Know about timing chains? Get in here!
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
Good deduction and tips above. Timing chains wear/stretch over time if the car has "super" high mileage this can get you into trouble depending on how much advance/retard you run on a heavily worn chain/gear set....doubt this is your issue as the others CF members made some very point key points to eliminate this. This thing isn't going to fix itself. My thoughts for other good places to start checking....Drivetrain:
If you can roll the car in neutral and not hear any banging then you can eliminate most of the rear portion of the drivetrain....except the tranny, flexplate/flywheel of course.
Engine: Do a visual check on the engine bay first....coolant/oil leaks and see if you see anything "new". You may want to pull the valve covers and look for bent pushrods/rockers that jumped off the pushrods/valve or broken valve springs...one valve not opening and/or closing will cause more throuble than you'd think. If you can't find anything gone wrong grab a video camera and record as you crank, start or run the engine....then post it here on the CF.
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Real quick way to tell if the chain is still in place. Removing the water pump is not the last step to get to the chain. The crank pulley and the balancer has to come off before the front cover. And I believe you also have to pull the oil pan.
Burning Brakes
Joined: Apr 2009
Posts: 877
Likes: 0
From: Broken Arrow Oklahoma
I destroyed a timing gear in my 70 Vette. They were plastic back then. At 5000 rpm's I bent every push rod , bent 4 exhaust valves and 3 intake valves. I replaced the cam ,but it was probably toast as well.
Pro
Joined: May 2002
Posts: 635
Likes: 6
From: New Jersey
the best way to check the timing chain is remove the distributer cap and valve covers a rotate the engine while checking the timing marks. the marks should near 6 deg. @DTC and on number 1 OR 6 spark plug. check that the valves are opening and closing. You can bump the starter and check it. But I'd pull all the spark plugs and turn it with a 5/8 socket and a long ratchet or breaker bar.
Randy
Randy
Pro
Joined: May 2002
Posts: 635
Likes: 6
From: New Jersey
I broke a timing chain once and it destroyed the engine, it broke the cam in half, the distributer was wedge in the block I bent some valve and crack the block. It wasn't a pretty sight. I nail it at light and when it change into 2nd gear it shutoff, and it didn't give any warning before hand. That my timing horror story.
But I have seen timing chains break or snap and it was no damage.
Randy
But I have seen timing chains break or snap and it was no damage.
Randy
Advanced
Joined: Nov 2009
Posts: 93
Likes: 0
Oakley,
It is rare for a chain to break, yes it does happen but rare. What normally happens is it stretches and jumps on a gear knocking the timing out. If the distributor turns it is not a broken chain, if you still have spark it is not electrical. Most of the time not all the time a new timing chain is all that is required. Problem is it is almost worth it to just freshen up the engine at that point. I have even done the sleeze way of getting a car running by turning the distributor until it fired or jump the plug wires 1 spot all the way around. This is just a way to baby it home or perform diagnostics in the middle of nowhere.
It is rare for a chain to break, yes it does happen but rare. What normally happens is it stretches and jumps on a gear knocking the timing out. If the distributor turns it is not a broken chain, if you still have spark it is not electrical. Most of the time not all the time a new timing chain is all that is required. Problem is it is almost worth it to just freshen up the engine at that point. I have even done the sleeze way of getting a car running by turning the distributor until it fired or jump the plug wires 1 spot all the way around. This is just a way to baby it home or perform diagnostics in the middle of nowhere.
Melting Slicks
Joined: Dec 2009
Posts: 2,237
Likes: 286
To check if your valves are ok, loosen the rocker arms, pump compressed air (use a comp. tester w/ the schrader valve removed) in the cylinder, unless the piston is at the bottom of the stroke, the crank should rotate. Listen for leaks at throttle body & tailpipes. If your iron headed 86 has pistons like my 84, those pistons have deep reliefs.
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Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
Just remove the distributor power wire and any spark plug, rotate the engine with the starter.
If no noise from spark plug hole, then you need to rent a hoist.
If no noise from spark plug hole, then you need to rent a hoist.
Race Director
Joined: Sep 2003
Posts: 16,838
Likes: 341
From: Database Error Indiana
