timing belt broke, replaced ,now i have a vibration

[lovemyram]

I have a 91 ram 50, 2.4l, it has 80,000 miles on it.
the timing belt broke while driving it yesterday,I relaced the belt. now while running it has a vibration that was not there before.
I am sure the timing marks were lined up properly when the belt went on. the balance shaft pulley felt ok, do you think when the
belt broke, the balance shaft could have broke??? can you think of another cause? please help. thanks

[pennyman1]

It only takes the balance shaft belt to be off 1 tooth to get a vibration from the motor. Check the balance belt timing - it is usually good practice to replace the tensioner pulleys and the balance shaft belt at the same time to prevent future issues. Most people replace the water pump too, but you may be able to wait on it as you have such low miles. Welcome to the forum.

[lovemyram]

balance belt timing? balance shaft belt? I thought the balance shaft was turned by the timing belt. sorry if i am being dumb.
please explain it to me.

[Merrill]

I was going to suggest the same as what Pennyman1 wrote.

One shaft is turned by the main belt, the other is turned by its own belt. It's a smaller belt that sits behind the timing belt and loops over to the passenger side of the engine. Your timing belt kit should have included the balance shaft belt. It's a smaller belt.

The main timing belt has 3 marks to line up - crank, cam, and oil pump (which drives the other balance shaft). All 3 have reference marks on them.

[BradMph]

Those shafts also have a weird way to set them. When installing a belt, hand spin the sprocket softly and it will teder todder around on its own from the counter weights. Kind of weird the way it rolls itself into the correct position on it's own weights. Just get everything set and balance shafts and then double check the shafts by slowly turning until it gravity rolls itself closely to the timing mark arrow, might be off a tiny bit, just do the rest by hand to point it exactly at the mark and install belt. I never knew this for a long time, I guess I just got lucky in the past.


Here is a demonstration on youtube that clears up my confusion. They use an EVO, but they are basically exactly the same motor.
http://www.youtube.com/watch?v=1NUBy-Q3djg

[KEOPS]

Does the small sprocket on the small belt also need to be balanced or just the oil pump?

[geezer101]

Both shafts need to be timed. There is an alignment dimple stamped onto the face of the counter balance shaft sprocket. You can also check the shaft timing by removing the inspection bolt on the side of the block and inserting a screwdriver into the shaft journal.