Author Topic: Vibration getting way worse (Read 5729 times)

sumyungguy · « **on:** June 04, 2007, 04:22:21 PM »

Since I bought the car a couple months ago there has been a vibration at 2500-3000rpm's. It does it in every gear at the same spot so that eliminates the driveline. My first thought was motor mounts.

Yesterday while accelerating on the freeway and got on it a bit (about 75% throttle), the engine started vibrating really hard so I let off and shifted into 3rd (around 6000rpm). Get on it again in 3rd and it still vibrated really bad so I completely let off put in 5th and continued on my way with out vibration under light load. Get off the freeway and now the motor vibrates under load (at about 50% throttle and up) and even continues to vibrate a little bit after I let off and put in the clutch.

Are motor and trans mounts shot so bad the motor is just flopping around under load?

Anyone else experience this?

kowalski · « **Reply #1 on:** June 04, 2007, 04:26:02 PM »

could be that, but i would check/replace your guibo, and your center support bearing first. To check your motor mounts just push on your engine and see how much give its got. That would give you more of a clunking when you get on the throttle tho and not a vibration. 90% chance its your guibo or CSB. Both located on the driveshaft, and both a fairly easy job.

sumyungguy · « **Reply #2 on:** June 04, 2007, 04:34:34 PM »

Both would mostly show symptoms under a load? I would think driveline stuff shows up at certain speeds. The vibration is in the front of the car and the shifter doesn't vibrate at all.

Ill get the car up in the air and check some stuff out, but last time I was under there all the driveline stuff looked to be in good shape.

kowalski · « **Reply #3 on:** June 04, 2007, 06:57:24 PM »

a i forgot that it wasn't at speed but rpm... regardless i would still check them if they havn't been replaced. So onto something new here, how bad does it vibrate? does it feel like it still has plenty of power (for an m42..)

sumyungguy · « **Reply #4 on:** June 05, 2007, 02:17:04 AM »

Its definitely vibrating to the point that theres a loss in power, Ill get the car up tomorrow.

I'm just looking for cracked bushings and maybe shake stuff a bit to see if anything moves right?

kowalski · « **Reply #5 on:** June 05, 2007, 09:50:46 AM »

yeah, look for play, loose bolts, and cracked bushing. I'm thinking one of the cylinders might not be firing, does it idle ok?

sumyungguy · « **Reply #6 on:** June 05, 2007, 12:09:22 PM »

Ahh Ive thought that as well, if you just tap the gas at idle its kinda rough getting up to 1500 rpm. It smooths out till you get to 2500 through 3000 then is smooth the rest of the way up. Ive never seen a car only miss fire under load though.

Its going to be up in the air in a bit, Ill keep ya updated.

kowalski · « **Reply #7 on:** June 05, 2007, 01:01:41 PM »

I've seen it happen under load. First check spark for each cylinder using the ground method (pull the wire off and plug and ground out to see how good the spark is. Holding it with an insulater between your hands of course) then if thats good, while your doing that check for wet plugs, If you have a compression tester do that and a leak down test. Let me know what you find.

sumyungguy · « **Reply #8 on:** June 05, 2007, 02:58:02 PM »

got under that car to find

at first

turn it a bit

a new bolt as well

and the diff mount doesn't look too happy either

I am really surprised how close the shift linkage is to this flex disk. The motor mounts look old but are still solid and I shook the motor and only the car moved. I also found no lateral or horizontal movement in the drive shaft. I'm thinking I'll replace the guibo, trans mounts, and possibly the center bearing (I don't know how much that is needed but maybe just do it while Im down there?).

I also found some coolant on the crank pulley, the bottom of the thermostat is dry so it may be the water pump.

tjts1 · « **Reply #9 on:** June 05, 2007, 03:02:51 PM »

Wow that looks bad. How many miles on the car? I guess I should get under mine and check it out but I don't have any vibrations... yet. That diff mount looks much worse than mine was before I replaced it.

sumyungguy · « **Reply #10 on:** June 05, 2007, 05:32:41 PM »

Its got 164k on it and Ive had it for the last 4k.

I just ordered:
Flex Disc/ Guibo
Guide Bushing for the shaft
Center Bearing
Trans mounts
Water Pump
Thermostat
Lower Pan Gasket (gonna check the pan for goodies next week)

Im gonna rip everything out now cause the parts will be here tomorrow. Ill get to the diff mount soon.

tjts1 · « **Reply #11 on:** June 05, 2007, 06:06:34 PM »

Make sure you get a new thermostat housing gasket too. Its sold separately.

kowalski · « **Reply #12 on:** June 05, 2007, 06:06:51 PM »

perfect. Let us know how it goes.

sumyungguy · « **Reply #13 on:** June 06, 2007, 12:57:33 AM »

Quote from: tjts1;27150

Make sure you get a new thermostat housing gasket too. Its sold separately.

Got it, along with the fan clutch tool and some redline water wetter

sumyungguy · « **Reply #14 on:** June 06, 2007, 01:14:13 AM »

Well got this far after about 2 hrs. not too bad for never doing this before on a bimmer, but I have been a performance tech for 4 years

Removed
Exhaust, heat shields, trans mount, drive shaft, hood, fan and fan shroud

some pics of course

the root of evil--

some brand

random bolts and nuts (16mm and 17mm)