I've been working on this car for over a year and still not able to drive it. The car wouldn't start so I checked everything I could think of as far as ignition goes. It's getting spark(new coil, resistors and switchgear) the fuel injectors are new. The car sat for the last couple of months. When I tried to start nothing but clack,clack,clack after a couple rotaions with the starter. I immediately panicked. I removed valve covers and noticed the chain had a lot of slop. The tensioner and chain were replaced about 53,000 miles ago. The rail on the drivers side cylinder bank is split and the others look very brown. Is it possible for a tensioner to go bad from sitting too long. It was 1987 when the first tensioner was replaced. Also is it necessary to change the lower rails inside the timing cover? The timing marks are off about 14 degrees retard. Compression is good on all cylinders ~125-130 psi. Could I have jumped a tooth. Is it possible that my valves are O.K. the engine turns freely with the crankshaft bolt?

Thank you in advance for any advice,
jmdunn

the failure to start may have been caused by your guardian angel -- if it had started and you had reved it a bit too much, the result might have been a lot of expensive damage.

Meanwhile, I wonder if another explanation for the failure to start might be that the ignition is timed 180 distributor and camshaft degrees out of phase (360 crankshaft degrees) so that everything looks right on the timing marks, but the spark is actually firing when each cylinder is at the end of its exhaust stroke rather than its compression stroke. I have encountered this several times in the past 45 years.

I took off the distributor cap to check and the rotor is pointing at #1 cylinder when. the tiiming mark shows O degrees on the harmonic balancer.

Ah, but the crank timing marks will show 0' at both top dead compression and exhaust. If you still have the valve covers off it should be easy to tell it it's comp. or ex., at TDC comp both cam lobes should be pointing up(away from the valve) and each lobe should be about equally split from being straight up from the valve, at TDC ex. both lobes will be down, holding the valves cracked open slightly(valve overlap). Hope this helps to determine timing, after that I agree, you should really look into the 14' cam timing/chain issue. Good luck.
MV

After looking at the camshaft on the right side the # 1 cylinder is on the exhaust stroke. OOPS. I'll flip the rotor 180 and reinstall the distributor. I guess it was my guardian angel. I took the distributor off earlier to replace the wire going from the distr. to the Ign. control box. I had it set at TDC I thought when I reinstallled good thing I was 180 degrees off and it didn't start. Now on to replacing the chain rails this weekend. The car has 173,000 miles should I replace all the rails and guides even the ones inside the timiing case? Then realign the cams at TDC with their timing mark?

thanks again
jmdunn

From painful experience, at 14 degrees with a stretched chain, and a weak tensioner, you have either jumped or are about to.

You obviously need to replace the upper rails. The folklore is that the lower ones are bathed in oil and a supposed to be good for more miles.

I would definitely try to get the tensioner to pressurize and hold the chain tight while cranking the engine before starting. And then check the alignment of the cam and crank marks with the chain tight.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe