CK5
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The RedBurb

Every Part Is Replaceable
Interesting. I only have dome light switches on my 2 front doors, not the other 4. I have always figured that this didn't seem right. Glad to know GM corrected the oversight eventually...

That was an Andy-initiated correction, actually.
 
That was an Andy-initiated correction, actually.

You said your switch disables the dome light when the doors are open. But on my truck there's nothing to turn it on in the first place. Unless the driver door opens or the dash switch is toggled, the lights do nothing.

I've gotten used to it, and it's still a step up from the CUCV. But I'd kinda like to have rear dome light switches.


You know...So I can add another switch to disable them. ;)
 
You said your switch disables the dome light when the doors are open. But on my truck there's nothing to turn it on in the first place. Unless the driver door opens or the dash switch is toggled, the lights do nothing.

I've gotten used to it, and it's still a step up from the CUCV. But I'd kinda like to have rear dome light switches.


You know...So I can add another switch to disable them. ;)


Lol. I understand what you’re saying now.
 
That seems pretty high, I have to tow a heavy trailer up a hill to get my egt's over 800. Idle they'll drop to 300 or less.

My theory was correct, I think.

This is what I experienced this time:

Idle: 250
Cruising: 500
Acceleration: 700

Though I did see it get up to 1000 while climbing a bridge.
 
That seems much happier.

Maybe. Was climbing up a steep bridge tonight at 65mph and the egts got up to 1400. :yikes:

But it seems the big concern is sustained egts. This was a predictable spike. As soon as I created the bridge and let off the throttle it dropped right back down to 800.
 
So I finally read through this. You've done a ton of work to this.

Maybe. Was climbing up a steep bridge tonight at 65mph and the egts got up to 1400. :yikes:

But it seems the big concern is sustained egts. This was a predictable spike. As soon as I created the bridge and let off the throttle it dropped right back down to 800.

Ok, now I know it was a spike but 1400 is way way too hot for a 6.5. You're probably lugging the engine too hard. These are not fans of lugging like a Cummins is. Let it drop a gear and rev, it'll be much happier.

The most you ideally would see is 1100 and that's for a turbo version. NA really shouldn't go much over 1000.
 
So I finally read through this. You've done a ton of work to this.



Ok, now I know it was a spike but 1400 is way way too hot for a 6.5. You're probably lugging the engine too hard. These are not fans of lugging like a Cummins is. Let it drop a gear and rev, it'll be much happier.

The most you ideally would see is 1100 and that's for a turbo version. NA really shouldn't go much over 1000.

Thanks! I appreciate it. This truck is plagued with difficulty in just about everything I do to it, so it’s easy to get discouraged at times.

You’re probably right about the lugging. This particular bridge (where I witnessed the 1400 spike) has always been a difficult one to pass; steep and long, and at highway speeds. I’m usually at about 70mph when I approach it and have always avoided dropping to 3rd gear thinking the revs would be too high. Usually lose 5-10mph by the time I get to the top.

Next time I’ll try going ahead and dropping to 60mph as I approach, and drop to 3rd as it gets steep, and see if the EGTs are any better.

Fortunately I hardly ever have to drive that route.
 
You're running 4:10 with 37s right? If so you definitely don't have to worry about dropping down the 3rd while holding 70. You'll hold speed better too.

I have 4:56s with 35s on mine and I never worried about rpms if it downshifted at 65 or 70. The governed speed of a stock pump on a 6.5 is around 3500rpms. You can run it right at and not hurt it.
 
You're running 4:10 with 37s right? If so you definitely don't have to worry about dropping down the 3rd while holding 70. You'll hold speed better too.

I have 4:56s with 35s on mine and I never worried about rpms if it downshifted at 65 or 70. The governed speed of a stock pump on a 6.5 is around 3500rpms. You can run it right at and not hurt it.

Actually it has tall 33s on it now. The 37” militaries that came with it were shot, as were the 16.5s. So I swapped with 305/70R16s.

“Its the more practical choice” I told myself.

Should’ve stayed with the 37” size. My rpms are about 300 higher now and my fuel economy suffers too. The engine was pretty happy with 4.10s and 37s. I’ll be going back to that when these get replaced.
 
Actually it has tall 33s on it now. The 37” militaries that came with it were shot, as were the 16.5s. So I swapped with 305/70R16s.

“Its the more practical choice” I told myself.

Should’ve stayed with the 37” size. My rpms are about 300 higher now and my fuel economy suffers too. The engine was pretty happy with 4.10s and 37s. I’ll be going back to that when these get replaced.

One of my rigs had 4.10 & 33" tires. Stock 6.5TD with NV4500. The combination was good for towing, but it was overgeared for cruising unloaded. 3.73:1 is a better ratio for my usage patterns.
 
4:10s with 33s you shouldn't be having any issues holding speed. It is better for towing but you are driving a giant brick.

What kind of mileage are you getting?
 
4:10s with 33s you shouldn't be having any issues holding speed. It is better for towing but you are driving a giant brick.

What kind of mileage are you getting?


Between 12-13mpg. Before I tossed the 37s it seemed like I was getting more around 17.
 
Between 12-13mpg. Before I tossed the 37s it seemed like I was getting more around 17.

Hmm, that's a pretty big drop. First are you sure the speedometer was accurate with the 37s? Did you correct it when you went with the 33s?

Even with 4:10s you should still get a solid 16/17 on the highway.
 
Hmm, that's a pretty big drop. First are you sure the speedometer was accurate with the 37s? Did you correct it when you went with the 33s?

Even with 4:10s you should still get a solid 16/17 on the highway.

Yeah it is a big drop. Has been kinda disappointing. The speedometer was definitely accurate with the 37s. Tested it with a gps speedometer app on the phone.

I haven’t corrected the speedometer yet with the 33s. Figured if I was planning to go back to 37s eventually, then that would be the correction. Would that be affecting my mpg?
 
Hmm, that's a pretty big drop. First are you sure the speedometer was accurate with the 37s? Did you correct it when you went with the 33s?

Even with 4:10s you should still get a solid 16/17 on the highway.

Did some research and learned that because the odometer is driven by the speedo cable, then it is also off by the same % the speedometer is.

So at cruising speeds, my speedometer says I’m going 10 miles faster than I really am.

According to a formula I found, I can use this formula to calculate my actually miles driven:

(Actual speed / indicated speed) x indicated miles driven = actual miles driven.

I hope that’s wrong, because that actually hurts my precious mpg figure of 13mpg:

55mph/65mph = .846 x 380 miles = 321 miles / 28 gallons = 11.46mpg :yikes::yikes::yikes:



I defer to people smarter than I am ...
 
Just remember that it's a variable %, as your speed increases how far off you reading vs the actual will be.

So is your +10 mph at a reading of 65? What's your reading when your actually doing 65? It's probably more then 75.

It makes it hard to get accurate reading for mileage.

How old are your air and fuel filters? Old filters can have a huge affect on fuel mileage.
 
Download a GPS app for your phone. Ulysse speedometer is one I have. It will track miles as well as speed.

Use it for a trip/tank get an accurate reading to check fuel mileage.

I'd look into a speedometer correction box if you want it to be accurate. It just goes inline to the cable and multiple correction amounts are available.
 
Just remember that it's a variable %, as your speed increases how far off you reading vs the actual will be.

So is your +10 mph at a reading of 65? What's your reading when your actually doing 65? It's probably more then 75.

It makes it hard to get accurate reading for mileage.

How old are your air and fuel filters? Old filters can have a huge affect on fuel mileage.

Yeah it definitely changes with speed. Lower speeds are usually 2-5mph off, but the higher speeds are pretty consistently 10mph difference. Maybe 12 when we start getting to 75mph+.

Air filter is pretty much brand new. I put it on a couple months ago. It’s a K&N cone filter clamped on to the end of an M998 air intake horn.

As for the fuel filter. I haven’t touched it since I bought the truck 2.5 years ago. It’s an aftermarket Racor unit, so I don’t know much about it. I probably should look into it.

Download a GPS app for your phone. Ulysse speedometer is one I have. It will track miles as well as speed.

Use it for a trip/tank get an accurate reading to check fuel mileage.

I'd look into a speedometer correction box if you want it to be accurate. It just goes inline to the cable and multiple correction amounts are available.

I’ve got an app that I use occasionally on out of town trips. I’ll make sure to reset the trip on it and record actual miles driven on our trip to Disney this week.
 
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