More Power
07-13-2004, 09:23
I received the following messages from a potential new Duramax owner who was interested in buying a used 2001 truck.
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Friday, June 25, 2004 11:42 AM
Subject: Re: 2001 GMC Duramax 6.6
I'm interested in purchasing a 2001 GMC 2500HD with the Duramax 6.6 Turbo Engine. I've never owned or driven a truck with a diesel engine. On a test drive with the truck I noticed that during idle, the engine seem to hunt or surge. I mentioned this to the used car dealer and he said he had called a GMC dealer and asked him about this and was told that it was a characteristic of the 2001 engine. DO YOU KNOW IF THIS IS NORMAL FOR THIS MODEL YEAR DURAMAX 6.6 Turbo Diesel. (Note: the engine has 99,500, miles on it)
Thank you,
Sidney
Hi Sidney,
No, it is not normal for the Duramax (any model year) to idle the way you described.
There is an updated ECM program available for the 2001 model-year trucks to correct for an idle surge, and I'd recommend you get the programming updated. Secondarily, there were a few trucks that exhibited idle fluctuations that were due to a faulty fuel rail pressure regulator. This could cause the condition you're reporting.
Good luck,
MP
Follow up message:
At 12:53 PM 7/13/04 -0400, you wrote:
The problem described below has been fixed by the used car dealer. The problem was a fuel rail pressure regulator as you thought. After this was fixed, I test drove the truck again and really gave it a once over. The only thing I observed wrong was as follows:
There was a lot of oil residue all over the under side of the vehicle. It does not appear to be leaking anywhere as far as I could see while idling or after driving about 10 miles. The Turbo Charger was replaced on this vehicle at approximately 52,000 miles; could the Turbo Charger cause oil residue to be blown all under the vehicle. I hesitate to buy this vehicle after seeing the oil residue on the undercarriage.
Thank You,
Sidney
Hi Sidney,
The position of the aluminum skid plate can cause oil to drain onto the plate when draining the crankcase during routine service. Secondarily, the crankcase is vented to atmosphere, which can produce some residue to form in the immediate vicinity of the vent tube.
Your description of "all over" sounds like there may have been a problem not necessarily due to the items in the previous paragraph.
There have been instances where either a loose fuel return line fitting beneath the valve cover or a faulty injector caused diesel fuel to contaminate the engine oil. If severe enough, this can raise the oil level to a point where a significant amount of oil/fuel escapes the engine through the crankcase vent, which then creates quite a mess under the vehicle.
GM dealers have access to the warranty repair history of this truck using the "GM Vehicle Inquiry System". Your dealer only needs to do a lookup on the truck's VIN, to verify whether or not the truck you're looking at has been a problem for its previous owner. The only time you have any real leverage with the dealership is before you sign the papers, so I'd make this a condition of sale.
Good luck,
MP
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Friday, June 25, 2004 11:42 AM
Subject: Re: 2001 GMC Duramax 6.6
I'm interested in purchasing a 2001 GMC 2500HD with the Duramax 6.6 Turbo Engine. I've never owned or driven a truck with a diesel engine. On a test drive with the truck I noticed that during idle, the engine seem to hunt or surge. I mentioned this to the used car dealer and he said he had called a GMC dealer and asked him about this and was told that it was a characteristic of the 2001 engine. DO YOU KNOW IF THIS IS NORMAL FOR THIS MODEL YEAR DURAMAX 6.6 Turbo Diesel. (Note: the engine has 99,500, miles on it)
Thank you,
Sidney
Hi Sidney,
No, it is not normal for the Duramax (any model year) to idle the way you described.
There is an updated ECM program available for the 2001 model-year trucks to correct for an idle surge, and I'd recommend you get the programming updated. Secondarily, there were a few trucks that exhibited idle fluctuations that were due to a faulty fuel rail pressure regulator. This could cause the condition you're reporting.
Good luck,
MP
Follow up message:
At 12:53 PM 7/13/04 -0400, you wrote:
The problem described below has been fixed by the used car dealer. The problem was a fuel rail pressure regulator as you thought. After this was fixed, I test drove the truck again and really gave it a once over. The only thing I observed wrong was as follows:
There was a lot of oil residue all over the under side of the vehicle. It does not appear to be leaking anywhere as far as I could see while idling or after driving about 10 miles. The Turbo Charger was replaced on this vehicle at approximately 52,000 miles; could the Turbo Charger cause oil residue to be blown all under the vehicle. I hesitate to buy this vehicle after seeing the oil residue on the undercarriage.
Thank You,
Sidney
Hi Sidney,
The position of the aluminum skid plate can cause oil to drain onto the plate when draining the crankcase during routine service. Secondarily, the crankcase is vented to atmosphere, which can produce some residue to form in the immediate vicinity of the vent tube.
Your description of "all over" sounds like there may have been a problem not necessarily due to the items in the previous paragraph.
There have been instances where either a loose fuel return line fitting beneath the valve cover or a faulty injector caused diesel fuel to contaminate the engine oil. If severe enough, this can raise the oil level to a point where a significant amount of oil/fuel escapes the engine through the crankcase vent, which then creates quite a mess under the vehicle.
GM dealers have access to the warranty repair history of this truck using the "GM Vehicle Inquiry System". Your dealer only needs to do a lookup on the truck's VIN, to verify whether or not the truck you're looking at has been a problem for its previous owner. The only time you have any real leverage with the dealership is before you sign the papers, so I'd make this a condition of sale.
Good luck,
MP