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.

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