Hello folks, Ive been a member here for a few years now, but I have not been on the forum much this past year. I finally got the confidence to replace my timing chain, and upper guides. I also replaced the tensioner, rail/rubber lining, and sprockets, and cam oilers. The problems i kept having were, while replacing passenger side sprocket, i noticed the cam kept trying to spring forward, and it did move alot, but i was able to turn it back and hold it where the mark lined up. I also kept getting hung up somehow, and then the problems got worse.... I noticed that my cam marks were still lined up, but my crank was no longer at TDC, which it was perfect before i started, and i may have somehow accidentally caused this. I then removed both cams, and carefully rotated the crank by hand until i could line both marks up again. I did not have the tool, or the patience to remove the rockers, so i proceeded.... and i looked everywhere online, and it seemed to be okay, even though its an interference engine. Did i bend valves? Or could it be ignition timing? It will not start, and Im getting depressed here. Any known symptom for bent valves or a solid indication? It seems to backfire or slighlty cough out some smoke every few revoltions, but not consistently. Please members, I need advice ASAP
Doesn't the crankshaft move through one revolution while the cam sprockets move through 2 revolutions? I'm no expert but could the crank be 180 degrees off? See what the experts say.
So you bolted it all up, crossed your fingers, then hit the starter? You're missing the step where you manually turn over the engine twice to extinguish your concern.
Doesn't the crankshaft move through one revolution while the cam sprockets move through 2 revolutions? I'm no expert but could the crank be 180 degrees off? See what the experts say.
Good luck,
John
Correct, rotating the crank a second time should have aligned the cam timining marks to TDC.
Mike
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1989 560SEC (US spec) 040 Black/Black, 17" Aero I's, H&R springs, Bilstein HD shocks, Euro Headlights,Tri Y's, First Gear Start Module and AMG (clone) Heads Solid Lifter Conversion
2008 GL450 040 Black/Black (Wife's Car)
What I meant was, isn't it possible to have all the marks lined up, but still have the crank 180 degrees off such that it looks correct but is not? So shouldn't JW560 rotate the crank assembly till the cams line up again, then rotate just the crank to TDC? Maybe I am misunderstanding....
JW, I'll send you the valve spring squeezers if you end up needing it. Put the rockers back in the same place after removal.
Although I STRONGLY RECOMMEND the "turn the engine over twice by hand FIRST" step, the symptom that you are describing sounds to me like the distributor is out of phase. You are going to have to determine piston #1 TDC (take the RH valve cover off and turn the engine over by hand so that both valves are closed at the zero mark of the balancer); THEN, put the distributor in so that the line and notch line up. If it is 180 degrees off, the engine will run - but just barely and like crap. I screwed this up on my first timing chain and I wet myself over it.
Wait until you can borrow the valve spring compressor because it's hard to guess what state the cam/crank relationship is in right now. I bought one before doing this; it's expensive, but removing the cam followers eliminates an opportunity for screw-up, which is important to people like me who don't do this every week.
Once you have the tool, removing the followers is a breeze. Removing the RH side in particular eliminates "spring kickback" and the worries that come from it.
Vehicle: 91-560SEC w/Custom Built Motor; 90-560SEL; 87-560SEC
Location: Lancaster, CA
Posts: 7,149
Quote:
Originally Posted by strife2
Although I STRONGLY RECOMMEND the "turn the engine over twice by hand FIRST" step, the symptom that you are describing sounds to me like the distributor is out of phase. You are going to have to determine piston #1 TDC (take the RH valve cover off and turn the engine over by hand so that both valves are closed at the zero mark of the balancer); THEN, put the distributor in so that the line and notch line up. If it is 180 degrees off, the engine will run - but just barely and like crap. I screwed this up on my first timing chain and I wet myself over it.
Wait until you can borrow the valve spring compressor because it's hard to guess what state the cam/crank relationship is in right now. I bought one before doing this; it's expensive, but removing the cam followers eliminates an opportunity for screw-up, which is important to people like me who don't do this every week.
Once you have the tool, removing the followers is a breeze. Removing the RH side in particular eliminates "spring kickback" and the worries that come from it.
Listen to the man. THis EXACT same thing happened to me twice. Once when I did my WP, and the other when I did the engine rebuild last year with Bondavi.
The key sympton here is the backfiring. It means that the valves are open when the spark is happening, meaning it is out of sync.
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It seems to backfire or slighlty cough out some smoke every few revoltions, but not consistently. Please members, I need advice ASAP
That alone tells me that the timing is out and it more than likely is 180 degrees off correct timing but,from the dizzy.Turning the engine by hand is essential after chain/guide rail jobs but, you can`t turn back time. Perhaps though,you got away with it this time. Correct the distributor and see what happens. Hopefully it runs properly again.
Cheers,
Mick.
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Last edited by Seltsamen mann; 01-08-2013 at 02:33 PM.
Doesn't the crankshaft move through one revolution while the cam sprockets move through 2 revolutions? I'm no expert but could the crank be 180 degrees off? See what the experts say.
Good luck,
John
Thanks for the replies everyone, jsebastian- I wonder if my crank indeed may be 180 degrees off. I did not know that about the marks lining up only every two revelations. When I started the job, the first thing I did was rotate to top dead center, and my marks lined up the first time. So later when I realized I had screwed up and the marks some did not line up anymore- the only thing I could do at the moment, was take off each sprocket, and rotate the crank carefully, while roll manuevering the sprockets and chain- until it all lined up again as perfect as I could get it. I tried to figure out if it would hurt the valves if I did this, but everything pointed to okay as long as it wasnt running. I probably rotated the crank maybe 10 times or so with the cams/rockers not moving.
I am greatly worried now, and feel I made a mistake by doing this.
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