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Fan on trans cooler?

Discussion in 'Chevy Trucks' started by meborder, Dec 2, 2011.

  1. meborder

    meborder Senior Member
    Messages: 142

    I'm just wondering if there is a general concensus about adding a fan to pull air through the trans cooler. Is it needed?

    I'm new to plowing, so I'm not totally sure what to expect.

    My only frame of reference with regard to trans temp is in my 2000 explorer. I added a trans temp gauge to the cooler return line (as per the instructions), and the ONLY time it reads above 160 is at very low speeds where there is no air flow. The hottest it has ever gotten was 180ish and that was backing my boat into the shed (up hill).

    So I guess what i'm wondering is if there is generally enough airflow while plowing to allow the aux cooler to do its job. As i said, i have no experience running a plow.

    My plan was to put tap a temp gauge into the trans pan, but i'm out of time for the year and it didnt get done. I had also hoped to put a plate and fin type cooler with a built in t-stat and fan, but that aint gettin' done either, not this year anyway.

    If it helps, my plow truck is a 83 K20, 350 4bbl, 700R4. It does have a 4-pass tube & fin cooler right behind the grill. The trans shifts firmly and the fluid is bright red. Also, and i think this is probably a good thing for plowing, the trans seems to hold 1st until 10-15 mph no matter what.

    The truck will only see service around the farm, and to get up over 15mph under the best conditions would require some effort. I have no intentions of setting any speed records while plowing, and it would be great if i could go easy enough to not break stuff. I dont plan to beat on it, unless of course you would just have to in order to break through a drift.

    Any thoughts? Should i just put one on? not needed?

    thanks in advance!
  2. larboc

    larboc Member
    Messages: 98

    700r4 in a k20? Weird.
    Since it doesn't have the transcooler in the radiator Id say you'll be ok if you've got 4.10's and don't do a whole bunch at one time. Plowing by nature gives you colder air to help with temps. A fan wouldn't hurt, I'd start with a gauge though.
  3. meborder

    meborder Senior Member
    Messages: 142

    perhaps i should have been more detailed.

    it has an aftermarket cooler added, so it has both the radiator cooler and the aftermarket unit behind the grille.

    as for gears, i have no idea. Personally, the truck feels underpowered, so i'm thiking it probably does not have 4.10's. but I'm not sure how to tell for sure.

    as for the 700r4, im assuming that is what it is. they were offered as the standard automatic in 83, according to my best research. the shifter says "automatic overdrive" and it does have 4 gears (they all work).

    im at a slight disadvantage here, I'm a ford guy thourgh and through, so i really dont know much about the chevy.

    thanks for the help!
  4. larboc

    larboc Member
    Messages: 98

    Hmm, most 3/4 tons of that era that I've seen have a th400 but if it has 4 speeds (1 2 3 od) it must be a 700r4. no 4l80e's at that time.

    If it's got an aftermarket cooler, I'd bypass the radiator cooler. It will heat up the fluid.

    Check the glove box for ratio codes, usually they are still readable.
    should be one of these two


    other codes for gears.

    GU2 2.73 Rear
    GU4 3.08 Rear
    GU5 3.23 Rear
    GU6 3.42 Rear
    GT4 3.73 Rear
    GT5 4.10 Rear
    HC4 4.56 Rear
  5. sweetk30

    sweetk30 PlowSite.com Addict
    Messages: 1,588

    this is act incorrect info on a auto .

    fluid to cold in a auto will hurt them also. there is more than 1 reason thay added the cooler to the rad.

    look here for all the basic info on auto tranny temps and coolers and gauges all with options. 1 i like the best is the flow stat plubed up it flows threw rad till 180* then opens to flow to aux cooler. helps get warm then if to hot it gets it cool.


    and as to k20 with 700r4 it was only for 1/2 tons . but if like most trucks of this era its a mut truck. prob someone swaped in diffrent axles or body swaped it to replace a rusted out body .
  6. meborder

    meborder Senior Member
    Messages: 142

    I'll check that out here today. thanks!

    As to the trans ... i'm 99.9% sure it is the 700r4. According to the info i can find the 700r4 was offered for the first time in 83. That and my gear shifter reads PRND321, and says "automatic overdrive" right above the gear indicator. If someone were to swap the trans, they would have had to swap dash pieces to match. 83 was also the first year the oil dipstick was put on the passenger's side, that's how i know the motor isn't origional to the truck, mine is on teh driver's side. (and cause a slew of problems because of it too)

    I'll see if i can find the gear codes, it would be nice to know regarless.

    One other thing i noticed is that the aftermarket cooler is plumed in before the radiator. Generally, this is backwards, but in this case, it should keep the fluid from getting "too cold", right?

    thanks for all the help!
  7. sweetk30

    sweetk30 PlowSite.com Addict
    Messages: 1,588

    these style trucks dont have shift index plate in the steering coulme . so thay wouldnt know the diffrence from 3 or 4 speed. and its only few screws to swp the shift indicator out also in the cluster. so swap tranny and dont swap that.

    best go look at the tranny pan and even take a pic and post up here to verify .

    th350 = square pan with 45* chopped off 1 corner
    th400 = texas shaped pan
    700r4 = longer square pan no cut offs .
  8. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    That's actually a very good way to plumb a cooler in a plow vehicle.

    How many lugs on your wheels? How many bolts on your rear differential cover? How many bolts on the transmission pan, and what shape is it?
  9. meborder

    meborder Senior Member
    Messages: 142

    8 lug wheels. door sticker indicates 235/85/r16 LRE tires. 8600lbs GVW IIRC (i'll try to double check)

    I didnt count bolts, but the rear diff is pretty big, i'm guessing it is a 12 bolt, but i didnt count. I cant immagine them using a 10 bolt on a 3/4 ton. It does not look like a dana, but i'm not an expert.

    From what i can remember, the trans pan is completely square. Besides which, ive driven it on gravel and it will grab 4th above 45-50. And there is a detent for each forward gear.... it is a 4 speed, trust me. I'm assuming it is a 700 and not a 200. i dont think the 200 was ever offered in a truck, that was the car version, right?

    Also, the glove box tag is gone. looks like someone peeled it off.

    I can't immagine that someone would have gone to the trouble of swaping in a 700r4 into a truck that didnt come with one. going the other way, sure, but not from a 400 to a 700 ... this was not a truck that someone was in love with, it has been badly neglected since 1997. I found a sales slip from a local car lot where it was purchased for $3750 with 97,xxx miles (current reading is 03,xxx) Since this time nothing has been fixed until i fixed everything this fall.

    I'll try to post up some pics tomorrow. I'll be using it so i'll crawl underneath and snap a few pics.

    should i be using (1) when pushing snow? i'm hearing that this may be better for the trans?


    thanks for the help!
  10. meborder

    meborder Senior Member
    Messages: 142

    So i got some pics. It was dark and some didn't turn out perfect.

    here's the dash showing the gear shifter indicator, kinda fuzzy but clearly showing PRND321, above it in white says "automatic overdrive"

    Here's a pic of the rear diff cover. I counted 14 bolts around the cover. Looks to me it is a GM Corporate 14 bolt? I also know it is a GM Gov-Loc Limited slip, which works about as well as any Gov-loc I've driven. Sometimes it does get stickey and does not want to engage, but if it has been driven recently it generally engages pretty quickly.

    Here is the trans pan. It is square to me. I'm pretty sure it is a 700r4, but i'm a ford guy, so take that for what it's worth.

    Here's the ugly beast as a whole. Not sure how clearly you could see if you zoomed in, but it says K20 Scottsdale on both fenders.
    Judging by the matching cancer, i'd say at least one of the fenders are original.

    So .... what does one need to know about plowing snow with a 350 CID 700R4 powered K20?
    Last edited: Dec 5, 2011
  11. sweetk30

    sweetk30 PlowSite.com Addict
    Messages: 1,588

    700r4 = yep

    14 bolt semi float light duty rear = yep

    and good old trusty rusty plow truck = yep.

    kind of funny to see 700 in a 3/4 ton but now we know its a light duty that explanes it a bit more.
  12. meborder

    meborder Senior Member
    Messages: 142

    So how well do the 700's work in a plow? I understand the lower 1st and 2nd gears do help, but also that the older versions (such as mine) are more problematic.

    Do they tend to overheat?

    I've heard some people use the pressure port for a temp sender. That makes sense to me, and is by far the easiest. If i'm gonna do something to it now, it has to be quick and easy. Or an emergency ... but that's what i'm trying to avoid :)

    Plow in (1)? Fan on cooler? Don't worry about it?

    This is my first plow truck, so i'm flying blind and i REALLY dont want to blow it up. If a trans goes out, im going to be kinda screwed.

    On a side note, i'm wondering if the 14 bolt full floater wasn't reserved for the diesels in 83. You say it is a "light duty" 3/4, and i suppose it could be, but when i had to buy a brake line for the front, the one for the lighter GVW didnt fit worth a hoot, and i had to get the one for the heavier GVW. It don't matter, i'm just curious. I wouldn't have considered this light duty, it rides like a lumberwagon and has no problem holding my 275 gallon water tank in the back. Like i said, i'm just curious.
  13. meborder

    meborder Senior Member
    Messages: 142

    So, nothing in particular about the 700R4? Just push snow?

    I'm in uncharted waters, any advise in general would be appreciated.

    I'm trying to find time to keep working on the beast, but I'm doing it in terms of "most important to least important", not sure how critical the trans is.

    Should I just plow in (D), or is (1) better? it is a couple of 200ft runs, and a couple areas. that need to be cleared.

    NICHOLS LANDSCA PlowSite Veteran
    Messages: 4,362

    You will be fine with the tranny, that isn't a full floater you can tell by the dif cover. I had a 700r4 in an 86' 3/4ton with a 6.2 and that had a semi floater in it too