[cnctech]

Hello,
This is my first post. What a great site!
I very recently bought my first diesel, a 1995 GMC 3500HD 6.5liter turbo flat bed. I know little about diesels, so I have a few questions.
I changed the oil after having it about a week. The old oil was as black,
as coal, and stained my hands like it had carbon in it.
I checked the oil after probably 1000 miles and it was three quarts low, with no leak being noticed.
Other conditions are:
The power output is low.
The vacuum pump locked up after I had driven it about a week.
The check engine light comes on often for about five seconds.
The fuel mileage is terrible.
Starts fine.
Mileage is 170k miles.
Oil pressure is 40 psi warm running, 20 psi warm idle.
Did I buy a dog?
Thanks for any help you experienced fellows may have.
Charles

 

[gmctd]

Welcome to the forum, cn.............

No vacuum = no turbo = no power = SES lite = DTC's

Black oil is normal, shortly after oil change

Read thru the FAQ's, do the Diagnostics Checklist for more info on your symptoms.

 

[Scrufdog]

Hello,
This is my first post. What a great site!
I very recently bought my first diesel, a 1995 GMC 3500HD 6.5liter turbo flat bed. I know little about diesels, so I have a few questions.
I changed the oil after having it about a week. The old oil was as black,
as coal, and stained my hands like it had carbon in it.
I checked the oil after probably 1000 miles and it was three quarts low, with no leak being noticed.
Other conditions are:
The power output is low.
The vacuum pump locked up after I had driven it about a week.
The check engine light comes on often for about five seconds.
The fuel mileage is terrible.
Starts fine.
Mileage is 170k miles.
Oil pressure is 40 psi warm running, 20 psi warm idle.
Did I buy a dog?
Thanks for any help you experienced fellows may have.
Charles

are you sure you put enough oil in it? About 7-8 quarts. Diesel oil gets jet black after about 2 seconds of being in a diesel, thats normal. It means its doing its job by trapping soot in it. Oil pressure is good.

Power output, vacuum pump and Check Engine light are probably all the same problem.

The wastegate on the turbo is controlled by vacuum. If no vacuum is present you wont get much power. The computer sees a problem and sets off the light. Get a scanner and check the codes and let us know.

Follow the Troubleshooting Checklist in the FAQ and post results. Keep your signature updated so we know what truck and engine you have. Get the 8th digit of the VIN, should be either an F or an S

 

[cnctech]

Talking about quick assistance!
Thanks,
Will consult faqs
Sorry about breaking the conventions here.
Cnctech

 

[jifaire]

It's not a matter of conventions, cnctech ... although some people are pretty snooty about that ...

Truth is, the guys who made the faq's dragged a LOT of info together in one spot, and reading it will give you a much better idea of how your truck's systems affect each other.

You can get help on anything here, but without knowing how things affect each other, you could be asking questions forever.

Filling out the signature IS important, though - without YOUR information, people will just be floating generic advice at you, and it won't be very helpful at all. In fact, a lot of it will be just plain wrong, depending on your truck.

Feel free to ask for help and directions, though!

Some of these guys are geniuses ... and the rest of us know where they're hiding.
Jim

 

[Scrufdog]

Talking about quick assistance!
Thanks,
Will consult faqs
Sorry about breaking the conventions here.
Cnctech

not breaking anything, just pointing you in the right direction

 

[PLANTMAN]

Hope your doing ok with your 3500 hd .i love mine i have a 1997 but i aint scared to jump in .paid $12,000 with 80,000 miles put $4,000.00 in new tranny and case,driveshaft balanced (twice).new rear yoke,dust cover,new motor mounts.mounts broke in mine and craked tranny(be sure to look for)ii whould spend another 4,000.00 if i need too.but this is me dont know much about diesels always had gas is past.if not afraid and have some cash to blow,keep the truck.if your strapped for cash and dont like to turn wrenches,and dont like to read you might sell truck. Remember hd means biggerrrr, larger,more money . Working on my brakes about a week ago,one of my employes beat on my tire for two hours and chould not get off. I got home and beat for 5-10 minutes with a larger sledge hammer and finally kicked off.still having prombles with anti lock system.good luck plantmanspc.yahoo.com

 

[cnctech]

Thanks again, fellows.
I now have a minimal sig. I will add to it as I compile the necessary info.
I did add eight quarts at the oil change, and replaced the vacuum pump when the bad one was discovered. I'll get through the faq's tomorrow night.
Thanks again.
CNCtech