1988 M998 Cold Start Problem

[ikoinu]

I know this is the most posted about problem, but I'll give this a go anyway to see if someone sees something I don't. I've been combing through the forums and the service manual.

Cold start issue only in the morning, no other time. New glow plugs were installed, as was a grounding harness between all the usual suspects.
Box is the Nartron engine electrical start system Yellow label, MFR-32498 19207 ASSY 12469158-1.
Wait light comes on consistently with a thunk from the box below 120 degrees for 9 seconds, no other noises.

Any idea on my next check?

Thanks for any input on the new truck.
Steven

 

[Dock Rocker]

Have you put a meter on the glow plugs to make sure they are getting power and heating?

Also what did the old plugs look like when you pulled them?


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[Action]

The light should stsy on for more than a second.

 

[tonydamato]

Mine does some weird **** when its really cold out. like below 30 degrees. The wait to start light will go on for longer as it should when its cold out and when I go to bump the motor over the starter will just disengage after about 1 second, it wont continue to crank. I usually have to bump it over 4-5 times to get it start when its cold out. Normal spring, summer, fall temps above 40 degrees it fires immediately.

 

[Retiredwarhorses]

These trucks will start in California Weather with only 4 glow plugs and almost no white smoke, but once
winter hits and the nights drop to 45 and below, they will struggle a bit.
i have more trucks then I can count, all have S3 EESS and new glow plugs, not all start the same when cold out...a coulle
like to chug a bit more....but it's just the nature of the beast.
check all your glow plugs....

 

[jeffy777]

My experience is that when it is cold the diesel has less fuel pressure. This is because :A typical value of the coefficient of thermal expansion for diesel fuel is 0.00083 per degree Celsius (0.00046 per degree Fahrenheit). Using this value, 1.000 gallon of diesel fuel at - 7 °C (2 0°F) will expand to 1.037 gallons at 3 8°C (100°F). ... Same -7 Deg. C.

Therefore in addition to your glow plugs you may want to put your foot on the diesel pedal for a second to rebuild the pressure that was reduced as the diesel contracted in the line. The system is injected so you should never need more than a second and you will want to do as you are starting but not like a gas carbureted vehicle(Old gas carburated system had you press the gas before you start on a old gas vehicle will set the choke).

 

[ikoinu]

Thanks for the feedback. The former owner had switched out the plugs just prior to my purchase. He said they were swollen and difficult to pull.

I had tested a few of the glow plugs in the block and they measured at 1 ohm, which looks to be good.

My wait light is staying on for 9 seconds, so it looks like controller is good.

Jeffy777, funny you mention that because I've been stepping on the gas pedal as a turn the key, and it hasn't made a difference. But this morning, I started cranking and then pushed the pedal to the floor once and got off it. After a few cranks it started up. Now this was the coldest morning we've had in at 56 degrees (Los Angeles freezing ) , so it shouldn't have been so easy.
Perhaps the grounding or just using the proper cold start procedure has worked.

I'll try again tomorrow and report back.

 

[ikoinu]

Tonydamato,
Sounds like it could be a grounding issue to your starter.

 

[jeffy777]

Mine does some weird **** when its really cold out. like below 30 degrees. The wait to start light will go on for longer as it should when its cold out and when I go to bump the motor over the starter will just disengage after about 1 second, it wont continue to crank. I usually have to bump it over 4-5 times to get it start when its cold out. Normal spring, summer, fall temps above 40 degrees it fires immediately.

My feeling is your batteries are weak. You can try to recondition your batteries. I use a 24 volt charger/starter system and recondition them in place. Many people take out their batteries out and charge them with their 12 volt charging equipment. The 24 volt system is kind of weird so if you condition one battery and leave one alone you will be generally in the condition like you did not charge it at all.

This maybe that the regulator on your alternator is outputting a little less than you need. If you have a 60 amp alternator I believe the regulator can be adjusted.

I like you lived in the land of Many Cheese Eaters and enjoyed a kringle at Christmas time. When your batteries are weak sometimes you might turn you lights on for a few seconds to get the current flowing to start you car in cold weather. You might want to get a block heater, diesels are hard starters in cold environments.

 

[papakb]

I'd never thought about this before but hitting the throttle to the floor is the same thing you do when you ford a vehicle. What this does is causes the fan to disengage for about 20 seconds. We all know the fan is a load on the engine when it's running, I wonder if releasing it allows the engine to turn over just a bit faster and lets it start?

 

[snowtrac nome]

sounds like air is getting into the system over night, try bleeding the fuel system first thing in the morning. If your battery's are in a weakened state the starter may turn over good but you wont have the power to open the fuel solenoid. cold start procedure for a 6.2 diesel is to crack the throttle halfway when starting cold. I live where it drops to -20 on a regular basis we used to start Humvees all the time with out preheating them. I admit the cucv's and Humvees we used on a regular basis were plugged in, but at freezing they should start just fine. Its dipping to 0 right now and my lmtv is starting just fine with a shot od starting fluid from the injection system, the point is these rigs were intended to be started in those conditions, if they aren't starting something is wrong follow the troubleshooting flow chart.

 

[Retiredwarhorses]

I'd never thought about this before but hitting the throttle to the floor is the same thing you do when you ford a vehicle. What this does is causes the fan to disengage for about 20 seconds. We all know the fan is a load on the engine when it's running, I wonder if releasing it allows the engine to turn over just a bit faster and lets it start?

The fan clutch is hydraulic...

 

[Milcommoguy]

First time "cold" start the fan should already be disengaged as soon as the PS pump get up to speed and pressure (less that couple of sec.) I don't think the fan module is going to respond at this point to disengage the fan on a cold engine. Now if engine was 230 degrees +/- and fan engaged, then you get 20 seconds +/- of a free wheeling fan with a bump of the pedal to the metal and system working correctly. (switch right side of IP, module, C valve and PS pump)

At the slower cranking speeds of stating, the fan is not moving that kind of air to tax the starting process... that's what I'am thinking.

Got to have good batteries. With the crazy and quick change in the weather, highs in the 80's all is good, 25 degree cold snap following week... tired batteries, could point to lower cranking power along with the 70 amps (intermittent) of glow plug current, little thicker oil, finicky IP, fingers crossed moment... Stand-Clear for engine start.

CAM

 

[1 Patriot-of-many]

Thanks for the feedback. The former owner had switched out the plugs just prior to my purchase. He said they were swollen and difficult to pull.

I had tested a few of the glow plugs in the block and they measured at 1 ohm, which looks to be good.

My wait light is staying on for 9 seconds, so it looks like controller is good.

Jeffy777, funny you mention that because I've been stepping on the gas pedal as a turn the key, and it hasn't made a difference. But this morning, I started cranking and then pushed the pedal to the floor once and got off it. After a few cranks it started up. Now this was the coldest morning we've had in at 56 degrees (Los Angeles freezing ) , so it shouldn't have been so easy.
Perhaps the grounding or just using the proper cold start procedure has worked.

I'll try again tomorrow and report back.

b. Using multimeter, check glow plug
internal resistance (Figure 12-5)
Connect one test lead to terminal (1) and other
test lead to threaded area (2).
Glow plug internal resistance should be 1.5-5.0
ohms. If resistance is not 1.5-5.0 ohms, replace
glow plug.
Figure 12-4. HMMWV Glow Plug. According to the hmmwv-test diagnostics pdf, it's 1.5-5 ohms.

 

[donquijote]

Mine does some weird **** when its really cold out. like below 30 degrees. The wait to start light will go on for longer as it should when its cold out and when I go to bump the motor over the starter will just disengage after about 1 second, it wont continue to crank. I usually have to bump it over 4-5 times to get it start when its cold out. Normal spring, summer, fall temps above 40 degrees it fires immediately.

One of mine does the same with the starter disengaging after 1 sec when its cold.

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[jeffy777]

Another key issue not mentioned here is how you are using your HMMWV. Mine is not a daily driver it is driven once a week or once every two weeks. If you drive your HMMWV regularly let's say every other day of more frequent your issues will manifest themselves differently than someone who is driving like me or less.

If you are driving very regular and your HMMWV has problem starting I would look into my glow plugs, I would look into troubleshooting flow chart right away. A vehicle sitting can have issues arise directly caused by sitting. So as we talk about the problems starting knowing the regularity the user has used the vehicle up to the starting issue changes how I would trouble shoot it. Ultimately it gets to what SNOWTRAC NOME said, follow the trouble shooting flow chart.

 

[tonydamato]

Mine are stored during the winter as I don't want the salt to eat them but I drive one of them nearly daily in the summer, back and forth to work 30 miles each way pretty much everyday.

 

[ikoinu]

Had a second today after doing coolant flush, replacing all hoses, thermostat & installing block heater.

Tested glow plug lead (only 1) and found that it's getting 24v when key is in the on position constantly, regardless if coolant is cold or hot and stays 24v after the light goes out. The wait light acts like it should, only glowing for 9 seconds during a cold start and not when engine is warm. The power goes off to the plugs after the engine starts.

Have to test the plugs, but more then likely the new plugs in there will be fried, hence the cold start issue.

So, I'm assuming I have a box issue, although the wait light is working properly. If I need to replace the box, do I get a new Nartron Electrical Start System & SSI?
I currently have a Nartron Yellow Label.

Additionally, does anybody find this system to be a little silly & overly complicated? Hard to keep track of all the parts in the system. Is there anything simpler out there to replace it? Manually operated glow plug switch set up perhaps?

 

[tonydamato]

Im wondering what box is best to buy. Seems Nartron and KDS both offer a box, but why one over the other?

 

[jeffy777]

Both work as far as I know. The KDS is suppose to be considered the best. Maybe I am clouded by my respect for RWH(Retired War Horses). I think searching through the threads you will find people are happier with the KDS S3 because it has no afterglow. Also I hear it last longer, tastes great and less filling.