Who has upgraded to the 4B0121251K Radiator? Benefits?

[LakeTahoeQuattr]

So just thinking out loud, I think it is safe to assume that the manual version of the radiator must fit more coolant and therefore allow for more cooling over the auto radiator with tiptronic cooler inside.

Has anyone does this retrofit and seen cooling gains?

For the first time on Friday I heat soaked my car boosting up a grade and saw coolants reach ~235 (instruments value)

[Korben007]

How hot the oil get?

-Avantwerks Audi Customization Specialist

[LakeTahoeQuattr]

Normal 200-250. Just thinking my radiator is the original from the blown motor now cresting 230k. It works but the brand new nissens K revision radiator is only ~$120

[Korben007]

Yeah if you're coolant is getting hot and your oil stain normal I would suspect the radiator

-Avantwerks Audi Customization Specialist

[LakeTahoeQuattr]

Well see coolant fluctuates from 188 - 210. So the fluctuation was concerning to me

[glennda5id]

Do you plant to cut the TIP cooling lines and add an external trans cooler?

[LakeTahoeQuattr]

You know I thought about it but since the TDI trans I have does not have an internal pump I would have to run an external pump. Even still, I would rather run an external cooler than have the shared heat of the radiator.

I just figured the a6 manual radiator core was larger than the tiptronic radiator. The manual allroad radiator has cooling ports as we all know.

[chris86vw]

Totally forgot I had taken pics of just this (need to verify part numbers) a few months back.



left is out of my 03 a6 manual parts car

right is out of my 03 AR (originally) tip

calipers show thickness of core from the AR over the A6 one.

I pulled this for the same reason expecting it to be beneficial to swap and it turns out that the manual radiator was actually smaller than the tip one.

[LakeTahoeQuattr]

Totally forgot I had taken pics of just this (need to verify part numbers) a few months back.



left is out of my 03 a6 manual parts car

right is out of my 03 AR (originally) tip

calipers show thickness of core from the AR over the A6 one.

I pulled this for the same reason expecting it to be beneficial to swap and it turns out that the manual radiator was actually smaller than the tip one.

Probably larger to accommodate for the oil cooler I must assume?..Does make me wonder. AR had an oil cooler on the radiator for manual as well, a different radiator.

[Scotty@Advanced]

The trans oil cooler for the manual cars served a dual function, it kept the trans temps down, and also warmed it up quickly.

[chris86vw]

Probably larger to accommodate for the oil cooler I must assume?..Does make me wonder. AR had an oil cooler on the radiator for manual as well, a different radiator.

My guess yes. I thought about it this weekend I should have (just reinstalled it and filled coolant :( ) attempted to check the volume of them.

I kept the auto radiator because I figured even if it holds similar volume that the mass of the unused portion of the trans cooler should hopefully result in the radiator being more efficient.

This thread had my trying to find coolant capacities, sometimes VW/Audi listed different ones for manuals for vs autos if they were different enough but I couldn't find anything. What I did find interesting was the 2.8 A6 had a higher coolant capacity by 1 or 2 (blanking now) liters when looking at the 2001 (oops 2001 typed 2003 first) capacity chart. This has me really curious about the radiator on those and want to check one out. The engines should hold roughly the same as I can't imagine the blocks would hold 1 or 2 liters difference with any reinforcements, heatercore and basic coolant hoses would be similar. There would in theory be less volume on the 2.8 vs the 2.7t for the lines going to the turbo which would lead me to the radiator being substantially different. Why they would go smaller on the turbo car I don't know so maybe the capacity chart was wrong but I'll try to look into it when I Get a chance.

[chris86vw]

My thinner radiator out of the A6 did not have a part number on it, having a friend check part number for me.

Didn't write it down but the Allroad one is an allroad specific radiator with a 4z7 part number so it is possible that like with many of the other subtle beefed up modifications that cooling was one also and they simply have larger cores than the a6s.

[LakeTahoeQuattr]

I bought an oem 8D0 121 251 N which is for the 2.8s fingers crossed it fits nicely like the old one

[PZ.]

The trans cooler is only in the side tank, so it would have no effect on the cooling capacity of the radiator. The larger the core, the better the cooling capacity.

[LakeTahoeQuattr]

Replaced radiator this weekend. Car still warms up quick to 188.6 and stays there until I start beating on it at which point it likes to hover at 204 degrees. Really start beating on it and I am able to see coolant temps rise to 235 again. It doers take a lot / several pulls to make this happen.

However, versus the old radiator, the coolant temps recover about 3x faster than with my old radiator, so possibly more of a normal operation. At this point, I am closing the book on this issue as it still is difficult to get the coolant temps that high and the car runs perfect all the time.

Also, during this oils never reached 250...