How long do you let her "warm up"?

[Glowplug]

My rule of thumb for my vehicles is to let the temp gauge begin to register. Usually about 3 min. during summer and 5 during winter.

That's kinda what I do indirectly. By the time I've done my little walk-around inspection, topping the fuel, etc. I check the temperature gauge and it has begun to nudge a little upward. At that point I feel like it's safe to go.

My tractor takes forever to register... so the old 3-5 minute rule is roughly what I use for it.

I'm sure that's the bigger volume of oil to heat.

I'll just keep warming up my equipment.... maybe it doesn't make that much difference... but it sure makes me feel better.

Ditto and amen!!

 

[chrisjbell]

I'll just keep warming up my equipment.... maybe it doesn't make that much difference... but it sure makes me feel better.

...and I don't think that I've seen anyone come up with a reason not to do it. (OK, fuel usage and emissions but my tractor is more important )

 

[RobJ]

Not to be difficult...is this much different that driving before the car is warm? Is there something specific to Diesels? I keep it in the un-heated garage that happens to not get under 45 degrees, but I don't take a HUGE amount of care to make sure she's "up to temp".

You are not allowed to bring common sense into this topic. 5 points taken off your final.

 

[RobJ]

I suppose you wanted some specific explanation.

I don’t know much about engines or the specifics of the mechanics of diesel engines but I have my own explanation as to why warming up a diesel is important. Most everyone knows the combustion chamber is different in diesels than in standard gasoline engines. There is no sparkplug in a diesel. The ignition of the fuel is basically done from the heat of the engine and is a self-perpetuating process. So, as the engine gets warmer the whole fuel burning process gets better and easier for the tractor. Also cars don’t have the same hydraulic set-up like tractors do. Getting the engine oil in the crankcase warm is one thing. But the hydraulic oil is the tractor’s “life blood”. It controls and lubricates many parts at the same time. It’s even more important in a hydrostatic transmission. There the oil is not only the lubricant but an integral part in the function of the transmission itself. Hydrostatic transmissions are not like automobile automatic transmissions. They are basically a fancy hydraulic circuit. They are a closed-loop hydraulically powered motor with variable speed. And everyone knows how important the oil is to hydraulics.

No matter what type of vehicle you’re talking about the oil will settle and cool and not be protecting the parts when the vehicle is sitting at rest. You really don’t want all that cold dry metal rubbing against other cold dry metal at a high speed before it’s had a chance to be coated in warm lubricating oil. Unlike automobile combustion chambers many diesels have very “tight” engines. This means that the space between the cylinder and the engine block is almost non-existent. It’s metal on metal. When first started you have cold metal once again contacting cold dry non-lubricated metal. As the engine warms the parts are not only coated in warm lubricating oil but they expand somewhat, thus creating more space between the metal contact points and thus less metal on metal contact. Oil’s viscosity changes in relation to the temperature. This viscosity-temperature relationship is called the viscosity-index and is a standard measurement. Interestingly, this viscosity index is measured between the temperatures of 104F and 212F, which is considered “operating” temperature for oils. If 104F is considered the minimal “normal” operating temperature for oil then why would you go tearing across the field putting excessive stress and load on the engine parts when the engine oil is obviously very much below that temperature? Much of the reasons for warming up an engine apply to both an automobile and a tractor. But a diesel IS different and thus more important to warm up first. I suppose that’s the reason that many truckers will leave their rig running often for hours as opposed to turning it off and restarting it.

I don’t know much about the topic. Heck, truthfully it may be better to not do a warm up. Perhaps some of the other guys with more mechanical engineering and fluids knowledge know better and can explain. But the information above is all I’ve got in my tiny brain and that’s the reason I warm up my tractor for about 10 minutes before doing any serious work.

So doesn't a car have a transmission? That's hydraulic. Plus it operates at higher rpms, greater speeds.

Most people don't sit in a car for 10 minutes when it's 50 degrees outside. In cold cold weather I can see some warmup, but in sub temps the engine just trying to say warm itself. the thermostat is probably working hard opening and closing as the rush of cold water comes on.

And there is no difference between diesel and gas. That's why glow plugs are used for starting, after a few seconds of running things heat up around the combustion chanber quickly to warm the air.

the warm up is all about metals, heat them to where they stop expanding and everyone is happier.

Fluids are also important. But in my geared tractor the ONLY thing that will head the gear oil while sitting is the oil being forced into a smaller pipe at the pimp and bypass.

I usually just let mine rip after a minute or 2 or after driving to my place or work. But my temps are a lot warmer down south.

Good Luck,
Rob

 

[Glowplug]

So doesn't a car have a transmission? That's hydraulic. Plus it operates at higher rpms, greater speeds.

Good Luck,
Rob

Hydrostatic transmission does not equal automatic transmission. True they both transmit power by oil but they are totally different. A HST is a variable displacement hydraulic pump that drives a hydraulically powered motor. I understand the very basics but I'm no expert on the differences. Maybe some of the true techie engineers can explain the difference.

 

[StrangeRanger]

Jeez... I sparked an actual discussion.

I'm very familiar w/ gas vs diesel engines, that was not the basis of my original question. I've worked on enough of both to know. But two things prompted my OP (original post). 1.) The recommended warm up times in the manual and 2.) my at the time lack of tractor hydrolics knowledge. Of which I've done considerable reading.

Diesel engines do generally have tighter tolerances than gas engines, hence the need to be nice to them until the metals and oil warm up. This will help reduce wear and tear on engine parts.

But it's the hydro system that really needs care. Even with synthetic oils when you live in a cold climate like me it's important for a number of reasons to allow the hydro oil to warm up. Apparently when your hydro oil is cold/less viscous there are much higher risks of damaging pumps and seals in the system. And especially HST trannys.

So for me, when it's cold, I'll waste a buck or two of fuel and let it sit and run, gently moving the FEL and 3pth for quite a while.

I don't see it as wasting a little fuel money or polluting a little (that's what ULSD is for right? ), I see it as greatly extending the life of my investment and not having to come up w/ $$$ for repairs.
j

 

[dynasim]

While I am no expert, I am reasonably sure that the absolute HST temperature is not critical(except for choosing the HST oil, and preventing oil breakdown). An Alaskan HST is going to run 100 F colder than a Floridian HST, and the manufacturers don't have a mechansim for controlling the HST temperature. In colder weather, the HST will have higher parasitic losses(do to the oil temp/viscosity), but I can't imagine temp hurting anything(if they indeed use HST tractors in Alaska).

Temperature shocks are a quite different issue. The internal HST tolerances are quite tight, and the parts are chosen such that they expand/contract equally with temperature. However, if the internal parts are at different temperatures, they will rub.

I believe that cool down after heavy loading is much more critical to HST longevity than heat up, but only if one is going to restart the tractor relatively soon.

Best Regards
Chris

 

[RobJ]

Hydrostatic transmission does not equal automatic transmission. True they both transmit power by oil but they are totally different. A HST is a variable displacement hydraulic pump that drives a hydraulically powered motor. I understand the very basics but I'm no expert on the differences. Maybe some of the true techie engineers can explain the difference.

The both use oil, they both operate under pressures, they both will have a problem with high heat. I don't see your point but that is an interesting explaination of a HST. I've never messed with one.

 

[RobJ]

Diesel engines do generally have tighter tolerances than gas engines, hence the need to be nice to them until the metals and oil warm up. This will help reduce wear and tear on engine parts.

I promise I'm not trying to be picky but I see this a lot of... "Generally" they have. Does that mean some do some don't? Sometimes? When I rebuilt both they all have specs that are close. A ring gap for a gas/diesel are pretty much the same (I guess generally the same , I can't quote specs at the moment ). I know the gase engines valve clearance was the same as some diesels (of course diesel by diesel specs change as to gas by gas).

ALL engines are built tight, main reason is we CAN do that now with CNC and computer controlled checking. In the old days it was a guy running a boring and honing machine. If he had to go to the bathroom while cutting, that cylinder might be a little bigger than the one next to it.

Just saying if you are going to warm up a diesel, then you should warm up a gas to, it will also perform better at a fixed temp. That why the thermostat is there, to get the engine up to operating temp ASAP, and maintain it.

Good Luck,
Rob

 

[Glowplug]

The both use oil, they both operate under pressures, they both will have a problem with high heat. I don't see your point but that is an interesting explaination of a HST. I've never messed with one.

Go to Tractorsmart.com, click on [INFO], then click on [Tractor transmission types]. That's where I got my information.

While I am no expert, I am reasonably sure that the absolute HST temperature is not critical(except for choosing the HST oil, and preventing oil breakdown). An Alaskan HST is going to run 100 F colder than a Floridian HST, and the manufacturers don't have a mechansim for controlling the HST temperature. In colder weather, the HST will have higher parasitic losses(do to the oil temp/viscosity), but I can't imagine temp hurting anything(if they indeed use HST tractors in Alaska).

Ummm, I kinda doubt that. True, Alaska may be 100F colder than Florida, but I doubt it affects the internal engine temp that much. I'm no expert either. But the combustion temperature in the engine is going to be the same regardless of the outside temperature. Why do you think they have engine coolant systems? Do they not need them in Alaska? Now it may take a little longer for the engine to "warm up" and the coolant and oil temperature may run slightly lower but I don't think there will be that much difference.

 

[dynasim]

Chuck,

The HST is not heated, not an integral part of the engine, nor does it have a temperature controller(it typically has a cooler, but the heat removal is not controlled). I wasn't talking about the engine, which will have the same temperature in florida or alaska, because it has a thermostat.

Chris

 

[Z-Michigan]

The manual for my 790 says to open the (hand) throttle completely, then start the tractor.
That sure seems like it would be tough on the engine, so I've never done started the tractor like that. I start with the throttle "closed", then increase the RPM to 1200-1500 once the engine catches.

The manual for my Deere 5105 said to open the throttle 1/3, and that the engine might not even start if I didn't do that. I did that ONCE, discovered that the engine came to life and raced to 2000rpm, I backed off the throttle. Now I open the throttle just a tiny bit and hope to see 1000-1200rpms after startup. Dealer told me not to let a new diesel idle at lowest idle due to problem called "wet stack" - unburned fuel collects in exhaust system and makes nasty sludge that can't be removed except by operating dozens of hours at full power.

Back to the main topic... I personally hop on, start the tractor, then hop off and do a quick walk-around inspection. I get back on, put seatbelt on, raise 3ph and FEL, move to a very low gear and start slowly moving where I'm going to be working. If temp is below 25 F. I may let it idle a bit more, but otherwise no. Temp gauge will not start moving for a couple minutes whether I let it idle or use it. Dealer told me not to let it idle at lowest rpm due to "wet stack" mentioned above, but to idle at significantly higher rpms, maybe 1500 or so. I don't think there's any difference from the engine's point of view in idling at 1500 vs. moving in 2nd or 3rd gear at 1500rpm (which is very light load).

I have two diesel vehicles - pickup and Jeep CRD. Neither one will warm up from idling very quickly - much slower than gasoline engines. The Dodge truck in particular (Cummins engine) takes over 5 minutes to show any temp movement if just idling, and the owner's manual says not to idle for more than 5 minutes. Go figure. With the Cummins I will typically idle for 10-30 seconds in normal temps, and maybe up to 5 minutes in temps below 25 F., but either way it won't be warmed up til driving several miles. The Jeep CRD warms up a bit faster but still doesn't get up to operating temp unless driven. I let it idle 10-20 seconds typically, partly to let automatic transmission get fluid circulating.

Tractor engines are made to run mostly at full power, so are overbuilt compared even to truck engines. After idling it long enough to get oil circulating, I personally don't think there is much benefit to letting it warm up more vs. doing very light work (moving in low gears, not anything ground engaging). On the other hand I am new to hydraulics and they do seem to take more time to warm up and get fluid circulating, so perhaps 1-2 minutes of idling is good for the hydraulic system (or longer in cold weather).

 

[RobJ]

The manual for my Deere 5105 said to open the throttle 1/3, and that the engine might not even start if I didn't do that. I did that ONCE, discovered that the engine came to life and raced to 2000rpm, I backed off the throttle. Now I open the throttle just a tiny bit and hope to see 1000-1200rpms after startup.

My guess is the "open throttle" at startup is just to help keep the engine up at some speed. Another guess is its for an area that isn't 80 degrees at 8:00am. The governor moves the throttle to wide open when the engine is off. As soon as it moves the weights pull it back to the selector position (idle). Also fun when the fuel rack sticks....at WOT...a runnaway.

Tractor engines are made to run mostly at full power, so are overbuilt compared even to truck engines.

Diesel engines are really the same. Our little Kubota/Deere engines are the best examples. You might find this engine in a generator set, stationary power unit, water pump, etc. The only difference is the fuel pump settings. They rate for continuous load or imtemitting load. On the gen sets I use to put together the engines came from the factory rated for something like 2200rpm, continuous load, we would have the pumps reset to 1800 rpm (for 60hz, 1500 for 50hz (if I recall...going overseas), the pump shop would also change out the governor weights. Lighter I think for more responsiveness. I didn't work directly on the pumps, we sent them out to M&D.

Rob