Few questions on 850 vs. 840

[xman]

I am very interested in a 8 series bimmer and have read the buying tips on the E31.net website. My question is besides the 4 extra cylinders are there any items that are more prone to go wrong in the 840? Also were all the Nikasil engine blocks replaced by BMW because some for sale ads will say engine replaced by BMW? Lastly, if I find a car with the service records for the last 4 years and the prone to go bad item checkout what is the typical annual maintenance cost for an 840i auto?

Thanks for your input.

Xman

[DeanP]

There are fewer items to go wrong a 840 verses a 850. My understanding is that the V-12 has two of most things, alternators, water pumps and things like that. And no, not all the blocks were replaced. If there is no paperwork indicating it was done, assume it wasn't replaced. You are only concerned of this issue with the '95's. If you were on E31.net then you read about the compression and leak-down test to help identify if you might be looking at a car with a problem. I am sure Terry will be along soon and fill in any other gaps.

[TerryY]

Hi
I'm feeling typing challenged this weekend so.

Start reading here http://www.e31faq.com/

Most of the issues to look for are covered in the buying guide. Some are simple fixe$, some are $$$$$.

Basically other than the drivetrain and a few upgrades over the years they are all the same inside.

Sometimes I feel like 840s are considered the redheaded stepchildren of the batch because of the extra 4 cylinders in the 850s. I'm not the only 840 owner to feel that way so I'm not too crazy (at least on that point )

So if status is important then the 850 is the best.

The beginning of the 840 run in 3/93 (MY '94) saw several upgrades to the electronics but never a manual transmission on any model other than an 850CSi after that.

We have organized groups of owners all over the US and in other parts of the world that can give a hand with looking before purchase and helping with problems after you become one of us. Satch Carlson of Roundel called us the new BMW Cult


So much for being typing challenged

[323I Junkie]

The 840 engine is fairly commonly supercharged and modded, can be replaced with larger displacemnt, higher torque blocks. The v12 modding is more narrow

[vteckilla]

well im no 8 series owner but i wish to have one but i just bought this bmw buyers guide book for information on all sorts of models of bmws so i figured why not share some of the neat infi i have been reading about.

It says the 1994-1995 840's m60 v8 engines had the nikasil problems.
watch for automatic trans slip and exspensive noises that are from not properly maintaing the trany.
check headlight ajusters since they work loose and the lights will fall out.
check power steering there is a filter that can be blocked causeing the power steering pump to fail.
check lower corners of the rear windshield for any sign of rust where water may have gotten in under the window seal and the sunroof at the center rear edge.
watch for incomplete obc display,twisted or distorted seats a result of the controll drive cables slipping or have just broken, and torn or tearing side window seal gaskets.

the book says listen for a whisleing sound from the rear of the engine block there is a vacume plate under the intake shroud that can fail.Test this by removein the oil filler cap with the engine running,if the plate has failed the vacume will be strong enough to suck the cap down.

it gives prices on some things here's a few
ps pump $360
front fender about$800
headlight unit complete popup is almost $700
front bumper retails between $850 with the squirters to $870 with out

hope this helps