Valve Lash Adjustment

[scorn001]

Anyone know of a good write up on how to adjust valve lash on a '99? I've got the manual and know it involves replacing the shims if any of the clearances are out. But in the manual they refer to using a specialized tool or two which I don't have access to. Is there a "shade tree mechanic's" version? Also, where is the best place to buy shims?

Thanks,

-Tim

[Mark52]

If you are lucky enough to beg, borrow, or steal the special tool used by the Dealer, it is a simple process. But if you don't have the tool, like me, it's a bit more involved. Here's the "poor man's" process that I use:

1. With the engine cold, remove the spark plugs and valve cover.

2. With a big wrench or socket rotate the engine until some of the the cam lobes are opposite the lifters and measure the gap with feeler guage . Write down the gap (or lash) for each of the lifters, i.e. I1 thru I8 and E1 thru E8. Repeat turning the engine until you have measured at each lifter. It's a good idea to recheck all of your measurements, believe me.

3. Determine which, if any, are out of spec. Figure out what thickness of adjusting disc is needed to bring the gap (lash) into spec. Match what is needed to the various thicknesses offered by Mazda (I have a list of part numbers) and order the new discs.

4. Once you have all the required new discs in hand, remove the timing belt and the cams. Remove the old, out of spec discs and replace with the new discs.

5. Replace the cams and the timing belt. Put some oil on all the cam lobes and rotate the engine by hand several revolutions. Recheck the lash like you did in #2 above and pray that everything is in spec like it should be.

6. Replace the valve cover, guzzle a couple of brews, and pat yourself on the back for a job well done.

The main advantage of having the special tool is that you don't have to remove the timing belt and cams. The tool somehow enables you to depress the lifters one at a time and remove/replace the adjusting disc with the cam in place. I understand that the tool costs something like $400, well worth the price for a Miata mechanic, but out of reach for most of us shade-tree mechanics.

[Mark52]

The process I described above may sound simple, but if you have never replaced a timing belt or pulled/installed cams out of a similar engine, it is probably more than you want to attempt. Also, realize that your local Mazda dealer is NOT going to have all the disc sizes that you need in stock, so you'll have to either do without your Miata for a week while the parts are on order, or you'll have to reinstall the VC and plugs in the interim in order to utilize your car.

[scorn001]

Awesome, thanks for the help. I probably do have access to the tool if I really need it. But my neighbor, the Mazda mechanic, has been very generous with help in the past. I sort of hate to take advantage.

The clicking isn't horrible, just slightly louder than what is normal from what my neighbor has said. Maybe I'll wait another 10,000 miles or so, and pay him to do the timing belt & valve lash all at the same time. You are right, I don't like doing timing belts.

Thanks a ton.

-Tim

[trickyrix]

Just out of curiosity, do you know what the adjustment interval is for the valve lash on a '99-00? I just picked up a '99 head/intake to swap into my '94, and I'm trying to get a ballpark idea of how often the valves need to be adjusted.