engine and drivetrain Question Re: 320 Radiator Upgrade Vs Stock Re-Core

[bcarey]

Hi all,

 

I have a 1973 automatic, weekend around-town driver with a bad radiator. Given my usage, is it necessary to upgrade to a 320 rad? Or will a new stock radiator, or re-coring my current radiator, do the trick?

 

I'm leaning toward the re-cored stock, if only because it sounds simpler to install, but I'm not afraid of a project if the 320 is a big improvement.

 

Additionally, I've noticed a few listings for 320 radiators make note that they're for manual cars only. Is there anything special I need to know about replacing a radiator, or upgrading it, in an automatic?

 

Thanks!

[Napes]

The lower outlet on the automatic radiators is different from the manuals.  The lower hose, going up to the thermostat, has a double "S" bend in it while the hose from the manuals is an "L" bend.  The reason being the automatic lower outlet comes out of the end of the tank across the bottom of the radiator whereas the manual outlet comes straight out of the lower end of the radiator (towards the rear of the car).

 

The automatic radiator has the larger tank on the bottom to accomodate the auto tranny fluid cooling.  Hence, the lower hoses for the two different applications are not the same.  You need the automatic lower tank, with the hose connections for the hoses coming from the automatic tranny, so you can have this cooling for the tranny fluid.

 

Bob Napier

'75 2002 A

'76 2002 A

Edited August 8, 2013 by Napes

[osbourne]

Interesting information, Bob.  However, not all 2002As had the auto trans fluid cooling feature.  My '72, for example, never did have one and a 320i radiator was a "plug & play" installation.

My guess is that BMW didn't add the trans cooling to the rad until at least '74.............but that's just my guess and nothing more.

 

Can anyone report when BMW made that change?

 

BTW, our '72 2002A never did have any overheating problems, from the time it was brand new until about 2 or 3 years ago.  Then, I began to notice it running a bit warmer than I liked to see (but still well below "hot").  So, after reading, on this forum, about the wonders of the 320i radiator, I bought a core 320i rad and had it reconditioned by a local radiator shop (can't recall what I paid for that, but it was quite reasonable) and it's been doing a great job ever since.  However, I suspect that having my car's original, 2 row core replaced would have produced the same results for most driving situations..............except, possibly, for sitting in heavy traffic on hot summer days.  But, since my car never sits in traffic, anymore........................

[Napes]

FWIW  bmwfans.info (and I suspect RealOEM also) show the same P/N for the radiators on both the '72 automatics and the square-tail '75s.  Maybe they are all that's available - I don't know.  I had not heard before that the roundie's auto trannys did not have fluid recirculating hoses running up to the radiator.  Maybe someone like Tom Jones can chime-in with some info.

 

Bob Napier 

[tjones02]

Stock recore with a three row. If your Automatic does not have a cooler in the radiator and you intend on keeping it an automatic I do recommend getting a new '02 one if available or rebuild a used one, and add the lines.

Some Automatics did not have a cooler in the radiator or corresponding lines. I do not recall what year it started...

Edited August 8, 2013 by tjones02

[bcarey]

Awesome. Thanks for the great info, everyone. 

 

I'll have to check when I get home, but I don't think that I have the tranny cooling lines on my radiator. If the radiator is original and doesn't have the lines, am I right in guessing that the transmission wouldn't have the reciprocating inlet/outlet? And, if that's the case, am I okay to use any radiator, or is it possible to modify the transmission somehow?

 

Thanks!

[tjones02]

The plugs and corresponding holes are almost always in the trans. There are just no fittings and associated hoses/pipes. Yes you can use any radiator; I just recommend getting one with the correct trans cooler in it. The ATF flows through the separate internal trans cooler in the radiator, not coolant. Just a little FYI... you can hook hoses from the trans up to the radiator later.

[Roland]

I no longer own it, but my all original automatic equipped '73 did not have separate cooling lines and managed to perform without problems beyond the 250K mark.  I attribute this long life to frequent fluid changes.  I would have no problem going with either radiator choice.  The primary advantage of the E21 radiator is weight savings and availability.  The disadvantage is inability to repair, unless it is an early E21 "brass" radiator.  The E21 radiator may require some minor alterations for a proper fit, including some easily fabricated spacers and hose shortening as described elsewhere on the forum.

 

I had fittings, external lines and an independent transmission cooler at the ready for years.  I Kept waiting for an excuse to install them - but never found one.  The automatic was always less of a performer than my manual equipped 02s, but it is quite durable with or without external cooling lines. That said, another family member has driven a 76 Auto, with the cooling lines, for 3 decades without any transmission problems.  The radiator and water pump were a little less forgiving having been replaced at least once with a standard transmission Kurt I special and the trans coolant lines were redirected to a simple heat exchanger that is independent of the radiator. 

 

Just like the early automatics, the M10 engine was not originally designed with an external oil cooler.  Even though there are definite benefits to the external oil cooling, the engine adequately performs without it.    Racing and hard use may be a reason to consider engine and transmission improvements, but obviously years of on-the-road experience speaks for themselves.

 

Pat Allen has extensive knowledge concering the ZF 3HP-12 autos, their design, construction and modification.  Search his posts and you may learn quite a bit.

 

hth

Edited August 9, 2013 by Roland

[bcarey]

Guys, thank you. This is an incredible amount of information, and I'm in way better shape for this job thanks to it. 

 

I'm leaning toward re-coring my current radiator/buying a re-cored stock radiator. I've gotten a few quotes on re-coring that seem high -- does anyone know the going rate to re-core/buy a re-cored stock radiator in the Bay Area? 

 

Thanks!

[tjones02]

I wish I could tell you how much but I haven't had one done in a long time. I wouldn't be surprised if the going rate for a good recore is as high as $400 these days.

That and the Automatic radiator might actually be available new. I'd check with your favorite BMW Dealer or Blunt. Part number 17 11 1 103 393 http://bmwfans.info/parts/catalog/17111103393/

[bcarey]

Bummer about the price, but I guess that's the cost of doing business. Thanks, Tom. You've been incredibly helpful. I hope to make it up to Petaluma at some point!

[John_in_VA]

Part Number 17111103393

Part Name OBS RADIATOR

MSRP $375.53

Online Price from BMW of Silver Spring $300.42

[Napes]

The online price from Husker BMW is $281.65 for the automatic radiator.

 

Bob Napier

[bcarey]

Guys, thanks again for the input, and for tracking down those radiators. The 02 community is the best!

 

Here's a quick status update, as of 8/9/2013, in case anyone else is in my position:

 

I've called up a few dealerships -- about six, including Husker and Silver Springs/getbmwparts.com -- and got varying stories. Some folks said the stock radiators are NLA, others said they're simply out of stock, but wouldn't be able to get an estimate on when the new ones are coming for a few weeks. IE is making another run of their aluminum radiators, but they won't be ready for a few months. Double002 Salvage charges about $350 for a re-cored radiator. The going rate for a radiator shop to re-core my existing radiator is about $300, plus or minus depending on the materials used (San Carlos Radiator estimate). 

 

Anyway, that's what I've learned about the availability of new/re-cored stock radiators. I hope posting it here saves someone some market research.