155D Starting Problems

[N8-126]

I searched the forum and couldn't find this problem described before, so I hope that I am not posting a redundant question.

I rebuilt my YM155D last year and everything seems good (except for a rear main leak, which I will deal with next winter). Each time I go out to use it , it is harder to start than the last time. Once its warm it starts easier, but not as easy as it used to. I noticed a little diesel leaking around the banjo fitting at the injector pump so I am replacing both copper washers tonight. I also checked the fuel injector and return lines. They both seem okay, although the rear (number 1 cylinder) injector is not as strong as the front injector.

Question-what is the probability that the small leak on the low pressure side of the injector pump would cause it to start hard. By hard starting, I mean it turns over for a good 30 seconds before starting and then acts as though its only getting just enough fuel to survive. Then after 5 or 10 seconds of rough running, it ramps up and runs like a champ.

 

[HoyeTractor]

Question-what is the probability that the small leak on the low pressure side of the injector pump would cause it to start hard.

Diesels dont like air in the fuel system. A leak on the low pressure may possibly allow air to get into the system under just the right conditions. Air in the fuel lines can cause it to do what you are describing. Normally there would be a little bit of pressure on the lines though since the Yanmar's tank is higher than the pump. Air should not be able to get in.

the rear (number 1 cylinder) injector is not as strong as the front injector.

I might be leaning more towards the pump or injector.

Aaron
Hoye Tractor Parts
(940)592-0181
Contact Us

 

[N8-126]

Thanks, I will try replacing the copper washers and give it another go. If that doesn't work, my next thought was rechecking the timing for the pump. Does Hoye sell the shims if I need to buy some more?

 

[HoyeTractor]

Yes, we should have them but, unless you suspect that the correct number of shims were not re-installed, you should never need to mess with the fuel pump timing.

Aaron
Hoye Tractor Parts
(940)592-0181
Contact Us

 

[N8-126]

The reason I am suspect the timing is that I put the original number of shims in (without checking the timing). But I replaced just about everything in the engine (except the crank). I didn't get time to work on it last night so hopefully, I will get it up and running tonight and provide an update.

 

[204saskman]

Does the 155D have a glow plug or anything like that??? I find mine very hard starting also. Its only got 690hrs on it and i dont think its injectors or a pump but im not to sure. It starts fine when its warm but once it gets cold out its a royal PITA to get it going. I just bought the tractor last year and havent had any major issues with it but id like it to start easier.

Thanks

Kiel

 

[N8-126]

Saskman, have you tried to bleed all the fuel lines. Mine only has 15 hours on it since the rebuild, but it was over 4200 hours prior that. It sounds like you have the same basic tractor, including factory loader.

Over the years I have had to bleed the fuel lines for a multitude of reasons. Last year, the o-rings in the fuel filter went bad causing it to take on air. Before you spend any money, bleed everything starting at the tank. Attached is video that Tractorbynet member DieselFuelOnly created. He has a different Yanmar, but the setup is nearly identical to the 155D. And no-there are no gloplugs on the 155

YouTube - HOWTO: Bleeding air out of a small Yanmar diesel

 

[204saskman]

Cool. Ill give it a try and go from there. I bought it off the original owner and he said it never rolled over on the hour meter. I like the tractor alot and runs all of the attachments i currently own. It struggles sometimes, but thats what low range is for. Ill try bleeding everything and go from there.

 

[N8-126]

I replaced the copper washers and it did help-but the problem didn't go away it just got a little easier to start. But as they say "no good deed goes unpunished", while trying to bleed the fuel filter I noticed a little fuel around the threads of the nut that holds on the bowl. I tried to give a little tighten and it popped right off. After 20-minutes of messing with it I came to the conclusion that either the threads on the body are too small or the nut is too big.

Does anyone know where I could buy just the nut for the filter. I purchased the assembly from Hoye Tractor over the winter. Its not Hoye's fault, I should have paid better attention when I put it on. It just sucks that as I try to chase down one problem, others keep jumping out in front of me.

 

[N8-126]

Okay, I am in need of help. I replaced the fuel filter assembly, copper washers and checked the timing. I also checked each injector spray pattern and cleaned the injector pump mechanisms. Everything checked out, but it still has difficulty starting. So, I tried to trouble shoot the injectors by loosening the line to each injector while the tractor was running to see if one caused it to die out more than the other-no luck.

When it starts, it runs on one cylinder for a few seconds before the other cylinder kicks into full force. I acts as though the pressure and fuel is draining out of the injectors, but more so from one than the other. Does anyone know how the fuel pump restricts backflow of fuel. I think the injectors are bad, however it could also be a check valve in the fuel pumps if there is such a thing.

 

[justkisssthis001]

asfar asi can figure out the fulepump might need rebuile . with all the changes in fule to lower and lower sulfer it has a bit of a drying out seal problem and that might be your problem

 

[N8-126]

Everyone sit down and hold on, the problem will knock you out of your seat. Before I explain what was wrong, I need to add some more details to the history of the engine. When I rebuilt the YM155 last winter, I sent the head out to have it checked for cracks and to have the valves seats remachined. I handed over the head with new valves and springs in a box and asked the machine shop to put the new ones in after machining the seats.

When I ran out of other options, I ordered new injectors from Hoye. I figured after 30 years it couldn't hurt to replace them. When they arrived I took out the old and noticed that what I saw inside the injector hole did not look like the pictures on Hoye's website. So after a couple of conversations with Sam (parts guy at Hoye) we realized that the upper injector chamber was installed backwards. I flipped them around, put new insulators and injectors in and she is good as new (I think). Appearently, during part of the inspection or machining process the machine shop removed the injectors and injector chambers and put them in backwards.

How the tractor even ran is beyond me. With the upper chamber in backwards, it effectively had 2 separate injector chambers that were separated by the 3/8" hole that is normally the oriface for the injector spray.

Absolutely amazing. Lesson learned--If you own it, it is your responsibility to check everyone's work. Even a reputable diesel engine machine shop.

 

[204saskman]

good to here man. I might do mine once the hour meter hits zero again. Only 300 more hours now and well i guess i rebuild itl.

 

[N8-126]

I think this is what they call a saga. I was incorrect when I stated that "she is good a new". Basically, I fooled myself by having just reassembled everything and bleed all the fuel lines. After an hour or two of sitting, she was once again back to her old hard to start self.

I can, with almost 2 weeks of use, attest that now everything is fixed. The basic deal is that if you do a complete engine rebuilt, get your injector pump rebuilt and put in new injectors. After all the confusion, I found a company in Toledo that speciallizes in Yanmar (and other) injectors and injector pumps. What I learned from them is that my story is not that unusual. If the pump and injectors are worn, they can't overcome the cylinder pressure on the upstroke to get the tractor started. Before the rebuild, the rings and sleeves are also worn so the cylinder pressure is reduced (on my tractor this was obvious by the blow-by). As long as both are worn out, no problem. If only the pump and injectors are worn-no starting.

I also wanted to thank everyone on this site. After getting the pump rebuilt, I needed a new timing pin. Several people helped me with photos so that I could make a new one. I also wanted to acknowledge 1danny (http://www.tractorbynet.com/forums/members/1danny.html)-he seems like a good guy with great customer service.

 

[swedish-fish]

So, what was the cost of new injectors and having the injector pump rebuilt? I've noticed my oil pressure light takes longer to turn off (about 6-7 seconds at 1500 rpm) and it starts a bit harder. There is no black smoke except when starting and under a heavy load.

I've never checked compression. What exactly is involved in an engine and injector pump rebuild?

My hour meter shows 850 hrs and the previous owner says it never rolled over.

 

[6thgpSF]

I had my injectors rebuilt on my 1610D at a 100 bucks apiece .thats with labor.one of them was dumping too much fuel and bent a valve. russ

 

[Raw Dodge]

I have a 3tn84 in my dixie chopper lawn mower. Its had low power all season,its an 05 model.Ive done all the basics,new fuel filter,new transfer pump,fuel pressure checks,repalced air filter,I check the wastegate in the turbo,checked for intake(boost leaks),checked muffler for restrictions.It starts and runs perfectly,however it used to be an animal,its 41.4HP,you could cut a hay field with it before.Now it feels like about 30hp.I also checked RPM,its running at the correct speed(3000 RPM hi idle).There is no blowby out the tube,the engine is tight,ive owned it since new,only 500 hrs on it,and ive changed the air filter/fuel filter oil/filter religously every 100 hrs,after changing it at 25 hrs when new,and again at 75 hrs.
I think the issue lies in the injection pump,as it NEVER smokes,not even a wisp,even under load if i bog it intentionally,it doesnt smoke.Every diesel ive owned would smoke if i lugged it.
My dixie chopper dealer here is stumped,say hes never seen a single problem with the yanmars,no one local knows anything about it.Im thinking the guy in ohio may be able to help me,with winter approaching i can pull the pump and send it out if needed,and afford the down time.I'd like to get back the power it once had.I will be doing an oil sample at the end of this season when i drain this oil out,to rule out an engine problem,but having owned it since day one,Im pretty sure the engine itself is strong.N8-126 if you could pm me with the number of the guy who helped you id appreciate it.

 

[N8-126]

The injectors were ~$80 a piece (new) through Hoye. I opted to buy new ones because my neighboor had his rebuilt and it cost him $75 a piece. The pump was rebuilt by International Fuel Systems (www.ifsinternational.com)-ask for Jim. The rebuild cost me about $300, but I don't think that is a fair comparison. My YM155 was used all the time. We had over 3000 hours on it and the injector pump had never been touched. IFS said that they usually only need to replace a few key parts and a typical rebuild is between $100 and $200.

IFS treated me fair and seemed to know what they were talking about. They will take the whole tractor/mower or if you want to remove the parts, they will just fix the parts and mail them back to you.