751 injectors removal and cleaning

[38bill]

Hi all, I have a 1996 Bobcat 751 that I bought new (the Kubota engine was $2000 more than the PUG so it seemed like the way to go at the time). The machine has been used mostly for snow removal and it only has about 450 hours on it since new. A couple of years ago it started to get a little harder to start. It turns over and will start and stumble and when it fires it sounds like it is missing on one cyl. Once it warms up and I rev it up it catches and runs just fine (reminds me alot of a two stroke outboard I had). I am guessing its just a dirty injector and I have tried adding cleaners to the fuel but that hasnt really done the job. I tried searching the forum and I see some posts mentioning that they had removed the injectors. Can you tell me how to pull the injectors and service them or can I pull them and send them out for service? Thanks.

 

[Tazza]

I'd start by checking the glow plugs. If it starts hard then gets better when it gets the revs up and gives off white smoke while doing so, its probably a bad glow plug.
Removing injectors is simple, remove the high pressure lines and remove the banjo fittings for the tap off lines and simple un-screw the injectors. Its not at all difficult.
As for servicing them, its not something you can really do. To do the job right, you need to send them to an injector shop to get them cleaned and calibrated.
Start with the glow plugs, they are easy to remove, they are in the top of the head near the injectors. Use say a battery cable, hold the hex of the glow plug with the clip, put the other end on the battery, rest the threaded part on the other terminal. The plug should glow right to the tip. Careful not to burn your self, the whole plug does get warm.

 

[bobbie-g]

I'd start by checking the glow plugs. If it starts hard then gets better when it gets the revs up and gives off white smoke while doing so, its probably a bad glow plug.
Removing injectors is simple, remove the high pressure lines and remove the banjo fittings for the tap off lines and simple un-screw the injectors. Its not at all difficult.
As for servicing them, its not something you can really do. To do the job right, you need to send them to an injector shop to get them cleaned and calibrated.
Start with the glow plugs, they are easy to remove, they are in the top of the head near the injectors. Use say a battery cable, hold the hex of the glow plug with the clip, put the other end on the battery, rest the threaded part on the other terminal. The plug should glow right to the tip. Careful not to burn your self, the whole plug does get warm.

The glow-plugs seem more likely to be causing your problem (maybe because they cost less!). I've swapped out a set a couple of times. Replacement is simple with a 12mm deep socket. I had to remove one injector line to access one of the plugs, but it was simple. I did not bleed that injector line after replacement, and it started right up. I won't argue with our esteemed Down-Under Moderator Tazza, but I only messed with testing one once, and I wasn't convinced that it was good, even thought I thought it glowed just fine. I just put in a new set and it started much better at lower temps. Bad news: Bobcat wants $36 each, last I checked. The original part number Bosch 0 250 201 019, has been replaced with Bosch 0 250 201 039, per the Bosch USA techie. Autozone used to sell these for $9 ea, but their stock number 80006 was discontinued. Shucks. Good news: as of 01/08, you could buy the gen-u-ine Bosch item for about $10 ea from JT Outfitters on line. Be sure you specify only the Bosch part. I got some from them that were supposed to be equivalent, but I didn't think they worked as well as the Bosch. Another note: The Bosch techie said they should reach max glow in 4 seconds, and they were OK to be left on for 3 minutes. I measure about 17 amps going into each one. OK, that's all you wanted to know and then some about Pug glow plugs. My Pug engine has 2100 hrs on it and is running fine. While I wish it were a Kubota, I really don't have any complaints about the Pug, except for the lack of parts sources other than Bobcat. One day, they'll quit carrying parts for it. Then we're sunk.... ---RC

 

[Tazza]

The glow-plugs seem more likely to be causing your problem (maybe because they cost less!). I've swapped out a set a couple of times. Replacement is simple with a 12mm deep socket. I had to remove one injector line to access one of the plugs, but it was simple. I did not bleed that injector line after replacement, and it started right up. I won't argue with our esteemed Down-Under Moderator Tazza, but I only messed with testing one once, and I wasn't convinced that it was good, even thought I thought it glowed just fine. I just put in a new set and it started much better at lower temps. Bad news: Bobcat wants $36 each, last I checked. The original part number Bosch 0 250 201 019, has been replaced with Bosch 0 250 201 039, per the Bosch USA techie. Autozone used to sell these for $9 ea, but their stock number 80006 was discontinued. Shucks. Good news: as of 01/08, you could buy the gen-u-ine Bosch item for about $10 ea from JT Outfitters on line. Be sure you specify only the Bosch part. I got some from them that were supposed to be equivalent, but I didn't think they worked as well as the Bosch. Another note: The Bosch techie said they should reach max glow in 4 seconds, and they were OK to be left on for 3 minutes. I measure about 17 amps going into each one. OK, that's all you wanted to know and then some about Pug glow plugs. My Pug engine has 2100 hrs on it and is running fine. While I wish it were a Kubota, I really don't have any complaints about the Pug, except for the lack of parts sources other than Bobcat. One day, they'll quit carrying parts for it. Then we're sunk.... ---RC

You'r more than welcome to argue with me Thats about what i paid for mine too, even going to a Kubota dealer you could get a better price.
I couldn't fault my Pug engine either, it had about 5,000 hours and still started and ran great.

 

[38bill]

You'r more than welcome to argue with me Thats about what i paid for mine too, even going to a Kubota dealer you could get a better price.
I couldn't fault my Pug engine either, it had about 5,000 hours and still started and ran great.

I assume that there is not any way to check the glow plugs without just looking for a good, bright glow? I checked and I have continuity through them all.

 

[38bill]

I assume that there is not any way to check the glow plugs without just looking for a good, bright glow? I checked and I have continuity through them all.

I googled the Bosch 250 201 039 and part #80006 and found a ton of places that sell them anywere from $7 on up. For that kind of money I am going to just replace them and see if that makes the difference. I'll let you know how it works out. Thanks.

 

[bobbie-g]

I googled the Bosch 250 201 039 and part #80006 and found a ton of places that sell them anywere from $7 on up. For that kind of money I am going to just replace them and see if that makes the difference. I'll let you know how it works out. Thanks.

38bill, good that you'll post the outcome. That's what makes the forum so valuable. Last time I tried to get the Autozone 80009, they offered a replacement part which was vastly different physically. Too large to even thread in the hole, so something was messed up in their system. Just a word of caution. ---RC

 

[Fishfiles]

38bill, good that you'll post the outcome. That's what makes the forum so valuable. Last time I tried to get the Autozone 80009, they offered a replacement part which was vastly different physically. Too large to even thread in the hole, so something was messed up in their system. Just a word of caution. ---RC

Just a thought , since you plan on taking out the glow plugs , it would be a good idea to do a compression test while they are out , if you don't have the adaptor to go into the glow plug hole , then you can make one easily with one of the old glow plugs by cutting the plug and brazing or tig or mig welding a threaded coupler to it and attaching a compression gauge

 

[38bill]

Just a thought , since you plan on taking out the glow plugs , it would be a good idea to do a compression test while they are out , if you don't have the adaptor to go into the glow plug hole , then you can make one easily with one of the old glow plugs by cutting the plug and brazing or tig or mig welding a threaded coupler to it and attaching a compression gauge

I just pulled all the glow plugs and one of them was stone cold dead. Of course it was the hardest to get at (under the fuel lines). Picking up a new Bosch at the closest NAPA today for $12 to replace it and then I will order 3 more to do the others later. It also looked like the wires to the glow plugs were slightly corroded (after only 14 years) so I am cleaning those up so I get full power to the plugs. I'm guessing thats all that was wrong with it but I will post back once its up and running again. Thanks for the help.

 

[Tazza]

I just pulled all the glow plugs and one of them was stone cold dead. Of course it was the hardest to get at (under the fuel lines). Picking up a new Bosch at the closest NAPA today for $12 to replace it and then I will order 3 more to do the others later. It also looked like the wires to the glow plugs were slightly corroded (after only 14 years) so I am cleaning those up so I get full power to the plugs. I'm guessing thats all that was wrong with it but I will post back once its up and running again. Thanks for the help.

If one was dead, thats your problem! it will eventually fire when the engine is spinning fast enough for the compression to create the heat to detonate the fuel in that cylinder.

 

[38bill]

If one was dead, thats your problem! it will eventually fire when the engine is spinning fast enough for the compression to create the heat to detonate the fuel in that cylinder.

It was only in the 20's (deg F) this morning and I replaced the bad glow plug. Turned the key, held it til the light went off and the Pug fired up just like new. Thanks alot everybody, without your help the $12 fix could have ended up costing me big bucks at a dealer.

 

[jerry]

It was only in the 20's (deg F) this morning and I replaced the bad glow plug. Turned the key, held it til the light went off and the Pug fired up just like new. Thanks alot everybody, without your help the $12 fix could have ended up costing me big bucks at a dealer.

38bill sometime when you don't have too much to do can you post a picture of that woodsplitter? sounds interesting. thanks.