On our 78A xxxx D4D dozer, equipped with direct drive & a wet clutch, the clutch drags when starting the engine up when very cold out, to the point that the tracks turn a bit, making the starter really labor a lot & today I could not get it going as a result of it dragging. Even with both the clutch disengaged, the main trans & the shuttle both in neutral, it still drags bad. I have also noticed when very cold out, soon after start-up, the clutch really "snaps out" when disengaged. I think we may have 30 wt. oil in the wet clutch. Should it be 10 wt in colder weather, or even year around? We have been experiencing unusually cold weather here as of late. When warmed up, all works fine & operates normal.
You should be using SAE 30 above 32 deg.F and SAE 10W below 32 deg. F down to -10 deg. F. Below -10 deg. F it is recommended to dilute the oil with kerosene in both the engine and the oil clutch. Some clutch drag is to be expected.
Will this cause the drag mentioned above when the heavier viscosity?
Yes, the higher the viscosity, the more the drag.
Ok, thanks OM.
We drained the #30 & replaced with #10 oil in the clutch & hope that takes care of the problem.