Best Tune Ups

sahls01gmc · January 7, 2008

I have a 2001 GMC 2500LD 4x4 EC SLT. It has 140,000 miles on it, and it hardly shows it. In the year and a half I've owned it, I've noticed that it has gotten slightly worse gas mileage. I have added the K&N FIPK II, and it actually seemed to help more than I thought. As far as maintenence, what should I do first and foremost? The only thing I have changed since I've owned it is the oil (whenever the light turns on), and the intake.

Plugs and wires?

Any low-buck sensors?

Recommended fluid changes?

I've heard that changing your tranny fluid after it has 100k on it may actually hurt it and cause it to fail earlier than not changing it at all? Is this true?

I've listed a lot of things, but if you guys can help with any of these, that would be much appreciated.

Thanks

James

ATMINF · January 8, 2008

One of the first things that I would replace is the O2 sensors, not cheap but over time they slowly go bad and the fuel milage suffers. Also replace the fuel filter. Plugs and wires would also be a good idea. And also all the fluids, coolent, trans, rear diff, transfer case. Then I would check all the fittings, and zerk points and get them greased.

As for trans fluid its a crap shoot with that many miles on it. I recommend changing out the fluid every 30,000 miles, but like you said changing it could "stir" things up?? I have heard it both ways. Also is your trans the 4L80 or 4L60? If its the 4L80 I have heard alot less issues with them. In anycase good luck.

sahls01gmc · January 8, 2008

One of the first things that I would replace is the O2 sensors, not cheap but over time they slowly go bad and the fuel milage suffers. Also replace the fuel filter. Plugs and wires would also be a good idea. And also all the fluids, coolent, trans, rear diff, transfer case. Then I would check all the fittings, and zerk points and get them greased.
As for trans fluid its a crap shoot with that many miles on it. I recommend changing out the fluid every 30,000 miles, but like you said changing it could "stir" things up?? I have heard it both ways. Also is your trans the 4L80 or 4L60? If its the 4L80 I have heard alot less issues with them. In anycase good luck.

How would I know the difference between the 4L80 or 4L60?

Thanks for the suggestions. I'll start making a list

James

wellinghurst · January 8, 2008

quote]

How would I know the difference between the 4L80 or 4L60?

Thanks for the suggestions. I'll start making a list

James

If am not not mistaken you have the 4l80 since you have a 2500--I am sure I will be corrected if wrong...

sahls01gmc · January 8, 2008

If am not not mistaken you have the 4l80 since you have a 2500--I am sure I will be corrected if wrong...

What is the difference?

I do just have a light-duty 2500...does that make a difference?

On a side note....I have noticed that I have a a 1-2 second delay when shifting gears. What would cause that? When i shift into drive, and quickly use the gas pedal....the truck will start going forward, but it seems like it is not fully in gear. Then it will "clunk" and fully engage into drive. The truck will also "hold" the same RPM's in upper second gear under full throttle, even though it is gaining speed.

What causes this? Torque converter going out? Low fluid? Bad fluid? Bad Tranny? High Miles?

This is my first automatic car/truck, so I'm not exactly sure as to how these things react.

James

user3657 · January 9, 2008

the clunk could be your u joints. easy fix while you wait thing at your local shop.

sahls01gmc · January 9, 2008

the clunk could be your u joints. easy fix while you wait thing at your local shop.

It's not the U-joints on the driveshaft....it had those symptons before and after i replaced them! lol

I'm thinking it's somewhere between the transmission and the front wheel drives (the actual axles that go to the front wheels)

Thanks for the help though. Anyone else got anything to add?

James

MEGA14 · January 10, 2008

I have a 2001 GMC 2500LD 4x4 EC SLT. It has 140,000 miles on it, and it hardly shows it. In the year and a half I've owned it, I've noticed that it has gotten slightly worse gas mileage. I have added the K&N FIPK II, and it actually seemed to help more than I thought. As far as maintenence, what should I do first and foremost? The only thing I have changed since I've owned it is the oil (whenever the light turns on), and the intake.

Plugs and wires?

Any low-buck sensors?

Recommended fluid changes?

I've heard that changing your tranny fluid after it has 100k on it may actually hurt it and cause it to fail earlier than not changing it at all? Is this true?

I've listed a lot of things, but if you guys can help with any of these, that would be much appreciated.

Thanks

James

I have had the K&N FIPK on my 8.1 for a couple of years now and I was happy with it until I got tired of the cleaning and oiling chores . Not that I'm lazy , I just found that it got dirty very often and the cleaning/oiling is an overnight task , as the filter must be allowed to dry .

The best alternative I've found is when I switched from Royal Purple oil to Amsoil and found that the warehouse carried an exact replica filter for the K&N .

The new filter needs only to be vacuumed and cost me roughly $60 CDN .

It may just save you a MAF due to the lack of a need to oil it.

Speaking of Amsoil , I switched to it at roughly the same mileage as you have and the frequency of changes is getting longer and longer . You'll also notice more power unleashed .

Cheers.

sahls01gmc · January 10, 2008

Thanks for the replies! This gives me some good things to look for in the future.

Anyone have any ideas what could be causing the weird "delay" when I shift the transmission? It does it going from park (or nuetral) to drive, as well as drive to reverse, and vice versa.

Thanks

James

mz2803 · February 2, 2008

Thanks for the replies! This gives me some good things to look for in the future.

Anyone have any ideas what could be causing the weird "delay" when I shift the transmission? It does it going from park (or nuetral) to drive, as well as drive to reverse, and vice versa.

Thanks

James

i've heard about this on other posts,it could be your slip yoke sticking in the transmission or transfercase.you need to remove the drive shaft and lubricate the yoke with"special lubricant",thats the actual name.you could also use a teflon greese.it will not be a permanent fix but if lubricating it solves your problem gm makes a new yoke that is nickel plated that isn't supposed to stick.the new yoke is available for 4wheel drive modes only,so i've heard?