Timing belt won't track straight

[engineerted]

As Mark stated, get a straightedge and check that the gears are aligned. One other thing to look at is the cam boxes, if they were removed sometime in the past they may be a little off. You do have a little clearance around the cam box bolts to wiggle them around. My two cents.

Ted

[Tappy]

i think i found the problem or @least part of it The little pin inside the cam that aligns the pully on the cam is bend , it also sticks in the pully instead of the shaft . I have other cams(complete) can i retract the pin from them in any way ? i tried to pull out one but i deformed already , is there an easyway to do this ? or can i get a replacement pins for that ?


edit : according to the parts manual this would be dowel 4130961

[Tappy]

ok fixed the dowel problem , i used my dremel to get a piece of a drill (5mm) and that worked like a charm
however the belt still likes living on the edge

i guess i'll check the alignment tomorrow ,

ohh, the metal gears do wear, including the crankshaft sprocket. There are two different crank gears and the spacing is different between them. If the wrong one is on your crank that could cause the problem. I'd use a straightedge and see if all of the gears are in line with each other

what is a straightedge ? and how can i determine if i have the same gears or not ?

edit: i found out a straightedge is a kind of ruler with a straigd edge , but i'm not sure how to use it to mesure if the gears are in line ?

[spiderman2000]

I haven't found the issue yet. I have replaced the Aux gear and the crank gear and reinstalled the belt. Turned it over by hand and it seems to track, but it did the last 3 times before, until I started it up. The weather has been too bad to get enough time to finish putting everything back together (ie installing radiator, fan, and hoses). This weekend will be the acid test. As for the straight edge idea, All the gears line up but the exhaust cam gear and thats only because its wider than the others. I have considered the idea of putting an intake cam gear on the exhaust side as is has a lip on it where my current one does not. And before anyone says anything I know the timing marks will be off, but I can do the timing alignment with the old gear (line things up) and then mark the intake gear that I put on the exhaust side with the correct alignment mark. But I am thinking I will use that idea only as a last resort.

Tabby , kinda curious about the bent pin. Seems to me that as long as the pin seats in the camshaft and the gear seats flush with the camshaft that it will have very little effect on belt tracking unless it keeps the gear from seating correctly against the cam.

BTW, last weekend Vick's had an open house. Jerry (the owner) told me to bring some of the parts with me so that we could get a consensus opinion of what might be going wrong. I took my tensioner assembly (bolts and all) and gears down there with me along with pics and had everyone stumped as to why the belt would not track. Not such a good thing when a bunch of gear heads can't come up with the answer.

I am curious though, someone mentioned 1 or 2 posts back about cam boxes being removed and that could throw things off. I have never had the cam boxes off the engine, but aren't there alignment pins that would keep the cams from being missaligned ? Otherwise that would seem like it would be a recurring problem we all would have if we did any serious disassembly of the engine. Can anyone speak to this point ?

Thanks everyone for you input and suggestions. They are really appreciated. I know that I will get this figured out eventually. When I do, I will be sure to post what I find.

[Tappy]

well i think the problem is we both have a 79' I assume your belt tries to run of the exhoust cam as well ?

wel probably the bend dowel had nothing to do with the problem , it does explain why we had so much trouble getting the timing belt on correctly (the markers never seem to line up properly they were of 1/2 tooth)

my camboxes are changed over and over again , so did the gears @ this point i have no idea wich ones ar on right now

since rebuild my belt didn't run straight (gay!), i remember the mechanic to have told me he witnessed the same problem also , but that was an engine ago. Since then i replaced the engine and the exhoustcambox and the gear on the exhoustcam

if i work this out i'll sure let you know , pls do the same

[Tappy]

ok did test some alignments

when i hold my ruler against my aux gear up to the intake cam there's a gap of 5 mm

is this correct ? can someone check that pls , seems like my intake cam should move up to the front 5 mm

[Tappy]

still no improvement , i switched the timing belt to rule out a belt problem , i've switched the pullys on both cams , ive switched tensioner wheel , changed the pully from the aux gear

only thing i can see is that the inlet camwheel seems to be 5 mm backwards in comparison to the exhaust camwheel and s5 mm back to the aux wheel

can someone check his/her spider and see if the inlet camwheel aligns up with anything

thx

[Tappy]

found it !!!!!


ok i confess I didn't really find it , i phoned to guy moerenhout he told me to put a little piece of cutout flat tin can behind the tensioner assembly (upper part) and it works !!


thx guys for all the input, another 124 mistery solved !!

[launieg]

Tappy,

I really like your new "signature" cartoon. Well done!

It always bugs me when I come up with a solution that works but cannot be explained! So although you have a solution, I've been wondering what could cause your tensioner to be slightly off. One possiblity is that the bracket is bent a little (causing the bearing to be at a slight angle). Have you tried a different one? Another thought is that the bearing you have might be recessed a bit more on one side than on the other, and reversing it might move it in (or out) a bit. Another thought, as Alvon said, is that the bearing might be a bit too narrow.

But if the belt is fully supported by the bearing, then my bet is that the bracket is bent a little.

Just some ideas, 'cause I can't leave a challenge alone!

[Tappy]

Tappy,

I really like your new "signature" cartoon. Well done!

It always bugs me when I come up with a solution that works but cannot be explained! So although you have a solution, I've been wondering what could cause your tensioner to be slightly off. One possiblity is that the bracket is bent a little (causing the bearing to be at a slight angle). Have you tried a different one? Another thought is that the bearing you have might be recessed a bit more on one side than on the other, and reversing it might move it in (or out) a bit. Another thought, as Alvon said, is that the bearing might be a bit too narrow.

But if the belt is fully supported by the bearing, then my bet is that the bracket is bent a little.

Just some ideas, 'cause I can't leave a challenge alone!

the bearing itself supports fully the belt , i didn't have another bracket to test ,the one from a lancia looks the same but can't bear the bearing , it rubs up on the block. only the thin sheet of tin metal (from the cover of a can tomatoes) is on the upper side of the bearing so the arrow on your picture should point other wise (so the bearing is tilted a little foreward)

when my batterycharger desides to load my camera's battery i'll post a picture

[So Cal Mark]

that's why I suggested a straightedge to check alignment. If you're using a shim on one side of the tensioner assembly, then it's misaligned

[Tappy]

Mark i did trie that but its not an easy place to move an straigdedge around , the metal piece is that thin, it would be hard to see with your bear eyes , at least for me

here are the pics :

[So Cal Mark]

pie filling?

[TulsaSpider]

Hmm well I am having the very same issue I have also built a 79 block. Gives me some things to check...

[TulsaSpider]

The tensioner bracket is flat against the block. I was using the plastic cam wheels because I am using the 1800 head and they are the same ones that I was using before. I will try the steel cam wheels and see what that does. The belt seems to be off the crank towards the back and off the aux pulley as well. A friend said to try using a cam pulley with a lip at the back. Sounds like a good idea to me. The one I have now has the lip at the front. here's some pics.