# Bad compression new used 93 740il



## lorrin (Dec 11, 2006)

hey all, looking for opinions- this is one of my "born blonde" mistakes in life 
this is my 8th BMW, and i should've known better than to trust mechanic. picked up a 93 740il- beautiful interior, few dings on body. 168k miles. test drove, was a little rough but mechanic said car was sound, previous owner didnt do much maintenance, but engine 'good'.
a few days later, engine light comes on with rough idle. new mechanic replaces intake manifold; water pump, etc for $2000 and change. he does compression test and says 8th cylinder is functioning at about 50%.
he recommends i sell car. says it may run for 6 months or 10 years. i feel bad selling to someone. what do you think about replacing engine? any and all ideas appreciated. 
ps i like this new shop and the two mechanics there seem to really know their stuff.
thanks much!


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## TerryY (Jul 20, 2003)

This is the Nicasil problem personified.

BMW has a replacement block that isn't really a short block for what seemed almost reasonable price a few years ago but was quoting a total of $13,000 to do the replacement.

Most used blocks are questionable (Nicasil?) and the later 4.4 engine isn't a direct drop in either. I think it can be done though by switching all of the external electrical stuff from the old engine. $$$$ though if you are not doing it yourself.

I suppose the choices are to cut your losses now or to Marry the car $ wise.


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## lorrin (Dec 11, 2006)

*thanks terry*

Thanks for taking the time to amswer my post. I researched the nikasil, and see your point about getting another engine, as I called a place Vines (?) in Alabama today. They had remanufactured ones for $5000, and used for $2500, the latter would be prone to the same problem. Would a remanufactured one have the alasil? 
Morally, cutting my losses means driving it till it dies, as I cant sell it to someone else now that I know about this problem. Its an expensive mistake 
BMW did offer a warranty but I'm waypast the 100,000 miles. I wonder why my mechanic didn't know about this? The rough idle continues despite the 2 grand I just put into it.
So Terry, what happens? Doe sthe corrosion continue until she just won't start one day?
Is there any additive I can use?
Maybe your idea about the later engine will work- howmay hours of labor do you guesstimate?
Oh boy, I really made a dumb mistake this time. I kinda think I'm looking to get hitched 
Thanks again, you're so cool to give me your time.
Hey your car- Ive never seen an 8 from the 90's! How long have you had it?
All the best,
lorrin


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## TerryY (Jul 20, 2003)

It is not too uncommon to be taken in by a bad Nicasil 740. I bought one myself based on a passing leakdown test at one of the 2 local BMW dealers. Of course the other dealer had failed it a year before for the original owner--long story that still pisses me off.

All of the gasoline in the US is now low enough in sulphur to not cause further damage.

Where the problem is now--
1) the crancase is operated under full vacuum so combustion blowby in the bad cylinder is a vacuum leak. Therefore the check engine light (code = Lambda #2)

2) oil trapped in the pockets in the cylinder walls is burned in the combustion chamber on the next stroke. If there is enough it will foul the plug and it misfires. 

3) Oil mist and smoke from inside the engine condense in the intake manifold of the V8 even with a good engine. All of the extra from the bad cylinder is what makes it smoke on cold start.

Heavy synthetic oil changed often will help with the smoking on start and under heavy acceleration. Dino oil can turn it into a Mosquito fogger.

US Chrome has a shop that can repair your block. They replate and diamond hone the block back to original BMW specs for about $1000 or so. (Couple of year old quote though) but with all of the labor to tear it down and put it back together it probably wouldn't be economical.

I ended up swapping spark plugs around on the bad side every few weeks to keep a clean plug in the bad cylinder. 

Do not use Bosch +2 or +4 platinums in any BMW 4. or 4.4 V8 or V12--they just don't work right.


All of the real 840s and 850s are from the 90's. Only the Z8 is from the 00's and it really has no common ground with the original 8.

I have had mine for 3 1/2 years now. It has a Good Nicasil engine at 145,000 miles. No signs of damage at all. California low sulphur gas for most of its life!


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