# 97 740IL (E38) Catalytic converters



## Rev. Andy (May 3, 2005)

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I have a 97 740IL which seems to be eating catalytic converters. I pick this up wholesale in Sept 2003, and immediately replaced both cats. Within 2 months the left side went and was replaced (under warranty) about a year later, the right one went and was also replaced (under warranty, with grumbling). Now a year and a half later, the left one is starting to rattle. The engine is in tune, I use only 93 octane (Mobil), so am I just getting bad cats, or is there something causing the cats to burn out abnormally fast?
Since I've owned the car, in addition to the cats, I've replaced the throttle cable, cruise control cable, all filters, the heater core, recharged the A/C, replaced the rear u-joint on the drive shaft, real ball joints, radiator (the upper hose nipple broke off), and all 4 02 sensors. We all know this is an incredible car to drive, or we would put up with this absurdity, but I'm looking at putting even more money into this and am actually beginnig to question my sanity.
The check engine light has been on since I bought the car, it's the torque converter code, but more indepth inspection has revealed that the torque converter (which was apparently new in 2002) is burning out because the valve bodies in the tranny are going - so at some point new tranny (for ~$5,500). I would do this if I knew that the car at some point would become dependable - meaning less than $1,500/year in maintenance/repairs. Right now the more immediate concerns are replacing the front struts (~$900), doing the breaks (normal maintenance), and dealing with the frustrating electrical problem called the center console. The radio/tape/CD will cut out, or simply not come on, at a whim. The display in the tape player which is also the equilizer are out for good now. If I snap hard on the tape player and push the station button a few times (some of the station/track buttons are broken), I can sometimes get the sound back. The little green lights on the climate control come on about 20% of the time. The A/C was recharged last fall and worked reasonably well. This winter, the heat on the passenger side started to just crank out, unless I turned the driver side down to 60, but then the driver side got cold also. Now the A/C is pitiful, heat is erratic. Oh yeah, the display in the dash for milage, temp, and trip are all missing pixels also. For about $1,000 I can replace the tape, radio/CD control and climate control panels. Would that actually solve the problem, or is there some obvious problem which is causing all these failures?
Suprisingly enough, I am willing to try and solve these problems, but the one that keeps haunting me is the cats. Does anyone have an idea as to why the cats burn out? I've talked with another 97 704IL owner, who has the same torque converter code and is also eating cats. Is there any end to the madness?


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## 89 325i (Apr 8, 2005)

Hi,

Wow. That's a whole lotta stuff going on. How many miles are on this car? I'v been thinking lately of looking for a late 90s 740 but I have to tell you, your experience is giving me serious pause. Is this litany of repairs problems common to late 90s 740s?

Thanks and good luck. You're a patient guy, I'll give you that.


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## Rev. Andy (May 3, 2005)

There is just under 160,000 miles (I bought it with 135,000). I knew buying this wholesale about the first set of catalytic converters, and we thought the torque converter code was a programming fluke, since we could tell it was a new converter. The display issues where also obvious, but the radio/sound cutting out and the climate control problems where not. Still and all, you can't beat the drive, and it only bothers me when I take it to the mechanic. Other than the cats, I haven't had to repair the same thing twice, which is why I'm concerned about the cats. It may not necessarily be the best investment, these are expensive cars to repair/maintain, but I think this car has had a hard life.


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