ok... so how DO you manage to get a gear puller on the busted timing gears
of a 4 cyl DIS engine, for replacement ??

With the engine still in the car...?

Or, Do you use some big screw drivers and pry them off ...velly carefurry ?

I admit ignorance.

(frequently)

Also... pros and cons on metal versus some factory or after-market fibre replacement timing gears ??

Larry

I also have a 4-cyl DIS engine in my daily driver. And I had to replace the timing gears a little over a year ago. Here's my experience:

First of all, you have to remove the camshaft from the engine. There's no way you'll be able to pry off the cam timing gear. It's pressed on with a slight interference fit. The only thing that will get it off is a hydraulic ram. Most machine shops have the equipment to do this. Just bring in your cam (with the gear still attached, of course) and the new timing gear and ask them to press the new one on.

As far as metal vs composite gears, I went with a metal cam gear. People say that the metal cam gear is louder (more gear chatter) but I haven't noticed any difference.

blacktree... makes perfect sense to me, as the haynes and chilton show the press being used to remove/install the gears.

another poster elswhere opined it could be done in the car..but didnt say HOW.

what other stuff have you had crap out on that engine ?

Mine is otherwise tight, with 101 K and little if any oil use..perhaps a puff past the valve stems.

is the DIS thing reliable long term ?

We got 30 mpg @ 65-70 on the interstate.
Hoped for 10% better, buts its an automatic.

If this link works, it will show you a couple of options. Before I forget, fiber gear is junk. This link came from using the search option, top right of Tech question index. When you reach the search entry page, enable 'tq&a archive' as the search data base, enable 'subject', use search keywords-
'timing gear replacement'. Or, maybe this link will work: https://www.fiero.nl/forum/Archives/Archive-000001/HTML/20010924-2-009179.html
The link worked when I tried it. Someone in the last couple months also posted a similar
procedure, using a small grinder for removing the broken gear, drilling a hole in the ctr of camshaft, tapping the hole, and using a long all thread bolt to push the new gear on. I don't remember if he preheated it or not.

[This message has been edited by maryjane (edited 01-21-2002).]

I can just imagine how much work is involved with grinding off the old gear and drilling/tapping a hole so you can press on the new one with a bolt. Probably more work, more money, and more time than the normal method. And what if the hole you drill is crooked? What if you accidentally grind a gouge in the camshaft? What if the bolt you put in breaks off inside the camshaft?

It's just my personal preference, but there's NO WAY I'd try to do something like that.

Regarding the DIS engines... well, my '86 coupe needed a new distributer at about the 145,000 mile mark. The '87 SE now has about 156,000 miles on it and the electronic ignition unit is still working fine. Although, I did recently replace the coil packs and crankshaft position sensor. They probably didn't need to be replaced, but I replaced them anyway. See my thread regarding "strange engine problem" for details.

Regarding the general condition of my 87 SE... it was pretty obvious that the previous owner(s) didn't know the meaning of preventative maintainance. So naturally I ended up putting a lot of work and cash into this car. My car probably isn't a good example because of this. But I can tell you my car runs a LOT better now than the day I bought it (50,000 miles ago).

[This message has been edited by Blacktree (edited 01-21-2002).]

I've been working on this one for some time in anticipation of changing my own gears or someone elses. As yet I have not been able to test my method. To do that, I need a scrap section of cam and a gear.... (Anybody got one? I don't even need the whole cam. Just enough to clamp in a vise.)

You'll be working thru the wheel well mostly. You'll probably want to take down the mud skirt.

If needed you can take out the strut and hub assembly. As long as you don't separate the hub from the strut you shouldn't need an alignment when it is reinstalled.

You can gain some room by pulling the motor mount. make sure the motor doesn't rest on the lip of the pan or the crank pulley. You might have to drop the cradle a little in back. (Don't forget to undo the dog bone and disconnect the battery!)

Also, per another GM TSB, buy a harmonic balancer for the motor. Don't reuse the original pulley unless you have to. These are available thru most parts stores. Buy a new one and not a rebuilt. (The original pulley isn't a Balancer. Just a cheap steel pulley.) (TSB 90-6-21 dated 2/90)

This is a varition on GM TSB 88-6-62 dated 6/88 since at present my version is untested. I'm going to include a summary of GM's original instructions as well.

GM recomends that, when the gear is off, a 1mm (.040 inch) hole be drilled in an oil galery plug to improve gear oiling. I DO NOT know exactly where this gallery plug is! (The hole can be smaller but must not be bigger than specified!)

Once everything is stripped to the gears.....

Align the timing marks on the gears.

Stuff rags under the gears to catch waste.

Drill an 8mm hole 1/2 inch deep in the center of the cam. (Use the SAE drill that the following tap requires if you don't have the metric bit. Good taps nearly always have the required drill size engraved on them.)

Tap the hole with a 3/8-16-NC Bottoming Tap. (This tap will cut threads all the way down. Regular taps won't. You can use a regular tap to start the hole if needed.)

The above hole will be used to install the new gear. GM says use tool # J25033-B for this job.

For my method, Untested, You'll need some 3/8-16-NC threaded rod or a long bolt. (I don't think it needs to be a hardened bolt.) You'll also need a matching nut and some large washers.

To pull the gear....

For GM's method you need GM tool # J24420-B

In the gear hub, Drill 2 holes 180 degrees apart using a 3mm drill. 1/4 inch deep.

Enlarge holes to 5.5mm. Make certain you don't knick the cam!

Tap to 1/4-28-NF with a bottoming tap. Again, make certain you don't knick the cam!

Install tool and pull gear.

My method. Again, Untested untill I can get ahold of a junk cam and gear...

To remove the gear, you'll need a good steering wheel puller like Lisle 45000. (I know this is a good puller. It also comes with 3/16 bolts.)

Next drill two small holes in the cam gear very near the hub. Drill all the way thru but be carfull not to hit anything.

Enlarge the holes to 8mm (Or whatever SAE size the tap says.)

Tap holes using the same 3/8 16 tap you used on the cam.

Install puller with 3/8-16 bolts. Make sure the puller doesn't damage the hole in the cam. use somehing to cover the hole if needed.

The cam should have .0015 to .0050 (inch) of end play with the gear installed. (You'll need a dial gauge for that...)

You can also go to http://www.pontiacfiero.com/ and buy their kit to do the same. I don't know anything about their kit beyond it's existance. (Their kit uses the access holes in the gear as pulling holes.)

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11-Sept-01, The day the world as we knew it ended.