M30 air intake manifold

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I am about to buy a 1991 BMW 535i (in Canada) that has 345000 km and a leak in the air intake manifold as well as an engine oil leak. Price 300 dollars. Car still runs. I plan on repairing the intake manifold
and sealing the engine oil leak. Then I will work on strapping on a hydrogen booster. Can anyone assist me with the air intake manifold? How do I replace it and what does it cost? Thanks, Noobiedoobie
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Sounds like the rubber boot connecting the airbox to the air flow meter, shaped like an "L". It runs about $28. There's another straight rubber boot between the air flow meter and the throttle body, about $25. Don't forget the myriad rubber hoses that are cracking. Easy and cheap, but time-consuming to replace. Check this site:
www.realoem.com
Bill in Omaha '86 535i
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I'll second the suggestion that the big rubber intake boot is cracked and likely has a vacuum leak on the bottom. You can check for it by squeezing the thing with the engine idling. If the idle changes (either up or down) as you do so, that's the problem. It's a half- hour job for a fumblethumbs like me.
There is also a very common and very cheap and easy-to-fix oil leak on the M30. Check the oil pressure switch at the back of the head. Costs about $8 (even AutoZone stocks 'em) and 5 minutes to replace. Next most likely (and next cheapest/easiest) is a leaky valve cover gasket.

I have *never* seen a reason to replace one, so there ought to be about a bazillion of 'em around, used, very cheap. But I'll bet you the rent that's not the problem. -- C.R. Krieger (Been there; done that)
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Thanks Krieger. I sincerely appreciate the insight. Thanks to you, I can get this fixed more quickly and cheaply. I may not even need my brother-in-law mechanic to look at it. What does the oil-pressure switch look like?
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Yes! Thank you Bill in Omaha. With your help, I think I am going to just about steal this thing off of the seller's hands tonight for only 300 Canadian. I will try these simple fixes first. I hope these work and I don't have to get at the head gasket. Is it common for head gaskets to blow on these cars, I mean, the car is 345000 kilometres and 16 years old.
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boot
M30 head gaskets are pretty tough and most would say the M30 is bullet-proof... if the basic maintenance has been done. I like mine for the timing chain and seemingly over-engineered design. No belt to break, just change the oil regularly, air and oil filters, plugs every other year, and valve clearances every other year or so. Do a compression check on the engine and that will tell a lot. Cylinders should be within 5% (?) of each other. Mine are and it has 173,000 miles. Air leaks are the main thing, but the M30B35 has a newer ECU and should be a little more tolerant than my M30B34. Don't look at the miles, look at the condition of the engine/body. Cheers!
Bill in Omaha '86 535i
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Hi Bill, I did it! I bought the BMW for 300 bucks Canadian. What a steal! I drove it home about 20 miles and it now sits in my garage awaiting my tools. The engine sounds really rough and it obviously wouldn't start in the winter, but only when idling. As soon as you drive away, it is almost as smooth as my brand new Odyssey or Altima. I figure the problem is with the air intake. On idling, it also misfires occasionally, so I think the compression of the cylinders is not in sync.
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I bought the BMW for 300 bucks Canadian. What a steal! I

Vacuum problems or air leaks usually present themselves as stalling or constant poor running at closed throttle with fine running at open throttle. Occasional misfiring at idle is more likely spark plugs and things like that in my experience.
$300 might be a steal but I figure you're either going to learn a lot about this car or end up spending a lot of money. Usually if there's one thing the owner doesn't want to fix then there's half a dozen more they haven't told you about.
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Ahhh...a pessimist. You gotta take a gamble sometimes. Thanks for the insight on the air leaks and misfiring. I am surely going to learn a heck of a lot about this car...I hope the oil leak isn't too much of a problem...
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Can you determine where the leak is originating from? MAybe spray some engine cleaner, soak about 30 minutes, pressure wash off. Run engine to operating temp to dry off. I used a car wash for $2 and did mine before finding the front crank seal was leaking. Quick and easy. I know of several locations and possible quick fixes. Please let us know where it is.
Bill in Omaha '86 535i
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Thanks, Bill. I will do exactly this. I'll keep you posted. Here is a photo of the car. http://www.livedeal.ca/ShowItemDetail?idv8083
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wrote:

several
Looks ok. You might consider a transmission fluid and filter change, too. You'll only be able to change half of the fluid due to half being in the torque converter, but it will make a difference. Considering the price of a new trans plus labor, you decide. I did my '98 528i in about an hour. You're lucky in that you have a fluid dip stick, the 528i did not. It shouldn't need special fluid either.
Bill in Omaha '86 535i
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I noticed that there is a timing belt missing. It connects from the main rotating mass which houses all of the belts to the rotating mass at the bottom right front of the engine. I am guessing that this runs the a/c unit because there are hoses with deteriorated foam casings on this side of the engine, and the a/c controls inside the cockpit are not functional. If I simply put this belt on and let 'er rip, what would happen?
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some
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You're
The A/C belt (to the compressor). It may have been removed to prevent parasitic drag from a component that a) isn't needed at the time or locale, b) needs recharging to be useful and owner couldn't afford it, or c) belt just came off (unlikely). At best the A/C will work, at worst it will not. Maybe the charge leaked out due to cold or bad seal. Judging from the snow in the pic, you don't need the A/C anyway. I've had my A/C belt off since last August in Omaha.
Bill in Omaha '86 535i
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Actually, the *WORST* that could happen is that the compressor is frozen and will cause the belt to break, possibly stall the engine, or the friction might cause a fire and destroy the car.
FloydR
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wrote:

belt
not.
snow
since
--
Gee, FloydR! I was excepting the "Bimmer on Fire" scenario. Did you by any
chance look at the pic from the place he bought it? There was a few feet of
  Click to see the full signature.
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There have been cases (mostly in the SW) where the compressor froze and the belt broke, which caused the engine to overheat, because the brilliant designers of US-made autos only use one belt for everything - a/c and water pump.
Thank heavens for German engineers.
FloydR
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I can see where the intake manifold is leaking. Right at the 6 connections where it meets up with the engine block the seals have stripped away. Looks and feels like cardboard now, but I'm sure they were originally a yellow coloured rubber of some sort. I haven't done any work on the car yet except unplugged the ICV while the engine was running to determine if the ICV was contributing to the rough idle (I mean the car is shaking, man), but this had no effect, so I will have to replace all of the hoses and the spark plugs, but first I will reseal the air intake manifold. Any idea on how to change the spark plugs without taking apart the engine?
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The spark plugs are on the passenger side of the engine. You are looking at the injectors. You'll need to remove the intake manifold to replace the gasket. I believe there is a support bracket and 12 nuts. While you're at it, get the injectors cleaned. They'll be easier to remove when the intake is off the engine. The six spark plugs take about 30 minutes to change. Check here: www.realoem.com It gives a full part breakout of each section of the car with part numbers.
Bill in Omaha '86 535i
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Hi Bill. Believe me, I have memorized the diagrams on that site. Thank you. Do I just pull the suppressors off the plugs and then unscrew the plugs out? Lucky for me the ignition wiring is all brand new! Thats a couple hundred bucks right there, and if the rotor is also new, then damn doobie scoobie, I paid only 300 which is less than the cost of just these components alone! With regards to the injectors, do they just screw out as well? I plan on using Simple Green for cleaning everything in the engine. Stuff is awesome, I used to use it to clean injection molds back in the day. Advantage: You can drink the stuff if you were thirsty and it would supply vitamins to your body, and yet it would clean the bejesus out of anything (except glass, but they have one variety of Simple Green for glass now)
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