cold start oil flow

[HarryMann]

i love people who say you should drive your car right away... its pretty much just an emissions gimmick.

Not true, there are several reasons..

Leaving a car idling to 'warm up' is one of the worst things you can do, as many manufactiurer's pont out. Por oilflow to the top-end and condensation are two reasons...

Holding the engine at about 2,000 rpm 'is' recomended - but only in preference to 'idling'. It ensures oil is pumped up to overheard camshafts, and stands a chance of warming up quicker..

Driving away slowly and carefully, putting a nominal load on the engine, ensures it warms up quicker and clears out any condensation from cold running, as well as getting to sufficient revs to pump oil 'all' around.

Obviously high loads or high revs too early when oil or water is still cold,  isn't a good thing.

That 'used to be' the manufacturer's recommendations very often, maybe times have changed...

[jtanguay]

i can think of no one who babies their cars to 2k rpm from a cold run though, and therefore its still a gimmick to me.  we're only talking about 4-5 minutes for -10C and below here people... are your lives that rushed??

if you're running synthetic, then yea i can see it working as synthetic stays free flowing until around -40C or so.   high end dealerships will provide really good synthetic oils to their customers, and in that case they can drive away when cold.

i still believe that a car needs to run at least 1-2 minutes when below 0 regardless of type of oil, but then again that's just me.  realizing that your car warms up faster because of the friction has to make you think...

[Turbinepowered]

of course the main reason that the car is heating up faster is because of the added friction from not having enough circulating oil lube the motor...  i don't know if i really like that idea...

Is it the increased friction or is it the sizable increase in fuel dumped into the engine when people zip off while cold? I'd actually tend to think the latter, personally. That burning fuel is quite hot, especially when you burn richer (Cold start systems, heavy feet, etcetera).

Also, a /cold/ engine block, pistons and other such things are going to have looser tolerances than the same block, piston and internals when they're up to temperature. Your normal forces are going to be reduced, resulting in reduced friction compared to the same pieces run non-lubricated when hot. It's when these pieces warm up that lack of lubrication becomes critical, in my opinion. I feel that this would be especially noticeable in aluminum cased/pistoned engines, but I don't think that there are many diesels out there with such things.

This looser tolerance explanation was also given to me as the reason why diesels, especially older diesels, are so much noisier when they're cold than once they've warmed up; you have all that tolerance to allow for piston slap, rod rocking, and everything else that produces noise in an engine, and because of the higher sustained temperatures the tolerances have to be looser at all temps below operating than a spark-ignited engine's.

[greyrabbit]

Back in the 70's I spent a lot of weekends crewing with friends fooling with stock car racing (not exactly NASCAR).  Our engines were small block Chevy's and the piston of choice was the TRW forging.  That piston used an alloy that expanded a lot, we'd typically use 6 thou to 7 thou clearance -- less was better -- you'd support the top ring better and make more horsepower longer -- but going tighter made warm up real critical...if you gave a cold engine too much fuel the piston would expand while the block was still cold which would cause the skirts to skuff/collapse ...time to rebuild.  These little diesels have amazingly tight piston clearance ... I keep the rev's up for oil flow but keep the engine very lightly loaded to keep the heating rate slow enough so the block has a chance to catch up until the engine can establish normal running clearances.  I'm careful to do this in NC where it doesn't really get very cold ... but I suspect it's even more important where many of you live ... a hot piston in a cold bore with 1 thou of design clearance is a bad idea.  I don't just let it idle for the reasons given above by others but I'm sure careful to keep the fuel down until I have normal temperatures and normal clearances.  Just my 2 cents don't really have any ultra cold experience.

[jtanguay]

Back in the 70's I spent a lot of weekends crewing with friends fooling with stock car racing (not exactly NASCAR).  Our engines were small block Chevy's and the piston of choice was the TRW forging.  That piston used an alloy that expanded a lot, we'd typically use 6 thou to 7 thou clearance -- less was better -- you'd support the top ring better and make more horsepower longer -- but going tighter made warm up real critical...if you gave a cold engine too much fuel the piston would expand while the block was still cold which would cause the skirts to skuff/collapse ...time to rebuild.  These little diesels have amazingly tight piston clearance ... I keep the rev's up for oil flow but keep the engine very lightly loaded to keep the heating rate slow enough so the block has a chance to catch up until the engine can establish normal running clearances.  I'm careful to do this in NC where it doesn't really get very cold ... but I suspect it's even more important where many of you live ... a hot piston in a cold bore with 1 thou of design clearance is a bad idea.  I don't just let it idle for the reasons given above by others but I'm sure careful to keep the fuel down until I have normal temperatures and normal clearances.  Just my 2 cents don't really have any ultra cold experience.

basically explains why you need to have a light foot on a diesel when cold.  most new cars have tight piston clearances now too.  you will start to wear the bore and make it oval if you drive it cold without lubrication.  Yes the car will heat up much faster because of the added heat from the burning fuel, but you still need to have a very light foot otherwise you will warp your head by heating it too fast, or even damage your possibly oil starved turbo.  remember we're talking about -10C weather here... anything above 0 is pretty much ok, but you still need to drive careful until up or near operating temp.

[Dr. Diesel]

somebody asked earlier what the wattage of a block heater is. (remember the origin of this post? hehe) Mine says 400W.

[clbanman]

We use a couple of products to accomplish both on our truck engines.  
http://www.kimhotstart.com/kimhotstart/sub.aspx?id=3826 for our coolant/oil preheaters.  Check this page for more on just the oil heaters: http://www.kimhotstart.com/kimhotstart/sub.aspx?id=3814#LOH

We have an option for oil prelubers that are attached to the starter.  http://www.prelub.com/index.html They work off a small pump on the front of the starter that pressurizes the oil system to a minimum pressure before the starter will engage.  When starting the unit, you turn the key to the start position and hold until the engine starts. It's as close to foolproof as you can get for this application.  They don't make anything for a VW diesel, but if you use a small electric pump, you could hook up a similar type of system with a relay and a pressure switch.

[jtanguay]

found this on ebay.

http://cgi.ebay.com/ebaymotors/1-OIL-PAN-ENGINE-BLOCK-HEATER-9845_W0QQcmdZViewItemQQcategoryZ33613QQihZ005QQitemZ150061705915QQrdZ1QQsspagenameZWDVW

probably a hundred times safer than a direct element in oil.  1500 watts should suffice, and not even make my 3000 watt inverter flinch.  :twisted:

once i do some oil flow tests, i'll get to see what 1 minute of this thing does to oil at -10C or so.

forgot to mention.  I will be finding a 1" nut or something, and welding that straight into the pan as a mounting point for the oil heater, as obviously its much bigger than the oil pan bolt on our comparatively miniscule diesel engines.  :lol:

[QuickTD]

1500 watts should suffice, and not even make my 3000 watt inverter flinch.  

If you're going to run this thing from a 12v battery, why not use a 12v heating element? That way you get rid of the losses/inefficiencies of the inverter. Duraterm glow plugs would make a good heater, VW uses them immersed in coolant in the TDI as supplimental heat, you can too. Half a dozen glow plugs would pull the same current as the 1500watt heater (~100-125amps) and require a bunch less wiring.

[jtanguay]

1500 watts should suffice, and not even make my 3000 watt inverter flinch.  

If you're going to run this thing from a 12v battery, why not use a 12v heating element? That way you get rid of the losses/inefficiencies of the inverter. Duraterm glow plugs would make a good heater, VW uses them immersed in coolant in the TDI as supplimental heat, you can too. Half a dozen glow plugs would pull the same current as the 1500watt heater (~100-125amps) and require a bunch less wiring.

you know... that is a pretty good idea!  only thing im worried about is the fact that the glow plugs get super hot... i'd have to run some tests

yeah newer tdi's have bigger batteries, and the glow plugs in the coolant only last a few years so I hear... but that is in coolant, and that is running them for 5 minutes and more during cold running to warm up faster.  using them to decrease oil viscosity during cold starts for maybe 1-2 minutes would seem harmless.

i will still be using my inverter to power small appliances, and recharge my laptop etc.  very useful tools!

[burn_your_money]

Why not have the glow plugs cycle on and off to increase their life? Or hook them up with a pump so that the cold oil keeps the glow plugs cooler

[jtanguay]

Why not have the glow plugs cycle on and off to increase their life? Or hook them up with a pump so that the cold oil keeps the glow plugs cooler

i'm wondering if using the regular vw glow cycle would be sufficient...  remember all this is for, is to decrease the viscosity of the oil at low temps.  i guess the plugs could stay on as the car warms up a bit... that would really get things movin and make my new motor last a really really long time (once its complete of course...)

[FineFrank]

Armed with this alarming information, I've built a little test oil heater. It's very simple, just a regular block heater welded into a 1.5" hole in the back of the oil pan. I filled the pan with the appropriate amount of oil and plugged it in.

Great idea, but labor intensive. I bought a thirty dollar Kat's oilpan warmer several years ago, and it's kept my oil warm ever since. Cheap, easy to install, and excellent quality. Great idea, though.

[FineFrank]

I use a magnetic oil pan heater that pops onto the bottom of the pan.

I used one a couple of times, until it fell off while I was driving down a dirt road. That sucked.

As for the accumulator, fantastic idea. I'd eliminate the ball valve and install a 12V ANCO solenoid (expensive) valve, though. Then you could operate it from inside the car with a switch. I think I'd also want to insulate the tank from engine vibration, too.

i just got a price on the valve- Asco 12VDC normally closed, viton seals, good to 350 degrees, 1/2 pipe, $128.00.

[Dr. Diesel]

I bought a thirty dollar Kat's oilpan warmer several years ago, and it's kept my oil warm ever since. Cheap, easy to install, and excellent quality. Great idea, though.

Do you happen to know to what temperature the heater will bring the oil on a below-zero celcius day? After seeing that video, I personally don't want to settle for anything less than within 20 degrees of engine operating temps for startup.