Replacement 4L80E hard lines are different from originals

[jcoopr]

New here, hello. I have a 2000 Yukon XL 2500. Just installed a new 4L80E and replaced the radiator and aux cooler. The thing is, the new hard lines I got are routed slightly differently. GM genuine brand.

The old route: Front trans outlet -> top of rad -> bottom of rad -> aux cooler -> rear trans inlet

The new route: Front trans outlet -> bottom of rad -> top of rad -> aux cooler -> rear trans inlet

So basically the fluid flows from bottom to top of the radiator now instead of vice versa. The new plumbing still fits just fine but it’s throwing me off that it’s different now.

Will the transmission be fine in this configuration?

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

I cannot personally assist you with your issue, but other members of this Forum much more knowledgeable than me in this area will chime in.

@NickTransmissions is our resident transmission expert, and he will chime in with his thoughts and perspectives.

 

[jcoopr]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

I cannot personally assist you with your issue, but other members of this Forum much more knowledgeable than me in this area will chime in.

@NickTransmissions is our resident transmission expert, and he will chime in with his thoughts and perspectives.

I’ve done plenty of reading on here and watched a lot of Nick’s videos when diagnosing my bad transmission. Haven’t yet found an answer for this cooling line question so here I am.

 

[justirv]

New here, hello. I have a 2000 Yukon XL 2500. Just installed a new 4L80E and replaced the radiator and aux cooler. The thing is, the new hard lines I got are routed slightly differently. GM genuine brand.

The old route: Front trans outlet -> top of rad -> bottom of rad -> aux cooler -> rear trans inlet

The new route: Front trans outlet -> bottom of rad -> top of rad -> aux cooler -> rear trans inlet

So basically the fluid flows from bottom to top of the radiator now instead of vice versa. The new plumbing still fits just fine but it’s throwing me off that it’s different now.

Will the transmission be fine in this configuration?

I beleive there should not be any (functional) difference with the "reverse" Rad flow, the key being Rad first (warms to minimum temp) then trans cooler. I typically recommend a trucool 40k regardless in place of the stock trans cooler, and keep the same piping config. Let's see what @NickTransmissions says.

 

[jcoopr]

I beleive there should not be any (functional) difference with the "reverse" Rad flow, the key being Rad first (warms to minimum temp) then trans cooler. I typically recommend a trucool 40k regardless in place of the stock trans cooler, and keep the same piping config. Let's see what @NickTransmissions says.

I asked the same question on another forum and it looks like the slightly newer trucks use this “reverse” configuration, I saw an 04 as an example. Found out the part numbers for these new cooler lines match the ones for the 04 as well. Same with the radiator and aux cooler.

So for an 04, this bottom to top flow is normal…which means it should be alright?

Also, I would like to upgrade to a 40k eventually. But I’d rather save up for a nice one that allows the original hard lines to bolt right up, I believe mishimoto sells one like this.

 

[NickTransmissions]

I beleive there should not be any (functional) difference with the "reverse" Rad flow, the key being Rad first (warms to minimum temp) then trans cooler. I typically recommend a trucool 40k regardless in place of the stock trans cooler, and keep the same piping config. Let's see what @NickTransmissions says.

Agree, it doesn't matter when it comes to flow direction insofar as the cooling system's ability to do its job. I also have customers who use Truecool coolers and they're happy with them.