Flush or Replace OEM transmission cooler

Should I Clean/flush, or Replace auto trans cooler?


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454cid

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Until I started poking around, due to this thread, I didn't know that Tru Cool is part of Dana. I could not find a Long Mfg that made coolers, so I wonder if maybe they were absorbed.
 

alpinecrick

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It's part of their LPD line, not sure which feature you're referring to specifically though.

https://trucool.com/products/tru-cool-lpd

After reading the website more closely, it llooks like the M7B has the low pressure drop. Most tube and fin don't have that feature, and some stacked plate coolers don't have it either. The factory trans cooler (which is appears identical to the Tru Cool L7B ) has the LPD feature.
 

LauraT

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Just trying to figure out if I can safely flush my oem auto trans cooler? I can remove it, flush it, use compressed air to clean out solvent, etc... But want to know if it is recommended? I know some say just replace it. I have a brand new GM remanufactured 700R4 in my 92 c1500 now, but trans before this, and right before I bought it went out. Now I just tore up the front crank thrust bearing, apparently from too much pressure on torque converter pushing against crankshaft and pushing crankshaft forward with pressure wearing out bearing. I'd rather clean it out if it is ok.

Waiting to hear what the experts around here have to say
I rebuild these all day everyday and my thoughts on it are first ...what did the fluid and bottom of the pan look like on the last transmission?...if there was any bits of metal or anything besides normal clutch material in the pan hands down replace it because no matter how good of a flush you think youve done a shops done a big huge machine or chemical dissolver has done or promised ....if you cant open that cooler up and see that its clean then trust me its not....little chunk of metal hanging out in the corner...for months days ...fluid changes ...even a trans change ...and then one day it decides it wants to go for a walk down tbe cooler line ...and boom transmission is done ....
On the other side ...if it was normal clutch material ...there isn’t significant rust present on the connectors or leaking ...and when looking into the lines or the connections you dont see a big nasty build up then reuse it with caution. Make sure to blow the lines thoroughly ...if youndo not have an air compressor a bicycle pump with the pointed attachment works just fine as well.
 

LauraT

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No problem!

Just FYI I would not bypass the radiator trans cooler. It actually provides a lot of extra cooling capacity and will also help the transmission get up to operating temperature faster. That last part may not be as important to you being in CA, but the extra cooling capacity will come in handy. Ideally I'd buy a new radiator if I were you, but that's quite a bit more money so if you're going to try flushing something I'd do it with that.
YES PLEASE DO NOT BYPASS THE RADIATOR....the term AUXILIARY means basically “in addition to” not “instead of”
 

Schurkey

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Now I just tore up the front crank thrust bearing, apparently from too much pressure on torque converter pushing against crankshaft and pushing crankshaft forward with pressure wearing out bearing.
The converter pushing forward will tear up the REAR thrust bearing.

Did you wreck the front, or the rear thrust bearing?

Is the crank any good?
 

CHEVYS4ME

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The converter pushing forward will tear up the REAR thrust bearing.

Did you wreck the front, or the rear thrust bearing?

Is the crank any good?
Metal appears to be coming from rear lip of the front thrust bearing. I don't have it apart. Still concentrating on getting new engine built, and truck back on the road
 

CHEVYS4ME

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I changed my trans cooler over to the M7B today. Upon inspecting, I found my truck has the exact same size cooler as the M7B. My stock one is the exact cooler, but with OEM flared fittings. I wish I would have looked at mine first, I would have rather just bought an OEM cooler that I didn't have to change fittings to use. My truck is a late production 1992 C1500 5.7l extended cab. My options tag says Heavy Duty Radiator, but no tow package. I'll post up pics tomorrow.
 

alpinecrick

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I changed my trans cooler over to the M7B today. Upon inspecting, I found my truck has the exact same size cooler as the M7B. My stock one is the exact cooler, but with OEM flared fittings. I wish I would have looked at mine first, I would have rather just bought an OEM cooler that I didn't have to change fittings to use. My truck is a late production 1992 C1500 5.7l extended cab. My options tag says Heavy Duty Radiator, but no tow package. I'll post up pics tomorrow.

Then somebody has already changed your cooler because the factory external cooler dimensions are the same as the L7B (5 3/4” x 11”).
The M7B is 8” x 11”.
 
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