# Is it possible to roll-start a diesel? **URL:** \ **Category:** Factual Questions\ **Created:** [January 22, 2011, 9:12pm UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600 "2011-01-22T21:12:42Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![saje](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saje/32/3631_2.png) [@saje](https://boards.straightdope.com/u/saje)\ **Post date:** [January 22, 2011, 9:12pm UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600/1 "2011-01-22T21:12:42Z")
Fairly self explanatory question, but a little background anyway: I have a 2003 F-250 4wd diesel 6 speed. So far I’ve not needed a jump start of any kind (which is good because jumping 2 batteries is way more scary than I want to deal with) but I noticed that with this unusual cold my truck is very slow to turn over in the morning, even plugged in, and I know it’s time for new batteries anyway. My driveway is on a considerable slope, and I have in the past parked my other manual transmission car in such a way that I could roll-start it if need be. Is it possible to do with a diesel? It’d be nice to have a little “insurance” before I get the new batteries in! 🆒 ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [January 22, 2011, 9:23pm UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600/2 "2011-01-22T21:23:01Z")
It’s theoretically possible, but the Navistar Powerstroke diesels generally need a longer cranking time for things like the high-pressure oil pump to build enough pressure to run the injectors, and for the engine management to pick up the cam and crank sensors. if it were a mechanically-governed diesel it’d be easier. ---
**Author:** ![Fubaya](https://avatars.discourse-cdn.com/v4/letter/f/c2a13f/32.png) [@Fubaya](https://boards.straightdope.com/u/Fubaya)\ **Post date:** [January 23, 2011, 1:05am UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600/3 "2011-01-23T01:05:11Z")
I’ve jumped many big trucks like that with two batteries and it isn’t so bad, except you often need more juice. A small held held jump box often won’t be enough, but two or a plug in charger with a jump start settings will probably do it. Jumping with another vehicle usually works. If not at first, let it run for a few minutes and try again. ---
**Author:** ![pericynthion](https://avatars.discourse-cdn.com/v4/letter/p/85e7bf/32.png) [@pericynthion](https://boards.straightdope.com/u/pericynthion)\ **Post date:** [January 23, 2011, 1:22am UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600/4 "2011-01-23T01:22:51Z")
I’ve roll-started my rusty steed, a 1982 VW “Jettason” Jetta diesel on several occasions. But it’s old school, no flight computer. Don’t know how your truck will fare. ---
**Author:** ![saje](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saje/32/3631_2.png) [@saje](https://boards.straightdope.com/u/saje)\ **Post date:** [January 23, 2011, 1:57am UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600/5 "2011-01-23T01:57:18Z")
I guess the corollary question is, will I do any damage trying it? Assuming I don’t drive into something of course, since I won’t have power steering or brakes… (eeep!) Also, as to jumping it, don’t you have to hook up the batteries to the jump battery in a particular sequence? Or how do you know which battery to hook to? ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [January 23, 2011, 2:05am UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600/6 "2011-01-23T02:05:12Z")
doesn’t matter. the batteries are in parallel, so they both receive charge. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [January 23, 2011, 2:07am UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600/7 "2011-01-23T02:07:11Z")
> [@saje](#): > > I guess the corollary question is, will I do any damage trying it? Assuming I don’t drive into something of course, since I won’t have power steering or brakes… (eeep!) > > Also, as to jumping it, don’t you have to hook up the batteries to the jump battery in a particular sequence? Or how do you know which battery to hook to? I’ve roll-started my F350 Crew-cab Diesel. So, no you won’t hurt anything. As far as the two batteries goes, they are in parallel, so it doesn’t matter which one you attach to. As an aside - my power steering failed a few months ago. I’ve been driving without it, mostly because I don’t feel like working on it right now, but also because I’m trying to increase my upper-body strength, and I figure it’s a good workout. ---
**Author:** ![Fubaya](https://avatars.discourse-cdn.com/v4/letter/f/c2a13f/32.png) [@Fubaya](https://boards.straightdope.com/u/Fubaya)\ **Post date:** [January 23, 2011, 2:25am UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600/8 "2011-01-23T02:25:18Z")
> [@saje](#): > > Also, as to jumping it, don’t you have to hook up the batteries to the jump battery in a particular sequence? Or how do you know which battery to hook to? The batteries are wired in parallel so I don’t _think_ it matters but you’re probably better off checking the owner’s manual. One side is probably closer to the starter and may be slightly better for jumping. The procedure I’ve used several times and seen many other people use is this: Hook to one battery, attempt to start. Cuss. Hook to the other, attempt again. Cuss more. Go get something bigger to jump with while cussing. Hook to either battery being sure not to stop cussing during the set-up. Start. Cuss at having to carry/drive all this jump equipment back to where it belongs. Hope that’s not too technical 😃 Seriously, I’ve never seen a truck that wouldn’t jump with a plug in charger or a “large” vehicle. By large, I mean a nice sized car or truck, not a Honda. If they don’t start with any of these, leaving them hooked up for a few minutes charges them enough that jumping works. I remember stringing 100 feet of narrow gauge extension cords out to a _completely_ dead truck once, hooking a charger to it for 10 minutes, then flipping the charger to jump mode and starting it. ---
**Author:** ![saje](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saje/32/3631_2.png) [@saje](https://boards.straightdope.com/u/saje)\ **Post date:** [January 23, 2011, 12:12pm UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600/9 "2011-01-23T12:12:55Z")
Thanks all! I hope to never need this info, but it’s nice to have a glimmer of a clue, just in case 🙂 > [@Fubaya](#): > > The procedure I’ve used several times and seen many other people use is this: Hook to one battery, attempt to start. Cuss. Hook to the other, attempt again. Cuss more. Go get something bigger to jump with while cussing. Hook to either battery being sure not to stop cussing during the set-up. Start. Cuss at having to carry/drive all this jump equipment back to where it belongs. Hope that’s not too technical 😃 Ha! That’s more or less been my SOP with my tractor a few times, but add in the factor of getting the jump vehicle TO the tractor. Lots and lots of Big Girl Words a-flyin’! 😃 > [@beowulff](#): > > As an aside - my power steering failed a few months ago. I’ve been driving without it, mostly because I don’t feel like working on it right now, but also because I’m trying to increase my upper-body strength, and I figure it’s a good workout. Brave soul! Parking must be fun… ---
**Author:** ![The\_Librarian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/the_librarian/32/402_2.png) [@The\_Librarian](https://boards.straightdope.com/u/The_Librarian)\ **Post date:** [January 23, 2011, 2:24pm UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600/10 "2011-01-23T14:24:24Z")
You can use momentum instead of a starter engine but modern diesels need a little bit of juice for engine managment and pre-heating (don’t know the english word, most engines need some heat to vaporize the fuel). So if your battery('s) are completely drained, as they likeliy will be after a failed start attempt you’re SOL. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [January 23, 2011, 3:22pm UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600/11 "2011-01-23T15:22:21Z")
> [@saje](#): > > Brave soul! Parking must be fun… Yeah, I really avoid parallel parking… I also have learned to keep both hands on the wheel, since a quick turn requires them both. ---
**Author:** ![rjk](https://avatars.discourse-cdn.com/v4/letter/r/ed655f/32.png) [@rjk](https://boards.straightdope.com/u/rjk)\ **Post date:** [January 23, 2011, 4:00pm UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600/12 "2011-01-23T16:00:18Z")
I once push-started a bus. (Well, I had help.) The driver had shut it down before he went for his scheduled break, and it was dead when he came back, so he wanted to call for another bus. Nobody wanted to wait around for an hour or more, so one guy suggested a push-start. The driver was doubtful but he didn’t want to hang around either. So visualize ten or twenty university students in a scrum at the back of the bus, heaving at it with all their might. We got it up to speed and it started first try. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [January 23, 2011, 5:26pm UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600/13 "2011-01-23T17:26:09Z")
My diesel tractor has glow plugs that have to be hot to get it to start. Perhaps if I spun the engine long enough, it would eventually get hot enough to cause ignition without the glow plugs, but I don’t know. If not, then it couldn’t be roll started without any electrical power, unless the generator could power the glow plugs. Would these be issues for trucks? Do they have glow plugs? ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [January 23, 2011, 5:42pm UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600/14 "2011-01-23T17:42:53Z")
> [@Napier](#): > > My diesel tractor has glow plugs that have to be hot to get it to start. Perhaps if I spun the engine long enough, it would eventually get hot enough to cause ignition without the glow plugs, but I don’t know. If not, then it couldn’t be roll started without any electrical power, unless the generator could power the glow plugs. > > Would these be issues for trucks? Do they have glow plugs? The Powerstroke engine in Ford trucks has glow plugs, but they aren’t necessary if the engine is hot enough. In fact, they are on a temperature-controlled timing cycle. In the summer, I can start my truck with a 2-second crank. In the winter, I need to use my block heater, because my glow plugs are all shot, and even out here (Arizona), it’s cold enough that I can’t start it without a lot of trouble. ---
**Author:** ![Polycarp](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Polycarp](https://boards.straightdope.com/u/Polycarp)\ **Post date:** [January 23, 2011, 10:06pm UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600/15 "2011-01-23T22:06:41Z")
If I’m not mistaken – Diesel engineers, please correct me – Rudolf Diesel’s concept was for an engine that would start from heat-of-compression. Glow plugs are useful in heating the fuel to speed up the process, not an essential element of the Diesel engine proper. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [January 23, 2011, 10:13pm UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600/16 "2011-01-23T22:13:02Z")
> [@Polycarp](#): > > If I’m not mistaken – Diesel engineers, please correct me – Rudolf Diesel’s concept was for an engine that would start from heat-of-compression. Glow plugs are useful in heating the fuel to speed up the process, not an essential element of the Diesel engine proper. Completely correct. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [January 23, 2011, 10:14pm UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600/17 "2011-01-23T22:14:19Z")
> [@Polycarp](#): > > If I’m not mistaken – Diesel engineers, please correct me – Rudolf Diesel’s concept was for an engine that would start from heat-of-compression. Glow plugs are useful in heating the fuel to speed up the process, not an essential element of the Diesel engine proper. right. they’re simply cold-start aids. The Cummins engine that was in the Dodge Ram I used to have did not have glow plugs; instead it had a grid heating element in the intake manifold. the old F-250 I had before it (with an indirect-injection engine) had glow plugs, and needed to heat them if the engine was cold, even in the summer. once the engine was up to operating temp, however, the glow plugs were not needed for starting. ---
**Author:** ![The\_Librarian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/the_librarian/32/402_2.png) [@The\_Librarian](https://boards.straightdope.com/u/The_Librarian)\ **Post date:** [January 23, 2011, 11:40pm UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600/18 "2011-01-23T23:40:22Z")
Glowplugs! ---
**Author:** ![Myglaren](https://avatars.discourse-cdn.com/v4/letter/m/f1d935/32.png) [@Myglaren](https://boards.straightdope.com/u/Myglaren)\ **Post date:** [January 24, 2011, 7:23am UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600/19 "2011-01-24T07:23:33Z")
We regularly used to bump start an old Transit diesel but I have since learned that this is very, very bad for the clutch. Direct injection diesels will start without glow plugs, mine only come on at -5°C. Indirect injection is more of a problem. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [January 24, 2011, 1:07pm UTC](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600/20 "2011-01-24T13:07:05Z")
> [@Polycarp](#): > > If I’m not mistaken – Diesel engineers, please correct me – Rudolf Diesel’s concept was for an engine that would start from heat-of-compression. Glow plugs are useful in heating the fuel to speed up the process, not an essential element of the Diesel engine proper. This is true, although in extreme cases (and with a crappy design), glow plugs may be inadequate. A couple of decades ago I was a college student in North Dakota. A friend and I wanted to go to Minneapolis for the weekend, but we knew from experience that there was no way his Volkswagen Rabbit (diesel engine) was going to start at 0F; he had tried previously, and even with the glow plugs and several turns of the key, it just wouldn’t catch. Solution: On Friday morning we enlisted the aid of another friend who owned a big ol’ Ford Galaxy, which we used to drag the dead Rabbit around the parking lot until it started. Basically it was like having a starter that could crank the motor for 20-30 seconds, until the compression events had warmed things up enough that the injected fuel could finally light off. After that drag-start, my buddy key-started his Rabbit a couple more times during the day to keep it warm enough to key-start late in the afternoon when we were ready to leave. A different issue _may_ come up on late-model vehicles. Last fall I tried to roll-start my '02 Nissan Maxima. While rollling at ~40 MPH, I declutched, turned the key off, turned it on, and then let the clutch out. The engine spun good, but as soon as I declutched again, the engine died. I finally figured out that the computer was refusing to run the engine unless I had actually turned the key to the “start” position and cranked the engine with the starter. My Maxima has a gasoline engine, but this was unrelated to that; it’s possible that someone trying to start their diesel-powered vehicle could encounter the same issue. [Next page](https://boards.straightdope.com/t/is-it-possible-to-roll-start-a-diesel/568600.md?page=2)