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Wednesday, December 17, 2014

Doug's Domain

Doug Vetter, ATP/CFI

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Saturday, August 23, 2008

Fuel System Treatment

I've settled on a 4500 mile interval for using fuel system cleaner and have scheduled it to coincide with the oil service so I put a bottle of Techron in the tank this week. I have noticed hard cold starts in the morning while using fuel with the Techron additive. Nothing much I can do about that aside from not using it, but I do believe fuel system cleaners serve an important role given that the detergency of gasoline has been reduced to the bare minimum levels required by law in an effort to add a few more billion in profit to the oil companys' bottom line.

Oil Service

The service indicator illuminated more or less on schedule this week so I dropped by the dealer today to pick up some 5W-30 and an oil filter kit in order to complete the oil service. I made quick work of the oil service and grounded pin 7 of the diagnostic connector for three seconds as required to clear the service indicator. While I was at it, I collected another oil sample and plan to send that out soon. I don't expect any change from the last report but I'll post the results here if there's something worth reporting.


I decided to use the opportunity afforded by the oil service to do a close inspection of the undercarriage. With my trusty (and extremely bright) 3 watt LED D-cell based mag light I got under the car and started my inspection.

Fortunately, a good look at the front suspension revealed little to complain about:

The rear of the car looked equally good. I paid extra attention to the rear suspension because I've been trying to track down an odd feeling the car has developed at speeds of 70 MPH or more that I can best describe as similar to the feeling experienced when the car buffets in strong crosswinds. The problem is only intermittent. I initially thought it might have been due to tires or play in the front suspension but the characteristics of the problem suggest it may, in fact, be caused by worn trailing arm bushings, which are still original. If these bushings flex too much it causes the rear alignment (toe, specifically) to change which can cause the rear to swing a bit. This can give the appearance of hysteresis or slop in the steering when there is in fact none at all. This is all very subtle, mind you, so most people would never notice it but, at usual, I do.

One other item I've been watching is the transmission. I now have about 40K miles on the remanufactured transmission and I think it's in need of an oil and filter change. I know a shop that has the fittings necessary to flush the transmission by disconnecting the transmission cooler so I plan to use that technique to replace all the fluid at once rather than dropping the pans several times. This will get at the oil that would otherwise remain in the torque converter and obviate the need to pull the smaller of the two pans when I change the filter. Now all I have to do is find the time to do that.

Record Keeping Note

For the purposes of documenting labor savings I figured I'd "charge" myself roughly an hour to do this inspection. I think that's more than fair because the dealer would charge a hell of a lot more than $100 to conduct either Inspection I or II, and I wouldn't expect an indy technician to do the job for free either. Hence the labor savings of roughly two hours or $220.

Mileage: 164850, Parts $65, Labor saved $220

Saturday, August 30, 2008

First Coolant Flush DIY

If I chose to follow the two year interval for coolant flushes as recommended on the E36 when it first came out (since changed to three years), I was due for a coolant flush in June. Due to my schedule and my desire to determine the proper method to flush the coolant I delayed the process...until yesterday when I completed my first DIY coolant flush.

I realize that certain purists may take issue with the method I used. Let me explain. A few months back while I was researching this task I discovered that in order to remove the block drain plug I would have to remove one of the pre-catalyst oxygen sensors. This is due to the use of the M3 headers on the M52 engine in 96-99 coupes. Since unscrewing the oxygen sensor would require me to repeat the process as documented in my Oxygen Sensor DIY article, I decided that I'd look for alternative methods and seek my technician's advice.

It's clear to me now that the dealer technicians do not remove the oxygen sensor and thus do what I choose to call an "abridged coolant flush". Just as an automatic transmission fluid change unavoidably leaves a good 30% of the fluid behind in the torque converter (unless, of course, you use a machine to cycle in new fluid as the transmission is running), the abridged coolant flush leaves about 50% of the coolant behind in the block.

The "abridged" technique is not as bad as it seems for one simple reason: the proof is in the pudding. My dealer flushed only half the fluid every other year and I managed to get 125K out of my radiator and 165K on the original heater core (knock on wood, of course), and I should mention that I replaced the radiator not because electrolysis had damaged the metal core, but because the plastic necks were about to fail. Fortunately, I won't bother to subject you to the sleep aid that would be a lecture on asymptotes as they apply to coolant flushes. Just trust in the knowledge that replacing half the fluid every year or two achieves the goal and protects the system.

The total cost for a coolant flush at the dealer is $220, $25 of which is for parts. Thus, I managed to save $195 by doing this job myself. It's not a ton of money, but as usual it's better in my pocket than anyone else's. Viva la DIY!

Mileage: 165115, Parts $25, Labor saved $195