Philes' Forum by Vic Lucariello

Hello, Bimmerphiles! The following is a product review from my June, 1988 colum n:

Here is a product review of an item I think you'll find very worthwhile. One of the corollarys of Murphy's Law as applied to automobiles is: "The likelyhood of your needing your spare tire is inversely proportional to the amount of air pre ssure existing therein", or, more simply stated, "When you need your spare, the sucker'll probably be flat!"

Since the spare tire in most BMW's is buried beneath a removable floor panel in the luggage compartment, many of us do not routinely check its pressure. Well, the G.H. Meiser Co. (Box B, Posen, IL 60649) makes a nifty remote pressure indic ator for this purpose which will make even Inspector Gadget smile.

The device, which is Meiser part No. Z-327G, consists of a length of hose with a valve stem adapter on one end and a pressure gauge with Schrader fitting on the other. Simply mount the gauge in an easily seen location in the luggage compar tment, and connect the hose to your spare. Now, if you've located the gauge prop erly, you'll check your spare tire pressure every time you open the luggage comp artment.

When the spare needs air, you can refill it, via the fitting at the gauge, witho ut removing your carpet and floor panel. Neat, eh? The "Chek-A-Spare" is avail able directly from Meiser for less than $10. [It's a couple bucks more in 1997. ] One caveat: Make sure you securely tighten the Chek-A-Spare's hose to your spa re's air valve. A slight leak at this connection will result in a flat spare in less than a day!

In last month's column I wrote about the Main Relay on E30 cars. I was attempti ng to give you the part number, but those who read that far in my column got onl y XXs and YYs for your trouble. Anyhow, the part numbers are: 12-63-1-710-726 [ BMW] and 332-014-112 [Bosch]. I guess Editor McIntyre won't be giving me that r aise I put in for!

Two months ago, I wrote about the trick little battery maintainer, from JC Whitn ey, which keeps your Bimmers battery from going dead when the car sits unused fo r awhile. You may recall that in this column I mentioned that I am opposed to j ump starting one [late model] car from another. The following info from BMW NA was published in the September, 1995 issue of the trade publication Import Servi ce. [Comments/info appearing in brackets are mine]

Jump starting of BMW vehicles should be avoided, as it may cause damage to certa in electrical components. Some jump starting equipment operates at 18 - 24 volt s. Damage to ......electrical components is a distinct possibility if this..... .equipment is used. Disconnecting the battery leads, then charging the battery, is the recommended alternative. (My emphasis)

Jump starting may be the only option under certain circumstances, however. To p rotect the vehicle's electrical components, use the following procedure:

Ensure that (the two vehicles) are not touching. [This could effectively connect the batteries' negative terminals prior to the jumper cables being connected] Ensure that both vehicles have batteries of the same voltage and of approximatel y the same ampere-hour rating. [The relative ampere-hour ratings of two 12 Volt passenger car batteries can be determined, in the absence of data on the batter y cases, by the relative sizes of the batteries. It is not a good idea to use a small battery to jump a large battery.] [Ensure you have eye protection on] [Ensure the jumper vehicle's engine is off] Carefully observing polarity, connect the positive jumper cable to the B+ [or po sitive battery] terminal of the vehicle being started, then to the B+ [or positi ve battery] terminal of (the jumper vehicle). Connect the negative jumper cable to a chassis ground on the (dead) vehicle, the n connect to a chassis ground on the jumper vehicle. This protects sensitive el ectronic components from voltage surges.....[It also keeps any arcs, which may o ccur, away from either battery.] [Start the jumper vehicle. I personally don't like to do this, preferring to ke ep the jumper vehicle off, but it seems to be the recommended practice in the se rvice industry. Comments, anyone?] .....start the vehicle. Before disconnecting the cables, switch on: the heater fan to its highest speed, the rear window defroster, and the low beam headlights . Switching on these (devices) reduces the voltage surge at the moment the cabl es are disconnected. Disconnect the negative jumper cable, then disconnect the positive jumper cable. Disconnecting......in this order ensures that any....arcing....is away from th e battery.

"Remember, failure to follow these procedures may result in damage to sensitive electronic components. Damage is a virtual certainty if jump starting is perfor med with equipment ....developing more than 15 volts." (my emphasis)

Another disadvantage of jump starting is that it places quite a strain on your c harging system, especially if you do the jump start, then immediately drive away with headlamps, defroster, etc on. Charging systems are not designed to supply a vehicle's electrical load while simultaneously recharging a dead battery.

Chapter Treasurer Hank Farber had an interesting problem with his recently-purch ased E30 325ic [The E30 cars are the `84-`92 3-Series]. The AC/heater blower [E 30 and other relatively modern Bimmers have an integrated heating/air conditioni ng system with a single blower motor. Older models, such as 320is and 530is hav e two separate blowers, one for the AC and one for the heater.] would run only on the higest speed setting [#4]. For switch positions 1-3, the blower motor wa s not running.

A review of the Chapter's ETM [Electrical Troubleshooting Manual] for E30s revea led that BMW used a common method of blower motor control on these cars. A resi stor block is wired between the blower switch and motor such that the motor rece ives reduced voltages when the switch is in position #1, 2 or 3. When the switc h is in position #4, the resistor block is bypassed and the blower motor gets fu ll voltage. Depending upon which resistor burns out, various combinations of sp eeds 1-3 can be inoperative.

Hank accessed the resistor block from the engine compartment by removing a sheet metal cover plate located behind the cylinder head. I am not sure whether the r esistor is accessed in this manner for all E30s. In fact, I had suggested to H ank that he could get to the resistor from the passenger compartment. Hank was kind enough to call and [gleefully!] inform me that I had been wrong.

That's all for now, Bimmerphiles. See ya! [Next month: Warren Brown changes hi s profile gasket!]

Anyone wishing to contribute to Philes' Forum should contact me via the info on the masthead. I'm interested in tech tips, repair/maintenance questions and/or tips, dealer horror stories, product evaluations, etc. Please call before 8 PM, and if you leave a message, PLEASE INCLUDE YOUR WORK PHONE NUMBER. Also, pleas e be patient, I try to return every phone call, but it sometimes takes awhile. The best way to contact me is via e-mail.

Copyright 1997 - V. M. Lucariello, PE