Any idea what this is or what it's for?
11-11-2015, 10:53 AM
#1
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Any idea what this is or what it's for?
My truck's got two of these in the transmission cooler lines, one right before the radiator in the front, and one right before the super-duty cooler in the rear. I imagine they're meant to allow the fluid to bypass the coolers in the event of a clog, but I'm curious if anyone can confirm this, or know what they're actually there for?
11-11-2015, 02:37 PM
#2
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That H-Valve is not thermostatically controlled, nor is it really a "valve" in the traditional sense – is simply an H-shaped piece of hollow steel tubing.
The operation of this piece of tubing was explained in another recent thread but it is directly related to the viscosity of the transmission fluid – the hotter fluid flows more freely than the colder fluid and that governs which leg of the "H" the fluid flows through. I would think that if the H-Valve is truly a closely calibrated size, then one should stick with OEM tranny fluid and not use something like Royal Purple synthetic, which probably is a different viscosity.
The operation of this piece of tubing was explained in another recent thread but it is directly related to the viscosity of the transmission fluid – the hotter fluid flows more freely than the colder fluid and that governs which leg of the "H" the fluid flows through. I would think that if the H-Valve is truly a closely calibrated size, then one should stick with OEM tranny fluid and not use something like Royal Purple synthetic, which probably is a different viscosity.
11-12-2015, 01:28 AM
#3
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Here you go.
As far as I know there should be only one bypass.
Super Duty Transmission Oil Cooler - Dodge Diesel - Diesel Truck Resource Forums
Jim
As far as I know there should be only one bypass.
Super Duty Transmission Oil Cooler - Dodge Diesel - Diesel Truck Resource Forums
Jim
11-12-2015, 07:32 AM
#4
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I think Jim's right. The grill mounted cooler has air going through it all the time. If it's real cold out, and it over cools the fluid, the fluid flow is reduced and most of it bypasses at the H fitting.
The frame mounted cooler is electric fan cooled and thermostatically controlled. It needs no bypass.
The frame mounted cooler is electric fan cooled and thermostatically controlled. It needs no bypass.
11-12-2015, 03:26 PM
#5
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My 93 W350 with dealer installed Super Cooler has tees at both the cooler lines going to the underbed cooler and where the steel tubes meet rubber at the radiator support.
11-12-2015, 04:57 PM
#6
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And I thought it was a bong. shows how much I know.
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11-13-2015, 11:38 AM
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Thanks for the answers, guys.
I'm wondering just how necessary this device is though. When I look at my '95, there's no sign of one, though the routing of lines up to the radiator.
I'm wondering just how necessary this device is though. When I look at my '95, there's no sign of one, though the routing of lines up to the radiator.
11-14-2015, 04:00 AM
#9
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It is probably not too important here in Southern California or Sunny Florida but wherever it gets down near freezing the high effency of the extra cooling works so well and could starve the transmission for its lifeblood hydraulic oil, from what I was told, this bypass was installed through a TSB and the dealer.
I think this explains seeing the bypass in two different locations.
TSB 07-01-89
Jim
I think this explains seeing the bypass in two different locations.
TSB 07-01-89
Jim
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