I think I blew my motor

[JKBe30m3]

I have a 94 540i 5-speed and I somehow managed to shift from 3rd gear at redline down into 2nd gear instead of 4th. It locked the back tires up and broke the p/s, alt, water pump belt as well as the p/s pulley. I made it home(1 mile away) and it did not overheat. I finally installed a new pulley and belt and now it won't idle and sounds like it spun a bearing or something. I was wondering if it could have just timing or something and what I am hearing is just detonation. The engine must have revved to at least 9000 rpm(6500 redline). The tach went down into the mpg gauge. :(

It threw an 02 sensor code and thats it. If the engine is blown, does anyone have any idea where to get another one. :(

[Bill R.]

top of the pistons, if you hear it popping out the intake and making a put put kind of noise out the exhaust then bent valve are most likely







I have a 94 540i 5-speed and I somehow managed to shift from 3rd gear at redline down into 2nd gear instead of 4th. It locked the back tires up and broke the p/s, alt, water pump belt as well as the p/s pulley. I made it home(1 mile away) and it did not overheat. I finally installed a new pulley and belt and now it won't idle and sounds like it spun a bearing or something. I was wondering if it could have just timing or something and what I am hearing is just detonation. The engine must have revved to at least 9000 rpm(6500 redline). The tach went down into the mpg gauge. :(

It threw an 02 sensor code and thats it. If the engine is blown, does anyone have any idea where to get another one. :(

[Derek A.]

I thought all the 540's were six speeds

[Jay 535i]

Bent valves was my thought too.

I'm also thinking there could be conrod damage, particularly near the crank, as the conrods would have far exceeded their designed maximum velocity.

[632 Regal]

the sticks were 6 speeds the slush boxes are 5 speeds which leads me to confusion here.

I doubt you trashed any of the bearings simply from an over rev, the rods would have shot through the block / pan before that happens.

Bill R is right on about the bent valve phenominum, do a compression test, maybe you got lucky and only bent valves on one bank (unlikly tho).

after the compression test re post what you find and we can go from there?

I doubt you will need to replace the whole engine.

[bjl4776]

my guess is you bent the exhaust valves, which would lead to unburned fuel going past the O2 sensor causing you to throw a code. Does the car run at high rpm, and just no idle. If so that is because the overlap on the cams makes the bent valves irrelavent at high rpm. But you definately could of cracked a piston also. You wont know until you pull the head. Do a leakdown test to find out if the valves are gone or not.

[DanDombrowski]

rods are designed for stress and strain, not velocity. The stress due to the rotating mass of a connecting rod is neglidgeable compared to the stress of combustion. Bearings are designed (or in mechanical design usually just spec'd) for load and velocity.

[digitaldragon03]

The auto is 5 speed. Manual is 6 speed. I thought all from 1994 were automatic?

[pyro]

i cant bieleve the auto trans let you shift that low or do you have manual?

[Bill R.]

.
i cant bieleve the auto trans let you shift that low or do you have manual?

[632 Regal]

maybe he has 2 E34s? maybe he is posting to throw us a loop...LOL

[Qube]

That's rough!

You must have dropped the clutch to go into 2nd... should have felt it before fully engaging 2nd. But that's in the past :(

I know in the Passat, a stupid downshift like that would be rev protected... I guess not in these fellows.

On that note, had a broken belt a long time back which basically destroyed all of the valves. Hope that's not what happened to you!

[Jay 535i]

I know in the Passat, a stupid downshift like that would be rev protected... I guess not in these fellows.

How? Even a rev limiter can't help if the engine is being driven above redline by the road wheels.

I know in my 20 year old Toyota, I would not have been able to get the lever into 2nd. But I guess the BMW's syncros are just too good. :) / :(

[Qube]

How? Even a rev limiter can't help if the engine is being driven above redline by the road wheels.

I know in my 20 year old Toyota, I would not have been able to get the lever into 2nd. But I guess the BMW's syncros are just too good. :) / :(

I was under the impression that a downshift overrev would cut on the VW... of course I never tried it as the wheelspin would make you think twice already... which leads me to my point whereby the clutch must have been dumped fast!

... or perhaps the high-speed downshift protection I'm thinking of only applies in autos... which makes more sense ;)

[mzarifkar]

The rev limiter wont brake your enginespeed, it will only cut fuel or spark

[brodee]

This is VERY common on the e36 M3's. Most of them at some point will be "money shifted". I got lucky with mine and never did, but the guy that bought it from me did it and blew the top half of the engine. I was ddriving home from the track with a buddy in a '95 when he blew his trying to shift from 4-5 and hit 3 at about 112mph.

[Jeff N.]

A friend was driving my 535 back from a long day mtn biking...I was too bushed to drive. He was having fun with it and missed 5th gear and hit 2nd instead.

Car did a forced overrev and we both looked at each other with that -oh sh*t- look. Turned out to be fine but it was not a comforting thing.

[mzarifkar]

A friend was driving my 535 back from a long day mtn biking...I was too bushed to drive. He was having fun with it and missed 5th gear and hit 2nd instead.

Car did a forced overrev and we both looked at each other with that -oh sh*t- look. Turned out to be fine but it was not a comforting thing.

im assuming he tried from 4 to 5? how did he end up in 2?

[Anthony (M5 in Calgary)]

im assuming he tried from 4 to 5? how did he end up in 2?

Mirror dyslexia? 5 | 2

[JKBe30m3]

I meant to say that it is a 530i 5-speed. I simply pulled straight (or so I thought) back into what I thought was 4th gear. It went into 2nd gear just as easily as it would have been going into 4th. No grinding, noises, etc. and it was to late to do anything because before I even knew what the hell was going on the tach needle was way down into the mpg gauge.

[JKBe30m3]

Someone said that this was also common in the e36 m3's? Does anyone know why exactly the trans would so freely allow me to make such a stupid mistake?

[Alexlind123]

If you were going around a corner, the transmission could roll a bit mroe than the car causing the shifter to move a bit as well, this would mess upwhere you thought 5th or whatever should be and you hit another gear instead.

[FiveOJester]

Someone said that this was also common in the e36 m3's? Does anyone know why exactly the trans would so freely allow me to make such a stupid mistake?

On the E36 M3s it has to do with the compliant stock bushings allowing the tranny to twist under load. If you pull back and slightly to the left you end up in 2nd.

[JAlfredPrufrock]

Not that it helps now, but for future reference always backhand into fourth.

[632 Regal]

probably bad motor/trans mounts if it wasnt driver error. Can you double check the mounts for reference?

[mattyb]

have i missed something, cause i wanna know how it got to 9000 rpms in the first place!

[Paul in NZ]

he was changing down and went into 2nd instead of 4th

[JKBe30m3]

does anyone have any ideas as to whether or not I can put an m60 4.0 v8 in my car. I have access to a long block 4.0 and I was wondering if it would bolt up. I know I would also need the dme or computer

[632 Regal]

you will also need the trans.

[silverc4s]

Not relevant to the question, but 1994 540i's were either 5 speed stick, or 5 speed automatic. The 6 speed was intro'd in 1995 in the US. Not sure about other countries...

[Bill R.]

.
Not relevant to the question, but 1994 540i's were either 5 speed stick, or 5 speed automatic. The 6 speed was intro'd in 1995 in the US. Not sure about other countries...

[JKBe30m3]

The 5-speed unit will bolt right up to the five speed. It might not hold the power but I will burn that bridge when I get there. If that does happen I might have to find the rest of the drivetrain from a 540i/6. I am planning on replacing the water pump(new on blown engine), egr(same as wp), intake manifold gaskets, valve cover gaskets, fix oil pump problem and pan gasket, clean the **** off the new engine and in my engine bay, and replace leaking powersteering lines. Are there any other preventative maint items you guys think that I should replace while my engine is out and accessible.

[tim s]

The 5-speed unit will bolt right up to the five speed. It might not hold the power but I will burn that bridge when I get there. If that does happen I might have to find the rest of the drivetrain from a 540i/6. I am planning on replacing the water pump(new on blown engine), egr(same as wp), intake manifold gaskets, valve cover gaskets, fix oil pump problem and pan gasket, clean the **** off the new engine and in my engine bay, and replace leaking powersteering lines. Are there any other preventative maint items you guys think that I should replace while my engine is out and accessible.
tim s.

[stx133]

only a precious few in 1995

[stx133]

i have seen pics of a GTR Skyline motor worked to 700+ hp that had done the same 'money shift' and snapped the conrods. Bummer of a way to go. if your engine runs you may have only the head to repair, depending on any damage to the piston heads. get it flowed and lapped while it is appart. good luck

[pyro]

Yo,
I did the same EXACT thing last night. Going from 3rd at 6500 into what I thought was 4th... Lets say it reved to atleast 9000 went to the 7 oclock position. Anyways the car still ran and I drove it to work (2 miles) It has a hard time idleing but runs perfact at higher rpm's so I know its a valve issue and I don't think atleast that any berrings are spun. When the engine is running it sounds like a m20 with slightly out of adjusted valves. Anyhow I did a compression test at work and had 190 psi after 4 cranks on cylenders 3-4-5-6, and 70psi on cylender 1 and, 120 psi on cylender 2. Then I pulld the head and every piston in the exhaust valve dish had been hit by a valve. The intakes have no marks whatsoever. So what im wondering is if i carefully sand the top of the piston to get rid of the burrs and then have the head rebuilt, SHOULD everything elts be jsut fine? Accept my ego ofcourse.

Well thanks for any help and ill post pix tomrow

[angrypancake]

its surprising how many times this has happened. i remember the very first day i bought my 525 two years ago, i was driving on rt 206 in jerzee, about 20 minutes from picking it up. some douchewagon was going something like 30 in a 45, and there were a line of cars passing him. i opted to take third gear for a decent amount of time to see what it could do, and instead of shifting to 4th when the time came, it went to second. strange enough, the revs instantly stopped, tach went to max, there was no sound from the engine, and i was still in the oncoming traffic lane next to said slow guy. "oh ****!" i thought, but i put the clutch back in, and shifted into 4th. everything went back to normal, tach went back to around 3000, and never had any problems with it after that. until i hit that tree that is. i'm guessing i was insanely lucky?


anyways, it sucks that it happened to you Pyro and everyone else, but sucks more that it happens so often.

[pyro]

i cant bieleve it actually went inot 2nd... Like it happend sooooo fast. Anyways im slightly worried about the engine lower end... I don't want to waiste all of this money makeing the cylender head new and come to have lower end problems from this insident a few weeks later.

[Jon K]

Well.. if the head is ****ed, and the bottom end is ****ed, will you really be wasting your money fixing the head? When you over rev a motor, the MINIMAL damage is to the valvetrain. I doubt you'd really do much damage to the bottom end other than knicking up the pistons... you could bend a rod maybe but the 1992 M50 (non vanos) rods are forged and should be stronger than M50TU or S50 rods. I'd do the head, flop it on, see what's up, and then go from there.

[pyro]

Yah thats what I think im going to do. I jsut have to be carefull and sand or grind the piston slightly where the valves hit them, There is a little burr where that happend. Any ideas on getting the tops of the pistons squaird away? Ill have pictures as i go to work in the morning. I must say im AMAZED at how smoth the cylender walls are on a motor with as many miles as mine has!

[JKBe30m3]

It goes into 2nd gear so easily at 100mph. I couldn't believe it either. I guess it turned out for the best b/c now I have a 4.0 in my car from a 740il. I wanted to do that swap from day one. I guess it gave me the necessary motivation. Check your trans mount bushings. Mine were completely torn up and I assume the main reason 2nd was right were 4th was supposed to be because the tranny moved to the side so much under heavy load. I got UUC's urethane mounts. Good luck!!! Oh buy the way when I disassymbled the engine I had valve marks on the pistons but the bottom end looked great.

[632 Regal]

did you use the 740 trans?

[JKBe30m3]

I used the stock 530i 5-speed. I works just fine with the extra power from the 4.0.

[GoldenOne]

wow, deja vu all over again...i was in my buddys 92 nonvanos m50 when he went from the top of third into second and snapped the timing chain, bent all 12 exhaust valves...but his motor died instantly so I think your lucky it still runs!