the engine heats up, thus allowing air to back flow into the lines, and would explain this, except I can't understand how the air would get all the way back to the fuel bowl:

I put a fuel can on my hood and ran a line straight down to the fitting on the bleeder valve on the injector pump. When the engine starts to kill, I open the bleeder valve and some fuel and air bubbles come out till the fuel runs clear then the engine picks up speed and runs better for a while then starts to kill again and I repeat the procedure.
It is impossible for air to get in the fuel line any kind of way with this setup.
The only conclusion that I can come to is that my injection pump is somehow bad and when it heats up it pumps some air backward into the fuel line.

If there was a shop close by that regularly worked on the yanmars then they would have plenty of spare parts and would have the ability to swap parts till they found the culprit, and may never know what actually caused the problem or what the failure mode was. You don't have that luxury. My suggestion is to take those injectors out. Look at the tips closely with a good magnifying glass. If you have a digital camera you can set it to the highest resolution and set it on macro for closeup, and take some pictures of them. Often times you can see things in a good picture that you can't see otherwise. I have been able to get model numbers off of tags before that I absolutely could not see any other way. If it is an injector, then it is probably just one, so you wouldn't have to buy an entire set. Good Luck!