Extreme vibration when in 2nd gear? Manual transmission


#1

Hi there,

Vehicle is a 99 Mazda Protege ES 1.8l. Manual transmission.

I drove this car in a trip to Arizona and noticed that it was shaking a lot if I drove it at 70 to 80 MPH. I thought it was the motor mounts since I could see some cracks in the lower front mount and passenger side mount.

I replaced both today and it made a difference in idle vibrations and shifting, but noticed vibrations when accelerating on the freeway. I thought maybe it was tire balance. I got the tires brand new and had to redo ot twice because the first shop. Did a crappy job. I also thought it could be the driver side. CV axle.

But the vibrations got even worse when I drove on a hill. I tested accelerating in all gears and they are all fine, except on 2nd gear.

I also performed a clutch test and it seems fine. Could it be the mounts? I ordered the parts directly from mazda, but noticed the rubber portion of the lower front mount looked different in terms of thickness.

I also replaced the spark plugs, but not the wires. I don’t see any leaking axles, they are supposed to be brand new. There is a lot of residue in the transmission area, which I believe is what was left from the cv axle seal leak the vehicle had before.

What could it be?


#2

It sounds like the throw-out-bearing is giving up the ghost.

Tester


#3

So what particular conditions do you feel it shake now? Only when driving up a steep hill in 2nd gear and going straight ahead? And no shaking in other conditions? Or does it shake other times too still?


#4

Okay, I just drove around town and it’s definitely not the new mounts. I have noticed the shake before, and there are no hills where I live. You can feel shake starting from the second gear but not as bad as in steep hills.

I can feel some shaking when idling too. You can see the needle on the RPM gauge move up and down a bit, doesn’t seem to stay steady. I don’t know if this is normal for a car that has 220k miles. My other vehicles are too “new” for a comparison.


#5

Since you’ve isolated the other systems, I’d say the transmission has a problem. In the area of second gear.


#6

=( Damn… I don’t think I can do this job on my own.


#7

What can it be? :slightly_frowning_face:


#8

And driving a 19 year old under-powered car like that makes sense…why?

;-]


#9

Maybe bad bearing in the transmission. The one nearest to 2nd gear.


#10

People drive like crazy. In Arizona, the freeway to Skywalk/Grand Canyon only has two lanes. I was constantly looking at my rear view mirrors. I had to do 70 - 80 MPH momentarily in order to move into other lanes, and pass slow moving trucks.


#11

And doing so has destroyed your car.


#12

Going from 65 to 70 - 80 mph on 5th gear destroys the transmission? hmmmm well I guess I should’ve let these kids rear end me and die in a crash with my family then. Time to leave the car in the garage.


#13

That could be a clue. All the shaking may be due to misfires. You’d notice a misfire more during acceleration. But misfiring is noticeable at idle too, as a slight engine shaking. Suggest to focus on why it shakes more at idle now than when the engine was running ok. Misfires often produce diagnostic codes, so that’s the first place to check. If it is a misfire, common causes are spark plugs, coils, cam/crank positions sensors, battery voltage, ignition module, cylinder compression.


#14

How many rear-end crashes did you see into the backs of those slow-moving trucks?..(rhetorical question)


#15

What is your problem? Lots of people were driving way faster than me during the whole trip. I kept my speeds at 65 MPH as much as I could in order to save gas. I only drove from 65 to 70 - 80 mph to pass slow moving vehicles and give way to the guys who were driving way faster than me. Sometimes you have to keep up with the flow of traffic too. 70 - 80 mph is nothing. It is not like I was shifting from 1st to 5th gear + high revs?


#16

Thanks George, I will start from there. Time to get that OBD scanner. Will it be any help if I upload some pictures of the spark plugs? There are “burnt” marks on the ceramic portion of the plugs, I don’t know what these are. I tried googling this but found nothing about it.


#17

Do you mean the part of the ceramic that’s outside the engine? Or the part that is inside the engine?


#18

I have uploaded some pictures. Please have a look.


#19

I uploaded some pictures, please have a look. :hugs:


#20

I don’t see any problem with the part of the plug outside the engine, but the working end right at the tips of 3 of the 4 plugs look to be coated with soot or dark residue of some kind. That doesn’t look normal to me. Either oil fouled or running to rich and coated w/soot.