Re: Timing belt

[Mark Eissler <tequila@interlog.com>]

Mike Miller (Volt) (Exchange), a-mikemi@Exchange.MICROSOFT.com wrote:

>- How much of a job is it to replace the timing belt? Anyone have a

It's generally a pretty big production. The most awful part of the 
procedure will be the removal of the crankshaft pulley bolt which is 
typically torqued to astronomical specs. Once you get that far, it's 
pretty easy. 

Generally it goes like this (the following is a summary, not a guide):

1. remove the front grille
2. remove all accessory drive belts
3. remove the timing cover(s)
4. With the trans. in Neutral, AND the ignition system disabled, set the 
engine to Top Dead Center on the number one cylinder by aligning the 
appropriate marks on the pulley, camshaft gear, and flywheel/bellhousing. 
IMPORTANT: you must disable the ignition system (e.g. unplug the lead 
from the coil to the distributor) to insure that the engine WILL NOT 
start (and break your arm or something) while you set the engine to TDC.

5. Next, you will somehow have to lock the crankshaft so that you can 
remove the bolt holding the crankshaft pulley to the...crankshaft. With 
that done, remove the bolt. An impact wrench is great for this type of 
thing. But a 3 foot breaker bar, a really strong 1/2" socket wrench, and 
a heck of a lot of reserve strength on your part will get the job done as 
well.

6. Remove the pulley with a harmonic puller. Do not remove the timing 
belt just yet. With the pulley removed, separate the timing belt gear 
from the pulley by whacking the gear using a SOFT-FACED mallet/hammer. 
Reinstall the timing belt gear, slipping the timing belt over the gear as 
you do this. 

7. Next, temporarily stick th pulley back on just so you can confirm that 
the TDC marks haven't run amok. You can also temporarily reinstall the 
pulley bolt and use your socket wrench to turn the engine, but you may 
end up inadvertently tightening the bolt too much so that you will 
misalign the marks (once again) as you remove the bolt. I like to use 
leather work gloves and just turn the pulley with my hands instead of 
putting the bolt back in. Remove the pulley and timing gear again (by the 
way, they're keyed to line up properly on the crankshaft). 

8. Remove the timing belt. Reinstall the timing gear. Loosen the timing 
belt tensioner (either a pulley or the water pump, in most cases) to aid 
installation of the new timing belt. IMPORTANT: with the timing belt off, 
moving the crankshaft and camshaft independently of each other could 
result in a coming together of valve with piston (in most engines), this 
is very bad, so don't forget it!! Slip the new belt on.

9. reinstall the crankshaft pulley and torque the bolt to specs.  

10. adjust the tension of the timing belt according to specs.

11. reinstall the timing cover(s), accessory belts (adjust all belt 
tensions to specs.), and front grille.

12. have a small meal and go to bed as it just might be about midnight by 
this point!



Mark Eissler          | UNIX, DOS, oh and MacOS too.
tequila@interlog.com  | Why wouldn't a developer use 
                      | a Macintosh?
http://www.interlog.com/~tequila/  My new hURL!!!!!!