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some warmth from below, normal?

Discussion in 'Transmission & Transfer Case' started by Mojave_Muse, Jun 18, 2021.

  1. Mojave_Muse

    Mojave_Muse Full Access Member

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    specs: 82 c10 burb 2wd 6.2 700r4

    now that i've got my big brown box legal i'm able to tool around town, get all the juices circulated, listen for odd behavior etc. so they can be addressed before I take it camping.

    after hearing my debt card cry putting fuel in it I note that the trans humb has some heat radiating off. not cooking eggs or anything heat just warmer than the brisk 103 degrees coming through whats left of the original carpet and underlay.

    sorry for the dumb questions :)
     
  2. SirRobyn0

    SirRobyn0 Full Access Member

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    I have gas truck so not exactly the same. I have never noticed heat off the trans hump, but also I can not think of a time I have put my hand on it after driving it. Also I put $140 dollars in gas in my truck yesterday between the two tanks, so I hear you there!
     
  3. Bextreme04

    Bextreme04 Full Access Member

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    It's a 700R4, so if you don't have an external trans cooler you need to get one ASAP. Especially with a big heavy burb in Cali desert heat. I would highly recommend a Tru-cool 40K, they run about $160 and have everything you need to mount in front of the radiator. You will want to keep the radiator cooler in-line to warm up the trans on those 15 degree desert nights. I'm planning on upgrading my current external cooler on my 2011 Suburban with 5.3/6L80 to the Tru-Cool one in the future, since I was down your way a few weeks ago with my smaller travel trailer and I was hitting 225 degrees pulling the grapevine. The 100+ degree ambient temps mean you need all the external cooling you can get, since the thermal transfer efficiency plummets at those temps.

    I would also suggest having a qualified transmission shop adjust your TV cable, that can also be out of adjustment and cause the trans to get VERY hot, VERY fast.

    The cheapest place I've found to get the tru-cool is Oregon Performance Transmissions at $149. https://www.oregonperformancetransmission.com/product/LNG-47391.html

    They also sell a Hayden 30k cooler that is probably a decent choice and about half the cost. I know that hayden just recently moved production to Korea though and has had some quality control issues. YMMV
     
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  4. Mojave_Muse

    Mojave_Muse Full Access Member

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    ok I braved the heat...well muggy heat which is worse, and I see a mini "radiator" in front of the main, following the hoses they go down and back, changing to hardline so I can only guess that would be a trans cooler and not a condenser
     
  5. 75gmck25

    75gmck25 Full Access Member

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    Also take a close look at the cab bushings (or equivalent on a Suburban) to see how much they have collapsed. When I replaced them on my K25 I found that the cab floor had been resting right on top of the transfer case, and with new bushings there was now an air space.
     
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  6. Mojave_Muse

    Mojave_Muse Full Access Member

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    after consideration, that's probably an oil cooler. so gonna add a trans cooler to the upgrades list.

    how much of a pain in the rear end were the bushings to replace. the running boards on the burban and riding at stock height...not super easy to crawl in and out of.

    theres good chance they're heat rotted from its previous life as an improvised shed.
     
  7. Bextreme04

    Bextreme04 Full Access Member

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    Yes, usually it will be on the passenger side for a trans cooler and drivers side for an engine oil cooler. Size and type are very important for trans coolers and it could also be plugged which would cause excessive heat. The Tru-Cool 40k is massive and also the most efficient design, which is the stacked plate design. A standard stock external trans cooler will be stacked plate, but about 1/4 the size of the Tru-cool. You are operating in what the manufacturer would consider an "extreme operating condition" at over 90 degrees ambient and I would bet everything is old and at least partially plugged as well. A thermal temp gun could help you tell if the cooler is plugged and also approximately what temp the trans is getting to. My 2011 with an external cooler and all new parts tends to run 75-100 degrees above ambient until it hits a big hill under load. Once its full load up a grade, it will hit a max of about 100-140 above ambient. A bigger external cooler should bring that down by at least 20-40 degrees.

    The cheap coolers are often just a tube and fin design, which isn't very efficient at all. The TV cable being out of adjustment and the torque converter lockup not functioning can be reasons for extra heat to build up in the trans due to slippage and can cause a 700R4 to go out much faster. TV cable can cause drivability issues followed by very quick trans death. Torque converter not engaging lockup would just mean you are running at a higher RPM than necessary at speed on the highway and therefore generating more heat.

    The point about body mounts is a good one. Your trans might be totally normal and you just feel more heat due to something like that. The higher trim trucks will have a thicker carpet and thick insulation on the floor and the trans hump. Check to see if you have thicker insulation or if its bare there. Also look underneath and see how much clearance you have from trans to the underside of the body. A third option is that you could be feeling exhaust heat transmitted through the floor. Look to see where your exhaust and mufflers run and how close they are to the body. Sagging body mounts combined with a cat to close to the floor and minimal insulation might cause some hot feet.
     
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  8. Mojave_Muse

    Mojave_Muse Full Access Member

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    it's got insulation, it's a Silverado trim (ooh lala)
    it's just been well used, I think i'm owner 4 or 5 and the carpet is original. Drivers side has a great circle where every foot has stepped to get in lol. but there is underlayment under the carpet.

    ya already sold me on the cooler, I got a pdf of how to do the TV adustment ready to go off summits website. it's potentially something that we can do ourselves. always nervous about going to shops because more than once i've been treated as unknowledgeable because I have headlights, but also if I fork it up its on me and not having to fight back n forth with a shop.
     
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  9. Grit dog

    Grit dog Full Access Member

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    I doubt a diesel Burb doesn’t have a trans cooler unless someone removed it.
     
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  10. Bextreme04

    Bextreme04 Full Access Member

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    I get it, I'd be careful with the TV cable adjustment though... apparently it is critical that it be done EXACTLY right. I've only ever worked on the more heavy duty TH400, 4L80E, and 6L80E so I'm not super knowledgeable on the 700R4's. I've heard more experienced trans people on here say that the correct way to do it is with a line pressure gauge hooked up. @Matt69olds and some others would be more knowledgeable on that for sure.
     
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  11. Mojave_Muse

    Mojave_Muse Full Access Member

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    the PO monkeying has been surprisingly minimal on this rig, it's just got the one cooler in front of the rad that I can see. the build spec sheet doesn't have a trans cooler listed, if that was something that would be on there (not that that matters so much on a 40 year old vehicle)
     
  12. Bextreme04

    Bextreme04 Full Access Member

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    The diesel will definitely have a trans and engine cooler in the radiator. It may or may not have external engine and/or transmission coolers. There are a few cooling packages that would maybe show up on the build sheet under various options. Is it a trailering special? That would have Z82 RPO. There was also a note in the vehicle information kit for 82 that says 4.11 axles will get you an external engine oil cooler on the diesel package.
     
  13. Mojave_Muse

    Mojave_Muse Full Access Member

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    just list 1B3J Diesel eqp package, standard rear axle locking diff.
     
  14. Mojave_Muse

    Mojave_Muse Full Access Member

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    Today is a bit less extreme out. looking at the schematic from LMC Truck looks like the the trans cooler lines run to the Radiator. so i'll pop the hood and take a lookie to see if we got that running.
    will report back.
     
  15. Mojave_Muse

    Mojave_Muse Full Access Member

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    lines on the other cooler run to trans, the cooler is kind of dinky though so might go ahead and upgrade.
    warmth might also be due to a good size patch of the underlay and carpet is gone and the exhaust runs near there too. but its not Hot/scalding temps just warm.
     

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