Belt Skipped a Few Teeth

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wetminkey
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Re: Belt Skipped a Few Teeth

Post by wetminkey »

Pull your exhaust cam cover and you can verify that #4 exhaust lobe is at the farthest distance from the #4 valve shim,...then you'll be sure that your exhaust cam is at the timing mark.
The lobe should point up, and toward the center of the engine at #4 TDC.
Best of luck! Todd.
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CharlieB
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Re: Belt Skipped a Few Teeth

Post by CharlieB »

Thanks Bryan and Todd...great advice. I have verified that they are indeed the correct marks. Of course my rotor is pointing at #1 instead of #4, I'll fix that and get the belt on. I took a vacation day to deal with my wife's grandmother's Mini today, but that's done. Now I can work on the Fiat.
I'll keep you posted
Thanks again
Charlie
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Re: Belt Skipped a Few Teeth

Post by RRoller123 »

Is it a 2L? You can look inside the oil fill cap on the Intake side to see that the lobe is in the same relative orientation (pointing up and inward) as the Exhaust side is. Don't have to remove the valve cover over on that side!
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CharlieB
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Re: Belt Skipped a Few Teeth

Post by CharlieB »

Well now I have a new problem, totally unrelated. The small radiator drain plug / tube broke off when I was trying to drain the radiator. I know, I should have just taken off the bottom hose.
It's an old brass or copper radiator, not a newer aluminum radiator.
What material is the radiator made of, brass? or copper?
Is soldering this tube back on an option or am I screwed?
1976 Fiat 124 Spider
CharlieB
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Re: Belt Skipped a Few Teeth

Post by CharlieB »

Sorry, I got a bit off topic.
Back to the task at hand. Ok, when I have the exhaust pulley on its mark, the rotor does not point to the #4 spark plug. It points toward the front of the car. I rotated it around a few times but simply will not line up with number 4.
I think something may have broken when I was rotating the exhaust pulley. The pulley got to a point where it wouldn't rotate by hand. I figured I wasn't getting enough muscle behind it so I put a chain clamp / wrench on it and turned. It made a pop sound inside the engine.
#1 How do I check to see if anything broke?
#2 If nothing broke, what am I missing as far as getting the exhaust pulley to line up?
Once again, thanks for the help...and the patience.
Charlie
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Re: Belt Skipped a Few Teeth

Post by 18Fiatsandcounting »

Well, shucks, that chain wrench and pop sound makes me think we've entered into a new game here. Here's what I would suggest at this point: Rotate the crankshaft so that none of the pistons are at the top of their stroke. Easiest way to do this is to rotate the crankshaft by hand to the timing mark and then continue on another 30 or 40 degrees or so. Make sure the auxiliary shaft timing hole is at the 1 o'clock position before you rotate the crankshaft. If you crankshaft suddenly stops as you rotate it, don't force it. Just let us know.

Totally remove the distributor. Also check the teeth of the distributor gear at the end, and if you can, look down the distributor mounting hole and see if you can see the teeth on the camshaft for the distributor.

OK, at this point, the exhaust and intake cams should be able to rotate by hand through a full cycle of rotation. There will be points at which you'll start to open a valve and it will get harder, but at no point should the camshafts lock up.

I'm hoping the "pop" noise was just a cam lobe hitting a tappet shim, but from afar, it's hard to tell.

-Bryan
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Re: Belt Skipped a Few Teeth

Post by 18Fiatsandcounting »

PS: A good radiator shop can likely fix your drain plug issue. And, I believe the original radiators are brass.

-Bryan
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Re: Belt Skipped a Few Teeth

Post by CharlieB »

Bryan, I just realized that the mark I was lining up on the auxiliary pulley was the wrong mark. i was lining up to a painted white mark that i assumed was the mark for timing. The hole is about 15 degrees counterclockwise from that mark.
Soooo that may be a major problem...I don't know.
Anyway, I rotated the aux. pulley to the 1 o'clock position and the crankshaft 30 degrees or so past it's mark.
I took the distributor out. The gears on the cam and distributor look good.
The cams rotate easily.
Here is the top of my distributor. Just to make sure, the white mark should be pointed at the #4 spark plug...correct?
Image
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Re: Belt Skipped a Few Teeth

Post by 18Fiatsandcounting »

This sounds like good news to me. On some Fiat engines under certain conditions, the connecting rod for one of the pistons (#2 I believe) can strike the lobe on the auxiliary shaft if the auxiliary pulley isn't timed right. The lobe actually drives the mechanical fuel pump which is just under the intake manifold. Of course, if you have an electric fuel pump, technically you don't need this lobe on the auxiliary shaft, but Fiat just left them in. Anyway, what might have happened is that you struck a glancing blow on your connecting rod and lobe, and that was the "pop". I doubt you have major damage, or even minor, but let's keep progressing.

Both of your camshafts and your distributor drive gear on the exhaust cam are all good, it sounds like.

At this point, you can turn the camshaft pulleys so that those holes line up with the nubs on the housing, and turn the auxiliary shaft so the hole is around 1 o'clock looking from the front. It doesn't have to be exact, and it could be 45 degrees past vertical, which would be 1:30. You get the idea. Just in that general area. I forget the actual Fiat spec.

Then rotate the crankshaft so that cylinders #1 and #4 are at the top of their stroke (TDC), in other words, the timing mark for the crankshaft lines up. Put the timing belt back on and verify that nothing moved. At this point, the valves for cylinder #4 should be both fully closed, and so cylinder #4 is the one that would be firing if the engine were running. So, put your distributor back in and fiddle with it until the rotor is pointing (yes, with the white mark) toward the plug wire #4 contact on the inside of the distributor cap. Just estimate by eye as best you can.

I'd check all the spark plugs to make sure they are in the right order, so looking at the (reinstalled) distributor cap clockwise from the top, cylinder #2 should be immediately clockwise from #4 that you just lined up, then cylinder #1, then cylinder #3 and then back to #4. The Fiat firing order is 1-3-4-2, or since we're starting from #4, it's 4-2-1-3-4-2-1-3 etc.

At this point, assuming there are no other issues, the engine should be ready to start. I always turn the engine over slowly a few complete rotations by hand (using a socket on the crankshaft pulley) before trying it with the starter motor, just to make sure I haven't screwed up somewhere.

-Bryan
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Re: Belt Skipped a Few Teeth

Post by CharlieB »

Well good, I'm cautiously optimistic that I have not done too much harm, yet.
Once again, your instructions are very clear and detailed so I'll put it all back together, most likely tomorrow and report back.
By the way, I did take the radiator to a shop today. So when I get that back I can pull the trigger.
If nothing else, I have learned quite a bit through this adventure so thanks for that.
Charlie
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Re: Belt Skipped a Few Teeth

Post by RRoller123 »

Just to be clear: "toward the plug wire #4 contact on the inside of the distributor cap". Not towards the #4 spark plug itself. This seems to be simplistic, don't want to be insulting, but we have seen a couple of cases over the years where it was misunderstood, and pointed at the plug itself. That causes big problems, like it won't run. So, as Bryan said: It should be pointed to where it just makes contact with the #4 connection on the inside of the cap.
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Re: Belt Skipped a Few Teeth

Post by 18Fiatsandcounting »

CharlieB wrote:Well good, I'm cautiously optimistic that I have not done too much harm, yet.
Worry not, Charlie, we will do our best to keep you away from Fiat wrath! And Roller's (Pete's) point just above is a good one, and one that cannot be restated too many times. When the camshafts and crankshaft and auxiliary shaft timing marks are all lined up, the distributor should be set to deliver a spark to the #4 cylinder.

-Bryan
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Re: Belt Skipped a Few Teeth

Post by CharlieB »

Pete I am not the least bit insulted and I appreciate any help.
I have not touched the car in a few days. I had my radiator plug reattached but there are too many other leaks so I'm going to replace the radiator. I'll get a new aluminum replacement from AR, unless someone has a better source.
I'm going to clean up the engine bay a bit before I get things back together.
Thanks for the help guys.
Charlie
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Re: Belt Skipped a Few Teeth

Post by 18Fiatsandcounting »

Sounds like a plan, Charlie, and let us know when you're ready for the next step. We'll be here.

-Bryan
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Re: Belt Skipped a Few Teeth

Post by CharlieB »

Well the plan changed again. I fixed the leaks in the radiator. Pressure tested it and all is well there.
I put everything back together and tried to start the engine. I cranked it and the engine rotated a little and stopped. If I try to crank it again, nothing moves at all. It's acting like something is stuck.
All of the marks are lined up, the rotor was set up on the #4 contact. It took several tries but I got the belt on. So I have no clue what is going on.
If the belt was off by a tooth or 2, would it act like this? Thats the only thing I can think of that might be off.
Thanks
Charlie
I'm not positive I have the belt on correctly
1976 Fiat 124 Spider
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