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2004 gmc envoy_sle_xl
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Discussion Starter · #1 · (Edited)
I took my popup on a 300+ mile trip over the weekend. Did really well going up and down the central PA mountains. Has 238,000 plus miles on the old girl and no complaints. Camper weighs a little over 3000#. Don't think I would want to go much bigger with only having the 4.2l, but overall very pleased. I recently rebuilt the transmission myself, and upgraded all the usual stuff, transmission temp only touched 195ish once for a minute climbing the biggest hill we hit, other that that stayed around 160-180ish.

Wheel Car Tire Automotive parking light Vehicle


Here's a photoshop I did with my other car...


Wheel Car Tire Vehicle Cloud
 

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2004 chevy trailblazer_lt
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Sounds good!

One thing of concern is the low engine temperature. For emissions and maximum fuel economy, the engine temperature needs to be in the range of 195 - 215° F once the engine is up to operating temp. Did you happen to install or have installed a 165° F or lower thermostat?
 

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2004 gmc envoy_sle_xl
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Discussion Starter · #3 ·
Sounds good!

One thing of concern is the low engine temperature. For emissions and maximum fuel economy, the engine temperature needs to be in the range of 195 - 215° F once the engine is up to operating temp. Did you happen to install or have installed a 165° F or lower thermostat?
Yes, the transmission temps were what I was noting, the engine stayed right around 210-215. I changed the thermostat and fluid this spring.
 

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2004 chevy trailblazer_lt
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OK, thanks for the clarification. Transmission temps did really well! Do you use an auxiliary cooler for the transmission fluid?
 

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'05 Chevy TB EXT
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Last night and part of this morning, I towed a broken down buddies Ford E450 Diesel extra long van, full of new trailer tires on steel RV rims, including some more of the same on the roof rack.
It had a 6x8 single axle trailer on the back of it that had another 48 tires on it .... northbound over the Chief Joseph Pass from Salmon ID to Lolo, MT with my 2005 TB/EXT 4.1/4L65E.​

In Montana, you can double tow on a standard license.

My transmission temperature got up around 220°F and the engine coolant was the same when I pulled the grade from Salmon to the top of The Continental Divide .... but it dropped back down to 175°F on the downhill side.

The turns on both sides are diminishing return (they gradually tighten up further into the turn) and I used mainly 2nd/Intermediate and 3rd/Direct in manual position and the TCC was in and out on the climb but quiet on the engine braking/downhill side.

I had to use 1st/Low a few times .... just to save the brakes. This was without being able to use my TB's trailer brake controller. Yeah, I know .... that's why we ran during the quietest traffic times.

This was without any add-on transmission cooler at all ... just the S10 convertor and a fresh rebuild with a Shift Kit and 5-pinions, etc.

If your transmission runs too hot and it's time for a rebuild ..... I firmly suggest the same buildup as mine.

You won't need an auxiliary cooler and your fuel mileage will get a serious kick up a few more miles per!

I'm pretty sure I towed well over 13,000 lbs.

I got crappy fuel mileage though .... crawling up the Idaho side at 40 MPH.... sometimes a little less ... but I sucked up a little more than 2/3rds of a tank of gas on the return part of the trip.

Oh yeah ... I had 5 people with me ... one in the E450 to steer and help (minimally) add some braking.

Soooooooo ..... the TB did pretty good for itself last night ....... and never complained.
 

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2004 chevy trailblazer_lt
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Thanks for the info!
 

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'05 Chevy TB EXT
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Yes, I have an auxiliary cooler installed downstream from the one in the radiator. Put that on when I did the rebuild last year.
Wrong placement for the cooler.

It should go before the radiator heat exchange unit to remove any thermal overload to the engine cooling system as a potential to making the coolant in the radiator work load increase so high that the engine suffers.

The so-called "transmission cooler" inside the radiator is actually a "heat exchange" unit that insures the transmission runs at a standardized value at right around 160°F as it will extract engine temperature to heat itself up to that value.

A transmission that runs too cold will damage it too.

Heat flow should be
>> from transmission >> to radiator heat exchanger >> to transmission.​

Adding an auxiliary cooler should be like this:
>> from transmission >> aux cooler >> radiator heat exchanger >> to transmission.​
 

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2006 gmc envoy_sle_xl
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Last night and part of this morning, I towed a broken down buddies Ford E450 Diesel extra long van, full of new trailer tires on steel RV rims, including some more of the same on the roof rack.
It had a 6x8 single axle trailer on the back of it that had another 48 tires on it .... northbound over the Chief Joseph Pass from Salmon ID to Lolo, MT with my 2005 TB/EXT 4.1/4L65E.​

In Montana, you can double tow on a standard license.

My transmission temperature got up around 220°F and the engine coolant was the same when I pulled the grade from Salmon to the top of The Continental Divide .... but it dropped back down to 175°F on the downhill side.

The turns on both sides are diminishing return (they gradually tighten up further into the turn) and I used mainly 2nd/Intermediate and 3rd/Direct in manual position and the TCC was in and out on the climb but quiet on the engine braking/downhill side.

I had to use 1st/Low a few times .... just to save the brakes. This was without being able to use my TB's trailer brake controller. Yeah, I know .... that's why we ran during the quietest traffic times.

This was without any add-on transmission cooler at all ... just the S10 convertor and a fresh rebuild with a Shift Kit and 5-pinions, etc.

If your transmission runs too hot and it's time for a rebuild ..... I firmly suggest the same buildup as mine.

You won't need an auxiliary cooler and your fuel mileage will get a serious kick up a few more miles per!

I'm pretty sure I towed well over 13,000 lbs.

I got crappy fuel mileage though .... crawling up the Idaho side at 40 MPH.... sometimes a little less ... but I sucked up a little more than 2/3rds of a tank of gas on the return part of the trip.

Oh yeah ... I had 5 people with me ... one in the E450 to steer and help (minimally) add some braking.

Soooooooo ..... the TB did pretty good for itself last night ....... and never complained.
Ravalli- greetings from a fellow Montanan on the other side of the state.Would you mind expanding on your trans build? I also have a 06 tb,but mine is the 5.3 version. I am experiencing very harsh shift from 1st to 2nd,enough so it will chirp the rear tires and set off the tcs. Reading various forums I've seen posted to replace the tps,drain and refill trans fluid and filter which I do every 50k anyways. Being you were a transmission guy I thought I'd seek some insight. Will the s10 convertor fit the v8? Talking to some gm mechanics they mention getting a setup with different valve diameters,does this make sense to you? Thanks,John
 

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'05 Chevy TB EXT
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Just when most people WANT 2nd gear chirps ---> ahem! ...well --- let's talk S10 convertors first .....

The sole reason for going to a smaller convertor is so that the engine can force it to higher RPM, allowing the engine to get into it's power curve sooner and easier.
This is therefor called a High Stall Convertor since it lets the engine rev higher from a startup condition.

Since the convertor also has a TCC clutch, no efficiency ie: (no) economy is lost --- well, not much anyway.
The convertor will still get to lock up depending upon the setting(s) in the TCM and/or the Shift-Kit™ and if or not a 'toon is installed.​
Harsh shifts into Intermediate/2nd from Low/1st are USUALLY caused by:

  1. Excessive main line pressure --- but this will create other problems that you've not mentioned * - yet.
  2. The Throttle Position Sensor (TPS) may be creating erratic electrical responses. If the response is jumpy or erratic at all:... replace TPS.
  3. If there's an Intermediate/2nd gear shift shudder at WOT ... and a delayed or abnormal 1-2 shift ---> BUT ONLY on the 1-2 shift ... you might have a cracked or cocked 1-2 accumulator piston in the bore. There's a yellow spring inside the 1-2 accumulator and it can force the piston to cock or the spring can dig into the walls of the servo and destroy the transmission case ... if so the transmission case must be replaced.
  4. SOMETIMES ---> if accompanied with harsh shifts from P or N, but shifts become normal at WOT ...... this might be the EPC solenoid.

* This may show up suddenly and also intermittently --- it may not be malfunctioning sometimes --- other times ---> it will
 

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'05 Chevy TB EXT
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Now --- about shift valve diameters -----

Just get Gil Younger's Shift-Kit™ called: TransCo and that should get you what you want ---
--- but I'd personally have that unit reman'd at least first and make sure that you get that PWN deleted too! .
 

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2006 gmc envoy_sle_xl
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Thanks for the info. I don't know if it's heat related but after about 10 minutes of stop and go traffic in the mornings and afternoon it starts the 1st to 2nd harsh shift pretty much everyday with an ocassional day of smooth shifts. Also of note at WOT it doesn't shift hard but I do get a whining noise that builds until it shifts. I've been procrastinating long enough and I can tell it is raising hell with my ujoints I can geta rebuilt trans from automatic transmission company (ATC) here in Billings for about $1400 with me doing the r&r. Thanks Ravalli.
 

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'05 Chevy TB EXT
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Yeah --- your latest statements suggest a wasted 2/4 servo wall in the case.

The whining is the reduction gearset.
They may explode because the pinions are likely wiped out and let the gears assume incorrect tooth patterns (the noise) ........ if you drive that unit much more.​

ATC is good people --- at least when I knew them .... but try to get some upgrading done to it with the Shift-Kit® and for SURE have the PWM-Delete installed.
 

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2006 gmc envoy_sle_xl
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Yeah --- your latest statements suggest a wasted 2/4 servo wall in the case.

The whining is the reduction gearset.
They may explode because the pinions are likely wiped out and let the gears assume incorrect tooth patterns (the noise) ........ if you drive that unit much more.​

ATC is good people --- at least when I knew them .... but try to get some upgrading done to it with the Shift-Kit® and for SURE have the PWM-Delete installed.
Thanks again Ravalli, I will call Rex at ATC and see if they'll do the upgrades without screwing the warranty.
Thanks, John
 

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'05 Chevy TB EXT
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It is usually separate from the Shift-Kit® and can be bought that way - but I know it also comes in the kit if you want it.

It ceases the TCC from slipping and sliding and creating heat and wasting energy and costing fuel and money and requiring you add an auxiliary transmission oil pre-heat exchanger --- etcetera, etcetera, etcetera.
 

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'05 Chevy TB EXT
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Well ..... when it comes down to the truth --- there is both a 'tooned ECM and a stock one with which I can (but don't) swap around for kicks and giggles.
 
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