I'm having some cold weather issues with the truck. In warm weather it starts fine. I replaced all of the glow plugs recently with motorcraft plugs. The batteries have been recently replaced as well, but in cold weather It's very hard to start the truck.

When I switch the ignition on, I see the "wait to start" light go on for a few seconds, and then it goes out. I hear a clicking that occurs every second or so and the indicator lights will dim with the clicking. I assume it's the glow plug circuit? I'll try this twice (to heat the cylinders) and will crank the engine over. It will crank for a bit, start, stumble and then die. Usually it's running on only a few cylinders as the engine shakes like mad and you can tell its not running right. After it dies I try to start it again. However, the engine is very hard to turn over. You can tell the starter is laboring and it sounds like it's fighting against something. I'll sit and wait a few minutes and try again. Eventually I'll get it to turn over to the point where it stumbles until all of the cylinders kick in. I'm sure it's not good for the engine to run unbalanced. I know the batteries are good and it happened in my old set of batteries as well. The plugs are good but the controller may be bad. I'm not sure what is making the engine hard to start after it initially tries to run and then stumbles. Any suggestions? The starter seems fine since it works fine when the engine hasn't been started, or the engine is warm. I plugged in the heater for three hours yesterday and despite the warmer working, I didn't notice a better start.

I'll summarize with the batteries are fine and it does not sound like a dying battery starter. It sounds like a laboring starter only after it starts and stumbles. The first start is always at a good speed.

 

Interestingly, the GPs on my 86 6.9l act the same way. I replaced the GPs and the GP controller. I think it may be due to a corroded GP relay.

When I initially turn on the GPs they're only on for 3-4 seconds. If I leave the key in the RUN position the GPs will start to cylce, 1-2 seconds on and then 2-3 seconds off. I usually let them cylce 2-3 times before starting if it's cold. Hopefully someone knows what's up with our wonky GPs.

 

I would guess that some of your glo plugs are burnt out.. If only 6 /8 are firing it will do this..

Try disconnecting the glo plug relay and shooting 3 short bursts of starting fluid into the intake..

If it fires smooth and easy, without same symptoms then that's the problem..

When mine started to go out it did this.. Rough and smokey till all cylinders got to firing after a minute..

The resistance may be the compression that has built in an otherwise still cold motor.

Just me, but I ditched the plugs many years ago in favor of a dedicated ether straw that runs into the cab plumbed into the hat.

Just one nearly dead battery still fires easy and smooth even in these sub freezing temps. Ether is okay as long as you don't use the glo plugs at the same time.. Controversial topic though and most disagree, in my opinion it's easier on a cold motor, starter, battery.. ect because it doesn't crank but a few seconds..

Could also fix the gp system and put on a relay with on off button and install a ether hose also for a choice of either starting option.

No matter what, when and where I need my motor to start.

 

sounds to me like you have air intrusion and it is running out of fuel, not a glow plug problem.
to check for air intrusion, remove the fuel filter after sitting overnight and see if it is full, or partly empty.

 

Ether won't cause an engine to fire smoothly. Quick Start ether injection kits were standard equipment on Detroit, Cummins, and Case diesels and when used, engines misfired and ran rough as a cob for a number of seconds, not to mention knock LOUD momentarily due to the pre-ignition. As tjc transport posted, sounds like air intrusion which is a common problem. Especially the rough running when it finally fires.

 

The whole misfire and run like a cob is not even remotely accurate (except for the Detroit's) the actual real ether start kits use a jet like orfice to help make the ether a really fine mist, and it only takes punching the button as fast on off as you can and they'll fire up smooth as butter. If you hear any premature knocking YOU used too much. Ether is the best thing ever invented for cold weather, it just gets a bad rep from stupidity

I agree it sounds like air intrusion the whole start and die thing gives it away

 

This is exactly right, the problems listed with the rapid clicking and cycling of the glowplug circuit clearly shows a problem there. Most likely a few burned out and the controller is just cycling to be obnoxious. But this is only part of the problem it seems. If Diesels are good for anything it is stumbling through a problem until a second one shows up to complicate things.
This is the other half of the problem. Again the clicking is a GP issue for sure. But the stumbling and starting then dying screams that Injector return lines and Ts are leaking. So I think we may be seeing a problem caused by two convenient failures.

 

Thanks for all of the replies.

Like I mentioned the glow plugs are brand new. I can double check all of them for continuity and resistance, but I removed the old ones and installed them new with motorcraft replacements.

If a starter is bad, is it better to get it rebuilt rather than risk an aftermarket replacement?

I'll check the glow plugs and try to manually run them before looking into the air intrusion issue after. I only say this because it starts pretty easily in warmer weather, and when it's running rough when cold there's endless white smoke coming out the exhaust before all cylinders fire up. Perhaps cold weather impacts air intrusion, I'm not sure.

 

You can get starter brushes at rockauto..

I myself ordered a set last time I made a purchase, just to have on hand next time they wear out..

also got a spare set of alternator brushes and bearings for when the time comes, new clutch set, tob, new spare injectors and misc. wear parts that require replacement once in awhile..

Can't say how difficult brush replacement is, as I haven't done it yet on this starter, but have on others and I can usually take it apart and replace them in about as long as it takes to take the thing from off the vehicle. Windings keep good unless you crank for a long time and burn it up.. It's usually just brushes that wear out.
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If you replace starter brushes be sure to clean out the groves in the stator (I think it's called) the rotating cylinder in the center) and wear breathing protection and gloves.

I can't say that I know for sure, but be careful because dust from hot wear parts, some brushes, brakes, clutches ect may contain asbestos sometimes. I don't Don a full body suit when making repairs, but at least take care not to blow off dust with an air gun and breath heavily while doing so.

Best regards.

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For those that have the most common starter, a Mitsubishi, the brush leads are not soldered but spot welded on. I was going to remove the old brushes, then drill, tap and screw on the new brush leads like on the big diesel Delcos. When I phoned the local auto electric shop he said that generally doesn't work out to well (why I don't know). All things considered, I took it to him, he did a complete rebuild in a couple hours and it was only $104. The grooves between the commutator segments can be cleaned with an ice pick or awl. then the segment surfaces sanded with emery cloth otherwise the brushes will wear prematurely. The grooves in the armature never need cleaning, plus after overhauling starters from semi tractors on down to pickups I'm fairly sure there's no asbestos involved.