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?