Broken timing chain...

[danielt]

Well, in the cold snap we have here in North Texas, I've been troubleshooting a no start issue that came up this weekend. This evening, I discovered it looks like a broken timing chain. I pulled the distributer and the camshaft is not turning when the engine is cranked. I'll start disassembly this weekend and pull the timing cover to confirm. I'm not sure of root cause yet. It happened right after re-installing the distributer. No sign of damage to the distributer drive gear or the camshaft.
Any guidance/recommendations of what all I need to check while I have it apart? It's only run for maybe an hour since I did the long block assembly. Short block is original (121K miles when I pulled it from the Mustang). Everything outside the short block is new with Ford OEM or Ford Racing parts.

[Joee]

That seems odd, mine went after a rocker arm came loose and that sent a lifter down the valley into chain. Needless to say it was in the middle of an AutoX run at 5000rpm. Mine resulted in 12 bent valves. Pull water pump and timing cover and see what's up. You may need to lower/drop front of oil pan to get cover off easily.

[Norm B]

If the cam wasn’t turning and the crankshaft was you will have a bunch of bent valves and damaged pistons. More than likely some pushrods got bent too.
Hope I’m wrong.

Norm

[danielt]

I was worried about the same Norm. I'm using the B303 cam with 1.6 roller rockers with a 1.94 valve and stock pistons. I'm hoping with the low lift of the B303 cam, I slid by, but that may be a fool's hope...

[danielt]

I have not pulled the motor since install. Since all the bellhousing bolts are easily accessible, is it easier to pull just the motor, or pull the motor/tranny together?

[Bob Cowan]

Could be a lot things, from faulty part to faulty assembly. No sense guessing what went wrong until you pull the cover off and look.

I always found it easier to pull the engine and leave the transmission in place. Then you didn't need to remove the hood.

https://i.imgur.com/np909cc.jpg

[NAZ]

I'd be tempted to bet $$ you have a few valves that made contact with a piston. But before you pull those heads you can pull all the rockers (gotta check the pushrods anyway) and do a leak down test on all cylinders. A bent valve will show up as a leak. May save you from pulling one or both heads.

[Joee]

Here is my post on my timing chain problem

http://www.ffcars.com/forums/17-factory-five-roadsters/606241-engine-carnage-blown-lifter.html

[danielt]

Parallel effort...
Need some feedback, I plan to pull the motor this weekend. Any reason I can't finish the chassis electrical, mount the body and send off to get the body work done/painted while I work on the motor tear down/rebuild?

[Jeff Kleiner]

Parallel effort...
Need some feedback, I plan to pull the motor this weekend. Any reason I can't finish the chassis electrical, mount the body and send off to get the body work done/painted while I work on the motor tear down/rebuild?

Nope. Only thing that may come into play without the engine in place are the sidepipe openings and I have modified them after paint in the past.

Jeff

[danielt]

Thanks Jeff! Started tear down this evening, I do have multiple bent valves. Starting to look for a local machine shop to do refresh the heads and probably rebuild the short block as well...

[danielt]

What’s the ballpark cost to get the heads refinished?

[Jeff Kleiner]

What’s the ballpark cost to get the heads refinished?

If you bent valves you likely bent some pushrods as well. Since you will need to buy valves by the time all is said and done after new guides, springs (not mandatory but prudent) and resurfacing you'll be half way to a set of Trick Flow, Edelbrock, etc. You see what I'm getting at, right? Of course no point in putting new heads on a tired bottom end.... It's a slippery slope.

Jeff

[Big Blocker]

Quote: "I was worried about the same Norm. I'm using the B303 cam with 1.6 roller rockers with a 1.94 valve and stock pistons. I'm hoping with the low lift of the B303 cam, I slid by, but that may be a fool's hope..."

Nope, the small block FORD design is an "interference design", meaning that the valves are in a position to hit pistons IF the cam stops moving them- you're not going to get by with NO bent valves.

Doc

[Bob Cowan]

Did you figure out why the timing chain broke?

[danielt]

Not yet. Got the intake out and the valve covers off. Everything on top valvetrain looks normal. No loose rockers like Joee. Looks like at least 4 intake valves are bent. I've taken the side pipes off, but not the headers yet so I haven't looked at any of the exhaust rockers. Was planning to pull the motor out of the car today, but it's too dang cold. As soon as it warms back up a little, I'll yank it out and back on the stand to finish tearing it apart.

For those engineers out there, I'm working through my fishbone:
Distributer jam? - NO, distributer spins freely.
Oil pump/shaft jam? - NO, I can easily drive the oil pump shaft by hand with primer tool.
Valve train jam? - TBD, no evidence so far of interference
Loose cam bolt?
broken crankshaft keyway?
Loose something caught in chain? (like Joee's lifter part)
Defective chain? (It was a new double roller for Ford Racing)

If the group has any other suggested things to check for, please let me know. This is my list so far.

[mike223]

Distributer jam? - NO, distributer spins freely.
Oil pump/shaft jam? - NO, I can easily drive the oil pump shaft by hand with primer tool.




A distributor jam would shear the pin that holds the distributor gear on (or break the shaft / etc).

Oil pump jam will break the oil pump shaft or shear the pin at the distributor gear.


Damage something to cause the cam to not turn with crank? - not likely.

[rich grsc]

I'm thinking cam gear bolt came out? If something got into the chain, or the chain broke, I'd think the timing cover would have a hole in it.

[GoDadGo]

Sorry About Your Engine!

While it stinks to hear the bad news, know that you will overcome this issue plus give you an opportunity to upgrade.

Good Luck & This Issue Will Pass!

[Big Blocker]

Quote: "I'm thinking cam gear bolt came out?"

- OR - the little pin that makes the timing gear actually turn the cam - bolt not torqued properly, washer missing, pin fell out (or backed out far enough to allow for a cam-to-crank timing issue) right into timing gear. Seen this many, many times working on FORD engines.

Doc

[CraigS]

Quote: "I'm thinking cam gear bolt came out?"

- OR - the little pin that makes the timing gear actually turn the cam - bolt not torqued properly, washer missing, pin fell out (or backed out far enough to allow for a cam-to-crank timing issue) right into timing gear. Seen this many, many times working on FORD engines.

Doc

I ended up making my own pin. Of the to that came w/ the CompCams kit one was too long and the other too short.

[Jeff Kleiner]

Quote: "I'm thinking cam gear bolt came out?"

- OR - the little pin that makes the timing gear actually turn the cam - bolt not torqued properly, washer missing, pin fell out (or backed out far enough to allow for a cam-to-crank timing issue) right into timing gear. Seen this many, many times working on FORD engines.

Doc

Possible. Some years ago I wound up rebuilding a solid lifter '70 Boss 302 after the pin sheared---all hell broke loose somewhere north of 6000 RPM. Valves, pistons...it was ugly. Sure did love that little screamer once it was all back together though :)

Jeff

[danielt]

Finally had a warm enough afternoon to get in the shop. Pulled the heads off. I have 6 bent pushrods and at least 2 bent valves. Taking the heads to a machine shop on Monday. I think I got lucky in that the contact occurred only when cranked by the starter, and not actually running. Will try and post pics tomorrow.

[Big Blocker]

Quote: " I think I got lucky in that the contact occurred only when cranked by the starter, and not actually running."

Not likely. The starter may have more then enough torque to crank a very high compression engine but won't overcome the "mechanical" solid contact you are wishing for here. Case in point, my high torque starter would not crank my engine with rocker arm to valve cover oil baffle interference, (I was trying new valve covers), stopped the cranking immediately. Push rods are a lot stronger then you think and do not bend easily. They bend when an engine is running at higher RPM then idle and they suddenly run into an obstruction that won't give. It takes a lot of sudden impact to bend a push rod or snap off the tip of a rocker.

Not trying to add any more rain to your parade, just trying to let you know that other things may show their ugliness as you get into the inspection of all the parts that need to be inspected after this timing chain issue.

Sorry for your troubles . . .

Doc

[Joee]

Have you removed water pump and timing cover to see what else is broken?

[danielt]

Have you removed water pump and timing cover to see what else is broken?

Hopefully tomorrow night. Stay tuned!

[danielt]

Quote: " I think I got lucky in that the contact occurred only when cranked by the starter, and not actually running."

Not likely. The starter may have more then enough torque to crank a very high compression engine but won't overcome the "mechanical" solid contact you are wishing for here. Case in point, my high torque starter would not crank my engine with rocker arm to valve cover oil baffle interference, (I was trying new valve covers), stopped the cranking immediately. Push rods are a lot stronger then you think and do not bend easily. They bend when an engine is running at higher RPM then idle and they suddenly run into an obstruction that won't give. It takes a lot of sudden impact to bend a push rod or snap off the tip of a rocker.

Not trying to add any more rain to your parade, just trying to let you know that other things may show their ugliness as you get into the inspection of all the parts that need to be inspected after this timing chain issue.

Sorry for your troubles . . .

Doc

Doc, greatly appreciate the feedback and guidance. Maybe i should give the whole story on when it broke.

I had a small oil leak at the back of the intake manifold (didn't have enough Permatex on the rail) so I removed and reinstalled the intake. After re-installing the intake, engine was idling(~1000rpm), waiting on it to warm up so I could set the timing. I had taken the distributer in and out 2-3 times before I finally got it to start. First time I put it on the exhaust stroke, not the compression.... Good news, no more oil leak!!!!

Engine had been idling 2-3 minutes tops and then just died. No weird noises/etc. On the first crank there was a loud pop. From that point, on no spark (Ford EEC-IV) After spending 2-3 evenings troubleshooting the no spark checking voltages/resistances in the coil/TFI module and error codes on ECU, I finally discovered the distributer wasn't spinning and so no PIP signal to the computer.

[danielt]

Found root cause:
Cam retaining plate bolts backed out and one fell into the crankshaft sprocket.
All hardware has been replaced and reassembled. Just need. Couple of warm hours to reconnect fuel injection nd back to running!

[Joe390]

You Got Lucky..! On my 1970 Boss 302 Ford used a lock tabs....that you bent up to keep the bolts from backing out ..!!