Freewheeling vs. interference engines (by year?)

[nelsonj]

Hi all,
Had some bad luck with my Spider over the weekend. While driving it started "clicking" and then the engine died. I tried to crank it, the engine would spin, but did would not crank over. It sounded a lot like I broke the timing belt and had no compression. After calling AAA and having my baby flat-bedded to my house, I tore the car down and found that the teeth on my timing belt were badly stripped down (I think this explains all the "clicking", it was the belt slipping and tearing the teeth apart...), but the belt was still in one piece, and my cam and aux timing was completely off due to the slipping. Also, I have no compression on the three cylinders I tested.

I could turn the crank by hand (and 1 1/2 socket) and the belt would slip even with my hand crank. Occasionally, the crank felt like it made hard contact, so would reverse turn it a bit, and then I could continue cranking it in the clockwise direction without contact.

Anyway, I was convinced that I bent a bunch of valves (or worse) until I did some digging here. Various people say that post 76, the engines freewheel, but, that the 2000cc engines don't fully freewheel because the Aux shaft can make contact with the some other spinning parts. Anyway, I have should have a 78 drive train in my car, which according to various post will fully freewheel without ANY interference issues. Thus, I am hopeful all is well and my lack of compression is simply due to the cam timing being so far off. If this is correct, it sounds like a 77 or 78 drive train is the way to go if your priority is an engine that freewheels. I sure hope I am that lucky.


Well I figure others could benefit from knowing 1) what engines are interference and are doomed if the timing belt breaks/slips, 2) what engines truly freewheel without any issues, 3) what engines sort of freewheel except for the Aux gear, and 4) how do you modify the Aux gear to get and engine that truly and fully freewheels.

Mark seems to know the real facts on this, but I think the board would really benefit if someone could post a definitive answer. I sure hope my drive train really is a 78 and it fully freewheels. That really is a great "live saver" even if you have to trade some compression for it. I will know for sure next weekend when I put the new timing belt on, set the timing correctly, hand crank the engine to make sure all is clear, and then hopefully fire up the engine and test the compression on all 4 plugs.

I will update this after I do the work (likely a week from Sat). In the mean time, I sure hope someone can document engine year and interference/freewheel/almost freewheel for everyone's future reference.

Thanks, and wish me luck.

[divace73]

ouch, how old was the timing belt, it's the first thing I change when buying a fiat, unless I KNOW FOR SURE it was done.
Can't speak for an 1800 but I thought that all the fiat's engines were not freewheeling (I always thought it was called free running??). The Aux shaft (I know with the 2L) has the lobe for the mechanical fuel pump which if not aligned can knock no.2 rod, if your car has an electric fuel pump, then you can get rid of the lobe (i did on my car)
I don't know if US power plant had much lower compression pistons that may allow the freewheeling, but here in Oz if the belt goes it's always a bit of trouble???

[nelsonj]

The belt was not that old - my mechanic charged me to change it about 3 years ago. But it had less than 10k miles on it (16k kM). However, it looks like the belt slipped because of all the grime that built up in the gear teeth. It could have been 20+years of grime. My guess is the grime filled the gear notches, this made the notches too "shallow", and the t-belt teeth lost their grip as a result...just my guess.

I am still hoping (against hope) for no damage. I plan to cut my t-belt cover in half when I replace the t-belt and tensioner. That way I can easily check the belt and rate of grime build up. It the grime comes back quickly, I have a seal issue that will need attention.

If I don't get good compression, I guess I will learn how to take off the head and replace valves (if that is the only thing damaged.) A first time for everything.

[So Cal Mark]

the engines were all interference engines until mid-77 when the compression dropped by enlarging the valve reliefs. So mid-77 and 78 should freewheel. In 79 when the 2L debuted you won't bend valves, but as mentioned already, the auxillary shaft can contact the crankshaft

[nelsonj]

Thanks for the repost. I note that US spec engines might no be the same as OZ specs...


So Mark, what is your bet with a slipped t-belt on a 78 and valve damage? It would not make valve to cylinder contact, but what about valve-to-valve contact? I am trying to remain optimistic, but valve-to-valve contact still means I will need to replace valves...

(Also, I cleaned every tooth of every gear, and they look close to new. No cracks or signs of excessive wear.)

[nelsonj]

Well good news/bad news...but mostly bad news

Good news: I successfully replaced my first timing belt! It was actually a bit easier than I expected getting the belt on and tensioned. I had to put the belt on twice because things just didn't line up perfectly after the first try. Also, I was able to get the belt on without removing the pulley from the crank shaft (and yes I have a flange). I did, however manage to break the "double bolt" where the spring rests when torquing the tension to the locked position. I removed it and the spring, but I only have the single bolt on the bearing holding tension for now..I wish that was my only problem...

Bad news: I hannd cranked the engine multiple times, everything was smooth, no contact, the belt stayed well tensioned and everything stayed in perfect alignment. However, when I used the ignition to turn the engine it still felt/sounded like like I had no compression... I checked compression on cylinders 1 & 2 and zip, zero, nada, nothing. My compression tester also picked up a few metal shavings along the way.

So...this weekend the t-belt comes back off, and I will, for the first time, pull the head off the car to take a look and see just how much damage I have done. Based on compression, my guess is that valves are bent on all four cylinders, at a minimum. Hopefully the pistons and cylinder walls are still in good shape.

Is there a thread on how to replace valves? Any tips on removing my head before I do the deed?

Thanks...

[vandor]

>the engines were all interference engines until mid-77 when the compression dropped by enlarging the valve reliefs.

While some manuals do say that, I have never seen a 1800 with the large reliefs. I've taken apart 2 1978 Spiders that I knew for sure had the original engines, and neither had the large reliefs.
The confusion may come from the fact that in Italy they use calendar years, while here in the US model years are used. Since the 1979 model year 2000cc Spider production was started in 1978, a manual translated from Italian info could say that in mid-1978 they changed to large reliefs, when in fact it was the 1979 model year cars that were changed.
So my bet is that if it is an 1800, then it is an interference engine. One can check for bent valves by checking the valve clearances. Very large clearance = bent valve.
The fuel pump lobe on the aux shaft can hit the crank on 1600/1800 engines too, it is just less likely, as there is more distance between them.

[nelsonj]

I am trying to post a few pics but Shutterfly won't cooperate.

I almost have the head off, so tomorrow AM I will get a look at the actual damage.

[RRoller123]

This is a procedure that I have been developing for a little while on how to post pictures here in the Forum. Hope it is useful, and comments are always welcome.

HOW TO POST PICTURES IN FIATSPIDER.COM

Well that picture-posting thing sure is confusing. Took me forever to figure it out. Here is what I do:

First, you must post your pictures on photobucket.com or one of the similar competing websites. You can't post pics directly from your computer. So set up a free account there first. The instructions here reference photobucket.com.

Then in your FS.com post, look for the "Img" box at the top of the post, #9 from the left in the row of command icons.

Put the cursor where you want the pic to appear in the post (leave a few spaces after text is a good idea) and click the "Img" button/icon above.

Then go to the photobucket.com site (or competitor) and find your pic. Hover the cursor over the pic and a drop down menu will appear. Then click the "Direct Link" or similar button. In Photobucket, it will respond with a "copied" indication.

Go back to your FS.com post and make sure the cursor is EXACTLY in between the 2 Img boxes: [img](cursor%20in%20here)[/img] then right click and hit "paste" and the web link for the pic will show up in between the 2 img boxes. DON'T hit the IMG button a second time. MOVE your cursor out of the IMG info you just created before you hit enter.

Now when you post the post, the pic will be there!

Remember that if you delete the photobucket "master" pic, it will no longer appear in the posting here on FS.com

Also: there is a size limit to the pictures that can be displayed here, I think it is 750 pixels in width, someone correct me if I am wrong. So you may need to resize (typically downsize) the pics so that they fit properly and all of the pic is displayed and not cropped. What I do is really simple: I email the original picture to myself within AOL. AOL will automatically prompt you to see if you want the picture "optimized". Say "yes" and send this new pic to yourself. I then save it with a "small" addendum to the picture name and put this optimized picture up on photobucket. It works every single time like a charm.

[nelsonj]

Ok - lots of news and I set up a photobucket account so I can post pictures.

First, here are picture of the ground-down timing belt (bottom) and the new one (top). Note the teeth are very thin and almost gone from the original.





In the process of changing the t-belt, one of the bolts on the tensioner broke while torquing. It it took me about an hour to get the broken stud out of the engine block. I used a drill in reverse without much success. I was able to use a small screw driver and turn it like a screw, little by little, until enough was exposed that I could use pliers. I now need one of these bolts if anyone has one...




I got the head off without any major issue. I didn't realize how much coolant was still in the head when I disconnected the heater hose to the intake manifold. I wasn't prepared and a lot wound up on the cardboard underneath my car (to catch drips). There were a lot of little things to disconnect (heater to the head, wires to temp gauge, vacuum lines to the advance and brake booster, fuel line, various vestige emission hoses, distributor to coil and magnetic pickup to coil, cable to the throttle linkage ...) All the air-injection stuff was in the way also, so I had to take all it off. I have a 4-2-1 exhaust and I have had a bear of time getting the pipes connected to the manifold, so I took off the exhaust manifold because it is easier to but back. Anyway, no bolts stripped or broke - over all it went very smoothly for my first time. I left the carb and intake manifold in place. (I highly recommend this because it is much easier to get the manifold off once the head if off.

Here is the head on the bench (carb still on)


Here is my first look at the block with the head off.



And yes, a lot of oil dripped out as I was taking off the head. I helper would be nice, I did it solo.

DIAGNOSIS:
The block and cylinder: Very good news, everything looked very good in the block. The pistons, while covered with carbon, seemed 100% in tact. The cylinder walls looks smooth and unscratched. There were no metal "parts" in the cylinders.
I spend about two hours scraping carbon with a screw driver like a dental technician scrapes plaque from teeth. The pic below shows the result. Things looked so good I was starting to fear I took the head off for no reason...



The head and valves:
On first inspection, everything looked good. All valves complete without any missing "teeth". I really started to feel like a fool for taking off the head...



But on closer inspection, I noticed that all four exhaust valves had a "contact line" right where the piston relief is...




As I a looked closer and turned the cam, I noticed that NONE of the exhaust valves closed all the way to a seal. This explains why I consistently had ZERO compression.



In contrast, all of my intake valves seems ok. Based on how some carbon fell off, they may have made very minor contact.

At least I was correct that the head needed to be removed because I had valve damage...

I then removed the cam towers with the hope of removing the valves. I got an egg carton to keep all the parts in order.



Just for reference, here is a picture showing the cam removed and with the tappet taken off of one valve.



I read on the board that the following tool could be used to remove valves, but that I might have to "tap" on things to get the keepers to release.




I found THIS TOOL DID NOT WORK. Perhaps other have had better luck, but I resorted to basically hammering away on the spring to get the valves to release. I only did this for the exhaust side and I do NOT recommend this method. (I lost one spring and several keepers, and broke one valve in the process).




Conclusion:
Even though my pistons have reliefs (1978 CA drive train, 1800), the exhaust valves made piston contact when the t-belt slipped and were severely bent. My intake valves seem to be ok. On the bright side, my pistons, while they have some dings if I look closely enough, seem to be in overall good shape and I won't do any repairs on the bottom. Based on all the carbon I removed, I am sure my compression will go down once this job is completed.

It was my hope to just put in new valves and oil seals, but I have concluded that unless I can find a tool that works, I will NOT be able to replace the valves myself. Moreover, given the degree of damage to the valves, I am concerned that the valve guides on the exhaust side need to be replaced.

At this time I am debating (with myself) three options:
1) The easy way: Pony up $500 and get a rebuilt head from IAP or Vicks and be done with it.
2) The hard and risky (but cheap way): Find a correct tool that actually lets me compress BOTH springs so I can replace the valves and just hope the guides and seats are in "good enough" shape.
3) The "coolest" way: Buy "big valves" (at least for the intake) and better springs, and take the head to a machine shop for a valve job. Bring them all the parts, but make them do all the work and resurface if needed. Replace the guides, seals and seats (that will need 45 cuts to accept the big valves), but when I am done, I have a head that is better than when I started.

Under any option, I plan to take the car to my mechanic to adjust my valves (and check all my other work), when I finally get the car running.

Q: Does anyone know where I can get the correct tool to compress the springs and change the valves? Thanks.

I hope this is helpful.

P.S. It looks like I can get to the starter very easily with the head off. Anyone know if it is easy to change while the head is off and I have direct access?

[DocGraphics]

This is the style of valve spring compressor that I have used for years on many different engines (no fiats yet).
This style only works with the head off, solid end sets on the inside end of valve & the forked end goes on top the spring to each side of the keepers, clamps down like a vise-grip to compress & hold the spring/valve so the keepers can come out/in.

http://www.ebay.com/itm/8-Inch-Valve-Sp ... 500wt_1156

The one I have is pretty much an antique but it still does the job.

[narfire]

If you were to use the head you have, I'm sure I have a set of stock exhaust valves(used) about somewhere. I'd be having the head milled and the valves done though. New guides and seals as well.The machine shop will put it all together for you, so you put it back on and will have to adjust the clearances yourself with... yes a special tool
Get a few quotes or perhaps someone here might recomend a shop near you. A guess might be a couple hundred plus the guides and seals. (valves would be cheap)
Chris

[So Cal Mark]

no need to buy perf valve springs unless you plan to rev the motor above 7k. I'd seriously consider replacing the cam gear that is plastic. They tend to have the center section come loose

[nelsonj]

I have all but one valve out now. I borrowed a tool from my dad that looks like it is 50+ years old.

Here are all the tools I needed:




Here is a close-up of the old compressor.


This spring compressor needed a hard top surface to lever against. I used the engine host/EGR valve holder and a cam bolt and some washers to improvise a hard top surface.




This compressed the spring and moved the valve out of the head. I then took a hammer and squarely hit the valve to get the valve keepers to release. Most of the time, this cause the spreader to fall out of position, so this took many tries per valves before I could get things apart.




I also wound up bending the cam tower bolt in the process...

Anyway, I have all my parts ordered from both IAP and Vicks. It looks like I will just bring the head, all the parts, and the cam towersto my mechanic. He will clean and reassemble the head, put in new seals on the cams, an(old metal) cam gears, reassemble the cam towers, and finally shim it for me. After that, I just (just as in another major part of the project "just") have to bolt the head back on an reassemble my engine.

Not the cheapest way to go - but not terrible either.

[nelsonj]

My saga continues on this thread for anyone interested in the reassembly story....

http://www.fiatspider.com/f08/viewtopic ... 30&t=12104