Miata Mailing List: May 1993, Message #109
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From: (none) Subject: Re: Timing? Date: (none)
In message <9305171431.AA11238@lemans.stortek.com> to miata@jhunix.hcf.jhu.edu on Mon, 17 May 1993 11:04:53 -0400, stortek!Steve_Grossman@csn.org (Steve Grossman) writes: > > From: fischman@nynexst.com (Gary Fischman) > > > > I'm about to undertake the daunting task of replacing my timing belt. The > > dealer wants $400 to do it. I can buy the belt for about $36. Another $25 > > The dealer wants $400 because it's a labor intensive job. I've never gotten one > done myself in less than a LONG weekend. It took me 2-4 hours, at a leisurely pace. I twist wrenches hardly at all these days, and so really take my time when I do. Of course I wasn't a really good boy and failed to replace the camshaft seals. The dealer's parts guy wanted to sell a pair to me when I bought the ~$30 timing belt, but the factory manual hadn't mentioned changing them with the belt, so I declined. Because there was hardly any leakage from the original ones I might be safe. I did buy a new valve cover gasket, which probably isn't strictly necessary. Also get some high temperature silicone seal (I used the "blue" kind) for putting the valve cover back on. As the factory manual shows, there are four or five little "corner" spots on the head were you put some silicone to help the gasket. Remove the old factory silicone from those spots before you button it back up. > > for the special tool that holds the flywheel steady while you unscrew it. The ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Eh? Maybe you're talking about one of those 'fan' belt pulleys. (Read on.) > > job seems relatively straightforward. But I have a question. Do I need to > > set the timing after completion of the job? I've never adjusted the timing > > in the Miata, not because I don't want to, but because it appears that a > > standard inductive timing light won't work. The factory manual refers to a > > special tool as well as a connection of the timing light to a particular pin > > on a particular connector. > > I've never done the timing belt or the timing on the Miata, but from general > principles I'd say it is not necessary to reset the ignition timing or the valve > timing provided THE ORIENTATION, RELATIVE TO EACH OTHER, OF THE TIMING BELT > PULLEYS ON THE CAMSHAFTS AND CRANKSHAFT DOES NOT CHANGE. To be specific, I'd > mark the position of all three pulleys relative to something (horizontal, > vertical) before removing the old belt. If the position of any one of the There are marks on the camshaft pulleys and head -- if you follow the instructions in the factory manual it's pretty simple. > three pulleys changes while the belt is off, the valve timing will have to be > reset. However, since the distributor is driven off of the rear of the > camshaft, the igntion timing should not have to be reset, as it will remain > relative to the valve timing, unless the distributor is removed. > > > > Any tips on replacing the timing belt? Any "gotchas"?? > > You'll probably need a puller to remove the harmonic balancer/alternator belt > pulley. This could be a real B**CH to do because of the close quarters in which > you're operating. Removing the radiator may be necessary. Lemme see, was that the water pump pulley, the one held on by four, um, 7 mm bolts? It came off easily. You don't need to pull the radiator, either. Just drain the radiator, pull the top hose and pull the air intake tube that runs across the front of the engine (that was a little dicey). Then you pull belts, that one pulley, valve cover, and the (3? 4?) plastic panels which cover the timing belt and pulleys. (Did you know that the front of your Miata's engine is covered in plastic?) Then you get to play with the tensioning idler and the timing belt itself. > > > > How do I set the timing? Do I need to buy an "old fashioned" non-inductive > > timing light? > An inductive one should work as well as a non-inductive. The problem is > that the computer will thwart your efforts by adjusting the timing for you > while you are setting it. There may be a way around this by unhooking the > battery, setting the ignition timing statically so the computer does not > know about it, but I've never done it on the Miata. Oh yeah -- what was the subject of this discussion? I didn't touch the ignition timing and never have. There was zero dectectable difference in the engine's behavior after I got it back together. > > > Once again, I have not replaced a Miata timing belt or set the ignition timing, > so this is all based on experience with other OHC engines. I'd be interested > in hearing from somebody who's already done it. I've got another 30k > miles before mine will need it. Well, now you've heard the whole gory thing. (Eric, you like I should still write this thing up for Tejas Miatas? All I'd have to do is go look at the manual and stare under the hood long enough to remember what I was doing and then re-edit this note!) > Hope this helps. > > Steve > >