Timing belt helpful hints..

[djb2]

Summary:
Steps to diagnose a broken timing belt.
What you can skip for an emergency repair


The Back Story

Last night the girl calls: "meet me at the downtown Oakland BART station and I'll drop you off so that you don't have to walk". Translation: "I need a driver so that I won't have to find parking for my errands". Two blocks later the car loses all power, the dashboard lights up, and we coast to a stop.

While waiting for the tow truck I did the usual diagnostics. The gas tank was over 3/4 full and the engine cranked strongly, although it sounded a little.. smooth.
I didn't hear the fuel flowing past the injectors, but there was a lot of traffic noise so that wasn't conclusive. I checked for spark: none.
The tach didn't wiggle when cranking, further hinting at an ignition problem.

I had replaced a failed ignition coil a little over a year before, so I knew what to do next. My laptop had the engine service manual. I jumpered the right pins on the diagnostic connector (with the only thing I could find, a pair of tweezers! Future: put paper clip on diag cover) and the dash light blinked out error code 12 -- no position pulse from the distributor sensor after 3 seconds of cranking. OK, that's a dead stop. There was nothing that could be fixed on the city street. It would take at least a parts run.

While waiting for the tow truck I had a chance to over-think the
situation. Perhaps I had disturbed something when changing the ignition
coil, leading to sensor coil failure. Perhaps the brief stumble on an
empty tank the day before meant something. Perhaps it still was bad gas
or a bad fuel pump. Perhaps it was something trivially simple that I was overlooking.

Once towed, I got a multimeter and tested the two sensor coils. They were working
with about 280 and 450 ohms. Doh, so much for the easy fix on something
that I had taken off before. With trepidation, I took off the
distributor cap (a real PITA) and had her crank the engine. No
motion. Arrrggg, a broken timing belt. "When was it changed?"
170K miles on a '93 and it had apparently never been changed.


The Belt Change

The steps to do a planned timing belt service are well documented, but I didn't find any posting about a panic fix. What can you skip when you only want to get the car running ASAP?

First, gather your tools. You can make do with very few: the trunk jack set, and 10mm, and 14mm drivers. Having both sockets+ratchet and box wrenches will speed things up, but you can mostly make do with just one type. You may need a short extension for the 10mm socket and something (e.g. hooking on an extra wrench) for leverage on the 14mm head bolts, and a 12mm if you choose to loosen the belt adjusters rather than lever them off.

The special additional tool is a 19mm or 3/4" (19.05mm) wrench with a long handle. She had a cross-style lug wrench in the trunk which turned out to be just the right thing.


First put the car in a good working position. Conveniently you can do everything from the right side. You'll need to jack the car up and remove the right front wheel, so allow room for that. The hood will be up and wheel off for part of the time, so think about a location or excuse to avoid wasting time answering "helpful" questions. ("Broken down?" "No, just swapping in a fresh squirrel.")

You have an option of what to do first. The work from the top is done with the car on the ground. Even if you fail or give up, the car is just as towable as before and you've shortened the shop time. Just tell the mechanic that the cover was removed to *diagnose* the problem and it won't look like you took it in after screwing up the job.

I suggest starting from the bottom instead. You may have to jack up and lower twice, but you'll get the hard, risky task out of the way immediately.

Break loose the right front wheel bolts, jack the car up and remove the wheel. Remove the two obvious bolts (10mm head) that hold the access panel. Once off you'll see the crank bolt (19mm or 3/4") that needs to be removed.

At this point you have to be clever and resourceful. You have to jam a wrench in there and crank the starter to break loose the bolt. All the time never getting under the car, or risking breaking you hand.
I made this work by putting one arm of the lug wrench under a bracket on the side of the strut, and jamming the tire under the other arm. I stabilized the end of the wrench while my helper cranked briefly.

An alternate approach is using a 19mm socket on a long breaker bar braced against the ground or the car frame.

When it works, it will appear that nothing has happened. The wrench just stops jerking.

Here are some lessons you don't need to re-learn: It's critical that you tell you helper that "briefly cranking" is barely turning over, not five second. Practice first. It's impossible to hold the wrench against the starter. You can't even hold one wrench arm with the other braced. Check where you hands and face will be if the wrench spins.

With the crank bolt removed, the other other challenging part is removing the pulley. I had loosed the alternator belt, but wasn't able to break free the P/S pump bolts. Even with the inner belt attached I was still able to gently pry and wiggle the pulley off without a puller.

If all has gone well, you are ten minutes into the job, only used the jack set and 19mm wrench, and are assured of success. You can remount the wheel, lower the car, and change you story from "yes, I'm changing a tire" to just "changing a belt".

For the work from the top, you can skip quite a few steps. You don't have unbolt the "dogbone" from the engine side. Just unbolt the two engine bracket bolts first, then the body side. Don't drain the coolant, just unclip the coolant overflow tank and drape it across the engine onto the manifold cover. Loosen the alternator bracket bolt and adjuster but don't remove it. (Even faster: pry off the belt while turning, and put it back on the same way. Same w/ lower PS belt.)

Unclip the diagnostic connector and harness from two places and push it aside to get room. Rotate the hose clamps so they don't cut your wrist. If you can't get to the 14mm head bolts on the engine bracket, jack up the engine slightly. (I didn't and left the bracket "captive" until the upper timing cover was off.)

Once the upper and lower covers are off (four 10mm head bolts, one of which is long, each) don't undo anything else. Only the tensioner bolt needs one or two turns with a 14mm wrench. Once the roller can move, remove the spring, push it down, re-clamp and reinstall the spring. (Easier than pushing down against the spring, risking nicking the smooth face.)

This is your chance to inspect things. Avoid the urge to clean. It will just spread grease onto the timing belt path. Spin the two smooth rollers and make certain that the bearings are OK. They will be loud or rough if going bad. Check the cam, oil pump and water pump seals for leaks.

You are now ready to put on the timing belt. It's fastest to install it on the correct path, ignoring the timing for now. You can slide it off the cam sprocket to adjust later. Don't forget the big dished washer on the crank before reinstalling the lower cover. Snug all of the 10mm head cover bolts before installing the crank pulley. Spin the crank bolt as far as you can by hand, then put the P/S belt on the crank pulley and lever it's onto P/S pulley while turning with the 19mm wrench.

Set the timing as the standard instructions tell you. There are no short-cuts here. You do need to always turn the crank bolt so that it tightens, and a few extra turns to check alignment helps to snug it up. After re-clamping the tensioner sprocket, set the engine on a compression stroke and give the wrench on the crank a few sudden hard jerks to tighten. Reattach the ground wires at the top of the engine, check that everything is clear, and *start the engine*! Yes, really. After running for 10 or 15 seconds the compression will be higher and you can tighten the crank bolt more with the same position-then-yank technique.

The car is now, just barely, OK to move slowly if you desperately need to. Without the "dogbone" engine support you have to be very gentle. The alternator belt isn't on, so you are running only on the battery. But you can move the car to someplace more convenient to finish up. Perhaps even to a store to buy a torque wrench to set the crank bolt (100Nm) and tensioner clamp bolt (42Nm) before installing the covers.

[GtariSSt]

Dude, you are The Man. Took some balls to undertake this. Nice write up.

[ARIST0]

I dont mean to complain, but i got to say:

"I'm a visual learner" Translation: "This thread need more pics and less blah"

Appreciate ur effort though.

[GtariSSt]

Originally Posted by ARIST0

I dont mean to complain, but i got to say:

"I'm a visual learner" Translation: "This thread need more pics and less blah"

Appreciate ur effort though.

Not to diss you, but if you need pics, this method ain't for you. There are more appropriate threads/manuals. This is for somebody with enough experience to improvise on the fly.

[djb2]

This posting is meant to be the opposite of the (very good!) postings that involve planning, fabricating a holding tool, and buying every part on the front of the engine. It's what to do when it's cold, wet and dark, you don't have a set of good tools, and the car needs to be running Real Soon Now.

I just edited it with an update. You don't even need a 12mm wrench if you flip the accessory belts off of the pulleys while turning with a wrench, and put them back on the same way. Doing that puts some extra stress on the belt, but saves time and avoids the need for re-tensioning when you put them back on.

Any other shortcuts?

[toyomoho]

What was the total time to replace the belt?

[djb2]

It was about 1 to 1.5 of working time to diagnose and remove the belt. I took a break in the middle to eat, do a few web searches for instructions, and think about the crank bolt. I had to wait for morning to get the part, so I spent some extra time inspecting and putting back things that I had unnecessarily taken off.

Once I had the belt it took under 30 minutes to install the belt / lower cover / crank pulley, set the belt timing and start the engine running. I took a solid hour that evening to put the upper cover/bracket/cover/wheel back on and double-check my work.

It would have been faster if I had this advice. I would have started with removing the crank bolt. Once loose, I would have known that the "impossible" part was out of the way. Then I wouldn't have been so timid removing the bracket and cover, checking that I could put everything back if I failed.

I think that jacking up the engine a little to get socket on the engine mount bracket would have cut 30 minutes from the time. I removed the two lower 14mm bolts a fraction of a turn at a time, and dropped the wrench many times. During installation I had to figure out how to put the bracket partially in place while installing the upper timing cover. Then I found that manipulating the upper cover around it knocked off the middle seal, and had to re-do my work.

[christine_lives!]

A nice set of socket extensions makes things easier, along with tools that have some weight. Getting those 14mm engine mount nuts off with a 12" extension and socket wrench makes things a breeze.

I also recommend buying a pair of 19" chain pliers. It's like vice grips bred with a chain wrench and produced an affordable wonder tool. As much as I lambast Duralast tools; Autozone was the only local place that had the pliers for $20. I wasn't taking Summit AutoRacing's offer of a $120 chain wrench (although very very nice). Rent a torch wrench while you're there.

I also used a steering wheel puller and a set of 4" long SAE 10mm bolts. The bolt holes SHOULD line up with the harmonic balancer and the back of the pulley. I didn't luck out, which was fine, I was replacing the harmonic balancer anyways and got a new pulley assembly.

I got the alt belt off and cut it up so it just fit once around the pulley (replace this while you're down there anyways). The chain pliers slipped around the pulley in a very sexy fashion, slipped an 18" section of pipe around that and used my 4' of cast iron leverage on a breaker bar with extension to the 19mm socket. I will say, it took so little effort with the right leverage my dead grandmother could break that crank bolt. Basically:

Bolt>19mm socket>24" extension>breaker bar>4' extension>lanky arms

6 min to break the bolt with ease, knowing going back on with the proper torque will be just as easy.

[djb2]

This was about how to do it with minimal tools.

At home, far from where this happened, I have plenty of tools that would have made this easy: three impact wrenches, full-length car ramps, four different jacks (standard, long "racing", and two different sizes of bottle jacks), gearwenches, pullers, etc. Even a 20 ton press for when frustration sets in.

The suggestion of a chain wrench was a good one. But that, and the extension pipe, might not be readily available. Every truck stop and convenience store seems to sell the 'X' lug wrenches.

[christine_lives!]

Being in college and lacking a garage, this was a cheap fix. Specialized tools and impact wrenches are great, but I did this task in a parking lot. I mentioned the chain pliers because they are readily available at Autozone, while the chain wrench is plenty hard to find.

Come to think of it, most of my major repairs happened in a parking lot or on the street. You learn to cut corners and act fast. When my radiator blew up, I patched the top with some JB Weld and made it to a Kragen. Radiator swap took me 20 min using the soft fluorescent glow of their store.

I'm not knocking your write, its fantastic. I'm just adding my own cheap-o experience.