Banshee365

ac4000, if the belt was installed with the factory toyota belt marks lined up on the marks on the pulleys; you should turn the crankshaft 2 full revolutions by hand and the marks will align again, as it is a 4-stroke engine. You should also not refer to a timing belt "slipping". Accessory belt's slip, shoes slip, etc... A timing belt may as well be considered a chain. If you want to justify the ammount of revolutions the engine must turn before the marks line up you should count teeth, not diameter of the belt and pulleys. Even the factory manual say's to check the installation by turning the crankshaft 2 revolutions then check the marks again.

If the engine is out of time pretty bad then you should remove the belt and put the crank at TDC and position the cams correctly. Install the belt and tensioner and turn the belt twice to verify the marks. If your timing is off by much you could be getting some crazy electrical issues causing fuel cut and weird stuff like that. Get your belt installed correctly and try again. You would be having a MAJOR mechanical issue with that stiff cam of yours if it is actually making the belt skip teeth.

ac4000

Correct me if I'm wrong, but the service manual says to check the match marks for alignment. That means the marks on the camshaft pulleys should align with the marks on timing belt rear plate. This is not the same as match marks on the belt and pulleys, which would not realign until 30 rotations of a camshaft pulley (see prior calculations; should be just fine to do that with lengths since the teeth have a precise measurement and, because they're teeth, the rounding error from the calculations is essentially eliminated).

The service manual refers to a timing belt allowing the camshafts to drift apart as "loose, jumping teeth." This is more precise than slipping, although frankly it's a belt, not a chain, so it can slip. I agree though that jumping or skipping eliminates any confusion for people who think a timing belt is toothless.

I'm with you on the stiff cam business--it would cause more than a minor rev fluctuation problem. So would a jumping belt, for that matter. I'm hoping that the camshaft misalignment (which is the only thing I know for certain was incorrect because the camshaft pulley marks were not aligned with the timing belt rear plate) was causing the rev fluctuation. At this point, I'm fairly certain it was causing the CEL 13, but I still don't have a theory about what caused the rev fluctuation problem to go away when the engine warmed up.

Parts arrive tomorrow.

Banshee365

I'd have to agree with you on the alignment marks on the cam, not the belt. I'm confusing the belt on my little Toyota 4-cyl that for some reason does actually line the marks back up after 2 revs, maybe pure coincidence. Comparing the cam alignment marks to the engine is definetly the only way to check the timing. If you've got your engine torn down to put the new belt on maybe think about pulling your cam cover over the stiff cam. I can't think of much that would make the cam really stiff without making some really bad noises. If you had something wrong in there you would really know it. If, in fact, your belt is skipping I would start thinking the tensioner is weak and should be replaced, as they should with any timing belt replacement. If your cams don't line up with the crank at TDC that's a big problem that needs to be fixed ASAP. The ECM uses the crank and both cam sensors and compare then when running the fuel mapping and ignition. If they aren't where they're supposed to be the ECM will do some weird things like cut fuel and mess with the timing.

ROLEXUS400

iTrader: (2)

ac4000 - Yes the problem on my car is gone,she runs great. The cam sensors should ohm out between 950-1250 ohms according to alldata. However when i tore mine down they read 1394 ohms and so did the 2 i have on the shelf left over from a previous parts car. My car was setting a code 13 and the belt was off a tooth on the pass side. To further answer your question-yes my car would do exactly what yours does with the rev fluctuation, and yes it did go away after warming up. Technically it never went away but the car seemed to compensate for the problem better. What i belive your seeing as a "rev fluctuation" is actually the ecm cutting out the distributor due to signal inacuracy. Im not an expert but that is the way i understood it and how i came to my diagnosis. The timing marks are kinda hard to read on the cams because they can look very close and actually be off a tooth. I will say this even when you get it lined up where you think its correct you have to have all of your belt slack on the tensioner side of the motor. If you dont do this when you release the tensioner it will be off because it will pull it in that direction. I may not be typing the explanation very clearly,but i hope this helps you some. i can tell you this,when you get it right your gonna love this car. I hate getting out of mine

ac4000

Well ... that was it! The CEL 13 is gone and, more importantly, the rev fluctuation is gone. I replaced the two pulleys and the timing belt, cleaned up the dirt and grime inside to a reasonable degree, replaced some missing gaskets, put on a new drive belt and carefully reassembled. Perfect. Smooth as silk. We can probably say, quite definitively, that the camshafts being off caused the CEL 13 (previously established) and the rev fluctuation (hypothesis, also confirmed by Rolexus). So now we have a video of what that can look like, in addition to the CEL 13 symptom.

Thank you all, and especially Banshee and Rolexus, for your help.

A hint for anyone else digging around in there without the Toyota SST to hold the crankshaft in place: I used the starter trick to remove the crankshaft bolt (which worked, but I wouldn't recommend it), then an impact wrench to remove it later (after temporarily tightening it). The impact wrench is the way to go. To properly tighten it to 181 ft. lbs., however, you can't use the starter trick and the impact wrench is not precise enough. What I did was wrap the old drive belt around the crankshaft (as if to start an old pulley starter lawnmower) and the other end around a suspension arm. This held just fine against the torque wrench. (Pictures attached.)

ROLEXUS400

iTrader: (2)

YAY! I helped someone. Thats awesome you got it all fixed up. I bet your super excited. I know i was. This whole site has been loads of help to me. So anytime im up here i try and find stuff i know about so i can try and help. Good luck to you and enjoy