To warmup or not?

[LarryT]

There have been a lot of discussions here recently on warming up tractors before using them. I'm not sure exactly where I stand, opinion wise, on this subject, but I just ran across something that I thought might be of relevance.

My son just bought a new VW Golf. In the instruction manual, it says "DO NOT LET YOUR VEHICLE STAND AND WARM UP; When the engine is idling, it takes a very long time to warm up. Moreover, during warm-up, both engine wear and exhause gas emissions are very high. Therefore, be ready to drive off immediately after starting the engine and avoid high engine speeds."

Granted, a tractor and a VW car are two different things. But, there are lots of similaraties too. The car has and engine and engine oil. It has hydraulics (automatic trans). It works pretty hard. And the standard factory warranty is 100,000 miles or 10 years. Much longer than my Kubota. (it cost about the same too).

I'd be interested in why a tractor would be a lot different than this new VW? I'm just curious.

Thanks,

Larry...

 

[Rowski]

Larry

Is the VW a gas or TDI deisel? I'll try yo give an explanation for a gas engine. I know some basics about deisels but not enough for me to talk about. Gas engines especially EFI, cars and light trucks is my profession.

First of it does take an engine a long time to warm up at idle especially if it is reallt cold. In the winter anything under +20F I use a block heater. Once the care is running I usually let it run for 10 to 20 minutes before driving. Around here when its cold you just can't start up your car and go. A lot of the fluids power steering, transmission fluid, etc. are so thick they make some really funny noises. Also if just start up and drive off you winsheild will fog over very quickly. So you end up pulling over and waiting anyways. In the summer I just start the car let it idle for a few minutes and go.

As far as wear during warm up personally I think that running an engine under load (even a slight load) does more harm than it idling, but the wear is so slight. This is provided that you have good oil pressure at idle. If wear is a problem just use synthetic oils (MarkC is an expert in this). Emissions are very high start up. There are a lot of hydrocarbons (HC) that fill the catalist converter. During a start the engine the fuel mixture needs to be enriched (choked) more fuel to air. As the car warms up ther mixture comes down to the ideal mixture lamba or 14.7to1 ratio. A catalist converter does not work (reducing emissions) right away, It need to be heated up (by the moving exhaust). Once heated the converter can burn the HC. Once this converter becomes warm and operating is starts to burn the excessive HC. If the HC are to much the converter can actually glow to a cherry red color and catch thimgs on fire. This glowing and catching this on fire can all happen at idle. So by driving you enduce some air flow under the car which helps cool the converter. Also being that you are from California (if I remember your profile right) emssions is a very big part. A conveter will heat up faster if the exhaust is flowing faster, part throttle. So "they" want you to do this to reduce emisions.

In a nut shell, two things come to mind about the statement from VW -> saftey (fire hazard) and emissions.

Hope this helps, again this is for gas engines on cars. There must be someone who can explain it for a deisel.

Derek

 

[dmccarty]

Larry,

My JD manual wants me to start the tractor, at 1/3 throttle, after the engine is running move to 1/2 throttle, and then let things warm up for five minutes. After five minutes the coolant temps are pretty much where it stays all day long. Five minutes is a long time to be standing around breathing exhaust so I try to do other tractor maintanence during that time. I'll grease the tractor, tighten nuts, kick the tires, etc. Actually I can't move the nuts on the tires or the tractor for that matter but its something the manual tells the owner to do. And you should. I checked the nuts on the tractor after 10 hours or so, whatever the manual specified, and found out that idiot who set up the tractor had stripped some of the nuts on the backhoe. Since the tractor had to go back to the dealer because of this idiot, they fixed the stipped nuts/bolts without question. If I had not checked I would not have found it out until much later.....

My boss when I worked on a farm did not do much preventative work on his equipment. One day one of the rear tires fell off his MF 165 while he was rotary cutting. I still can't figure out how that did not kill him. Not fun. At the end of the summer he busted an oil line on his dozer. That was the last day we worked. I'm not sure if he cooked the engine or not but he used the dozer to skid logs out of the woods that I would then split into cord wood. I imagine it would take quite a few cords of wood to pay for a new Cat engine... After I worked with him, he had the chain come off his chainsaw, I assume he had not tightened it correctly, and it wacked him upside the head. He was unconcious for a couple of hours before he woke up and managed to get to a neighbor. He must have looked like heck with all that dried blood from a bad scalp wound....

I really try to maintain the tractor AND my chainsaw per the manual.

Hope this helps...
Dan McCarty

 

[Thomas]

From your small compact tractor also your heavy equipment warming up should be a must.
The last thing you want to do push cold hydraulic fluid thru your transmission system filters..packing.."o"rings etc..
This will give your equipment longer life down the road.

Just my 2 cents worth.

Thomas..NH /w3tcompact/icons/wink.gif

 

[ScottF]

Larry,
I'm going to have to agree with everyone else on this - let it warm-up before taking off. Oil flow and lubrication are two main issues - and I think everyone has covered that pretty well, but thermal expansion is another factor to consider. Tolerances in rings, bearings, pistons, valves,...etc. are not established until everything is at operating temperatures. Loading an engine up while it is cold can lead to premature failure (I've heard of people seizing up their two-strokes because of cold take-offs).

Anyway, for whatever it's worth.

Scott

 

[LarryT]

Scott, those are all valid considerations. But, they equally describe both the tractor and the auto. I'd say it's worse for the auto since the RPMs can reach high level quickly where a tractor never turns very high rpm at all. I don't know what to expect from a tractors life before rebuild, but if you assumed an average of 25 mph over the 100,000 mile warranty of the VW, that would be 4000 hours. Seems fairly respectable. On the other hand, I also agree that the car manufacturers are most concerned with emissions and average fuel economy and will certainly slant things to achieve those.

Lastly, having read all these posts and everything considered, I think I'll change to synthetic oil and hyd fluid, then wait plenty of time for warmup! Better safe than sorry!

Larry...