Distributor or Timing Belt off?

[sepling]

Hey all, this is my first post, so hopefully I make it count. . .

I just purchased a 1984 Tercel SRS and changed all the fluids, belts and gave it a general tune-up this weekend. Everything went fine except for the timing.

When we went to time the engine, it was advanced by about 25 degrees! I loosened the distributor, turned it and was able to get it to about 12-15 degrees advanced but not the 5 degree spec. At 12-15 degrees advanced, it's at the limit of adjustment This leads me to believe the distributor is a tooth off or the timing belt is a tooth off. Any ideas?

Is the distributor idiot proof? Meaning, it only goes in one way? That would lead me to believe the timing belt is off by a tooth-- much more time intensive fix.

Any help would be much appreciated! Thanks in advance guys.

Sean

[tercel4wdrules]

Did you disable the vacuum advance when you were checking the timing?

[sepling]

Yes I did. I removed the outer most vacuum tube on the vac advance and plugged it.

[sepling]

I've been told it could also be advance weights "freezing" in the open (advanced) position. I can test that by taking the cap off, twising the rotor a bit and making sure that it "springs" back.

[keith]

First pull the upper timing belt cover. On the cam timing gear, there are a couple of marks that align with the cover rail (the valve cover surface) and a hole at the top that aligns with a triangle on the head, when the engine is at top dead center (TDC) for #1 cylinder on the compression stroke.

If the timing marks on the harmonic balancer are at TDC and you can see the triangle through the hole, then the timing belt is properly aligned. If not, there is always the possibility that it has the wrong harmonic balancer so you will have to pull it (and the radiator, water pump, alternator belt, ac belt and power steering belt) to check the alignment with the crankshaft pulley. If its off, replace the belt and tensioner, if not, you will have to degree the harmonic balance, that is file a new notch showing where TDC is. If your down to this point, you might as well replace the belt anyway.

Then move the engine to 5°BTDC and remove the distributor. While its out, spray some oil (WD40) up into the hole by the mounting bolt to oil the weights. Turn the distributor as you do this. Then check the vacuum advance by pushing on the rod going to the mounting plate in the distributor from the vacuum advance, then cap off the ports and release. It should hold. You can also hook up a hose and try to suck air through it, if you can, then the diaphragm is ruptured.

If all is ok, then you look at the gear end of the distributor. The pin that holds the gear to the shaft has a drill indentation next to one end. You align that end of the pin with a protrusion on the shaft housing and insert the distributor. Allow the rotor to turn into position. Then line up the rotor vane nearest the reluctor with the metal strip on the reluctor (aka pickup or ignitor).


Snug down the holding bolt and check the timing. Without the vacuum advance it should be 5° BTDC and 13° BTDC with vacuum advance. Total advance should be around 20 to 25° BTDC at around 2500 - 3000 rpm.

[Typrus]

Hey... I didn't even think of that.... Sweet! I'll have to "degree" my HB on white so I can actually time the danged thing....
Thanks for that thought.

[sepling]

I don't think you can ask for a more complete answer than that. Thanks!

[sepling]

Well I messed around with the timing light yesterday and figured out the problem. I tried moving the rotor one tooth forward and one tooth back with no success. I then took the disty out, and rotated the whole assembly one tooth clockwise (without turning the rotor within the disty. This changed my adjustment range from 15 degree plus advanced down to 5 degrees retarded. I was able to get the needed 5 degrees of advance.

I set the timing, set the idle and headed down to the emissions testing station. The car idled beautifully, but it had NO POWER AT ALL. I couldn't even get it above 3000 RPM on the road. However, the car passed emissions with flying colors. Go figure.

I went home, put the distributor back to the original position and advanced the timing beyond the scale. It must be at least 25 degrees advanced-- probably more. I had to time it by sound and did small adjustments by blipping the throttle and trying to minimize hesitation. The car runs great now, and doesn't ping at all.

What is going on with this thing? I'm pretty sure the vacuum advance works as it does advance about 8 degrees or so when I hook up the vac line. The car runs great, so I'm not too concerned but it would be nice to know why it runs so horribly at the correct timing and runs great with it so advanced. I had an 84 subaru that had the same problem.

Any theories?

[keith]

You mechanical advance is stuck and probably the vacuum advance as well. You can spray some oil on the weights to free them up through the little hole at the bottom of the distributor as its mounted on the engine. The hole is really a weep hole for any oil leaks or water that might get inside the distributor, but its inline with the weights. If the engine is running at the time, it will distribute the oil evenly.

If the vacuum advance is bad, its almost worth the money to just get a reman distributor. Once these start to go, they can nickel and dime you to death before you end up putting in the reman anyway. If there is any play in the center shaft bushing, the distributor won't be around for long. You check that by turning the engine until a vane is lined up with a reluctor. Them push the shaft toward and away from the reluctor. You need to have a feeler gauge when you do this because you can see the difference that can keep the ignition from firing. Push the shaft toward the reluctor and measure the gap, then push it away and do the same thing.

[takza]

Except...I have 3 dists...one in the car in use for 45K miles or so...and 2 spares. All 3 have about the same shaft slop. One spare has around 160K miles on it. The one in the car works just fine...I've never adjusted the gap. Only running issue is a slightly rough idle.

[ARCHINSTL]

IF - you check the air gap between the rotor and the projection on the pickup coil . . . (quoting AZ now):
Get a non-ferrous (paper, brass, or plastic) feeler gauge of 0.3mm (0.012 in.), and insert it into the pick-up coil air gap. DO NOT use an ordinary metal feeler gauge! The gauge should just touch either side of the gap. The permissible range is 0.2-0.4mm (0.008-0.016 in.).
Tom M.