Can We Get a 'Warm Start Issues' Sticky?

[tgtaylor64]

For years, my 1984 M1009 has not missed a beat starting. Whether it was 20°F or 110°F, it fired right up. Lately, after sitting around an hour or two after fully warming up, it takes several tries to get it to start. Cold start is no issue; only warm after sitting. I have replaced the temperature sender for the glow plugs but that has not helped. This appears to be a very common problem and I would love to see a hopefully short list of what to investigate first, second, third, etc.

 

[antennaclimber]

Next time this happens, try manually turning on the glow plugs for about 5-8 seconds and see if it starts.

I have 2 trucks that do the same thing, after sitting for 30-60 minutes it takes at least 10 seconds of cranking. I found that turning on the GP's for a short period of time, they start right up. The 3rd truck starts no matter what the temp is.

I was thinking that the engines may have low compression on one or more cylinders, after testing them, all were within spec according to the TM.

The next thing to check is starter motor cranking speed. We all know engine cranking speed, fuel and compression all have to be just right for these engines to start. All my trucks seem to be spinning about the same speed during starting.

This past Friday we started testing a modification/option for the new glow plug cards for trucks that exhibit this problem. It may be a permanent production change to have user selectable option to have a "hot" card. The modified card will turn on the GP's at a higher engine temperature and more often than the stock cards.

Yes, this hot card option will turn of the GP's more often and may shorten the life of them. But I would rather replace GP's than a starter motor due to excessive cranking time.

Right now I have one of the hot cards in my M1009 and it has helped eliminate the warm start issue. We still have a lot more testing to do before (if any) changes are to be made.
Karl

 

[m16ty]

I have found on several CUCVs that a warm starting issue was a dying injector pump. Next time is doesn't want to start, try pouring some water on the IP. If the water seems to help, your IP is going bad.

 

[Keith_J]

Also, could be the starter. The brushes wear, making for poor contact. Then when hot, the combined resistances of the brushes on the commutator and windings mean for low cranking speed.

Get the starter motor overhaul kit (listed in the wiki) and dust off the -34 to see how to replace brushes and bushings. If the bushings are worn, the brushes need it too. I've turned commutators with a 1/2" drill press and a file, works great.

 

[tgtaylor64]

I have done as you suggested and it did help. Does that mean my temp sensor is failing by not giving a lower resistance to cause the GPs to come on?

 

[tamecrow]

The hard start when hot problem is usually a warped head on the injection pumps head and rotor assembly. If it starts better when you run cold water on the pump or override the glow plugs this is likely the issue. Common problem with the 6.2 DB2 pumps.

 

[antennaclimber]

I have done as you suggested and it did help. Does that mean my temp sensor is failing by not giving a lower resistance to cause the GPs to come on?

I don't have an explanation as to why some are hard start and some are not.

As others have suggested it could be an IP problem.
However, one of my trucks that has this issue has a new pump on it.

So far the modification to the GP card has greatly reduced the hard starting issue on the M1009, the M1008 will be the next trial vehicle.

 

[tamecrow]

However, one of my trucks that has this issue has a new pump on it.

Is the pump new or rebuilt?

Many of the rebuilt pumps have this problem because when they're rebuilt and run on the test bench they test fine at room temperature. Since a worn head and rotor usually shows symptoms when the pump is hot, the problem doesn't occur until the pump is installed and becomes heat soaked under the intake.

There's an updated head assembly for these pumps. Stanadyne part # 31816. A new head assembly cost ~$500.00, so not many rebuilt pumps will have a new one.

As long as there's no other symptoms from the pump, the modified GP cards or manual override should be a good work around.




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[antennaclimber]

Is the pump new or rebuilt?

Many of the rebuilt pumps have this problem because when they're rebuilt and run on the test bench they test fine at room temperature. Since a worn head and rotor usually shows symptoms when the pump is hot, the problem doesn't occur until the pump is installed and becomes heat soaked under the intake.

There's an updated head assembly for these pumps. Stanadyne part # 31816. A new head assembly cost ~$500.00, so not many rebuilt pumps will have a new one.

As long as there's no other symptoms from the pump, the modified GP cards or manual override should be a good work around.

The pump is a rebuilt unit.

I was not aware of the head temperature issue. I appreciate your sharing us with that info.

But for now I will just continue to heat it until I get the urge to install another IP in it.
Thank you.
Karl

 

[GPrez]

I have the same issue on my 1028. I've replaced the temp sensor and glow plug card with no improvement. I'm going to go ahead with the momentary switch to energize the glow plugs manually like I did on my 1009. I wanted to do this anyway since it doubles as a anti theft device if you put the switch in a non visible area.