Notes on a Timing Belt and Front Oil Seal Change

By Joe Gerhardstein

For all of you who made it to Talladega Grand Prix this month, you probably got a chance to push your Miata to the limit (and some of us beyond!), and learn about it’s wonderful handling. All of you who drove also got to do the same thing the weekend before the race that I did, namely fill out your tech inspection form. Tire tread depth, check. No fuel leaks, check. Throttle cable tight, check. Bleed the brakes, check. Hey honey, what is this big pool of oil under the car for? We’ve been losing a quart of oil every 3000 miles??? No oil leaks - oops, NOT check!

Now, the next thought going through every Gear Head and Gear Head wannabe is “can I fix this myself or do I need to take it in?” The more sane readers of this article would immediately jump to the later option and give their local shop a call to schedule an appointment. And to be honest, the thought of taking it to a shop crossed my mind, too. Especially since Talladega was only 5 days away and I have what I call the 24 Hour Rule. The 24 Hour Rule states that I shouldn’t be working on the car less than 24 hours before we are going to take it some place. So I gave a friend a call to find out if he could spare a half day some time this week to help me, which, being a Gear Head himself, he readily rearranged his schedule. And then that unavoidable urge to tinker led me to spend 2 hours Sunday night taking parts off the car looking to determine where the leak was coming from. Off came the plastic splash guard under the car. Hmmm, must be the front half of the engine. Well, the air intake and radiator were going to be in the way for any work up there, so out they came. Then the drive belts for the alternator, water pump, power steering and air conditioner, followed by the water pump and crank shaft pulleys. After cursing at some Japanese engineer with smaller hands than I have, I removed the spark plug wire box and then the cylinder head cover. This allowed me to take the front cover off of the timing belt and have a look around. Lots of dirty, messy oil by the crankshaft - must be the front oil seal.

At this point, I hadn’t removed anything that I couldn’t put back on or needed a new gasket for. So back to the question, Do I want to mess with this or pay someone else to fix it? Well, heck, it’s only Sunday night and I already have most of the problem taken apart. I’ll order parts Monday and finish it up Wednesday. Plenty of time to not violate the 24 Hour Rule. Anyway, my friend is coming over Wednesday to help. And I always wanted to try a timing belt anyways. How much more work can there be (as I ignored the red lights going off in my head about that statement)?

On Monday I called Roebuck Mazda in Birmingham to order parts. Since the oil seal is behind the timing belt, I figured I might as well replace the timing belt, too. So I ordered their Timing Belt Special, which includes the timing belt, front oil seal, cam shaft oil seals, a new spring for the timing belt tensioner, and a new cylinder head cover gasket. Plus on a hot tip from my Gear Head friend, I ordered new tensioner and idler pulleys for the timing belt. Everything was in stock. Monday night I spent another hour and took off the old timing belt and timing belt pulley, plus the front sway bar to make more room. A flash of brilliance reminded me to take a couple of pictures on how the timing belt looked when put together correctly.

Tuesday the parts arrived from Roebuck. I spent about 2 hours that night taking out the old oil seal and replacing it, plus putting on the new idler and tensioner pulleys for the timing belt. Lots of time wasted by not reading all the directions in the shop manual for replacing the oil seal. However, I did learn that a 36 mm socket works well as a driving tool for the new oil seal. Got a call from my Gear Head friend who was suppose to be comingover tomorrow. He got called out of town and he was sorry but he wouldn’t be able to make it. Oh, well. I was only a little behind schedule, right? I could catch up tomorrow.

Wednesday I got stuck at work by the boss later than I wanted to (the nerve of him expecting me to stay at work the full day when I have an important job at home to do!). When I got home, I popped the timing belt pulley back on. I needed to tighten the bolt for the pulley to 125 ft-lbs. I put the car in gear and pulled on the parking brake really tight, figuring the engine and transmission were stiff enough to allow me to tighten the bolt. Wrong. I pulled on the wrench, and the crankshaft just turned with the wrench, then sprung back when I let up. Down to the basement to find something to grab the crankshaft with. I found a 1/8” thick metal bar which I drilled a couple of holes in and bolted it to the timing belt pulley using the crank shaft pulley holes. I put my foot in the engine compartment and pressed down on the bar while trying to tighten the bolt. No luck - I broke the metal bar. What now? Well, it was definitely too late to be taking the car to someone else to fix, especially since I couldn’t drive it there! And boy, was that Special Service Tool in the shop manual to hold the crank shaft with looking good right about now. But I couldn’t admit defeat, so off to Home Depot to buy the biggest piece of metal they had, which turned out to be a 2” angle iron, about 1/4” thick. Back to the basement to drill a couple of holes and then back to the car to tryagain. *Click* went the torque wrench at 125 ft-lbs, and a potential disaster was diverted

Homemade Special Service Tool

Unfortunately this took most of the afternoon. I spent another hour trying to get the timing belt on right and worrying that it was too loose, then fighting with a gasket on the lower timing belt cover. And thus ended Wednesday.

Setting the timing belt tension with my trusty Snoopy ruler.

As I was nearing the deadline for the 24 Hour Rule, I decided that Thursday morning would be an excellent time to call in sick and finish up the job. Luckily the rest of the parts went back on without any fights, and by 10 am, the car was purring away in the garage. And, heck, I had almost 19 hours of time remaining before breaking the 24 Hour Rule.

Total time for the job: about 9 hours. At Talladega, I talked with Joe Alfonso from R*Speed. He said it only takes them about 2 hours to do a timing belt. Guess I need more practice:)