Crank turned without timing chain, issue?
Thread Starter
Racer
Joined: Jul 2008
Posts: 254
Likes: 0
From: Everett WA
Crank turned without timing chain, issue?
I was putting a new timing chain on an engine the other day and the crank was turned about 45 degrees so we rotated it around back to line up the timing dots with the cam. While the crank turned, so did the cam, however there was no timing chain connected.
When assembled, the car won't seem to fire up even though it has fuel and spark which leads me to believe it's a timing issue. Any thoughts?
When assembled, the car won't seem to fire up even though it has fuel and spark which leads me to believe it's a timing issue. Any thoughts?
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
Certainly its an issue if you didn't get things back to normal...as in, aligning the crank gear to the cam gear. There is no room for error here as it has to be perfect. Even one tooth off, it either will not run or possibly run very badly.
Thread Starter
Racer
Joined: Jul 2008
Posts: 254
Likes: 0
From: Everett WA
I aligned the dots by rotating the crank, which also rotated the cam in the opposite direction until the dots lined up again. A full 360 turn. The cam and the crank turned at the same time and before I took the timing chain off the engine was at TDC for sure.
The question is, with the heads on, when the crank rotated did it throw off the TDC? It would seem it didn't since they both rotated exactly how they should when the timing chain is hooked up, however I might be missing something.
thanks guys!
The question is, with the heads on, when the crank rotated did it throw off the TDC? It would seem it didn't since they both rotated exactly how they should when the timing chain is hooked up, however I might be missing something.
thanks guys!
Tech Contributor
Joined: May 2008
Posts: 2,843
Likes: 16
From: Howell Michigan
St. Jude Donor '09-'10-'11
I'm not fully understanding your last question in your post. However, the dot on the cam sprocket has to be pointed down and the dot on the crankshaft sprocket needs to be on the top if the sprocket, pointed up. While aligning these marks the rocker arm hold down bolts need to be loose and best to have the push rods out. If not you stand the risk of bending a valve if it should contact the piston. Another key step is to ONLY rotate the engine by hand while setting the timing. Best of luck..
Thread Starter
Racer
Joined: Jul 2008
Posts: 254
Likes: 0
From: Everett WA
With the heads/rockers/pushrods on the engine I took off the front cover. I took off the old timing chain. Before I put on the new timing chain I accidentally rotated the crank.
When the crank rotated clockwise, the cam rotated counter-clockwise.
I then continued to rotate, by hand and with no hard resistance, the crank until both the crank and cam realigned properly.
Once the dots were both aligned properly, I installed the new timing chain.
Does that make more sense?
Thanks for the help!
When the crank rotated clockwise, the cam rotated counter-clockwise.
I then continued to rotate, by hand and with no hard resistance, the crank until both the crank and cam realigned properly.
Once the dots were both aligned properly, I installed the new timing chain.
Does that make more sense?
Thanks for the help!
Melting Slicks
Joined: Jan 2009
Posts: 3,181
Likes: 286
From: Puyallup Washington
I may not know what I am talking about, but how does the cam rotate when the crankshaft is turned when the timing chain is off. Isn't the purpose of the timing chain to turn the camshaft when the crank turns?
What made the cam turn when the timing chain was off?
What made the cam turn when the timing chain was off?
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Burning Brakes
Joined: Jun 2005
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From: Toronto Ontario
You wrote what I was thinking.
Tech Contributor
Joined: Jan 2007
Posts: 19,343
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From: Dyer, IN
With the heads/rockers/pushrods on the engine I took off the front cover. I took off the old timing chain. Before I put on the new timing chain I accidentally rotated the crank.
When the crank rotated clockwise, the cam rotated counter-clockwise.
I then continued to rotate, by hand and with no hard resistance, the crank until both the crank and cam realigned properly.
Once the dots were both aligned properly, I installed the new timing chain.
Does that make more sense?
Thanks for the help!
When the crank rotated clockwise, the cam rotated counter-clockwise.
I then continued to rotate, by hand and with no hard resistance, the crank until both the crank and cam realigned properly.
Once the dots were both aligned properly, I installed the new timing chain.
Does that make more sense?
Thanks for the help!
Tech Contributor
Joined: Jan 2007
Posts: 19,343
Likes: 1,123
From: Dyer, IN
Here's the way I see it based on your explanation. For the sake of discussion, lets say you had #1 cylinder at compression stroke TDC, and the cam is stationary. If you rotate the crankshaft only 360 degrees, the #1 piston will now be at TDC exhaust stroke. That being said, if you put everything back together, it would be out of time. Hopefully, this does not describe your scenario......if so, those heads probably need to come off to check the valves.
Drifting
Joined: May 2008
Posts: 1,517
Likes: 319
From: Hewitt TX
Here's the way I see it based on your explanation. For the sake of discussion, lets say you had #1 cylinder at compression stroke TDC, and the cam is stationary. If you rotate the crankshaft only 360 degrees, the #1 piston will now be at TDC exhaust stroke. That being said, if you put everything back together, it would be out of time. Hopefully, this does not describe your scenario......if so, those heads probably need to come off to check the valves.
Tech Contributor
Joined: May 2008
Posts: 2,843
Likes: 16
From: Howell Michigan
St. Jude Donor '09-'10-'11
With the heads/rockers/pushrods on the engine I took off the front cover. I took off the old timing chain. Before I put on the new timing chain I accidentally rotated the crank.
When the crank rotated clockwise, the cam rotated counter-clockwise.
I then continued to rotate, by hand and with no hard resistance, the crank until both the crank and cam realigned properly.
Once the dots were both aligned properly, I installed the new timing chain.
Does that make more sense?
Thanks for the help!
When the crank rotated clockwise, the cam rotated counter-clockwise.
I then continued to rotate, by hand and with no hard resistance, the crank until both the crank and cam realigned properly.
Once the dots were both aligned properly, I installed the new timing chain.
Does that make more sense?
Thanks for the help!
Get the rocker covers off and check for any stuck valves which would be the case with a bent valve.
The manual states:
Notice: Do not turn the crankshaft assembly after the timing chain has been removed in order to prevent damage to the piston assemblies or the valves.
Lucky, I'm not following what you are saying. The crank doesn't care about compression or exhaust. 360° puts the crank in the same position. The cam does care and takes 720° with the chain connect of crankshaft to put the cam back to its 360° position. As long as the cam sprocket dot is facing down and the crank sprocket dot is facing up, connect the chain the engine is timed correctly. Even if someone put the cam sprocket dot facing up with the crankshaft sprocket up the timing will still be correct. In all cases the crank sprocket ALWAYS has be facing up. The photo in the earlier posting is the best way to align.
Last edited by Eric D; Dec 29, 2011 at 08:07 PM. Reason: added a few things..
Thread Starter
Racer
Joined: Jul 2008
Posts: 254
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From: Everett WA
I appreciate the help guys! I just tore everything down again and pulled the head. The valves look to be in good shape with no marks and seem to be seating correctly. If they did bend, they would have marks on them from hitting the piston, right?
On the other hand, the carbon build up is NUTS, this engine has about 10,000 miles on it, max and look at the gunk. I cleaned one piston to give a contrast. Weird!
I know for sure that when I put the new timing chain on the dots were lined up correctly, crank dot up, cam dot down. And since nothing seems to be wrong with the valves, I'm going to say it's timed correctly. Would you guys agree I can cancel out a timing issue?
If not, I'll pull the front cover and just re-time the whole thing to TDC ... I just don't want to if I don't have to.
On the other hand, the carbon build up is NUTS, this engine has about 10,000 miles on it, max and look at the gunk. I cleaned one piston to give a contrast. Weird!
I know for sure that when I put the new timing chain on the dots were lined up correctly, crank dot up, cam dot down. And since nothing seems to be wrong with the valves, I'm going to say it's timed correctly. Would you guys agree I can cancel out a timing issue?
If not, I'll pull the front cover and just re-time the whole thing to TDC ... I just don't want to if I don't have to.
Thread Starter
Racer
Joined: Jul 2008
Posts: 254
Likes: 0
From: Everett WA
After further clean up and investigation it looks like the valves are bent. They do have a common scuff on all the valves and 3 of 4 are not seating ... with a gap big enough to see through in one of them. 
So, it looks like the answer to the original question: Was the timing effected when the crank/cam moved
was yes, the timing was off enough to damage the valves.
Oddly enough, I turned the motor by hand before using the starter and it had no out of ordinary resistance and when I used the starter I couldn't hear any piston/valve slap.
Thanks guys! I'll keep it updated...
So, it looks like the answer to the original question: Was the timing effected when the crank/cam moved
was yes, the timing was off enough to damage the valves.
Oddly enough, I turned the motor by hand before using the starter and it had no out of ordinary resistance and when I used the starter I couldn't hear any piston/valve slap.
Thanks guys! I'll keep it updated...
Tech Contributor
Joined: May 2008
Posts: 2,843
Likes: 16
From: Howell Michigan
St. Jude Donor '09-'10-'11
After further clean up and investigation it looks like the valves are bent. They do have a common scuff on all the valves and 3 of 4 are not seating ... with a gap big enough to see through in one of them.
So, it looks like the answer to the original question: Was the timing effected when the crank/cam moved
was yes, the timing was off enough to damage the valves.
Oddly enough, I turned the motor by hand before using the starter and it had no out of ordinary resistance and when I used the starter I couldn't hear any piston/valve slap.
Thanks guys! I'll keep it updated...
So, it looks like the answer to the original question: Was the timing effected when the crank/cam moved
was yes, the timing was off enough to damage the valves.
Oddly enough, I turned the motor by hand before using the starter and it had no out of ordinary resistance and when I used the starter I couldn't hear any piston/valve slap.
Thanks guys! I'll keep it updated...
Damage is pretty easy seeing you have a two to one leverage crank to cam.
Sorry to here it happen.
Thread Starter
Racer
Joined: Jul 2008
Posts: 254
Likes: 0
From: Everett WA
Yeah, I'm dropping the subframe and pulling the steering right now. What really sucks is that I JUST put everything back together, engine/drive train/etc. All so I could screw up something small that would have been an easy fix with the engine out.
Lessons learned... again! haha woops...
Lessons learned... again! haha woops...
Tech Contributor
Joined: May 2008
Posts: 2,843
Likes: 16
From: Howell Michigan
St. Jude Donor '09-'10-'11
Wow, I looked at your photo again on my computer. I had been using my phone to view it. Your pistons show valve relief marks. Were these machined in or was this from an earlier valve to piston impact? If this is what just occurred check the pistons over carefully for cracks.