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BMW 7-Series 2006 and earlier

1317 messages,  Last post on Sep 16, 2012 at 11:07 AM

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What is this discussion about? BMW 7 Series

Messages Page 92 of 133

#906 of 1317 blockislandguy by f1buick

Oct 22, 2003 (7:21 pm)

"But, do you really think that a used 7 Series with a CPO is the same price as a Lexus? What is the CPO premuim? 3K or so?"
 
You'll have to answer that for yourself. I really have no idea. I do know that in comparison to a Lexus 400, my 750 cost a lot more new and is worth a lot less used. I think BMW 7-series depreciates faster because BMW lacks the reliability rep that Lexus has built for itself. Further, the reputation for technological advancement may create more sales for new cars, but used car seekers translate that same rep into words like "complex" and "expensive."
 
I can't disagree. My '93 750 has this gizzmo on the firewall plumbed into the brake system. I couldn't figure out what it was. Then I found out it was the "traction control module." Seems that in 1993 the Bosch ABS pump couldn't effect traction control because it didn't allow separate manipulation of the rear brakes. So BMW built a custom ABS module, plumbed into the rear brakes, which allows for traction control. The unit costs $2495 if it breaks (mine hasn't) and is almost impossible to access (add another $800 for the labor).
 
But I agree with bmwseller on one issue: ain't nothin quite like a BMW when running down the road. These are driver's cars with a veneer of luxury--iron fists in velvet gloves. The top of the door sill in my 750 is the same height as the sill for a C5 corvette. At a stop light I find myself looking UP at drivers in Mustangs and Civics. Can you say "low center of gravity?" My 7 is a 160mph sports car that happens to be a luxury car. A Lexus is a luxury car and nothing else (can you say "boring?")

#907 of 1317 ??? for f1buick by tasillo

Oct 23, 2003 (7:58 am)

750 guy, how many miles on your '93? I ask because my '00 740 is fast approaching 60k and I'll put another 50k on it in the next 2 years. Trying to decide if I should keep it and "run it into the ground" or bail out now while it still has a shred of value. Any significant problems with your 10 year old 7? I'm more concerned about major accessory systems, etc. I think the 7 series drive train is pretty bullet proof, but I hate those nickel and dime (or in a BMW, $500 and $1000) frequent repairs on things like power windows, cruise control, A/C, etc. What' your experience been?
 
By the way, couldn't agree more about the "drivers car" statement. On the interstate or rural secondary roads, nothing compares to a big, fast German car!

#908 of 1317 traction in chicago.............. by bmwseller

Oct 23, 2003 (12:38 pm)

Handling in the chicago suburbs will be fine in either car with the proper tires and technique. Maybe with the 5 weighing less it would have an advantage if it was to be said one way or another but there are plenty of sevens running around up there, pull someone over and ask.
You'll do great!!! I like the size of the 5 but would certainly "settle" for a seven.

#909 of 1317 tasillo by f1buick

Oct 23, 2003 (5:11 pm)

I've owned the 750 for 6.5+ years and 60k+ miles. On a day-to-day basis the car is very reliable. There have been very few "nickle and dime" repairs for items not in the normal maintenance schedule.
 
Hmm, lets see . . . I just replaced the switch for the rear sunshade $50. One xenon headlight went out and I passed on the $1250 replacement (!!!) and rewired for halogen. Just replaced the master cylinder. Still have original shocks, alternator, starter, a/c, cv joints, bushings, exhaust (except one your car doesn't have). Pretty darned original, really.
 
I totally replaced the cooling system, but that was because of a defective expansion tank cap (missed the recall). The headbolts failed and I had to rebuild the top end myself (no competant mechanic would touch the V12), but that's a long story not relevant to your V8.

#910 of 1317 Headbolts Failed on a 750?? by blockislandguy

Oct 23, 2003 (7:56 pm)

F1Buick, your head bolts failed? How do head bolts fail? Bolts stretch, bolts fatigue, but bolts usually don't break. Were you in there retorquing a head and a couple broke off? Did someone not used Grade 8 head bolts?
 
This is mind boggling.

#911 of 1317 Headbolt issues by f1buick

Oct 24, 2003 (1:05 pm)

Well, if you grew up with cast iron chevies and fords like i did, the mind indeed does boggle.
 
Many all-aluminum engines, including the BMW M70 V12's, use a head bolt system known as "torque to yield." Do a google search if you want more detailed info. (I can talk about it for pages, but I'll pass). At the simplest conceptual level, the "stretch" in the bolts is an integral part of the clamping force used to seal the head/block/gasket. The bolts are stretched just short of the point of permanent deformation (the "yield point").
 
One of the benefits of this system is that the bolts can be used as "circuit breakers" in case the block/head is overstressed, with the most obvious example being overhearting. It the bolts were extremely strong and held fast, the block and head would have to absorb the thermal expansion by warping. This would be very expensive with a V12. But with torque-to-yield the bolts already are stressed just short of permanent deformation, so when the block/head expand, the bolts just fail by stretching too far. This releaves expansion stress on the head/block, but leaves you having to install new bolts and head gasket. Way cheaper than new head/block castings, but still a pain in the arse (you can imagine how accessible the engine compartment is in a 750).
 
Anyway, my V12 did not overheat. The bolts just failed in normal use. This is a rare occurance, but it appears that BMW just couldn't get the V12 bolts quite right. There were several iterations of bolt design. To analogize: they stuck a 19.5 amp fuse in a 20 amp circuit and it thus was possible to overload the bolts during normal use.
 
Have I said enough?
 
Many motors by BMW and others use torque to yield head bolts. I've been told that Honda had similar issues with some of its 4cyl motors in the late 80's and early 90's. I would imagine that others also have not got the bolt design correct at first. I believe that most BMW I6 and V8 motors use torque to yield but have not exhibited premature failures like on my V12.
 
My other car is 2000 Buick Ultra. It has a CAST IRON BLOCK AND HEADS, which makes me feel very secure . Now if they could just work on the chinzy interior . . . .

#912 of 1317 Head Bolts Failing, continued by blockislandguy

Oct 26, 2003 (6:56 pm)

F1Buick, thanks for the well done bit on t-t-y bolts. Yeh, to people raised on flathead, indeed inline 6 cylinder flathead, cast iron blocks and heads, this is new stuff. Kind of like when capscrews replaced studs.
 
BUT, you went opaque when you got to the good part. What do you mean by "The bolts just failed in normal use." How did you recognize this? A bolt just fell out? A blown head gasket?

#913 of 1317 I recognized it by f1buick

Oct 27, 2003 (9:05 am)

when I started loosing coolant and then I got 9 quarts of fluid out of a 7 quart pan during an oil change. Uh oh! A compression check confirmed the worst--one cylinder about 40% low and several down about 20-30%. This on a motor that during a previous check had shown only 5lbs variation between cylinders.
 
TTY bolts usually do not fail by "breaking." They are stretched until they permanently deform (yield point) and thus loose their ability to hold the deck/gasket/head seal. They seldom reach the modulus of rupture, ie., the point where they actually crack and break. None of my bolts broke, but when I removed them I check the torque with my click-stop wrench. None retained more than 50 ft/lbs and some were under 40. This will not hold compression very well!

#914 of 1317 CPO Warranty Not the Same as New? by blockislandguy

Oct 28, 2003 (8:20 pm)

Bmwseller, you posted a week or so ago that the warranty on a CPO wasn't the same as on a brand new BMW. Without asking you for an exact comparison, what are the big differences? Here I was all prepared to save 30 large (70-40=30) on a 745 AND still get a factory warranty.

#915 of 1317 not under cpo by bmwseller

Oct 29, 2003 (12:14 pm)

I recommend the cpo's. It is a BMW product and that's good.
 
Maintenance is obviously not covered. Also, paint, glass, headlamps, mirrors,body seals, gaskets, iterior trim, exterior trim, moldings, fatsteners, upholstery, headliner, air/water leaks, wind/body noises, wheels, and "wear and tear". There is a big explanation for "wear and tear" and includes possible exceptions that may include piston rings, valves and valve guides, suspension bushings, ball joints, etc.....
 
Add in the $50 deductible and it is a fair departure from a new car warranty. But, check on one of these 'free warranty quote sites and see how where non-BMW products are going for so, it's good, but it's not too good to be true. As you would expect.

Messages Page 92 of 133

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