1976 Fiat 128 Air Pump and Timing Belt Troubles

Triestino

Triestino

Daily Driver
Today, I began to study how I'm going to replace my timing belt and tensioner bearing. Namely, how can I replace these items in the car. As I moved over the timing cover (after removing the top 3 bolts and a center bolt - still looking for the very bottom bolt..arghhh), I discovered that the air pump belt teeth were completely gone. After removing the belt, I noticed that the air pump, although turning, seems to have friction in one spot making it hard to spin. Are these pumps repairable or do I need to get a new (rebuilt) one? Any one have a spare they would like to sell perhaps?


As an aside, it seems pretty difficult to replace the timing belt on the 128. How do you get to the crank pully or remove the bottom timing cover bolt? :wall: It almost makes me think removing the engine might be the way to go. Any help would be appreciated.
 
I did this on a Ritmo (Strada) some 30 years ago, same layout and same engine family as the 128. I don't remember it being particularly difficult, but space is limited. The crank pulley does not need to come off, you can thread the timing belt behind it and onto the crank timing belt pulley.

Can you get access to the lower cover bolt through the front right wheel well if you remove the fender liner?

Like with the X1/9, pay attention to the aux pulley. Unless you have a cam driven distributor, the distributor will be driven from the aux shaft. The aux shaft has a nasty habit of rotating out of position, altering your ignition timing.
 
air pump

As noted, you should not have to remove the crank pulley to remove the old timing belt and install the new one.

As to the air pump, no experience with the 128 but had a bunch of 124 spiders with them. Yes, they can seize up and if that's what yours did then it explains the missing belt teeth, they were stripped off. My spider airpumps could be taken apart. I had one where the vanes had frozen in place so I just broke them off and reassembled the pump, it looked functional but was internally disabled. I live in Virginia and older cars do not have emissions testing. If your state does not require it you could just remove the belt but leave the pump in place or just remove the whole assembly. Removal or disabling the pump does not require any tuning adjustment of the motor and you pick up a small performance gain since the motor does not have to spin the pump.

carl
 
The bottom bolt for the timing cover should be accessible from the engine bay. It's been a while for me (I only throw the cover on to set initial timing, and prefer to use the flywheel pointer for fine tuning). If not, go up from the bottom but remove the splash guard first (if your car still has it installed) to provide more access.

It's been a while since I had one apart, but I believe the air injection pump has a rotating hub that is offset from the center of the case, and the pump vanes slide in and out of the hub as it rotates. If one seizes, it prevents the whole thing from rotating. If you remove the pump, you can unbolt the back of it and gain access to the vanes.

Removing the pump is a PITA with the engine in the car. The long pivot/mounting bolt won't clear the inner fender, and the pump obscures the bolts that secure the cast iron mounting bracket to the cam tower. I always ended up removing the big "Y" support bracket, loosened the pivot bolt, and then used a combination wrench to remove the hard-to-get-to bracket bolts by rotating one flat at a time. I've also seen cars where people had just hammered the inner fender for clearance, but that's not really my style... I guess you could also lift the engine a bit.

I'll take a look and see if I have any spare pumps. I am hanging on to the two good ones I have for my 128s in case I ever move back to CA!
 
Thank you all for your insight and support. Haven't had a chance (since this past weekend) to take a better look at things in the engine bay. 128Kid, I was going to remove the air pump but ran into the very problem you mention. As it was getting late in the day and I was getting increasingly frustrate, I decided to stop and revisit the problem(s) I encountered on another day.
It seems awfully tight to replace the timing belt while the engine is still in the bay. Pulling the engine to address the varies items that need attention is starting to look like a viable option.

Regards,
 
Hi sorry for your troubles with the timing belt and air pump. Fortunately there is a little bit more room in the Strada to access these components. It does not solve your problems but it should be noted that the 128 belt is probably easier to maneuver than some of the late model front wheel driver cars, ie Volvo, which require special tools. A working air pump will be necessary to pass smog. I do have a used one from a Yugo GVX 1300, I believe it is the same as the 128. $25 + $11 shipping in a priority flat rate box. Its in working order, a small amount of bearing noise. Perhaps it can be lubricated. If you are interested let me know, I can email some photos.
 
Hi Kevin,
Thanks for your offer. I'm going to work on the 128 this weekend (weather permitting) and will determine my next steps and see if 1) I can remove the air pump without too much trouble and 2) try to find the bottom timing cover bolt and proceed with the timing belt/tensioner bearing replacement. I'll let you know about buying your air pump once I get past these steps.

Thank you!
GT
 
Smog pumps

The '74-76 128s used a smog pump with a toothed belt drive, driven off the cam pulley. The '77-up 128s had pumps with a V-belt drive. I think it was driven off the water pump pulley. I'm not sure what the Yugo pumps were like.

Here's what the 128 toothed belt version looks like installed (but missing one bolt on top).

std_engine_15.jpg


std_engine_16.jpg
 
=)

Triestino said:
As I moved over the timing cover (after removing the top 3 bolts and a center bolt - still looking for the very bottom bolt..arghhh)
Click to expand...

It's at the very bottom corner of the cover, in a bit of a recessed area (like the center bolt is). Best accessed from under the car & using a flashlight.


Triestino said:
...I noticed that the air pump, although turning, seems to have friction in one spot making it hard to spin. Are these pumps repairable or do I need to get a new (rebuilt) one? Any one have a spare they would like to sell perhaps?
Click to expand...

If the offers from other folks don't pan out, there's a junkyard X1/9 near me that I could pull this part from (use as-is or have it rebuilt). :huh:


Triestino said:
As an aside, it seems pretty difficult to replace the timing belt on the 128. How do you get to the crank pully or remove the bottom timing cover bolt? :wall: It almost makes me think removing the engine might be the way to go. Any help would be appreciated.
Click to expand...

Did you remove the metal splash shield fitted between the front wheel & the engine? Removing the right/front wheel & that shield makes things MUCH easier... :)
 
Huh, what? I have no idea what you mean ;)

And it passed with flying colors, even without a cat (federal car). Barely got the dyno rollers moving with the timing set to the factory specs.
 
Thanks 128Kid and Jeff! I finally figured that accessing the bottom timing cover from the passenger wheel well makes life a bit better :) although having spent too much time figuring out how to remove the air pump, didn't get a chance to do anything :(
I guess this will be next weekend's project. Thanks for the guidance!
As an aside, has anyone tried removing the air pump without major surgery? Especially, removing the lower right side (longer bolt) found on the air pump?

Thanks,
GT
 
I moved to NC 7 years ago and my emissions equipment has been safely stowed since then, so I'm going from long term memory here :)

I've removed the pump as briefly described above. Remove the big Y bracket (the inside top bolt is blocked by the carb, which is why it's missing in my photo). Loosen the long pivot bolt and remove the belt. Then remove the four bolts that secure the cast iron pump bracket to the cam tower. This is a total pain because you can't get all of the bolts out (since the pump is in the way). I slowly loosen them all, working underneath with a socket and extension (probably a wobble or universal too, I don't totally recall) and from above with an open end wrench. I think a couple bolts can be wiggled out in the process. Then the whole pump and bracket will come off together with the remaining bolts.

When I reinstalled it, I only used a couple of the bolts to make future removal easier. Not my favorite but it worked. That thing has more bolts than the engine/transmission mount!
 
Thanks 128Kid !
I'm going to give it a try this weekend. I ended up buying a new (refurb) air pump for $82. Keeping my fingers crossed that all goes well. :)
 
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