6.5 L Diesel Truck Won't Start When Warm

I have a question regarding our 1998 K3500 6.5 diesel truck. I have posed this to many service people, many of whom have made suggestions, none of which have helped. Here is the problem; the truck starts fine and runs well until I shut it off. Then it is difficult or even impossible to restart, unless we leave it sit for four to five hours. When we are traveling, we just cannot stop the engine, unless we are stopping it for 4-5 hours. Service people have already replaced:
  • Computer,
  • Injectors,
  • Batteries,
  • Starter motor,
  • Glow plugs,
  • Glow plug control box,
  • Fuel filter
  • Etc., etc.

Any ideas?

Tom, Austin TX


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Replace the engine thermostat with one that is at least 5 degrees cooler and replace it at least every 2 years. Stop using oil and use only a full synthetic chemical lube of at least 15w50 and possibly 15w50 for the warmer months. Read you manual that came with the vehicle. GM tells you to run the engine for one or 2 minutes when cold then shut off the engine to check the level on the dipstick. You will see that it is now down at least 1/4 to 3/4 of a quart off the not started dip check. This means that your engine has never had the proper amount of oil in the system if you have not done this before. If towing or on super hot days, i always added 1/4 quart over the fill mark on the dipstick to help it run just a bit cooler. The difference can be felt inside the car or truck because the air conditioning will work better as well due to the lower underhood temps. That will save on fuel as the aC system will not have to run full tilt all the time because it is operating cooler. Expect a drop inside the car of at least 5 degrees in city driving with that little trick alone.
Even if the engine has consumed only half a quart after changing it, top up with another half to keep the engine cooler. This makes a huge difference to the air conditioning as well as underhood temps drop. change the fuel filter more often than spec. Add the best brand of diesel fuel additive, bought in 2 quart containers at truck stops. Use it year round for netter performance, mileage and to rid the system of any moisture or water. It also helps to lube the fuel pump better and therefore it will run cooler and last twice as long. Replace the PMD with a remote mount aftermarket unit ( away from the engine heat )as it is designed to remove heat and but it can't do this with the stock GM system as it runs too hot.
Go and drain the trans fluid ( pan )and replace with Mobil One synthetic auto trans oil with a new pan filter. Heat is the killer of transmissions, so to have longer life, run a toggle switch rad fan in front of the rad. Again, this will allow the AC system to run cooler and operate less often saving fuel. Never ever ever overfill the trans fluid by even a drop after it warms up. It will run too hot if it is overfilled because it will foam. Change the trans oil in the pan every springtime or every 25,000 miles.
Check all vacuum hoses 3 times. Use a gauge to be perfectly sure as a pinhole leak sometims cannot be spotted by the old thumb over the end routine. Change any other air cleaner filter buts that go to the end of the hoses. Less than 4 bucks and fast & easy to do.
let the engine fast idle in neutral(1,200 RPM )for at least 3 minutes after coming off the highway before shutting off the engine. This allows the turbo and engine to cool down a little as well. Pop the hood to let excess heat out when going in for a bite or even at a fuel stop. This cools the engine and trans significantly. And guess what else runs cooler too ( see above )?
When the air filter gets grey, replace it or at least reverse blow it out with compressed air, gently so you don't blow a hole in the filter membrane. I always kept a new spare air filter in the car or truck as i bought them on sale 2 at a time and saved big money on long trips.
Lastly sell your vehicle and buy a gasoline engine next time. Convert it to propane leaving the gasoline system in place and use only a LPG port fuel injection system. Get a long term fuel contract from a national LPG supply company and get a fleet discount of at least 25 cents per gallon. LPG is 105 octane, has 18 % hydrogen and the engine will last longer than a diesel with less cost for parts and service.
I am a former owner of 7 diesel cars and trucks and have driven about a million miles on diesel and biodiesel. I was a cross border diesel truck driver doing as much as 3,500 miles a week. I used propane in commercial cars and trucks for about 1.2 million miles. For medium and lighter duty propane is best. For any truck with a gross weight of over 28,000 pound, you are better off with diesel if hauling with full loads or towing anything more than 7,000 pounds in a one ton truck.
Been there, done that. Now i am going to go a duck out of the way as all the EXPERTS throw used engine oil at me. By the way, i have an SAE behind my name since 1988 as i was involved with the very first company in Canada to make synthetic engine oils. None of the guys who want to throw darts at me are SAE engineers, so stop listening to the ignorant folk and go with what works. Why pay $9,000 extra plus taxes and finance charges for a diesel engine when you can have a 130 liter propane tank and port fuel injection conversion done for about $6,200 on a pickup truck??
Did i mention that the FEDs give at least a $2,500 tax deduction for converting to propane? Or did i mention that some states give a partial sales tax rebate on the vehicle of $500 to $2,000? No? Sorry, i din't think you diesel lovers liked money. LOL Exit stage right>>>>.
April 08, 2010
Votes: -1

Ryan said:

Its the fuel injection pump, if the injection control module has been replaced. Not sure if that was the computer you stated above.
April 30, 2013
Votes: -1

pat said:

pmd module
It's technically called a pmd module. Pmd stands for pump mounted driver. I know this from my own personal experience.
May 07, 2014
Votes: +0

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Bill Heath owns Heath Diesel Power in Ellensburg, Washington. He races at Bonneville in his 6.5L Land Speed Racer whenever he gets the chance.


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