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Wednesday, October 4, 2023

Doug's Domain

Doug Vetter, ATP/CFI

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January 27, 2005

Windshield Washer Fluid Update

We've had some pretty huge swings in temperature lately. One night a couple weeks ago it was 60 degrees at 9PM. This past weekend, however, we experienced a blizzard with single digit temperatures (and ridiculously low wind chills). Due in large part to the weather, I've gone through two tanks of windshield washer fluid in the last month. Each time I refilled with one bottle of concentrate and then topped off the tank with the premixed stuff. This ratio (which is actually pretty weak based on the directions), appears to work well. The washers have worked in as low as 5 degree weather. I *am* getting high from the vapors every time I use the washers, but at least they work.

Oil Service

(Image: On Lift During Oil Change) The oil service indicator illuminated on schedule after approximately 4500 miles, so I made an appointment. As usual, they were booking about two weeks out for loaner cars, but just around a week if I wanted to wait, so I decided to hang out. The night before the appointment, I decided to make a list of the things I needed my mechanic to look at -- a sort of "squawk list" as we say in the aviation biz.

Ever since I brought the car back from the body shop, I'd noticed the windshield jets weren't spraying in the right place. They were so misaligned, in fact, that I had to use a few more spritzes of fluid to fully clean the windshield. The spray pattern made me think that they had mistakenly reversed the jets when they reinstalled them in the hood, but as it turns out, my mechanic told me they are fully adjustable. You just need to swivel them in the desired direction with a small screwdriver or other small tool. I asked him if he could take care of that, and he did.

In addition to the needed oil service, I figured that since the odometer cranked over 110000 miles this week, I figured I'd do the tranny and diff fluid. The good news is that the diff fluid looked as clear as the day it was new, so no service was required. The bad news is, well...read on.

Transmission Troubles

I was making my way to a family dinner over the holidays, climbing and descending the hills of western New Jersey, when I felt the car suddenly downshift from 4th to 3rd and then upshift to 4th again. RPM started at around 2200, jumped to 3000, and then went back to 2200. I knew this 800 RPM difference to be associated with the difference in ratios between 3rd and 4th gear, so I knew the transmission was shifting vs. unlocking the torque converter. The latter sequence is usually accompanied by a smaller change in RPM, usually 400 RPM in my car. BMW specs indicate 500 RPM is more typical, but it's still not 800RPM.

This happened two more times before I decided to test a theory. I figured maybe the transmission adaption program was confused with all the subtle ups and downs, so I decided to punch it at a light, depressing the downshift trigger at the base of the pedal, thereby telling the transmission "I'm not driving like a pansy anymore...please change your shift profile!". Sure enough, that appeared to solve the problem, as I didn't experience it again that day. Unfortunately, on another trip to a friend's house the next week, it happened again. I collected some basic performance data, in an effort to draw some kind of conclusion about causal factors. Hmmm...same parameters -- cruising in 4th gear, around 50 MPH and 2200RPM, except this time on a level grade.

Fast forward to today. I'd experienced this problem several more times in the last month, so I knew something was definitely wrong. The common thread appeared to be a particular throttle setting, so when I described the issue to my mechanic, I speculated it might be a glitching throttle position sensor. He fairly quickly dismissed that because he said a throttle position sensor problem usually triggers a check engine light and associated code, but said he'd pull the codes and look into the problem.

When all was said and done, he spent close to an hour researching service bulletins and speaking with BMW's chief liaison to their transmission manufacturer in France (Getrag). My mechanic showed me a printout of a service bulletin that affected E36 transmissions and specified symptoms like pendulum shifting (oscillating between gears during cruise), general gear hunting, and delayed engagement, particularly immediately following startup. The only problem? The bulletin applied only to a batch of transmissions produced roughly 100,000 units earlier. In other words, my transmission was much newer that the problem units. The solution for that problem, if you want to know, was replacement of the torque converter lockup solenoid.

The Getrag liaison ultimately suggested that my mechanic take it out for a drive with the BMW diagnostic computer connected so he could look at data produced by the Engine Control Unit. This would allow him to determine if the engine was doing what it should do and was sending correct signals to the Transmission Control Unit. I'd experienced how misfiring, for example, caused the transmission to shift inappropriately, so I agreed this was a good troubleshooting technique. My mechanic returned from the test drive and discussed the (normal) results he found with the Getrag liaison, who then suggested that the transmission itself was, um...faulty.

Faulty. If you didn't know, that's another word for $3600, or $2600 in parts and $1000 in labor. To make a long story short, there was an alternative to a new (remanufactured, actually) transmission. It involved a $100 repair kit that would have required the same amount of labor to drop the transmission. This option would have cost me a third of the cost of a new transmission, but there was no guarantee that this would actually fix the problem, and when all was said and done, I'd be left with a transmission with 110000 miles on it. So, given the car's mileage and the fact that I have planned to keep the car for another 4-5 years (or 100000 miles), I figured the new transmission would be the best route. This is, after all, my primary vehicle and it needs to be reliable. The work is scheduled for two weeks from now.

If there is any "silver lining" to this problem, it's that the transmission in the E36 is one of BMW's "value line" units. In other words, it's used in several cars (the 328 and 528 of the same vintage, for example) so based on volume production, BMW is able to reduce margins on them. Other transmissions in BMWs newer and less popular models can be upwards of $6000, and my original guesstimate for this work (which I considered inevitable as long as a year ago) was about $5000. And, when I again consider that a new car is $48000, I guess I should consider myself (gulp) lucky.

Parts $37, Labor $133. Total $189, Total mileage, 110303.