Philes’ Forum – Spring 2020


By Vic Lucariello, Sr.

Hello, Bimmerphiles! Pursuant to a number of recent inquiries, this time out I am going to talk about brake fluid flushing and brake bleeding. What, you say, they are the same thing? Ahhh, read on…..

The hydraulic brakes found on any modern passenger car depend upon a principle of hydrostatics that pretty much states that the pressure in a hydraulic system under static [non-flowing] conditions is the same throughout the system [given no elevation changes]. So when you step on your brake pedal and pressurize the brake fluid in the brake master cylinder to, say, 1000 psi [pounds per square inch], this same 1000 psi pressure is applied equally to each of the brake calipers via small pipes that connect the master cylinder to the calipers via the ABS module, thereby applying the 4 brakes. This might sound pretty simple, but the adoption of hydraulic brakes in the 1920s was one of the most significant advances in the development of motor vehicles. Some manufacturers, like Ford, resisted the adoption of hydraulic brakes, continuing to rely on mechanical brakes with their system of levers and linkages under the car.

An important factor in the performance of hydraulic brakes is the incompressibility of the brake fluid between the master cylinder and calipers. Most liquids are virtually incompressible, at least at room temperature, while gasses, such as air or steam, are quite compressible. Hence if you have any gas bubbles in your brake system, the result will be a “spongy”, or soft, low brake pedal. Or in an extreme case, a brake pedal that goes to the floor. Depending upon where in the system the gas is, it can also cause the vehicle to veer right or left while the brakes are being applied.\

How does air get into a brake system? While in rare cases, air can sneak in through a bad master-cylinder or caliperpiston seal, air mostly enters systems when a component is disconnected for repair or replacement. Regardless of how air has entered a system, the procedure known as “bleeding the brakes” is intended to remove said air.

As a side note, brake calipers are in many cases physically interchangeable side-to-side. However, if a caliper is installed on the wrong side, usually the bleeder screw is in the wrong location. This makes bleeding the brakes either extremely difficult or impossible. I have read reports that professional technicians have made this mistake.

The polyglycol-based DOT 3, DOT 4 and DOT 5.1 brake fluids found in virtually all cars today are hygroscopic, meaning that they have an affinity for and tend to absorb moisture. A typical DOT 4-rated brake fluid still in the can might have a boiling point of about 500 degrees Fahrenheit, while water of course boils at 212 degrees Fahrenheit. As you might expect, a mixture of the two will have a boiling point below 500 degrees Fahrenheit. According to a graph in Brake Handbook, by Fred Puhn [HP Books, 1985], a typical brake fluid will boil at only about 350 degrees Fahrenheit after it has been contaminated by only 1% water. According to another graph in this same book, this 100 degrees Fahrenheit reduction in boiling point will occur before the brake fluid has been in service for 6 months. My own brake fluid-boiling-point data, collected for more than a decade now, suggests that a 100 degrees Fahrenheit drop in boiling point in only 6 months would be quite unusual. In fact, I have never seen new fluid degrade that much in 6 months.

How does this moisture get into the brake fluid? Mainly through the vent in the master-cylinder-reservoir cap. [Some cars have a “rubber” diaphragm under the cap to minimize contact of the brake fluid with air.] Some say that a lesser amount gains entry through the brake hoses via osmosis. Regardless of its point of entry or method of entry, moisture does infuse the brake fluid, and this is a bad thing.

Although water in the brake fluid foments corrosion of ferrous components in the brake system, for performance driving [or driving in hilly terrain] the boiling-point suppression is by far the more diabolic villain. When the brakes get hot enough to exceed the boiling point of the brake fluid, gas pockets begin to form in the calipers and brake lines. Remember: gas is compressible. Although you might get a warning in the form of a “spongy” brake pedal, in some cases the driver’s first inkling that something is wrong is that the brake pedal goes to the floor! Then, assuming you don’t crash in the interim, after the brakes cool and the gasses condense back into liquid, the brake pedal is magically restored – until the next time the brakes get hot…………

Obviously, the only way to keep your brake fluid at or near its rated boiling point is to flush out frequently the old fluid and replace it with new, quality fluid from a sealed container.

So there you have the difference: Brake bleeding is intended to remove entrained air from the brake system while brake fluid flushing is intended to replace contaminated fluid with new fluid. In many cases, such as the replacement of a caliper or brake hose, the brake bleeding procedure only involves expelling a few CCs of fluid from one caliper – just enough to get the air out. Proper fluid flushing, on the other hand, will require putting at least a liter of new fluid through the system; and of course opening up all the bleeder screws. So, as part of your driver-school-car-prep regimen or normal brake maintenance, you need to flush out the brake fluid,not merely “bleed the brakes”. Some shops, if you bring in the car and ask them to “bleed the brakes”, will do just that: bleed the brakes. The fact that you are not getting a fluid flush won’t be their fault, either.

If you have a shop do your brake fluid flushing, I recommend that you bring the brake fluid of your choice in an unopened 1-liter container and tell them you want the entire contents put through the system. A labor charge of 45 minutes to an hour is appropriate.

What methods are available for flushing fluid and bleeding brakes? I’m glad you asked. More on this next time!

Anyone wishing to contribute to Philes’ Forum can contact me at I’m interested in tech tips, repair /maintenance questions, repair horror stories, emissions-inspection sagas, product evaluations, etc.

Copyright 2020; V.M. Lucariello, P.E.

Philes’ Forum – Spring 2019


By Vic Lucariello, Sr.

Hello Bimmerphiles! This time out I have a couple follow-ups to recent Philes’ Forums, the That Ain’t What It’s For [Spring 2018] column and the Coolant Schmoolant [Summer 2018] column. Archived files of these newsletters can be found at our website

In That Ain’t What It’s For, I wrote about the under-dash OBD II diagnostic connector [See Photo #1] and how I, along with some respected, experienced BMW techs, do not recommend using the OBD II connector to supply auxiliary battery power to your Bimmer while changing batteries.

Photo #1 – OBD-II Diagnostic Connector

Well, a recent thread on iATN [The International Automobile Technicians Forum] presented an example of why. On some BMW models, use of the OBD II port for auxiliary battery power can result in a blown fuse, one that supplies the instrument cluster.

In Coolant Schmoolant, I wrote about the different types of automotive coolant available today, and that it is very important not to mix coolant types. I also offered to write a follow-up on cooling-system flushing.

Well, to the hundreds of you who emailed to ask for said follow-up and who have been waiting with breath abated, here it is.

Photo #2 – The Sneaky One

This description applies specifically to the E30 M3, but is applicable to Bimmers with engine-block-drain plugs and without electric coolant pumps. BMW has seen fit to eliminate block drains on some later models. On electric-coolant-pump models, a special procedure is required to bleed the air out of the cooling system after it has been drained and refilled. I’ll save that for a future column [A follow-up to a follow-up?].

The S14 Motorsport engine in the E30 M3 has a plethora of small coolant hoses in addition to the normal radiator and heater hoses. Given an OE coolant-hose life of about 15 years, or according to the Roundel’s Mike Miller’s Lifetime Maintenance Schedule, 120,000 to 150,000 miles, your M3 either has new coolant hoses or it needs them.

Since the S14 radiator, thermostat and heater hoses are straightforward, I will focus on the hoses more likely to be overlooked, particularly one sneaky bugger.

BMW provided a self-bleeding cooling system on the S14. [On some other E30s, along with E36s, E46s, et al, there are coolant bleed valves that need to be opened to expel trapped air.] On the left side of the S14 cylinder head near the front is a little hose [the sneaky one, see Photo #2] that connects to a tube that runs to the rear of the cylinder head. This tube connects to another hose [Photo #3] which attaches to the coolant-expansion tank. A second bleed hose [Photo #4] connects to the top radiator tank. This hose connects to yet another tube that runs along the right side of the engine compartment, leading to yet another hose [Photo #5]. The sneaky hose connected to the cylinder head and its cousin connected to the radiator are subject to full engine operating temperature, the same as is the upper radiator hose. The hoses connected to the coolant- expansion tank are subject to almost this same temperature. So, changing the radiator hoses, a common maintenance procedure, without changing the coolant-bleed hoses is, to me, rather foolish.

Photo #3 – Sneaky’s Connection at Expansion Tank

Mike Miller recommends a two-year coolant-maintenance cycle and the use of BMW OE coolant and distilled water. While my experience suggests that two years may be on the conservative side depending upon how much you use your Bimmer, I recommend the use of BMW coolant and distilled or deionized water, and said so in Coolant Schmoolant.

The following is the flush procedure I have developed over the years and use on my personal Bimmers. You may think that this procedure is on the lunatic fringe, and you may be right. If so, you can skip the flushing part and simply drain the radiator AND ENGINE BLOCK and refill the system with a 50-50 mixture of BMW coolant and distilled or deionized water. This alone will be much better than what is done at some professional car-repair facilities.

Photo #4 – Radiator-Bleed Hose

I start with a cool engine and by setting the heater-temperature control to full hot and removing the radiator and engine-block drain plugs. On the S14 and many other Bimmers, the block drain is a 19-mm hex located behind the exhaust manifold. I use a flex socket and long extension to remove the block-drain plug, and a magnetic socket insert works even better. Coincidentally, as I was composing this today I received an email from our Webmaster and recent Champ Series winner Colin Vozeh stating that he, too, uses a long extension and flex socket on the drain plug.

Photo #5 – Radiator-Bleed Connection To Expansion Tank

When you remove the block drain, be sure to capture the drain- plug sealing ring. Sometimes it remains on the drain plug, sometimes it falls to the floor, and sometimes it remains stuck to the engine block. You do not want to re-use this sealing ring, but you definitely want to ensure that it has not remained stuck to the block.

What I do next is install a special drain fitting to the block-drain port. [See Photo #6.] I made this fitting by drilling and tapping a spare drain plug with 1/8 NPT threads and installing a 45-degree street elbow and a drain cock with a hose connection. I connect a clear hose to the closed drain cock. The 45-degree street elbow is not mandatory, but it makes life a lot easier.

Photo #6 – Custom Flush Fitting

Next I pour in distilled water until the water draining from the still-open radiator drain runs clear, then I close the radiator drain and continue filling the system completely.

Next I start the engine and quickly open the drain cock on the block drain. I let the engine idle and continuously pour in distilled water, keeping the expansion tank full, until the fluid escaping the block drain runs clear, then I shut the engine off. Note that you do not want to let the engine warm up, and by continuously pouring in distilled water, it won’t.

Then I open the radiator drain and let everything drain out, after which I reinstall the block-drain plug [the exhaust manifold will be hot, so you may want to let it cool a bit] with a new sealing ring and close the radiator drain.

I installed a gallon of BMW coolant [you can use 4 ½ – 5 quarts on the S14 if you prefer] and finished filling with distilled water and 8 ounces of Redline Water Wetter. After warming up the engine, driving the M3 and letting things cool to ambient, I checked the coolant concentration with my refractometer and it came out to 48%, pretty close to the desired 50% if ya ask me. I had to add a few more ounces of coolant to get the level in the expansion tank to the Cold-Fill level.

That’s all for now, bimmerphiles. See you next time.

Anyone wishing to contribute to Philes’ Forum can contact me at I’m interested in comments, tech tips, repair /maintenance questions, repair horror stories, emissionsinspection sagas, product evaluations, etc.

© 2019; V.M. Lucariello, P.E.

Philes’ Forum – Summer 2018


By Vic Lucariello, Sr.

Hello bimmerphiles! This time out I would like to talk a bit about that often neglected fluid inside your Bimmer’s radiator and engine: the coolant.

When I got my first gas-station job, uh, some years ago, so-called “permanent” coolant [AKA: antifreeze] was a relatively new thing, and the old non-permanent coolant was still available. At the time, “permanent” coolant denoted a coolant that could be left in service year-round. It did not denote a “lifetime” coolant or “long-life” coolant. One brand’s non-permanent stuff was Zerone while their new-fangled permanent stuff was Zerex, which is still available today from Ashland Oil [Valvoline].

In addition to providing freeze protection, coolant must also provide corrosion protection. Most permanent coolant is based on ethylene glycol, which provides great freeze protection – [-34 F] when mixed 50/50 with water – but little or no corrosion protection. The corrosion protection is provided by the additives in the base ethylene glycol stock.

Prior to the advent of permanent coolant, each Fall one would have to drain the cooling system of its water [with “rust inhibitor” added for corrosion protection], and fill the system with Zerone, or the equivalent in another brand. Then in the Spring, the Zerone would be drained, the system flushed, and water/rust inhibitor reinstalled for the warm weather. [If the non-permanent coolant was left in for the warm weather, it would boil out of the non-pressurized cooling systems of the day.] This was one of the first auto-repair jobs I did with my Dad on our 1951 Chevy, as prescribed in the owner manual, which I still have.

Dad taught me that, in addition to draining the radiator, we needed to remove the drain plug on the block as well. He also taught me that the pipe-thread drain plug could be replaced with a petcock so that future drains would be easier. Every car I have ever owned that had pipe-thread block-drain plugs received this modification. Thanks, Dad.

In those days, and for decades afterwards, there was really only one type of permanent coolant, and it could be used in virtually any car or truck. I recall pallets of it being delivered to the gas station each Fall. Even though the permanent coolant did not need to be replaced annually or semi-annually, we did so for quite a few years. In today’s auto-repair-industry patois, this would be called “wallet flushing”. In defense of that decades-ago practice, the owner manual for Dad’s 1961 Comet, which came equipped with permanent coolant, does prescribe annual coolant changes. The manual also makes the distinction between permanent and non-permanent “antifreeze”, even by 1961. Auto-repair-industry consensus is that, while traditional permanent coolant provides good corrosion protection, its service life is limited to a couple years, after which the corrosion inhibitors have become depleted.

Circa 1996, General Motors introduced its Dex-Cool coolant formulation, which is a long-life, say 5 years, ethylene glycol coolant with a significantly different additive package than traditional permanent coolant. It is also repair-industry consensus that one does NOT want to mix traditional coolant with Dex-Cool. The resulting goo is dubbed by some as “Death-Cool”. This is NOT a fault of GM or Dex-Cool. Rather, it is the fault of ignorant installers, professional or otherwise.

Other vehicle manufacturers adopted their own versions of long-life coolant, each differing significantly, in terms of additives, from Dex- Cool and traditional permanent coolant. [See Photo #1 for what I use in my shop.] The automotive aftermarket followed suit with their own offerings, SOME of which have specific auto-manufacturer approval. Dex-Cool, other long-life ethylene glycol coolants, and traditional permanent coolant fall into about six major types, some of which overlap. It is a source of great confusion among professional auto technicians, and the subject of debate on professional forums such as iATN, the International Automobile Technicians Network.

[Photo #1]

BMW has for years had their proprietary version of long-life coolant, and I have used it for years with success. Several aftermarket coolant manufacturers offer coolants that THEY RECOMMEND for BMWs, but I know of no such manufacturer that advertises that their coolant is APPROVED by BMW. [If you know of any, please advise.] This is a significant distinction that you need to be aware of when choosing coolants and motor oils. “Recommended For” and “Approved by [auto manufacturer]” are not the same.

On the other hand, aftermarket companies such as Ashland Oil/ Valvoline and Pentosin expend significant resources developing coolant-additive packages to satisfy the major coolant types used today. So I don’t think these companies, with inveterate reputations to uphold, would cavalierly recommend coolant for use in a particular vehicle marque. Both companies offer coolants that they recommend for use in BMWs.

Mixing any full-strength ethylene glycol coolant with water in a 50/50 ratio will result in a freeze point of about -34 F. You may say, “Hey, it doesn’t get anywhere near that cold here, so why do I need to use that much coolant?”. The answer is that diluting the coolant with more than 50% water will raise the freeze point, but it will also dilute the additive package, which is designed for a 50% dilution. Diluting the additive package will shorten the life of the coolant. You can buy an inexpensive hydrometer which will tell you the approximate freeze point of your coolant. [See Photo #2.] You really should keep the concentration around 50%, preferably a bit higherthan lower. For the more technical [anal?] among us, a refractometer will tell you the coolant concentration within a few percent.

[Photo #2]

If you have read this far, here are some suggested takeaways regarding coolant:

  • If there is any doubt in your mind whether a particular aftermarket coolant is APPROVED by BMW, use BMW coolant. I do. It may cost a bit more than others, but so did your Bimmer.
  • There is a nationally-known company that offers a single coolant that they claim is suitable for “all makes, all models”. Given the wide variety of coolant formulations available today, I am quite skeptical of this claim.
  • The color of a coolant is not a reliable predictor of its formulation.
  • You DON’T want to mix coolants of differing formulations.
  • Use distilled or deionized water for mixing with coolant.
  • Get yourself an inexpensive coolant hydrometer to check your coolant level.
  • If you have any doubt as to what coolant is in your Bimmer, have the system THOROUGHLY flushed [This takes hours, so be prepared] and refilled with BMW coolant and distilled water.
  • Keep a container of BMW coolant mixed 50/50 with distilled or deionized water for topping-up use.
  • Some coolants are available either concentrated or “pre- mixed”. I recommend that you buy the concentrate and mix your own. You can check your work with your new hydrometer or refractometer.

If you found this column to be interesting, let me know and I will follow up with some coolant-flushing tips.

That’s all for now, bimmerphiles. See you next time.

Anyone wishing to contribute to Philes’ Forum can contact me at I’m interested in comments, tech tips, repair /maintenance questions, repair horror stories, emissionsinspection sagas, product evaluations, etc.

© 2018; V.M. Lucariello, P.E.

Philes’ Forum – Spring 2017


Trip Lee (1947 – 2017) – New Jersey Chapter Icon

The New Jersey Chapter, as well as humanity, suffered a great loss when Trip Lee passed away on 14 February. Trip was a unique, consummate gentleman of intellect and character, and I feel privileged to have known him for more than 30 years. If you are thinking I greatly respected and admired Trip, you are correct.

While some gearheads tend to be one-dimensional, Trip had varied interests, including history and aviation, in addition to his love of all things mechanical. One time he told me that as part of his study of the U.S. Civil War, he was reading soldiers’ letters written during the conflict. That’s some pretty serious study if ya ask me.

Trip and I would occasionally recommend books to each other. Our most recent correspondence, late in 2016, concerned a book about the closing months of WWII and how British airmen, at great cost, helped ameliorate the swarm of Kamikazes over the waters near Japan. The Brits did this by attacking Kamikaze airfields.

I can neither count nor recall all the times Trip helped me out, whether it was instructing novice-driver me at Lime Rock, mentoring me when I aspired to become a driver-school instructor, tactfully advising me when I became Chief-of-Tech for our driver schools, giving me lathe-operation pointers, or finding cool gearhead stuff for me or us. He once found a source in Germany and had imported two “dogleg” or “close-ratio” 5- speed transmissions, one for wife Judy’s M3 and one for mine. Trip found me a very nice, industrial-quality, [made in U.S.A., no less] floor-mount drill press that I use in my shop nearly every day. When Trip upgraded his TIG welder, I got his old one. One time he gave me a completely functional, 12” Clausing turret lathe.

I could continue, but knowing Trip, he would say, “Enough already; let’s get to the good stuff”. [But Trip would phrase it tactfully.] So Trip, if you are reading this, thanks, man.

The good stuff this month concerns BMW power-steering reservoirs. I looked in the Philes’ Forum archives, and the best I can tell I have not written on this subject in more than 10 years.

In January 2007 I was writing about oil filters, and I wrote that in addition to the oil filter, air filter, fuel filter, and cabin filter, your Bimmer also has a power-steering filter. This filter is located in the bottom of the powersteering- fluid reservoir, and unfortunately, unless your Bimmer is 40 or so years old, the filter is not replaceable without changing the reservoir.

Photo #1 depicts the power-steering reservoir found on many Bimmers from model year 1982 right up to much later models, such as the E84 X1 and E87 1-Series. Photo #2 shows a reservoir cut in half to reveal the internal filter. I think it a good idea to change the reservoir/filter whenever you do maintenance on the power-steering system such as changing the fluid, hoses, pump, or steering box. While you’re at it [actually, before you install any new parts], it’s also a good idea to flush out the system. The January 2007 Philes’ Forum [available on the NJ Chapter Website], describes one procedure for flushing the power-steering fluid.

Photo #1 – Ubiquitous Power Steering Reservoir
Photo #2 – Power Steering Filter Revealed

Driver-school Padrone Jeff White emailed me about his 2000 528i E39 5-Series touring [manual trans!]. Jeff is replacing the power-steering reservoir, and the replacement-reservoir’s cap indicates that Pentosin CHF 11.S fluid is required, and Jeff has been using Dexron-type automatictransmission fluid [ATF] as specified in his owner manual. Jeff was told by the aftermarket supplier of the new reservoir that Jeff needed to convert the system to CHF 11.S fluid, and Jeff questioned me on how to do this.

The current BMW part number for Jeff’s power-steering reservoir is 32 41 6 851 217. The only apparent difference between the current version and superseded versions [eg: 32 41 1 097 164] is that the cap on the current version specifies CHF 11.S fluid, not ATF. See Photo #3 [Courtesy of Jeff White].

Photo #3 – Cap From Current Replacement Reservoir
Photo by Jeff White

My response to Jeff is that the steering-system design, not the reservoir, is what determines which fluid is to be used, and that he should continue to use ATF in the E39’s power steering. Just to double-check, I contacted Matt Kimple, service manager at Bridgewater BMW, and he confirmed that IF YOUR BIMMER ORIGINALLY USED ATF IN ITS POWER-STEERING, DO NOT PUT CHF 11.S IN IT, REGARDLESS OF WHAT THE RESERVOIR CAP INDICATES. If you are in doubt about which fluid to use, call Bridgewater’s parts department [888-579-0048] with you VIN and they will supply the correct fluid. Pentosin CHF 11.S fluid is greenish in color while ATF is reddish. Old yucky ATF can be a reddish-brownish.

Further investigation suggests that when BMW switched to CHF 11.S steering fluid on most models beginning circa the E60 5- Series, they changed the fluid-reservoir cap such that it indicates that CHF 11.S is required. But what if you, like Jeff, need a reservoir for an older model? BMW thought of this as well, and provides a label indicating that ATF should be used.

The part number of this label for Jeff’s E39 is 71-24-6-798-132. Or you can make your own label like Jeff did. That’s what I would do. So too would Trip.

That’s all for now, bimmerphiles. See you next time.

Anyone wishing to contribute to Philes’ Forum can contact me at I’m interested in tech tips, repair / maintenance questions, repair horror stories, emissionsinspection sagas, product evaluations, etc.

© 2017; V.M. Lucariello, P.E.

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