Today I crossed into territory where not too many people dare to tread. I dug into the very innards and performed open heart surgery on my little red gem. She didn't necessarily need it, but since the last timing belt change occurred at about 80 – 90,000 miles, and now that she is at 170,000, the belt was long overdue. She still ran just fine, but I wanted to do this as a preventative measure to make sure she was good to go for another 60 – 100,000 miles.
The first thing I can suggest to anyone willing to undertake this is that it isn't as hard as it seems. There are some things you need though, beyond the parts. But you don't need any special tools beyond a Torque wrench that is good to at least 150 foot/pounds. I happen to have two of them. One goes to 960 inch/pounds, the other goes to 150 foot/pounds. They are a requirement, for sure.
Another thing that I suggest anyone changing their own belt do is go to Miata.net. Head into the Garage section and read up and even print out the sections on timing belt and water pump replacing. Also, go into the forums and search and read all the posts you can stand so you know full well what you are getting into and also what to look out for. You will also find some tips to make the whole thing easier. Tips like using two crescent wrenches and a c-clamp vice grip to hold the cams in place at TDC. Another very useful tip I found was a picture of a piece of steel that a guy fabricated to bolt to the crankshaft pulley and the A/C unit to hold the crankshaft in place so the motor doesn't turn while you break the crankshaft bolt loose and torque it back down.
Finally, buy all your parts ahead of time. And make sure you got the right parts. I went to the local auto parts place and got a set of gaskets that included the crank seal. I happen to have a later 91 Miata, which has a big nose crankshaft. The gasket set I got was for the short nose version, so the gasket was smaller than what I needed. So, a trip back across town to two auto parts stores finally found the right set that had the correct gasket.
Now, for tools, this is what I have used so far:
Torque wrenches (I use one for things in incn-pounds and a big one for jobs up to 150 foot-pounds)
Crescent wrenches (two to hold the cam shafts steady when you remove the belt)
10mm, 12mm, 14mm, and 21mm sockets and wrenches (Its amazing how Mazda put the entire car together with those 4 bolt sizes...)
Ratchets and extensions (I use a 6 inch and a 12 inch extention)
A breaker bar (mine is a big 36 inch one for those extra special occasions)
Phillips and Slotted screwdrivers
Knife
Paint pen (To mark the timing belt and camshaft pulleys)
Sharpie (To mark the bags of bolts and assorted parts of car that were removed)
My personally fabricated steel crankshaft holder
A 2.5 pound hammer
Gasket sealer (I use the black stuff)
A radio or iPod with speakers
Beer, or your beverage of choice
I won't go into details on how to change out the timing belt, cam and crank gaskets, water pump and gaskets, valve cover gasket and hoses because if you did as I suggested, you went to Miata.net and found them for yourselves. There is an excellent writeup there that tells you all you need to know, and the forum posts I suggested will give you the extra tips and tricks to make the process a lot less painless than it could have been. After spending a week reading the directions and posts I felt like I had done this job many times before, when in fact, this is the first belt I have ever changed.
Another thing to consider is that whether you are changing only the timing belt of the water pump, you may as well do it all at once to save the pain of having to do it all again. I think my water pump was the original, and it was starting to make some noise and such, so I went ahead and replaced it. I also replaced the crankshaft gasket, timing belt and accessory belts, upper and lower radiator hoses and fluid too.
I did not change the camshaft gaskets at this point though, even though it was suggested. Partly this was out of my own laziness, but more than that, I inspected them and they looked beautiful. Fully intact, no seepage at all around them, no scratches, breaks or even dust on them. They looked brand new. The Crankshaft gasket was kinda worn looking though, and though it wasn't leaking, I went ahead and changed it out.
I started at about 9 am this morning, and didn't stop until about 9 pm tonight. But that time also included about an hour and a half of running to the parts place to get stuff I forgot, or in the case of the radiator hoses, stuff that I had to destroy to get them out. It also included a 2 hour break to go meet someone to pick up some radios I am using for the upcoming trip to Deal's Gap. I'll be at Miatas at the Gap XI in just a week and a half, so I wanted to be ready.
So in this long day, I got everything disassembled, cleaned, fabricated my steel crankshaft locking plate, swapped out the crankshaft seal, timing belt, water pump, inlet gasket, inlet O-ring, timing belt, and manged to get the timing belt covers back on after it started getting dark. Tomorrow, I plan to get the valve cover gasket back on, replace the radiator hoses, put the plugs and wires back in, hook everything back up and start her up and pray that I did get it right.
I am pretty sure that I did, but if I didn't I am going to scream like a little girl, cry and curl up in a ball of agony. Then I guess I'll pull it all back apart and try again with the timing.
Remove the radiator and fans. You get a WHOLE LOT more room to work. That was one of the best tips I got and it certainly went a long way to making this process better.
Pay attention to the write ups, be sure to mark the timing belt and camshaft pulleys and use the tips and tricks you learn thanks to the vast knowledge of the Internet and Miata.net and you will be able to change out your timing belt and water pump and save yourself a few hundred dollars in labor charges.
While you are at it, and have the Cam cover off, replace the Crank Angle Sensor o-ring. It's a pretty common place of oil to leak and is a simple and cheap thing to fix. You will find that doing it with the cam cover off is a LOT easier than doing it with the cover on, and since you are already under the hood, why not? The o-ring is easy to find. Most all auto parts stores have them for a dollar or so, and I even got mine at a Mazda dealer for about 4 bucks. There is a great writeup of this proceedure that can be found here and a slightly different version can be found here.
ADDITION: Day Two, the finishing the job.
So today I finished up. Again, I stress that you read the writeup and Miata.net, and even print it out like I did. Everything went back together nicely in reverse order and I had little surprises. One other thing I did while I was doing this was to replace the upper and lower radiator hoses. The upper runs from the top of the radiator to the water neck on the engine. There are two lower hoses. One runs from the bottom of the radiator to a metal tube along the driver side wheel well, and the other runs from the other side of that tube to the water inlet pipe on the side of the water pump.
Mine had been on there for 17 years, So I had to actually cut them off to get them off the necks. So I would suggest replacing all these hoses since you have everything off the car. I would also suggest getting nice screw type hose clamps as they are a lot easier to get on and off than the spring clamps that the factory uses.
So, as I was saying, I got everything taken care of and put back together. I poured some coolant into the radiator, and finally, the moment of truth.
With great trepidation, I sat behind the wheel, praying to the Gods of Automobiles and the Lords of Shade Tree Mechanics to be merciful. They nearly gave me a heart attack when I turned the key and started the car. Where I was hoping for a nice smooth purr, I instead got hacking, coughing, sputtering and black smoke puffing out my tail pipe. I was mortified. The thought that I was going to have to tear everything back out and re-do the timing again had me nearly in tears.
But HO! I thought. First, I shall use the Holy Timing Light of Inductance and see just how far off it is. I hooked up the Holy Timing Light of Inductance to the spare power spot under the hood, and clamped its inductor over the number 1 spark plug wire, and shorted the GND and TEN pin in the diagnostics box. I dont have an external tachometer, so I used the dash one and set her at as close to 850 RPM as I could get.
By the way, to set the RPM, there is a screw that is usually coverd by a black rubber plug on the front end of the intake. YOu cant miss it. Just turn the screw to make the RPM go up and down.
So now that I was all set to use the Holy Timing Light of Inductance, I did so and was shocked to discover that the timing mark was way off. About 15 degrees higher than it should have been. That is when the Gods of Automobiles and the Lords of Shadetree Mechanics smacked me firmly on the head and screamed DUH! When I changed out the Crank Angle Sensor o-ring, I had reset it a bit off from where it was. So I loosened the bolt holding it on and turned it just a hair and the car smoothed out, the timing mark found it's way to 10 degrees before TDC and all was right in the world.
Just for kicks, I then advanced it to 14 degrees bTDC to get just a little more kick out of the car, now that I had a shiney new timing belt and water pump.
So there we are. She is now sitting peacefully in the drive after two long days of open heart surgery. She recovered well, purrs like a kitten and I won't have to worry about another timing belt for at least 60-70 thousand more miles. In fact, I'll probably have to replace the engine at that point, since she has 170K on her already. But that is way down the road, at least three years from now. Until then though, I will keep on doing little things here and there and sharing my advice in these, The Miata Chronicles.
UPDATE: DO NOT, UNDER ANY CIRCUMSTANCE WHAT-SO-EVER forget to soak the o-ring that goes on the block pipe and fits into the water inlet in new coolant before you assemble the mess. I did just that, and it caused me, after a day of driving, to have to tear most of it all back out to replace the o-ring that had twisted and been torn in two. Also, the inlet goes on the block return pipe MUCH MUCH easier if you lubricate the o-ring first. That is all
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