Engine Warm Up/Cool Down

[gizmo]

I have seen a number of posts where folks state without hesitation or qualification that a tractor engine will last longer if allowed some kind of warm up and/or cool down period. My question is, does anyone know of objective data that indicates improved service life. I am not an engine expert, but I have never run across a case where someone pointed to an engine and said "...yep, no warm up or cool down killed that one." My gut feel is that it is good practice, and I do let my engine warm up a couple minutes before use. Less often, I give it a cool down period, but I think I do that just so I can sit there a little longer and view with satisfaction the work I just did.

 

[RalphVa]

I think tractor use is almost like car use. If you start a car and live next to an interstate and go right out there right up to interstate speed in really cold weather, you're not being good to the car/truck. However, most of us live where we can drive gently for the first few minutes before putting much stress on the engine and drivetrain. So, we just start, immediately drive out of the garage and drive down the road.

I do the same with my tractor. Think the main thing is to use a low vis or low initial vis of a multi vis oil in both the engine and transmission, particularly in the winter. Around here, for instance, JD recommends use of the low viscosity hydraulic oil; whereas, we're probably right on the border line of needing to use the higher vis stuff in our hot summers. The low vis is for protection in our (relatively) mild winters.

My oldest vehicle is my 23 year old Benz. It's still doing great. No warmups for it.

Ralph

 

[RobJ]

The cool downs probably come from diesels with a turbo, the idea is the oil can burn in the hot turbo if the engine is not allowed to cool down. I mostly agree with this. A diesel engine really produces little heat without a load on it. When I rebuilt diesels we would run them (and some new ones) on a water dyno to test them. On new engines you could run them for hours with no load and the paint wouldn't burn off the muffler. Load it and the paint would burn off in minutes. Why, exhaust temps going from 200 degrees to 900 degrees in 15-30 seconds. These were stationary units that were loaded all the time, pumps, genarators, etc. If you are bushhogging a nice field, FM a yard that was cut last week, you are not putting much of a load on a tractor. Drop a disc behind it in some sandy loam and now you are talking about a load. But in the time you mosey back to the pick up truck the exhausts temps and the engine is about as cool as it'll get because the thermostat is keeping it at a constant level (it's job). So your cool down is complete.

With that in mind... I've always said the warm up is more important than the cool down. An engine works better and will last longer at working temps.

 

[Soundguy]

My take is turbo charger and hydraulics.

My Nh 7610s has a big warning plaque on the dash telling you to not use over half throttle for 5 minutes so that all hyd components can come up to temperature, and that after operating at full load, you must idle down for at least 1 minute to protect engine components.

My take on this is that oil can be thick when cold. This makes me think pumps may cavitate more, or reliefs may have to lift due to that oil not being warmed up in the hyd circuit. On some heavy equipment we have, that have large torque converters, you have to manually kick the torque converters out with a foot switch before starting or the auto trans on the engine is such a load it will cause hard starting ( road graders ).

As for the engine.. sounds like turbo issues.. like cokeing. i lost a turbo on a car before due to that. It was when i was younger and knew more. Never let it cool down.. just zoomed up and stopped. That oil int he turbo bearings burns if the turbo doesn't cool down.

Soundguy

 

[KiotiJohn]

I don't have anything but subjective data where a non-turbo is concerned, but I do remember learing some years ago that without a cool down first, temps tend to spike up a little when an engine is first shut off due to a lack of the cooling that occurs while the coolant is flowing, then cools down after that.

I don't know how that would equate to longevity, but I've always warmed up and cooled down. The major reason I warm up even beyond any first-start smoke is to warm the hydro fluid in cold weather. I don't want a thicker viscosity on start up running through my pump and valves.

I'm sure I'll always believe that shutting down after cooling a bit is a good practice just because I feel that less heat has to be better for the components after there no longer a cooling flow.
John

 

[browns40]

Hi gizmo,

Guy I used to fish for said warm-up was to build compression, and cool-down to let engine cool...

Don't know if it's accurate, or if it has to do with ring expansion, oil viscosity, block temperature... hey, I'm not an engineer--I don't design engines! /forums/images/graemlins/frown.gif

His other business was construction, so diesel was what he worked with...

I figure it doesn't hurt them to let them warm up a while longer, and it doesn't hurt them to let them cool down a while longer, so I follow old-timer's advice--grease fittings while it warms up... walk-around, inspect for damage & clean-up before shutting it down...

Unless you have a fire, wedding, funeral, school play to get to, an extra 3-5 minutes on the front & back of operating isn't going to kill you, and can only do your machine good for the TLC that routine gives it.

Just my .02! /forums/images/graemlins/grin.gif