1990 Mits van vibrates after water pump, timing belt replacement?

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wishnet - 02 Oct 2008 00:11 GMT

I have a 1990 Mits van with 100k miles on it. I had it serviced and the
water pump and timing belt were replaced. Ever since that service, the
van has had a strong vibration. It's related to the motor, not the
tires, but it's a vibration that feels almost like I have snow tires on
or something. The vibration is easily perceptible in the gas pedal, and
my backbone gets a good shaking. Steering wheel shakes. Everyone that
knows the van well noticed it right away when they were in the van for
the first time after the service.

What kind of issue might be causing this, that might be associated with
replacing a water pump or timing belt?

I've asked the mechanic and he says it seems ok to him. He wants to
write it up as a change in my perception....but he's wrong. Its
positively very different. I've had this van for a long long time, it's
never been like this.

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Stewart DIBBS - 27 Oct 2008 12:29 GMT

>I have a 1990 Mits van with 100k miles on it. I had it serviced and the
> water pump and timing belt were replaced. Ever since that service, the
> van has had a strong vibration.

You don't state the model, but I'll bet it has a 4G63 or 4G64 engine (see
the plate on the top center firewall). The engine feels rough, does not rev
well and there's a strong vibration at about 2500 rpm. You risk vibrating
the oil filter off if this is not fixed. Don't laugh, it happens.

What you nitwit of a mechanic has done is messed up the belt alignment. He's
got the cam belt timing right as the engine runs, but most likely he got the
oil pump 120 or 240 degrees out of phase because he cut some corners to save
time. He's probably also got the balance shaft alignment off as well.

Look at http://www.pixcl.com/summitgtx/lancerproject_2.htm and scroll about
1/4 the way down. There's some pix showing the correct alignment.

Be polite to your mechanic but do not take no for an answer.

The front cover has to come off and the job redone correctly, without
cutting corners. Its not hard to get right if you ...

a) set #1 TDC on the crank, set the cam sprocket mark to the mark on the
head
b) align the balance belt to the mark on the front casting.
c) align the oil pump (this is where I suspect he went wrong) to the mark on
the front casting.
d) fit the cam belt, ensuring the teeth line up and maintain the oil pump
e) tighten the belt idler then release the hydraulic tensioner.
f) put it all back together.

Signature

regards
Stewart DIBBS
www.lancerproject.ca

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