Why do some diesels require ether and some dont??

Hopefully this post doesnt get thrown in the fire since it doesnt have to do with an AC machine but if so I understand. So it is obvious from the title of this thread I am not the worlds greatest mechanic or Id likely know the answer to this question but.. I have various diesels from pickups, tractors, welder/generator that are diesel and fire right up even when it is freezing cold WITHOUT ether. However I have a Case forklift with a Cummins 4 cylinder engine that will not start at all unless it gets a shot of ether. It is a strong running engine, but wont start without it. What possible causes could make this machine not start without its shot of ether? Thank you in advance.

Must be something wrong with it the 3 Cummins we got all start good some below 32.   Timing off????? Compression must play into it I have I 6080 that if it was below 50 you were screwed put the 16:1 kit in it and starts great to upper 20’s

In order for any diesel engine to fire up on a cold start, there has to be enough heat built up in the combustion chamber to ignite the cold diesel fuel that gets squirted into it. An engine with 17 to 1 compression ratio will start better than one that is 16 to 1 or 15 to 1 or 14 to 1. The heat is made by the compressing of the cold air on each compression stroke. So, faster cranking speeds helps, higher compression ratios help, injection pump timing closer to TDC instead of BTDC helps, some sort of electric coolant heater helps, an intake manifold heater helps, combustion chamber glow plugs help, etc, etc. A hard starter when cold doesn't automatically mean there is something wrong with the engine, because some engines are just naturally better at cold starts than others. In this particular application, maybe there are hydraulic pumps that are keeping the starter from its best possible cranking speed ?? Maybe your battery needs to be two batteries?? and not cheap batteries either. More CCA's the better. Maybe your starter needs freshening up ??  But, not saying inj pump timing couldn't be off, I'm saying pump timing doesn't CHANGE itself. So, I doubt that it is the problem, if there is a problem. My Dad always plugged in his chore tractor to be sure it would start when needed. Kind of like Marshall Dillon tying his horse up when he got out of the saddle.

Edited by DrAllis - 19 Jan 2023 at 8:06am

There are alot of things that go into a diesel to start. It has to have compression to start. Cylinder temp. has to get to some where around 800 degrees for the diesel fuel to ignite. Cam timing, cam design, inj timing, pump, cranking speed, air temp, and many other factors that effect a diesel to start.                       MACK

Tbone95 wrote: Every chore tractor we've ever had of any color has a block heater that's on a Christmas tree light timer.  It's set to be on for about 4 hours, 2pm - 6pm.  It's just sooooo much nicer to hit the key and go easily.  If I need it at a different time, can set another on period, or simply turn the switch on.  Even 20 minutes helps some, rarely need it in a more urgent emergency than that.  If I do, well, there's some I own start better than others.  One tractor in particular has a unloading valve for the hydraulics that helps a bunch.

DMiller wrote: Tbone95 wrote: Every chore tractor we've ever had of any color has a block heater that's on a Christmas tree light timer.  It's set to be on for about 4 hours, 2pm - 6pm.  It's just sooooo much nicer to hit the key and go easily.  If I need it at a different time, can set another on period, or simply turn the switch on.  Even 20 minutes helps some, rarely need it in a more urgent emergency than that.  If I do, well, there's some I own start better than others.  One tractor in particular has a unloading valve for the hydraulics that helps a bunch.   Anything below 40 my 180 is set up that way.  Timer was for old incandescent lighting so can carry the amps.

My Yanmar has a thermocoupler and compression release it starts at any temperature I have never used ether on it,I have owned two 7.3 and two 6.0 navistars they all had block heaters and glow plugs so as long as they were plugged in they started at any temperature , I've had Cats, Cummins and Detroit's they all had block heaters but if it was going to get into the single digits I'd turn them up to about 1,100 and let them run.Years ago I had a Cummins 335 that had a compression release and a little compartment with a lid on it,you dropped what they called an ether egg in it when you closed the lid it punctured the ether egg giving it a pre measured shot of ether,that system wasn't around that long. The long and short?? Want to tear up a diesel and severely shorten the life of a diesel?? Use ether.

Years ago we had 2 185's on the lot. One would crank before the finger could be released from the button. The other would not crank w/o ether and or air heater on a cool day. We said YES we will find the secret to cranking. We swapped starters, batteries, battery cables, injectors and even the fuel pump from one to the other - the one that would start would start all the time the other - nada... we checked compression - the one that would start actually had a tad less compression than the non starter.  We checked valve setting, timing again - nothing we could do would make one start as easy as the other. We were running up a big bill when we thought about checking valve timing - the cranking one had valve timing that was about 2 degrees (non scientific measurement) sooner - didn't dig into why as we had one sold, but that was the only thing we found different, why or how we do not know.  Go figure ...  

It also helps a lot if you use 0W-30 or 5W-30 synthetic in winter!! Cranking speed is important.

And direct injection is a huge advantage.

Lots of good information here guys I appreciate it. Ive got a good diesel mechanic coming over soon for something else so Im going to talk to him about this Case and see what he thinks he can or cant do with it. The block heater doesnt work on it so I do need to replace that. One other thing this lift has is a factory installed thing a ma jig that you screw a canister of ether into and it gives the motor a shot of ether when starting. I know its factory because it shows it in the owners manual. So apparently the company thought some ether with this motor was ok. But Id best swap out that block heater and start plugging it in. I just put a new group 31 battery in it last week. Got it from batteries and bulbs and told them give me the best group 31 you have so cranking amps are good.

bigcreek wrote: ...One other thing this lift has is a factory installed thing a ma jig that you screw a canister of ether into and it gives the motor a shot of ether when starting...

Yup, when the factory installs an ether thing a ma jig you can pretty much count on hard starting

One of the things no one has spoken about is the starting fluid. I don't know why, but when I do have to use starting fluid, I find John Deere starting fluid is much better than any other brand. Am I getting senile or is there a difference?

I believe  JD juice is"higher strenght" than most others. Think it has been discussed here before.

JD juice is designed to make you buy more of that expensive green paint.