DK45 hard starting

[KJVT]

I have had this 2001 tractor for a month. I was warned it was cold blooded. I have not yet failed to start it but it takes an ungodly amount of cranking. It does have an inline coolant heater which helps on cold days. I have read through a number of similar threads and done some checking with a meter but am at best a shade tree mechanic and am not completely confident of my measurements. I understand the basic requirements are fuel and air coming in and enough heat supplied by compression including fast enough cranking, supplemented by the glow plugs. When cranking I get white smoke until ignition which suggests adequate fuel. I have not checked compression. The air and fuel filters are new. The engine oil is 15-40 Rotella.

The battery is a couple of years old. The ground connection to the frame is rusty so I am going to take it off and clean it up. Is there a way to test the ground cable for internal corrosion, which seems to be an occasional problem? I measured 12 volts across the battery terminals. Is that correct? I will take it to be tested; what should I consider adequate specs? It seems to turn the engine over at a reasonable speed but I have no way to measure that.

The automatic timed glow plug current supplied by the start switch doesn't work, but when I turn the ignition switch to a point in between the last two positions I get 9 volts at the glow plugs. The glow plugs appear to have been replaced fairly recently. I removed the bus strip and checked each plug's resistance by touching one meter lead to the terminal and one to the block. Three read about 1.5 ohms and one 1 ohm. I have read in a post here that the cold resistance should be .4 ohms, but there is no spec in my service manual. I would remove the plugs to see if they actually glow in the dark but they are very difficult to access. I would need to remove the valve cover to get a socket on them. Should I have a new gasket in hand before I do that?

Any suggestions?

 

[MTGreen]

Wow lots of questions. I might be able to address a few of them:
The way to test for internal battery cable corrosion is to remove it from the battery and test for resistance from the battery connection lug to the other end at your chassis ground.
Battery should make a minimum of 12.8 volts. However you're saying that it's cranking fine so I don't think that's the problem.
Usually the valve cover has an o-ring gasket and is designed to come off and back on without needing replacement.
I wouldn't worry about your glow plugs with those readings, but if you want to test them you would have to pull them off and you would have to provide a means of grounding the body of the plug in order to make a complete circuit. This can be done by using a c-clamp against some projection of the block or you can run a jumper with clamps.
I would adjust the valves first and see if that fixes the problem as that is a $0 solution, then buy or rent a compression tester. I don't know if that particular machine is a self-priming one or not, but it is possible that you could be losing prime and you need the extended cranking for the machine to reestablish prime. I would look very closely at all of your fuel hoses especially at the clamps along with your fuel filter assembly and seals. If there is any path for air to get sucked in you can potentially lose prime. You can also install a one-way check valve in the feed line. They are cheap and can help if you are losing prime

 

[KJVT]

I removed the battery ground cable, cleaned up its ends and the frame attachment point and re-attached it with dielectric grease, also polished the positive clamp and battery posts. The ground cable registered almost no resistance and on retesting between the battery terminals I got 12.5 volts. I may have set the voltmeter to the wrong range at first. I will have the battery tested and look for a tachometer to see how fast the starter is spinning the engine.

I checked the connector for the glowplug timer/controller and read 9 volts on one of the terminals, which is what I got at the busbar. Is that too low? Could there be a problem be in the ignition switch? I sprayed electrical cleaner in the switch and rotated it several times. I am not seeing any obvious problems with the fuel lines. I will check the valve clearances when/if it warms up. I wish I had a heated workspace.

 

[MTGreen]

I would check the resistance between the negative battery terminal and the body of one of the glow plugs to verify grounds between the engine block and your frame. You should get a very low reading.
You could bypass the glow plug relay timer and wiring assembly entirely by running a jumper from the positive battery terminal directly to the glow plug bus bar, waiting 15 or 20 seconds, then trying to start. If it fires right away then you know that the glow plug circuit is the problem.
If bypassing the glow plug control circuit doesn't fire right away and you know your glow plug bodies are grounded properly, then you have improperly adjusted valves, lack of compression, you're not spinning the engine fast enough, or you're losing prime.
You said you are getting white smoke while cranking which indicates unburnt fuel and inadequate temperature, so I think the losing prime scenario is probably the least likely here

 

[KJVT]

Circling back- turns out the previous owner had replaced the glow plugs with incompatible ones. I didn't want to pay the dealer's inflated price, but the ones I got off Ebay for under $10 work fine and fixed the problem.