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#1 HBrianW

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Posted 24 July 2012 - 10:42 AM

Good day all, I have a UD 525 engine I am attempting to put back into service as a small sawmill power plant. After many drawbacks I now have it running on gas and diesel, but it smokes from the rear exhaust pipe when running on diesel. Found a carbon obstruction between the head and "low compression" valve, and cleared that, but it still does the same. Runs perfect on gas, and doesn't really run that bad on diesel but it has the white smoke/smell of diesel when set to run there. So...what is my best direction from here? I do not have many custom tools, but have been an auto tech for 30+ years, how to test for compression or for a bad injector nozzle? Any likely or popular problems? Thanx for any input.
Brian, Deer Island Oregon

#2 Owen Aaland

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Posted 24 July 2012 - 04:41 PM

You may have a damaged starting valve. Check it by removing that spark plug and see if you have any compression leaking out while running in diesel mode.

#3 M Diesel

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Posted 24 July 2012 - 05:39 PM

Zactly. Spring pressure is only 25 lbs so they tend to stick kinda easy.

There are more items in waiting but first things first.
Gary M
1951 M -- 1951 MD
1953 Super C -- 1957 Farmall 450
1953 TD9 "Ichabod JR" aka "Icky"
1949 TD18 "Brutus" -- 1956 TD18-182 "Yard Dog"
1964 Loadstar 1600 -- 1975 Loadstar 1700 dump truck
1949 Massey 44

#4 HBrianW

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Posted 26 July 2012 - 09:28 AM

Thanx guys, "starting valve" is what I refer to as "low compression" valve, had one held open but had cleared it; rechecked, all are closed. Really thought I had it when I found that, but oh well. Gonna determine which cylinder it is this weekend, will write in here again if/when I get somewhere with it. Understanding the obvious (cleanliness, organization, etc.) of it, is there anything technical about removing an injector nozzle for inspection/teardown/cleaning? I have confidence in doing it, but not in getting repair parts when needed. My manual doesn't have the best info, and lousy pics. Thank you for any help.

#5 M Diesel

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Posted 26 July 2012 - 03:18 PM

Injectors are easy to take apart other than setting the break pressure when putting it back together. Parts are entirely different matter. The copper rings can be annealed soft again if needed, but in the recent past I was told they were available at IH.

You are probably aware, but that engine is a 6 cylinder version of the D350 in the 9 series tractors. Binderbooks.com has the injection pump service and parts books in good quality for a decent price.
Gary M
1951 M -- 1951 MD
1953 Super C -- 1957 Farmall 450
1953 TD9 "Ichabod JR" aka "Icky"
1949 TD18 "Brutus" -- 1956 TD18-182 "Yard Dog"
1964 Loadstar 1600 -- 1975 Loadstar 1700 dump truck
1949 Massey 44

#6 HBrianW

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Posted 06 August 2012 - 10:00 AM

Well, I found I have 2 smoky cylinders, #'s 4 and 6. 4 will clear up some if I let it idle for 15 minutes or so, 6 will hit and miss, mostly miss. It does still add poweer to the engine, as I hear an rpm drop when I open the nozzle bleeder. I dis/re-assembled the #6 injector (went well I thought), no change. The problem is much worse when I try to run the rpm up, with it even starting to "pop" out the exhaust pipe. Both cylinders smoke plenty when at higher speed. I'm beginning to think I may have a sticking valve, but it runs so well on gas.
I do not know if it makes a difference, or if I made my own problem by doing it but I have installed an electric fuel pump to bypass the unuseable mechanical one. I used the body of the old pump and blocked off the fuels capability to get anywhere except for one hole that goes into the body of the injector pump; I found no use for that passage but felt it better to leave it open.
Another set back, all okay. Thanx on the info on Binder Books, there's one a little ways away I better go visit. I guess I better read up on that pump. I'll monkey with this thing again, get a note back if I do get it figured out. I will look here for comments as well, please do write with any advise you can share.

#7 M Diesel

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Posted 06 August 2012 - 12:52 PM

Which pump do you have? Plain, "A" or "IH"?

The little hole basically supplied pressure to open the scavenger pump valve. It serves no purpose in your case but if not an "IH" (that means a B pump in the books) then the primary pump also serves to empty the main injection pump leaky bits that drain into the case. It must be dealt with.
Gary M
1951 M -- 1951 MD
1953 Super C -- 1957 Farmall 450
1953 TD9 "Ichabod JR" aka "Icky"
1949 TD18 "Brutus" -- 1956 TD18-182 "Yard Dog"
1964 Loadstar 1600 -- 1975 Loadstar 1700 dump truck
1949 Massey 44

#8 HBrianW

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Posted 07 August 2012 - 10:18 AM

Well, I got some numbers from the tag, top line says International (logo) Harvester; second line Chicago Illinois USA; third line has a"B" in a stamping area, then the next stamping no270; after that Is what I believe to be a "1" (it may be a deep scratch) 64R91; 4th and last line in a stamping area Serial 3234. By "stamping area" I mean a space on the tag that is apparently meant for a number to be stamped there. There is also a large IH logo on the cast top section of the pump unit.
To add to my previous post, I should say I left the port for that orifice open and connected to my fuel return line; figured if any came out it could run back to the tank, and I could see no way pressurized fuel should have gotten there. But my figuring has been wrong before, lol. Are these numbers indicative of which unit it is?

#9 M Diesel

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Posted 07 August 2012 - 01:00 PM

You definitely have a B pump. Should not be an issue.

Part number is 6 digits, starting with 270, so 270164R91 makes sense. Yes it tells you how the pump is configured. The governor weights, springs and plunger are all detailed by that. You also do the various adjustments according to it as well.

270164R91 is listed for the UD525/UD554 under special applications and is set up for 1395 RPM, 5% regulation.
Gary M
1951 M -- 1951 MD
1953 Super C -- 1957 Farmall 450
1953 TD9 "Ichabod JR" aka "Icky"
1949 TD18 "Brutus" -- 1956 TD18-182 "Yard Dog"
1964 Loadstar 1600 -- 1975 Loadstar 1700 dump truck
1949 Massey 44

#10 HBrianW

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Posted 07 August 2012 - 01:55 PM

Thanx for your help! I believe the smoking is a cylinder issue, but any info is greatly appreciated. Hope to have better news soon.



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