403 compression

mmkid · Aug 2, 2016

Hi I have a 403 in a uts and lately it has not had the amount of get up and go that it seemed to used to have. I did a compression test and cylinders 1&3 had 140 lbs, and 2 and 4 had 120. Are those numbers in the range of what it should be? Thanks

mmfan55 · Aug 2, 2016

Moline compression varies with the head used. Your numbers sounds like maybe the 4209 or Ge 30 E. You can search the internet and find a site for "Minneapolis Moline head specification chart." The difference you see could be as simple as a valve adjustment needed. The head chart will tell you if you're compression is line for that head.

mmkid · Aug 2, 2016

I have 10a4210's

mmfan55 · Aug 3, 2016

Compression a bit low for that head. Maybe try another tester, first. I have 3 testers and will get different readings on all 3. Not a lot but different. May just need valves adjusted. Also: are you taking your readings cold engine or hot ? Readings will be less cold. Squirt a little oil in cylinder and test again. If compression raises a good amount with the oil, rings are allowing compression to get by. Also should have a good bit of "blowby " if rings are weak. Hope this helps.

403 compression

mmkid

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