OT: timing belts

From: jpero_at_sympatico.ca <(jpero_at_sympatico.ca)>
Date: Sun Dec 26 09:34:28 2004

> Yes, I know some small Vauxhall/Opel engines don't run interference.

Chrysler 2.2L and 2.5L (both four inline) aren't interference engine.
 And runs long timing belt.

> >> A new timing belt costs a tenner at the most and even on an
> >> absolutely evil b*st*rd of an engine to work on (step forward, Citroen
> >> XM 2.5TD, not nearly as nice an engine as the CX 25DTR) it takes at
> >> worst a couple of hours to fit. I can do Volvo 2- and 3-series belts
> >> in about half-an-hour...

A good mechanic can do this on 2.2/2.5 also. Partially drain
coolant, you'll see later. Take both belts (one runs PS, other belt
runs alternator & water pump) or three if equipped with A/C. Now
remove bolts and two nuts (all 10mm) for both upper and lower covers.
 On earlier 2.2 (before mid 87) external trox socket to remove
crankshaft pulley bolts (four), later 87 used regular bolts. Now
lower cover falls off. Take a car jack that came with that car and
piece of wood to protect oil pan, jack up the engine to take load off
the right side engine mount. Undo the nut and yoke bolt & nut,
remove two bolts on the inner fender then remove mount. Undo the
bolt on the eccentric tensioner to get it rotated away and lightly
tighten to keep it there. Align marks according to the service
manual, intermediate spocket turns too freely makes this job tricky
while putting new belt on. Line up the groove on flywheel to 0 deg
(TDC), line the cam spocket with arrows evenly with parting line on
head with small hole uppermost. Rotate the intermediate spocket that
it's nick in rim of spocket is pointing to tiny drilled hole in edge
of the crankshaft spocket. Tension the belt with weighted tool or
twist belt longest side almost 90 to check tension. Manually turn
over engine 2 turns and recheck alignment and retension belt again.
Reassemble in reverse order.

This what I did on my 1987 caravan 2.2L carb.

> >> As to why we use timing belts, well... The problem with timing chain
> >> designs is that the chains wear and go slack.

That's true, it depends on user to do regular oil changes and quality
of design originally. For example, mitsubishi 2.6 is very fussy on
maintaince. But even with good care the guides are covered with
nylon wears through then wears through aluminum guide like no
tomorrow and bam, balance shafts stops rotating that oil pump and
engine self-destructs with oil pressure loss. Chain tensioning is
done with oil pressure. This 2.6 mitsu has two long chains because of
balance shafts far apart and camshaft is on top of head.

Mitsu currently uses their quirky designs in later engines and more
involved compared to others unlike Citroen is bit quirky. V6 3.0L is
one another quirky engine to work on. Water pump driven by timing
belt and to do this job repair, everything on front end of engine has
to come off and have to replace water pipes to prevent coolant leaks
because old ones is rusted.

> > I don't know too much about chains used with overhead cams, but on push
> > rod engines this doesn't happen until many miles are on the vehicle.

Chain is still used on some modern engine with overhead chains even
some used a short length of chain to turn twin cam, either driven by
belt or chain.

> Because pushrod engines typically have very short chains. Compare them
> with the miles of chain used in Volvo B27 engines (2- and 7-series V6,
> Renault 30, Delorean)!

I really like push rods for that design, and I really don't see the
reason that chrsyler engineers (allpar.com has artcles on this) had
to use belt on 2.2 & 2.5L due to weight issues. WTF!?
> > The only problem I've had with a chain, actually was the top timing
> > gear, not the chain itself. It was on my 69 Buick LeSabre. The top
> > gear was aluminum with nylon or plastic teeth. They stripped off, while
> > on the highway. This happened in 1995, so the car was about 26 years
> > old, with 100K miles on it. I thought the gear design was dumb, but I
> > assume it was done for sound or vibration purposes. I know GM may not
> > rank very high with the Europeans on the list, but it's one of my
> > favorite cars that I've owned.

Noise reasons that most makers went with nylon coated spockets or
gears. Time had progressed that they went back to all metal since
understanding in making quiet drive trains.

> Yeah, as I think I said in another post, the Essex V6 used in old Fords
> had fibre teeth. You can replace the gear set with an all-steel one but
> it's hellish noisy.

Fibre gears is rather durable compared to nylon for their time but
heat & wear equally destroys the wear resistance on both types
of composite drive trains.

> > I did have belt problems once on my 1982 Dodge with a 2.2L engine. I
> > got it wet in the snow, since I plowed into a snowbank, with the plastic
> > cover off.
Tsk tsk... now you know better to keep covers in place, that's the
major reason. I had to go to junkyard to get upper cover for mine or
from dealer's. Not expensive.

> Argh. Yes, a lot of engines seem to need a special tool to move the
> tensioner.

That's true still. Some are not that special, just make a flat tool
to tension off the assy belt or put belt back on on chrysler 3.3 &
3.8L engine, oh yes real old fashioned push rod engines with short
chain, all metal spockets. Rather reliable.

> Gordon.


Received on Sun Dec 26 2004 - 09:34:28 GMT

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:36:39 BST