how about a second beamer?

Rocking-M

Rocking-M

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well we bought a 318i 91 that I was trying to get my youngest son to buy.
a great car with 152k on it. perfect interior. Now the son likes bmw's but the wife want sell him the 318.lol Anyway we found a 325 that he wants. It has about 160k on it and the body is in good shape it seems. Are the 2.5's as good engine wise as the 1.8's? Thanks. Robert
 
Pete K

Pete K

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The '91 318i is a sweet car. It's the last year of the durable E30 body and the first year of the high-performance (relatively speaking) 4 banger M42 motor. I'd hang on to it. But the 325i is a great car too. You didn't say what year 325i. I believe 91 and earlier have the old durable M20 motor while 92 and later have the newer, torquier M50 motor. They're all pretty durable though.
 
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epj3

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M20 is arguably more durable and reliable than the M42 (4 cylinder) since it is a simpler design and lower compression. By all means, the M42 is a great motor.
 
Chesty Bonds

Chesty Bonds

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Why are we talking about the M42 here? The 318i has the M40. '91 aint the first year of the M42B18 either - my 318is is a 1990 model.

Eric is right about the M20 being a more simple design, and the M42 does have a fairly high 10:1 compression ratio (engine braking is superb), but I must say that it does have very few recurring problems. The main ones to look for are noisy hydraulic tappets (cam followers) which automatically compensate for wear and temperature, are prone to gunking up. As Eric said, they are very complex and difficult to fix when they rattle.

The diff is also sensitive to abuse, and the clutch master and slave cylinders (these usually fail together) can go at around 120,000kms... Apart from these issues, there are no major problems with the M42, so long as it is REGULARLY and PROPERLY serviced by someone that is familiar with their complex design.

Damn the M42 screams at 6,500RPM [headbang]

But yeah, why are we talking about the M42 anyway [hihi]
 
Rocking-M

Rocking-M

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thanks for the info fellows. Its an 86 325 so it should be the m20, right?
We're gonna hang on to the 318 for sure. Seems like a great car and
all I have done is replace the ball joints, the bushings and the tires.
Oh, yea, i did break down and buy the code reader/reset to fix the
inspection light. :)
regards, robert
 
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ldzpstnr

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Since its an 1986 325 then its got the ETA 2.7 engine. Its an economy engine. My 325 with an ETA gets about 33-35 mpg on the highway. Its a bigger engine then the 215i engine but it has less horsepower. It does have more torque then the 325i though. The ETA engine is known to go a long time.... one guy on this board has one with alomst 300K on it i think. Mines got 225k and runs great.... wont die for a long time. Yes they are both M20's by the way, just different configurations.
 
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epj3

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Chesty Bonds said:
Why are we talking about the M42 here? The 318i has the M40. '91 aint the first year of the M42B18 either - my 318is is a 1990 model.

Eric is right about the M20 being a more simple design, and the M42 does have a fairly high 10:1 compression ratio (engine braking is superb), but I must say that it does have very few recurring problems. The main ones to look for are noisy hydraulic tappets (cam followers) which automatically compensate for wear and temperature, are prone to gunking up. As Eric said, they are very complex and difficult to fix when they rattle.

The diff is also sensitive to abuse, and the clutch master and slave cylinders (these usually fail together) can go at around 120,000kms... Apart from these issues, there are no major problems with the M42, so long as it is REGULARLY and PROPERLY serviced by someone that is familiar with their complex design.

Damn the M42 screams at 6,500RPM [headbang]

But yeah, why are we talking about the M42 anyway [hihi]
Click to expand...
In the USA, the reintroduction of the 318 was only 318is (coupe) in, I think, 89 or 90. It ONLY had the M42, and the M44 is what the E36 318i had.
My question is what's the difference between the m40 and m42?
 
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epj3

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Big Daddy said:
In the US the only E30 with an M42 was the 1991 318is. It was produced through 1996 and placed in the E36 318's and the Z3's! The M44 was not used until 1996 and later.
Click to expand...
You sure? I always thought the E36 had the M44 throughout the whole time it was used...the DASC site says "only works on e36 318i's which have the m44"
 
Chesty Bonds

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epj3 said:
My question is what's the difference between the m40 and m42?
Click to expand...
Yeah there are a lot of differences!

The alloy head is a chilled-cast 16V twin cam unit with the sparkplug centred between the valves (like the M1, M5, and M635csi cars with the M88). The top of the rocker cover has a liquid/vapour seperator to reduce oil consumption.

Camshafts have 15mm hollows (that's right!) to reduce inertia and are of short duration but high lift. The valves themselves are sodium cooled and are double sprung. The throttle body is a twin-stage unit while the inlet manifold is a double piece with its long length improving low-down torque. A free flow exhaust header is also fitted.

Here's a pic of the extractors, which are quite impressive if you ask me:


The crank is forged (rather than cast) and is fitted with 8 counterweights. It can be revved to 7200rpm with no trouble. The forged steel con-rods are 12g lighter than the M40's. The pistons are lighter than the M40's and it also featured a dual mass flywheel to reduce low speed vibration.

In order to reduce the maintenance of the engine (always a help to povvo students like us), direct driven hydraulic tappets (lash adjusters) and a hydraulically tensioned duplex chain are used in the cylinder head.

Significantly, the M42 has a chain-driven camshaft. The M40, like the M20, has its cams driven by belt... Not cool.

Lighter conrods and pistons, used along with hydraulic engine mounts (like the S14), help to make the M42 a lot smoother and free-revving than the M40.

I think that's most of the differences explained for you... The M42 has a vastly different character from the M40. While there are obviously many similarities, I can tell you from experience that the M42 just has that extra angriness and "revvability" which makes it such a great BMW engine. While it's undoubtedly pretty low on sheer power, it more than makes up for it in the way it delivers every one of its 100KW!
 
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ldzpstnr

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How long will the M42's last? Last as long as an ETA? After your post chesty it sounds like the M42 is more trick then I thought. I havent played with an M42 to yet, I am too poor and can only afford my ETA at this time. What kind of milleage does the 318is get? A 318is just might be my next car.
 
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Big Daddy

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My 91 318is had over 140k on her when I sold her. Other than routine maintenance and the dreaded profile gasket she never had a problem. I would take that car back in a heart beat. The M42 is a fantastic motor that should run well into the 250k mark or more!
 
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epj3

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ldzpstnr said:
How long will the M42's last? Last as long as an ETA? After your post chesty it sounds like the M42 is more trick then I thought. I havent played with an M42 to yet, I am too poor and can only afford my ETA at this time. What kind of milleage does the 318is get? A 318is just might be my next car.
Click to expand...
M42 could last just as long - I imagine it will run BETTER for longer - but I dont think it'll literally run forever without major work like the M20 eta motor probably could. If you're poor - you dont want a BMW. Assuming you can do all the work yourself, you're still going to be spending a lot of money for the little repairs that pop up now and then.
 
Rocking-M

Rocking-M

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Now y'all have thoroughly confused me. I tought the 91 318i was the m40 engine if it was the e30 body. If it had the newer e36 body then it had the m42. The only thing I've done on the engine is put in an air filter:) But it doesn't look like a timing belt engine. Though I have nothing against timing belts...my race car is a Fiat spider 2 liter.:)
 
Chesty Bonds

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Yeah I guess you could say that the M42 is like a "light" version of the S14. Indeed, there is a physical resemblance between the two engines, especially the design of the rocker-cover.

Rocking-M this is how it goes: the E30 318i was equipped with the stock M40 4-banger. The more powerful and sporty E30 318is was equipped with the M42. BMW used the M42 in the E36 318is as well up until 1996 after which the M42 was redesigned into the more mild-mannered M44. The M44 had more midrange grunt than the M42 but lacked the former's top end sting which, in my opinion, isn't such a great thing since the M42 howls to the redline.

Idzpostnr the M42 is a pretty complex little engine; of that there is no doubt. This engine needs regular maintenance because of the self-adjusting tappets etc. This engine also has quite a sophisticated emissions control system so it's quite sensitive to servicing. You really need a mechanic that knows what he's doing here.

In terms of tuning I wouldn't waste my time to be honest. I would love to tune my M42 hard but unless you make serious changes (like Schrick cams, bespoke cat-back exhaust, strengthened internals etc) and spend shitloads of money you're not really going to gain much. Personally, adding a chip to raise the redline to 7K is a nice idea but you have to remember that you're going to lose some of the engine's ability to last a long time. Air-intakes are a waste of time and there are virtually no bolt-on exhaust systems for the 318is.

I hope some of this stuff helps.
 
Rocking-M

Rocking-M

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Hey BD, i went to the sites you posted and it looks like the 91 318i had the m42 too.
I didn't even see the m40 listed as a possibility for the 91.
 
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