Hard starting

[bird dog]

Okay clear up my thinking here. Tractor is a Kubota M6800. I have owned it about 8 years. Its been a good machine but has slowly gotten harder to start. If you get on it and just turn the key it will barely turn over like the battery is dead but using the glow plugs for about 30 seconds will allow it to fire right off. It has gradually taken more time on the glow plugs. Even now in the warm weather, it will take 20 to 30 seconds of glow plug use. Its the same even after the engine is warm. You can run it for an hour, shut it off, then go to restart and have to go through the same starting procedure you do when its cold.

So am I having
battery problems-- a new battery didn't seem to make any difference
battery cable problems -- they are clean at the battery, no corrosion
starter problems
something else I am not thinking of

Thanks for all ideas.

 

[sstterry]

@Caustic Burno can tell you if he thinks it is a fuel problem and if you need an additive. Otherwise, it could be the starter going bad.

 

[Stocker Steve]

Slow turning is hard on starters. If the starter is not bad, it will be.

I would add another bat using jumper cables to rule out low cranking amps, then pull the starter for a rebuild.

 

[D2Cat]

I'd suggest checking the battery cables at the frame ground and starter. The positive could be corroded under the sheath. The ground needs to be removed and shined up, and the frame polished clean.

 

[Caustic Burno]

I'd suggest checking the battery cables at the frame ground and starter. The positive could be corroded under the sheath. The ground needs to be removed and shined up, and the frame polished clean.

I am right with you.
Houston we have a ground problem 9 times out of 10 in my experience with DC current.
If it's not cable's I am pulling the starter heading to the shop.

 

[D2Cat]

Yes, with a known good battery I'd always check the ground specifically and the other battery wire ends before blaming the starter. Also, the battery needs to be tested under a load to prove a cell in not weak. Oh, it could also be something as simple as a bad connection on the battery clamps, especially if they are not the original ends.

 

[bird dog]

Thanks all. I think the cables are original which means they are around 15 - 20 years old. I will pull and clean both ends of those first chance I get which may be a week or so.
The cables were my original thought but because it will jump right off with the glow plugs engaged, i wasn't sure if my thinking was correct. No one has ever mistaken me for a mechanic.

 

[Nick Wagner]

Thanks all. I think the cables are original which means they are around 15 - 20 years old. I will pull and clean both ends of those first chance I get which may be a week or so.
The cables were my original thought but because it will jump right off with the glow plugs engaged, i wasn't sure if my thinking was correct. No one has ever mistaken me for a mechanic.

A bad ground can cause all kinds of weird problems, but you definitely have a head scratcher with the glow plug thing. Please update us after you have checked and cleaned your battery cable connections. You might consider loosening then tightening the starter bolts as well, since current has to flow back to the battery through that connection.

 

[Chevy]

Thanks all. I think the cables are original which means they are around 15 - 20 years old. I will pull and clean both ends of those first chance I get which may be a week or so.
The cables were my original thought but because it will jump right off with the glow plugs engaged, i wasn't sure if my thinking was correct. No one has ever mistaken me for a mechanic.

The copper can corrode under the insulation of the cable if you are in a humid or coastal area. Did you change your fuel filters and stuff? What year is the tractor?

 

[jltrent]

I have a M6800 and am pretty familiar with them. As mentioned if it barely turns over you have a ground cable issue or both need cleaning and or replacing. Also have you changed the fuel filter recently and cleaned the screen in the water separator? They are indirect injection engine and have glow plugs and if it gets to be hard starting with assist then you have a bad glow plug. I always use some fuel treatment to extend the fuel systems life and one trick I learned here from CB is put a small amount of 2 cycle oil on every fill up for extra lube. I believe it even helps it run better. I have fluid in the back tires with weights mounted on the inside of the back rims.

 

[ClodHopper37869]

The copper can corrode under the insulation of the cable if you are in a humid or coastal area. Did you change your fuel filters and stuff? What year is the tractor?

I've had that happen more than once over the last 73 years in the hills of E TN.

 

[bird dog]

I pulled service on it about 10 months ago. Filters were changed and the fuel separator was cleaned. It was having the same issues before then just not quite as bad.. The cables were cleaned on the battery ends at that time. The tractor is 2003 model I think.

So Mr. Trent, how much is a small amount of 2 cycle oil? I don't think it is a glow plug problem since it has the same issues when the engine is warm. It will be a few days before I get back on it. Replacement cables from Kubota thru Messicks are expensive. For some reason the positive cable had the part number changed and the price went from $80 to $153.

 

[sstterry]

As I recall, @Caustic Burno recommended Walmart brand Super Tech 2 cycle oil for added lubrication. I will defer to him to tell you the ratio. I have also read about adding Dexron ATF fluid, but I have never tried it.

What puzzles me about this is the fact that using the glow plug helps with starting.

 

[SBMF 2015]

What puzzles me about this is the fact that using the glow plug helps with starting.

Me too. Makes me wonder if the fuel pump runs while the glow plugs are warming? If you are loosing the prime in the fuel lines when the tractor is shut off? We had a JD6320 that you had to turn the key to the on position for 20sec every morning before starting. It would loose its prime over night. Let the pump run 20 sec and it would fire right up.
Might be two separate issues.

 

[jltrent]

My Ford 3600 is the same way and been that way for years. If you try to start, it is hard starting unless you use the engine warmer and then it starts instant. I have an OEM Injection pump I got for a deal from Ebay that was rebuilt at Acme Diesel in Knoxville as an employee there sold it and have not put it on yet. The tractor has good compression and I have had the injectors tested and went through the fuel system. It is a CAV pump and there is nothing electronic about it, all mechanical. When I put the new pump on I will know 4-sure if that was the problem, but works fine now just have to warm about 15-20 seconds if the engine is cold.

On the 2-cycle oil I have probably done went through 5 gallon as I even put a little in my riding mowers. On the tractors I put about a pint every fill up. It has to help with fuel system lube and top cylinder lube, just don't want to put to much an possibly cause some carbon buildup.

 

[truckdriver2]

Okay clear up my thinking here. Tractor is a Kubota M6800. I have owned it about 8 years. Its been a good machine but has slowly gotten harder to start. If you get on it and just turn the key it will barely turn over like the battery is dead but using the glow plugs for about 30 seconds will allow it to fire right off. It has gradually taken more time on the glow plugs. Even now in the warm weather, it will take 20 to 30 seconds of glow plug use. Its the same even after the engine is warm. You can run it for an hour, shut it off, then go to restart and have to go through the same starting procedure you do when its cold.

So am I having
battery problems-- a new battery didn't seem to make any difference
battery cable problems -- they are clean at the battery, no corrosion
starter problems
something else I am not thinking of

Thanks for all ideas.

See how many amps starter is pulling might be a bad starter

 

[dodger2]

See how many amps starter is pulling might be a bad starter

I I had a hard to start problem on a Ford 7740 that would crank a long time, start then cut off. A Ford 3600 started loosing prime and had to be replaced. The mechanic said Diesel service fuel conditioner has changed its recipe and to find another product. Howe is working good now in the 7740, it starts quick now. The Rotary pumps need a lubricant. Tractor dealer mechanic foreman for years said to use dextran Transmition fluid @1 oz./gallon of fuel. He said they had a surge on bad rotary pumps and this slowed it down. He also said lots of people with equipment that has a inline pump that has a lubricant in the pump forget to change the lubricant or check it and it can run dry. I change the lubricant with every oil change.

 

[bird dog]

An update on this. Yeah I know, I'm slow getting around to some things.

Anyway I cleaned the cable ends, and tested the battery to start out. This helped some but would still not start well when hot. Took the starter off and hooked it to a battery. It appeared to work as designed. I took it to a starter shop and he confirmed it was working correctly but decided to take it apart.
The brushes were working but getting pretty short but that wasn't the problem. Problem was the casing was not getting grounded so it was not transferring the ground to the engine block if I understand how it works correctly. So congratulations to those who thought it was the starter.

Like a lot of things these days, it was cheaper to buy a new aftermarket one than to fix the old. $225 and she starts like a new one.

 

[ccr]

Problem was the casing was not getting grounded so it was not transferring the ground to the engine block

bird dog, why was the casing not getting grounded?

 

[Redgully]

An update on this. Yeah I know, I'm slow getting around to some things.

Anyway I cleaned the cable ends, and tested the battery to start out. This helped some but would still not start well when hot. Took the starter off and hooked it to a battery. It appeared to work as designed. I took it to a starter shop and he confirmed it was working correctly but decided to take it apart.
The brushes were working but getting pretty short but that wasn't the problem. Problem was the casing was not getting grounded so it was not transferring the ground to the engine block if I understand how it works correctly. So congratulations to those who thought it was the starter.

Like a lot of things these days, it was cheaper to buy a new aftermarket one than to fix the old. $225 and she starts like a new one.

I have an old Ferguson where i had the same issue. Mine was caused i believe by excess oil between block and starter including inside bolt holes. I ran an extra earth strap straight from battery to starter and haven't had and issue since.