HELP: Aligning Cams

[CA124]

Hi All,

I finally started working on my fiat again and wanted to change the timing belt.
I did my research on this forum/manuals and it states that I should turn the engine so that #4 is at TDC before removing the belt. I was using a wrench to turn the engine when the intake or exhaust cam gear slipped a couple of teeth on the belt. I couldn't tell how many teeth and which of the cam slipped so I just removed the belt thinking I'll just re-align them when reinstalling the new belt.

I made sure the crank was set at #4 TDC, Aux cam at 34 degrees, and the exhaust cam at 1 o'clock and intake at 11 o'clock using the markers.

Question: I have the cam covers off checking the cam positions and it doesn't look right for a #4 combustion or does it?? See attached pics.

Any help would be appreciated - thanks!

[vandor]

It does look like #4 is on the power stroke. BTW, since piston #1 and #4 are at the top at the same time, it does not make a difference which one you use. It's when setting the ignition that you have to remember that when the cam marks are aligned it's cylinder 4 firing.

Be sure to turn the engine BY HAND (ie. wrench) TWO revolutions before you start it, to make sure nothing is touching.

[klweimer]

When you were turning the engine by hand, did you have a wrench on one of the cam pulley bolts? I'm guessing, if the cam slipped. If you haven't already, you will need to get a 38 mm socket to remove the crank pulley as part of your timing belt replacement. You should use this to turn the engine. Loosening/removing all the spark plugs also makes it easier to turn over. Lots of good write ups here on the whole process.
Kirk

[CA124]

Thank you Vandor and Kirk

I checked and made sure the dizzy was in position for #4 but it seems like when the aux cam was at 34 degrees the dizzy is aligned passed firing #4. I turned the aux back a few degrees to have it aligned to #4 in the dizzy. How true is it to have it at 34 degrees as the manual says? I've heard 1 o'clock and also to align the aux cam "marker hole" to the tensioner bolt?

As for Kirk's comments - yes I did try to turn the engine via the intake cam bolt and that's when it slipped. I don't feel the need to remove the 38mm crank bolt - is there a benefit? I have plenty of space to fit the new belt.

I do need to buy a 38mm to turn the engine tho.

Also the car didn't come with the belt cover so I had to use a straw in spark plug 4 hole to determine TDC.

Thank you!!

[phaetn]

The only 38mm socket I could find locally to turn the crank was monstrously large. It effectively meant pulling or moving the radiator to even be able to get access to the nut with a 1/2" drive ratchet or breaker bar on the end.

Then someone pointed out to get a specialized 38mm oil filter changer socket. If you do an online look-up you'll often find them for $15 or less and they are much thinner - probably 3/8" drive, though.

It's handy for something like this.

Cheers,
phaetn

[klweimer]

CA124, you may not have to remove the crank pulley if all the belt covers are gone. I don't know, as I had all the covers on mine. Lots of discussion on leaving them on or taking them off. If yours are already gone, you won't have that decision to make.

[vandor]

FWIW, in the US it's a lot easier to find a 1.5" socket than a 38mm, and they are virtually identical in size.
Looks like a 1438 engine, so it should have the centrifugal oil filter on the crank pulley, so not easy access to the 38mm crank nut.

The aux cam wheel does not have to be exactly at 34 degrees, on the short stroke 1438 you have a lot of space between the fuel pump lobe and the connecting rod.

Just be sure to turn it by hand 2 revs beofre starting it.

[CA124]

Thank you all for your help and advice.

I'll source out a shallow 38mm or 1.5" socket to turn the engine.

Vandor: the crank pulley does have the cap covering the 38mm bolt. I removed it to access the bolt.
I'll make sure to turn the engine twice before starting.

Cheers!

[aj81spider]

This is the 38mm socket I bought. On my car it is short enough that I can get it on the crankshaft pulley without having to pull the radiator (which is why I bought it!). I use it to turn the engine, but have found I can change the timing belt without removing the pulley.

https://www.amazon.com/gp/product/B00FE ... UTF8&psc=1

[CA124]

Ok thanks again for all the advice.

I put everything back together but really had a hard time installing the belt. What are your tips and tricks to making this process easier specifically in keeping the tensioner tensioned while slipping the belt on? I've searched the forum but didn't find anything on this particular subject.

Cheers!

[JohnMc]

How i have always done it on 1438 is to loosen the two bolts for the tensioner - that is the nut on the timing belt tension bearing and the timing belt tension spring bolt (my Fiat manual calls it a belt stretcher pivot and spring and rest "screw"- but it a bolt. Slip the belt on and then tighten up the nut and bolt to specs. Then I took out the spark plugs so no compression and turned the engine over by hand two times to ensure nothing slipped and checked the marks.

[JohnMc]

As Csaba said above, the 1438 has a centrifugal oil filter on the end of the crank. So you would have to take off the few bolts that attach it to the crank, get small amount of oil spilled on floor but then, at least mine, had the washer that was bent over the pulley nut to keep it in place - so you would have to straighten it out to put your large socket on it and then bend back in place to keep the nut from turning.
Personally I did not find it all that hard to turn the crank with the spark plugs removed.

[CA124]

Thanks JohnMc!

I've loosen both the tension bolt and spring bolt but it doesn't loosen up to where the belt can simply slip on. You still need to apply a fair amount of pressure to push the tensioner for the belt to fit onto the cams. Anyway wanted to see if this was the case for everyone.

So after I installed the belt and manually turned the engine two full rotation, put everything together and then started the engine.
Engine was running rougher so could it be the cams are not aligned or off by one tooth on the belt? As mentioned I had a harder time installing the belt and might have moved the exhaust cam.

Thanks!

[klweimer]

CA124,
If your engine is running rough, you may well be off a tooth off somewhere. Easy enough to check. Loosen up your spark plugs and turn the engine around to TDC (based on your ignition timing marks), with the two cam wheels holes lined up on the indicators on the cam towers. See if they're lining up correctly. If the holes are nowhere close, turn the engine another 360 degrees to see if that looks better. At this point, you should be able to decide if something is off by a tooth. If so, loosen the bolt that goes through the belt idler and slightly loosen the pivot bolt for the idler bracket and use a screwdriver or pry bar of some description to push the idler away from the belt. Retighten the bolt to hold the idler away from the belt while you slip it off the cam wheel to reposition the cam. Slip the belt back on and loosen the bolt in the middle of the belt idler again, to let the spring put tension back on the idler and then retighten both bolts. Double check the position of the aux shaft gear wheel. Turn the engine over a few time to see if the timing holes on the cam gears now line up better. Repeat as needed.
Kirk

[blazingspider]

When fitting a new belt I've always loosened the tensioner bearing nut and the other bolts then I use a small pry bar to push and hold the tensioner bearing away from the belt and then I lock it in place by tightening the nut and the bolts. Now the tensioner bearing is out of the way so to speak.

Once the belt is on, then I loosen the tensioner bearing nut and other bolts and let it "spring" into it's normal position to take up the slack in the belt, then tighten all the nuts and bolts to hold it in the "tensioned" position.

My 2 cents