Helping Cool the BMW Cooling System.

"Jake Stumph Racing" (jakestumphracing) 05/26/2015 at 11:30 • Filed to: BMW, 135i, motorsport, garage, blackflag, oppositelock, oppo, jakestumphracing, SCCA, trackdaybro

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If you ask most car enthusiasts, who drive modern BMW’s, their opinion on the factory cooling system in their cars, responses will often range from “My Honda never had it’s water pump explode,” or “I hate it,” to “what’s a cooling system, and who are you?” These are all valid points. BMW models of yore were never renowned for their cooling systems, but the switch the all electric water pump has further increased the volatility, with the car offering no warning sign before the water pump seizes and the motor overheats.

When you pack a long Straight-6 engine into a small engine bay, cooling that 3-liter-heater will be tricky. I am working on a new project to help the car run better at the track, but in the mean time, I want to cover any angle I can find, that might give me an edge in lowering operating temperatures. So, it’s time to HEAD TO THE INTERNET GARAGE!

Jokes on you, I had already went to the Internet, and armed myself with knowledge (Read: hearsay). After five years, it was time to flush the engine coolant with distilled water.

From the factory, 135i are filled with a 50/50 mixture of BMW coolant and distilled water. Contrary to the sound of the name, coolant isn’t particularly great at cooling the engine, the water does that job. Vehicles are filled with coolant to prevent the water from freezing in cold climates. The glycol-based coolant actually reduces the capability of the water to cool the system. 100% distilled water will more efficiently “grab” heat and disperse it than a glycol-water mixture. Conversely, as the coolant:water ratio is increased, the cooling system is able to protect from freezing at progressively colder temperatures.

That’s well and dandy, but I live in SoCal, where if it gets below 50*, the locals think the world is ending. Antifreeze only offers one perk then for me, which is offering additives to lubricate the water pump and other bits in the cooling system. Fortunately for me, the aftermarket has stepped in and developed solutions for this.

Redline Oils, and several other manufacturers have developed water “wetters” or additives to add to your cooling system to help the efficiency and lubrication of large mixtures of distilled water. They all make some pretty bold claims on that efficiency bit:

Not sure how much I believe that, but it’s worth a shot, and I will take any little bit that I can get.

Did you know that draining the radiator on a turbo BMW is way more of a pain in the ass than other cars? I guess this is what I get for mocking those whose cars have difficult to reach oil filters. Oh well.

Step 1: Break a Bunch of Clips While Removing the Front Bumper.

Watch out for the headlight sprayers, you have to slip their caps off the remove the bumper. They will fight you the whole time, and you will wonder if they’re even worth having when it rains three times a year in Southern California.

Step 1 complete:

Step 2: Ogle at Things Previously Hidden.

Passenger-side oil cooler, and ducting. They really packed a lot of stuff in a small space. We will be revisiting this to get more cooler in there…somehow.

Vented access cover for the cooler in the wheel-well. Not much to optimize here in terms of heat extraction without compromising the shielding benefits of the shroud. Booo.

Step 3: Remove ze Intercoola.

Ha, and you thought removing the bumper to reach the radiator was silly, the intercooler also has to be removed to even see the bottom of the radiator. Oh joy.

Fortunately, besides the additional plastic clips that I broke, removing the OEM intercooler is a breeze, the piping is plastic and they snap together with C-Clips. Simply wave your flat head screwdriver at them like a wizard’s wand, and poof (or, pop?), they’re off!

Let’s check the intercooler plumbing for oil blow-by. I installed my catch can around the 32,000 mile mark, but before that, it was as it left the factory. Let’s see how much oil we can find!

The tubing has a light sheen of oil on it, and the ribbed edge of the collectors have accumulated a teeny-tiny bit, but not enough to drip down the piping, or pick up with my gloved fingers. Doesn’t look too bad to me for a car that he seen a lot of hard miles, and has been tuned to 14PSI of boost since ~15k miles.

Step 4: Wonder Why This Required the Three Prior Steps.

Turbo problems, I tell ya. Okay, whining over, we now have access to the radia…what the hell is this?

There is a small cooler in front of the A/C condenser and radiator. My car is a manual-trans N54 car, do these things have transmission fluid coolers? I can’t think of what else this narrow little thing would be for. Any idea, Internet?

Looking beyond that, I spy with my little eye, something green and blue.

Jackpot.

Now Internet, I’m glad I sought council with you before trying this, otherwise, I would have broken it. You don’t remove the whole drain plug, like you do on most cars. Instead, you unscrew the inside blue piece only, and not with a screwdriver, that would be too easy. No, you need to use a quarter, due to the weird shape of it. If I didn’t read someone’s story about how they broke this thing the first time they tried to drain the radiator, I would have done the same damn thing. Another fine example of German engineering, Ladies and Gentlemen.

I drained the radiator, topped off the expansion tank, cycled the electric water pump, and drained again, until most of the water coming out had run clear. I’m guessing that there is some residual coolant in the system since there isn’t a coolant drain plug on the engine block (?). That’s fine, again lubricate the cooling system, blah blah blah, lest we upset the fiddly electric water pump and blow this whole operation sky high.

Perhaps we should still plan on offering a monthly sacrificial feast to the BMW Gods to ensure that the water pump doesn’t grenade itself, just in case.

Can we go back to that whole electric water pump thing? It does do one pretty cool trick. With modern BMW’s you don’t need to manually “burp” the cooling system after draining and refilling the radiator, there’s an easy trick to make the water pump burp the cooling system for you.

Fill the expansion tank to a bit below the normal level mark, leave the cap off and do the following:

Put the key in ignition, tap the power button once, so the car is in the “on” position, floor the accelerator for ten seconds. You will hear a loud whirring sound, and presto, your electric water pump is cycling the system for you. Check it out:

This takes about 10 minutes in total, but once it’s started, you don’t need to stay on the throttle or do anything else, the car takes it from there.

After that, the level in the expansion tank was a bit low, as anticipated, so I poured that bottle of water wetter in there, bled the cooling system again for good measure, checked the level, and then reassembled the car.

Track day at Buttonwillow was the following week, so that would be a perfect arena to test the efficiency of the stock cooling system “optimized” with a mixture of mostly distilled water and water wetter. Stay tuned.

Michael Maguire > Jake Stumph Racing 05/26/2015 at 11:43

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I really enjoyed this.

And.....german engineering? Always baffling me.

Textured Soy Protein > Jake Stumph Racing 05/26/2015 at 11:54

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The BMW Performance Power Kit 2 has upgraded cooling parts including an auxiliary radiator in the driver’s side duct in the bumper, and upgraded main radiator fan. If you don’t want to do the ECU reflash that’s part of the PPK 2 you can add just the auxiliary radiator and/or the fan.

http://www.1addicts.com/forums/showthr…

http://www.e90post.com/forums/showthr…

RallyWrench > Jake Stumph Racing 05/26/2015 at 11:59

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How many miles on your car? I know it’s stupid expensive, but if you’re past 50k you should do the water pump and thermostat. I see 2-3 a month fail, usually between 50 & 80k. That cooler ahead of the condenser may be power steering, though I thought they just had a cooling loop up there, not a proper radiator.

CallMeTURBO > Jake Stumph Racing 05/26/2015 at 12:03

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I am incredibly jealous of that auto bleeder system... M50 owner here

Mosqvich > Jake Stumph Racing 05/26/2015 at 12:05

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I haven’t had problems with my 135i’s cooling system, but this gives me a great heads-up. My X5 just went through an expansion tank. My E46 used to have all sorts of cooling issues until I replaced everything except the radiator.

Can't wait to hear if your work bears fruit. Why not upgrade the inter cooler while you were at it?

BKRM3 > Jake Stumph Racing 05/26/2015 at 12:33

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Cooling an N54 for track use in Cali? 1) aftermarket intercooler, 2) dual race auxiliary oil coolers - fill ALL the fender wells (!!), 3) hack up your bumper so the aforementioned items fit/work.

We just replaced the entire cooling system on our E46 330i race car build, after pulling our hair out trying to track down a weird minor leak that only happened on track (and only leaked enough to drain the reservoir).... let me tell you, it’s nicer to drain a cooling system in a garage than outside at the race track, and it’s a LOT nicer to have to drain distilled water from the engine block than the 50/50 antifreeze mix. That stuff does not make for an attractive hair gel product or cologne.

Repair/maintenance/upgrades to the cooling system are nice because they’re relatively easy and produce awesome results, but the downside is that it’s very unsexy work. Few if any people will notice. I’d rather add neat things like a splitter or cool graphics or a data system but it would also be swell if the engine didn’t explode so yeah...cooling system. Blah!

daender > Jake Stumph Racing 05/26/2015 at 12:40

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Don’t you have to put additives in to prevent rust from occurring inside the radiator and etc while using a 100% water setup?

Jake Stumph Racing > Textured Soy Protein 05/26/2015 at 12:41

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I actually will be adding the PPK second radiator to my car in due time. No need for the tune, my car has a JB4. :)

Jake Stumph Racing > daender 05/26/2015 at 12:42

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Water wetter serves that purpose, also, I didn’t get 100% of the coolant out. I’m guessing that I got about 80% of it.

Jake Stumph Racing > BKRM3 05/26/2015 at 12:45

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I’m quite fortunate, for an N54 car, mine runs quite cool on track. I’ve had D.E’s @ 110*F, water held at 205* (t-stat value), and oil ~ 275*F. Limp mode strikes when water is over 230, or oil over 300*. I don’t want to give away the results from my next article, but I’ll say this: Changing to a mixture of mostly distilled water (guessing ~90%) and water wetter helped.

Jake Stumph Racing > RallyWrench 05/26/2015 at 12:46

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38k miles. My plan was to change it around 60k. I’ve had friends with N54 cars have theirs last 90k+, and others 20k, YMMV.

Jake Stumph Racing > Mosqvich 05/26/2015 at 12:52

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Fortunately, the cooling systems in these cars don’t have the expansion tank blowing up issues of anything E46-based. I have only heard of one of two cases of that happening on these cars, very isolated (winter, hot coolant, you see where this is going). It’s all plastic, if you bake it, or freeze it, I’m sure it would give.

I don’t want to give away my findings just yet (track results were positive), it’ll be up in a few days.

Intercooler has pros and cons:

Pros: Lower IATs

Cons: Blocks radiator even more, $$$$, requires replacement of all the post and pre-piping to make it fit. My car is actually a bit of a trouper, and hasn’t had much in the way of issues, despite running 14# of boost. Why mess with a good thing?

I’m sure it will happen in due time. For now, I’m hellbent on getting more footprint under the narrow-body car.

Jake Stumph Racing > Michael Maguire 05/26/2015 at 12:56

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The reason I am really smitten with this car, is that for most part, it lacks most the annoyances you could think of in terms of ze finest German engineering . It’s a zero option car, no iDrive, Nav, etc. Manual trans, manual seats (this one always blows people’s minds), fully hydraulic steering, etc. Also, for a modern Bimmer, it’s pretty light, race weight, with me in the car is 3409#, full interior, minimal weight reduction.

Jake Stumph Racing > CallMeTURBO 05/26/2015 at 12:57

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The one perk of the electric water pump.

Michael Maguire > Jake Stumph Racing 05/26/2015 at 13:03

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Damn didn't even know you can get manual seats in a Bimmer anymore

Twinpowermeansoneturbo > Jake Stumph Racing 05/26/2015 at 13:09

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Very good write up. Entertaining too, with some almost Demuro-esque jokes. My 335i Xdrive does not have the auxiliary oil cooler. The M235i which I will be taking delivery of soon, will though. I’ve excited to see what sort of difference it will make for me in the hot weather months.

Jake Stumph Racing > Twinpowermeansoneturbo 05/26/2015 at 13:16

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Enjoy the M235i. Having driven both, an E90 335i and M235i, it feels very slick and fluid around town. My 135i feels like a tractor compared to it.

Twinpowermeansoneturbo > Jake Stumph Racing 05/26/2015 at 13:40

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Thanks, although I find it hard to believe your 135i could ever feel like a tractor. Those things are little rockets! I actually haven’t really driven the M235i. The dealership had an AWD with the auto trans which I drove, but I’m sure my car will feel very different being RWD and manual. I’m sure it’ll be a revelation compared to my 335i Xdrive which feels really big and heavy.

Smoggi - powered by 3 cylinders > Jake Stumph Racing 05/26/2015 at 14:45

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Mixing coolant and water wetter COULD end badly if the two things react with each other. I assume there is complex chemistry involved so you never know. Maybe try mixing some coolant and water wetter outside the system to see how it reacts?
My dad always tells me about the different antifreeze/soap stuff you put into your wiper washer water thingy. Apparently there is a winter and a summer version which react with each other and shouldn’t be mixed. But I don’t know if it is a problem in your case.

BKRM3 > Jake Stumph Racing 05/26/2015 at 15:37

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That’s encouraging news! We’re running straight distilled water in the 330 at the moment, which hasn’t done any track days above 85 degrees ambient so far this year, and our needle hasn’t moved above dead middle in terms of water temp. Haven’t been paying too much attention to OBD readings regarding oil (yet). Going to add water wetter for our next event in NJ in August, which tends to be hot, just to be safe.

I tracked my 335 years ago before I sold it and never had temp problems with just the standard BMW aux cooler that came on the sport package cars. My friend, however, had terrible issues with his 2007 335i automatic and had to go with an aftermarket oil cooler, which did help. Some cars really seem to be worse than others (although in my friend’s case the AT didn’t do him any favors...). You’re lucky you got a cool one. James Clay has a theory that no BMW engine should run hotter than the average for such engines, and the ones that run on the hot side have underlying issues somewhere else. The idea is that heat is a symptom meaning you need to go back to the drawing board and troubleshoot elsewhere if your cooling system is fresh and the problem persists. First time I had heard that!

Jake Stumph Racing > Smoggi - powered by 3 cylinders 05/26/2015 at 16:11

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Actually, I know people who have added only water wetter to their existing 50/50 coolant mixture. Not sure why, but they have, and it hasn’t ended in tragedy (as far as I know).

Smoggi - powered by 3 cylinders > Jake Stumph Racing 05/26/2015 at 16:42

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I guess it won’t be too bad then.

computiNATEor > Jake Stumph Racing 05/27/2015 at 12:16

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Jeez, you have to remove the bumper to drain the radiator? On my e39, it’s just the belly pan and the car then sits there with its ribs cracked open for open heart surgery...

Jake Stumph Racing > computiNATEor 05/27/2015 at 13:33

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and the intercooler! Packing the N54, and all the accessories in the small engine bay leaves no empty space to work in.

PG; the scalpel wielder > Jake Stumph Racing 05/28/2015 at 03:15

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“responses will often range from “My Honda never had it’s water pump explode,”

oh man, you are about to become my mentor big time.

currently looking for a 135i, specifically one with the cuban cigar brown interior!

Jake Stumph Racing > PG; the scalpel wielder 05/28/2015 at 09:52

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If you have any questions, feel free to ask. Not sure if Kinja has a messaging system, but feel free to join the fray at the 1Addicts forum for more information. My handle is Ginger_Extract.

computiNATEor > Jake Stumph Racing 05/28/2015 at 12:49

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My mechanic said to get an e39, saying “anything newer, and you’ll be visiting my shop for everything.” Glad I took his advice!

Jake Stumph Racing > computiNATEor 05/28/2015 at 12:52

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Only for the incompetent. Thus far, I have not run into anything that has ultimately defeated me, and I’m just a jackstand warrior, no fancy tools here. I don’t even have air tools at present(!!!).

computiNATEor > Jake Stumph Racing 05/28/2015 at 13:08

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:) Good to know! I consider myself somewhat competent. I had to change the thermostat in my car recently, but to do so took the following steps: Remove belly pan; remove fan/fan clutch; remove fan shroud and rotate out of the way; remove two 8mm bolts; remove radiator hoses; pull radiator (for extra room, not really necessary), change thermostat and hoses. Pretty simple. With all that intercooler piping and extra heat, I’d imagine the cooling system is much more highly stressed in these cars, too.

Next up for the 530i will be front wheel bearings, dampers all around (Koni FSDs), headliner (know any good auto upholstery shops?), and stainless brake lines. Maybe a manual swap later this summer if I can get a cheap parts car and save a bit more cash.

computiNATEor > Jake Stumph Racing 05/28/2015 at 13:13

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No air tools here, either. A good electric impact ( like this one ) can work wonders!

PG; the scalpel wielder > Jake Stumph Racing 05/30/2015 at 08:03

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thanks bud, yeah ive joined the forums. I think I just need to bite the bullet and get it. Keep going in and out of wanting it. My fault for getting such a well-sorted car in the first place with literally zero issues in 10 years, it has really ruined me lol. Although I have to say, the beemer is cheaper for me to insure and also has a way cheaper aftermarket.

Jake Stumph Racing > PG; the scalpel wielder 05/30/2015 at 14:02

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Yes, surprisingly the N54 car aftermarket is relatively pain free. Engine tunes that pick up a safe and easy 50+whp = $500. Suspension is largely the same in price as it was when I was modding my old Mazda3. Wheels and tires...well, I run a 17” track setup, so cheap for me! The only stuff that I find expensive is brakes (our calipers are big!) and cooling stuff (looking at you, overpriced oil cooler kits). Touching on that last note, I am actually starting a project for a budget OC for the N54, and am going to try and make it available for sub $500 as a complete, plug and play solution. Should be fun.