Using air con rad as oil cooler? - PeachParts Mercedes-Benz Forum

m1tch · #1 09-18-2015, 03:47 AM

Hi all,

Just had a thought, my air con system isn't currently working and will probably just remove the whole lot to save weight on the project car. The air con rad is attached to the front of the coolant rad and is quite large.

I was wondering as I wouldn't be using it for air con gas, could I repurpose it to use as an oil cooler or indeed another radiator for perhaps a charge cooler?

I am guessing that the rad would be good for pressure as it would usually hold pressurised gas - not sure if anyone has used it for anything else though.

97 SL320 · #2 09-18-2015, 09:40 AM

The pressure capacity would be fine however the flow rate of the AC condenser won't due to the tubing diameter and total length.

Look towards some cars / trucks for an oil cooler, you probably want something 6" x 12" or a similar area. ( Just guessing. )

pawoSD · #3 09-18-2015, 10:41 AM

Yeah that will be too restrictive of the oil flow, its also the first thing to take a hit if any debris hits the car in front so your trans fluid would be spewing all over the ground.

I'd stick with a smaller one tucked away somewhere, maybe even with its own small cooling fan if you want extra cooling power.

Mimzer · #4 09-18-2015, 11:24 AM

Maybe it could handle ATF, but engine oil would be way too thick to push through the tiny passages.

m1tch · #5 09-18-2015, 11:44 AM

Quote:

Originally Posted by pawoSD

Yeah that will be too restrictive of the oil flow, its also the first thing to take a hit if any debris hits the car in front so your trans fluid would be spewing all over the ground.

I'd stick with a smaller one tucked away somewhere, maybe even with its own small cooling fan if you want extra cooling power.

The stock oil cooler is side mounted and has a fan as standard, might just remove the rad for weight saving.

barry12345 · #6 09-18-2015, 12:04 PM

Perhaps too much heat introduced in front of the radiator anyways.

leathermang · #7 09-18-2015, 12:40 PM

Some oil pressure systems are plumbed to where if the resistance is too much going to the cooler.... that unfiltered oil is directed into the regular system... to keep something like cold oil from cutting off the lubrication to the engine....
Like the human body will shut down blood flow to other parts of the body to keep the brain supplied....

dude99 · #8 09-18-2015, 12:49 PM

There are several people over at STD that have used the condenser as a water cooler fot an A\W intercooler.

Mxfrank · #9 09-18-2015, 01:18 PM

What makes you think your oil is too hot?

Too cool causes more problems than too hot: oil temps below 170F will cause premature engine wear. You will need an oil thermostat if you're adding a cooler.

leathermang · #10 09-18-2015, 01:20 PM

I think his system has an oil thermostat.

DieselPaul · #11 09-18-2015, 01:22 PM

It does, but I would think the stock oil cooler is adequate. Mercedes uses good sized oil coolers on turbodiesels.

leathermang · #12 09-18-2015, 01:50 PM

Quote:

Originally Posted by DieselPaul

It does, but I would think the stock oil cooler is adequate. Mercedes uses good sized oil coolers on turbodiesels.

I totally agree.... I was just saying that another one would not need to be added.

m1tch · #13 09-18-2015, 02:49 PM

My car currently has the oil cooler looped - eg I only have the transmission cooler and not the engine oil cooler, they are thermostatically controlled and I will be running a much larger turbo so need the extra engine cooling.

I do have an aftermarket 19 row oil cooler which I am planning to fit - just looking at other options before I fit it.

97 SL320 · #14 09-18-2015, 03:20 PM

Quote:

Originally Posted by leathermang

Some oil pressure systems are plumbed to where if the resistance is too much going to the cooler.... that unfiltered oil is directed into the regular system... to keep something like cold oil from cutting off the lubrication to the engine.....

The above is somewhat mixing systems.

Oil filter , there is a pressure bypass that opens when oil is too thick / filter that has clogged. This is a pressure deferential valve. Unfiltered oil will enter the bearings when this opens. This occurs more often than you would think.

Oil cooler, there is also a pressure bypass on this system to allow thick oil to bypass however it has nothing to do with unfiltered oil bypassing a filter. Better systems use a thermostat to control temp but they cost more than what amounts to a spring loaded check valve with a high cracking pressure.

leathermang · #15 09-18-2015, 03:55 PM

I did not claim to not be mixing systems... I do not know about his car... I just know that some automobiles have some of these things.... I was just noting that one would need to research their situation well before starting any big redesign project.
and you are sure correct that the unfiltered oil situation happens more than most suspect...