Engine running rougher when warm - TN75F

   / Engine running rougher when warm - TN75F #1  

svcguy

Gold Member
Joined
May 30, 2005
Messages
362
Location
West Kootenays, British Columbia
Tractor
Yanmar YM240D / Massey Ferguson 135 / New Holland TN75F / Pasquali 988 and 997 / Goldoni 20A, 226 and Maxter 70RS / Ferrari 76 and 85 / Holder A50 / Valpadana VMC 180 / Long 610 4WD
I have found that my TN75F starts and runs beautifully when cold. Once warmed up and operating, it starts to run rough at about 1500 rpms and up. I have checked the valves and all are within specs. At low rpm it is perfectly smooth. When under load, it is always smooth, but if no load or really light loads @ 1500 and more - it runs rough. I am thinking perhaps injection pump timing?
 
   / Engine running rougher when warm - TN75F #2  
It probably is timing. It's fine when cold, so the base timing is ok. I'd bet the cold advance isn't working. It could be a wax motor that heats up whe 12 volts is supplied, or a solenoid that's wired to a temp switch. Both styles are used on these engines.
 
   / Engine running rougher when warm - TN75F
  • Thread Starter
#3  
Thanks, wasn't familiar with that, I will take a look.
 

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