M6800 Spongy Engine Valve Springs

AD4GC

New member

Equipment
M6800
May 17, 2015
7
0
0
Bee Lick, Ky
I have a late model, not sure of the year, M6800 with V3300-E6 engine, the engine has just a touch over 3,000 hours. I bought it used, in good shape. The problem I'm trying to figure out is that it has a loose valve lash "smack" and almost a knock sound when running. I removed the valve cover to make sure there wasn't a VERY loose valve rocker, which all appear to close to the same. I am going to adjust the valves anyways just to be sure as soon as the service manual arrives. But what I did find has me confused and concerned, all the exhaust valve springs are very spongy. By spongy I mean I can compress the exhaust valve about halfway open with one finger and maybe 5lbs of pressure. I've been a mechanic for years and have never seen anything like this. Is this normal for Kubota or do I have a problem?
 

Jim L.

Active member
Jun 18, 2014
855
158
43
Texas
Thinking that you already know the answer.

The WSM will give you the valve spring setting load. It is probably twice what you have now. You would need to compress a given distance and measure the pressure to compress. Sounds like you could skip that step and put in new springs.
 

North Idaho Wolfman

Moderator
Staff member
Lifetime Member

Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
30,577
6,619
113
Sandpoint, ID
I have found that the valve springs in a Kubota diesel are very soft compared to most other engines.
I would say you might need to test them if you think they are too soft, with that many hours, it might be in your best interest just to have the whole head rebuilt. ;)
 

AD4GC

New member

Equipment
M6800
May 17, 2015
7
0
0
Bee Lick, Ky
Thanks guys. I just learned a little bit ago from my father-in-law that there is a guy just out the road from me that retired from our local Kubota dealer where he was a mechanic for 30 years. Anyways, the pappy-in-law knows him quite well and stopped at this guys home shop, long story short, this guy is supposed to come out to my place later in the week to look the tractor over and show me the process to adjust the valves and check for abnormal wear in the valve train. Talk about luck, I feel like I just hit the lottery, maybe I need to buy a ticket! Thanks again, my name is Greg and brand new to OTT, nice to meet ya!