1980 320i Runs Hot

[Z4madehere]

I have any old 1980 320i with 1.8L 5-speed.

It has air conditioning.

I'm the car's only owner.

On hot summer days, at any speed, it over heats or
runs very hot.

I don't think its a maintenance related problem since it has been like
this since the car was new.

I have the radiator off the car now (due to a leak between core and
plastic tank). There is no corrosion what so ever inside the radiator.

I have always felt it was a radiator efficiency problem.

The air conditioning system was an add-on that year, and not
available factory installed. Perhaps BMW did not size the
radiator large enough for the add-on A/C condenser installed in
front of it that restricts air flow to the radiator?

I am in the process of replacing this radiator, but don't want
to install the same standard OEM size replacement.

I am looking to find a slightly larger radiator with the same
basic configuration to go in the old one's place.

323i (6 cyl) radiators are larger, but their inlet and outlet configuration
is completely opposite, and can't be used without extensive
rerouting of the radiator hoses.

I don't really know the best way to approach this problem since
radiator companies don't catalog their radiators by type, but
rather by car model.

I've done google searches of "320i oversize radiators", and see
where it has been done before, but no specifics given.

I guess I am fighting an uphill battle on this minor modification.

Any suggestions?

Thanks in advance!

Josh
greenville, sc

 

[jrt67ss350]

Hey, another Greenville person. Greenville is my hometown!

If you were willing to invest some money into this, you can go to Griffin radiator in the Anderson area (their plant is right off of I-85) and they will custom make you an all aluminum radiator (including aluminum tanks) to fit your car. They can easily make you a 323i size radiator with the 320i inlets and outlets.

I have seen their custom radiators in the flesh and there is no other radiator out there that is higher quality. They do cost several hundred dollars - but you do get what you pay for in this case.

 

[echothreezero]

You should go somewhere that sells these and would have a few differnet bmw radiators in stock then you can have a look and see if say the e30 radiators can be used instead - OR - cheaper than getting a custom radiator, buy a radiator with different inlet/outlet as you said and get some custom hoses made.

Finally - you could try hooking up an auxilary electric fan in front of the radiator.

Did the car do this from new? If not- its probably a faulty thermostat restricting flow or a water pump on the way out. These are both cheaper than a new radiator.

 

[Z4madehere]

Thanks suggestions!

I am in the process of getting dimensions of
the OEM radiator and tolerances for a slightly
enlarged radiator that will drop in place
of the old one.

I am going to submit the dimensions to
Griffin Radiators and let them give me
an estimate on bulding a custom radiator
for it.

Griffin Racing Radiators already have a radiator design
for E30 body, but not the E21. I read somewhere Griffin
uses an epoxy in the construction of their all alluminum
radiators. If it keeps the cost down,
fine with me. Griffin makes their own cores and
their radiators have a 2 year warranty at least.

My 320i already has an electric auxiliary fan
in front of the A/C condenser that I leave
running all the time with no noticable effect.

I added a fan shroud on the engine side of the
radiator a couple years ago, but that also has little effect.

I have a general question concerning the BMW factory
practice of painting the aluminum cores black? I'm wondering
if that affects the efficiency of the tube fins in the radiator
core? Probably little if any, but that is just a guess.

The (BEHR) OEM radiator has a black painted aluminum core.

Last but not least: Modine has an optimized core design
(called x-2000?) that cured my Dad's cooling problems
on his 1984 Buick Roadmaster used for towing
a small travel trailer. Unfortunately Modine hasn't
built a replacement radiator using this advanced core
design for cars as old as mine. [thumbd]

The Modine X-2000 design optimizes tube fin length.
This critical fin length is not exceeded in the X-2000 core design.

Way it works: Heat is transferred from the tube to the
fin, then transferred to the air *before* this critical fin length.
So making fins in the cores longer than this critical length
reduces radiator efficiency per unit of area.



Josh
greenville, sc

 

[Z4madehere]

1980 320i Runs Hot - Update

Its now mid-december 2006 and I have my new oversized custom built radiator for my 1980 320i. Ron Davis Racing from Phoenix built and delivered it last week. It took them about a month and a half to make it ($638 dollars shipped). Very reasonable!

Jessie James has used Ron Davis Racing for some of his custom bike and street rod cooling requirements.

Griffin Radiators wanted over a $1000.

Its all aluminum and looks great! Exceeded expectations. Exact to the drawing I made.

I will have to slightly modify the lower radiator mounts in my 320i to get it to install. Then I'll have to make two rubberized aluminum C-brackets for the top.

I can't wait to get it installed.

Will report back on its performance when I get it installed and road tested.

Merry Christmas!

Josh
greenville, sc
ID: Z4madehere

 

[jrt67ss350]

Nice! Take some pics if you can once you get it installed. I'd like to see it.

 

[Z4madehere]

Custom v.s OEM Radiator Displayed

Attached is a photo contrasting the dramatic size difference in the custom radiator I had built vs. the OEM for my 1980 320i (1.8L).

Its a tight fit, but the only required alteration to the car was a five minute lower radiator mounts modification and one hose needed shortening.

Adding the attach points to the radiator was more of a challenge. My third design proved to be the most robust, i.e. homemade C-brackets made from 1/16 thick 3/4 wide steel strip adhesively attached to radiator using General Electric Silicone II sealant.

I should have the new radiator operational tomorrow and will report back on its performance. The acid test will have to wait until the first hot summer day.

Happy New Year!

Josh
greenville, sc
ID: Z4madehere

 

[Doughnut]

Looks pritty damn good, are you going to paint it?
and wasnt Tig welding a possibility when you put the C-brackets on.

Looks great, post some pictures of it inside the car when your done

 

[Z4madehere]

Custom (Oversized) Radiator Installed

( See attached photo of new custom radiator installed in my 1980 320i )

In the photo, had just returned from a test drive with the new Ron Davis custom radiator installed and cooling my old 1980 320i.

The difference is like day and night between the oversized custom vs. OEM radiators.

The OEM radiator had the temp gauge ranging from 1/2 scale on cold days, to 3/4 to full scale on warm to hot days.

With the new oversized custom radiator cooling the engine, I never saw the temp reach half scale!

With the car at highways speeds with air conditioning running, the gauge was hovering between 1/3 and 1/2 scale. It never got to 1/2 scale!

Conclusion: If your car requires the use of a radiator fan shroud or auxilary fan and its still runs hot, then you need a bigger or more efficient radiator.

Glad this project is complete! Now on to revamping brakes.

Josh
greenville, sc
ID: Z4madehere

 

[E30m42cab]

Sweet! Now you just need to clean up that valve cover and your engine compartment will look amazing!

 

[Doughnut]

paint the rocker cover caterpillar yellow

 

[Z4madehere]

Total engine view with Ron Davis oversize custom radiator installed.

JoshIII
ID: Z4madehere
josh3i at hotmail . com
www.bmwboard.com

 

[Z4madehere]

E21 Custom Radiator Part Number & Misc.

The part number Ron Davis Racing assigned to my
E21 (320i 4cyl 1.8L) oversized custom radiator was:

1C-CU100

Invoice Number: 6-03047
Invoice Date: November 30, 2006

Note: The custom radiator as designed included
a drain hole in the same location as the OEM
radiator. Its used for mounting the
electric auxilary fan temperature switch (made of brass).

Unfortunately, brass parts (sensor) should not come
in contact with aluminum due to corrosion
attack (to the aluminum threads).

To account for this deficiency, I used a zinc
plated (silver color) oil drain
plug in place of the brass temp switch.
It works just fine and zinc plated steel
has no corrosion incompatibilities with aluminum.

The Oil Drain plug is available from Auto Zone
with P/N 365324 . Its cost was $4(US).
Threads on it are metric (M14x1.5pitch).

Hope this helps

JoshIII
ID: Z4madehere
josh3i at hotmail . com