Chain Ramp replacement gone bad -Crank won't turn
03-24-2012, 08:00 PM
#1
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Chain Ramp replacement gone bad -Crank won't turn
https://rennlist.com/forums/images/smilies/frown.gif I changed out all of the chain ramps on my '82 911SC (several were broken on this vehicle with >230K original miles). I had secured the chain with tie wraps to keep it from slipping when I removed the ramps, but something went wrong.
Folks at Pelican Parts thought that I might have a kink in the chain. I loosened ALL of the valves; removed the non-pressure-fed chain tensioners; removed two of the chain ramps; and loosened both camshaft bolts to create slack on the chain.
When I use the wrench on the alternator/fan to turn the crank - it will only rotate about 15 degrees either clockwise or counter-clockwise. I can see the distributor rotor move a little. Since the camshafts are loose - I don't think it is the valves and the camshafts keeping the crank from turning.
Anyone have any ideas on what is happening and how to fix it? As you might imagine, I am very frustrated.https://rennlist.com/forums/graemlins/banghead.gif
Folks at Pelican Parts thought that I might have a kink in the chain. I loosened ALL of the valves; removed the non-pressure-fed chain tensioners; removed two of the chain ramps; and loosened both camshaft bolts to create slack on the chain.
When I use the wrench on the alternator/fan to turn the crank - it will only rotate about 15 degrees either clockwise or counter-clockwise. I can see the distributor rotor move a little. Since the camshafts are loose - I don't think it is the valves and the camshafts keeping the crank from turning.
Anyone have any ideas on what is happening and how to fix it? As you might imagine, I am very frustrated.https://rennlist.com/forums/graemlins/banghead.gif
03-24-2012, 09:02 PM
#2
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Welcome to Rennlist.
Are you sure you have every last nut, bolt, washer, and chain ramp? Is every tool accounted for? Is every rag accounted for? Far more likely that something dropped in than the chain jumped the track.
Anyway,
Are you sure you have every last nut, bolt, washer, and chain ramp? Is every tool accounted for? Is every rag accounted for? Far more likely that something dropped in than the chain jumped the track.
Anyway,
03-24-2012, 09:46 PM
#3
RL Technical Advisor
https://rennlist.com/forums/images/smilies/frown.gif I changed out all of the chain ramps on my '82 911SC (several were broken on this vehicle with >230K original miles). I had secured the chain with tie wraps to keep it from slipping when I removed the ramps, but something went wrong.
Folks at Pelican Parts thought that I might have a kink in the chain. I loosened ALL of the valves; removed the non-pressure-fed chain tensioners; removed two of the chain ramps; and loosened both camshaft bolts to create slack on the chain.
When I use the wrench on the alternator/fan to turn the crank - it will only rotate about 15 degrees either clockwise or counter-clockwise. I can see the distributor rotor move a little. Since the camshafts are loose - I don't think it is the valves and the camshafts keeping the crank from turning.
Anyone have any ideas on what is happening and how to fix it? As you might imagine, I am very frustrated.https://rennlist.com/forums/graemlins/banghead.gif
Folks at Pelican Parts thought that I might have a kink in the chain. I loosened ALL of the valves; removed the non-pressure-fed chain tensioners; removed two of the chain ramps; and loosened both camshaft bolts to create slack on the chain.
When I use the wrench on the alternator/fan to turn the crank - it will only rotate about 15 degrees either clockwise or counter-clockwise. I can see the distributor rotor move a little. Since the camshafts are loose - I don't think it is the valves and the camshafts keeping the crank from turning.
Anyone have any ideas on what is happening and how to fix it? As you might imagine, I am very frustrated.https://rennlist.com/forums/graemlins/banghead.gif
OTOH, I've seen people replace tensioners and ramps incorrectly and experience the same problem when the valve timing slipped and a valve was getting pushed into a piston.
For whatever reason, your cam timing has changed and now you get to do that procedure, or have someone do that for you.
03-24-2012, 10:43 PM
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If timing slipped -should I remove the rockers?
"OTOH, I've seen people replace tensioners and ramps incorrectly and experience the same problem when the valve timing slipped and a valve was getting pushed into a piston."
I'll check if something fell in the case when I was changing the ramps. But if the timing slipped - how do I loosen up the crank to be able to set the camshaft timing? Both camshaft bolts are off and the dowel pin in the sprocket out to allow the camshaft to be independent of the crank.
Do I need to remove the rocker arms? Do they need to be removed from just the top (intake) or also the bottom (exhaust)? I've already loosened the adjustment nuts fully.
As a last resort, any recommendations on mechanics who do house calls in Redondo Beach?
I'll check if something fell in the case when I was changing the ramps. But if the timing slipped - how do I loosen up the crank to be able to set the camshaft timing? Both camshaft bolts are off and the dowel pin in the sprocket out to allow the camshaft to be independent of the crank.
Do I need to remove the rocker arms? Do they need to be removed from just the top (intake) or also the bottom (exhaust)? I've already loosened the adjustment nuts fully.
As a last resort, any recommendations on mechanics who do house calls in Redondo Beach?
03-25-2012, 03:14 AM
#6
Rennlist Member
At this point, in looking at your questions, don't attempt this on your own. You don't loosen the crank to set cam timing-it is done with the dowel pins and the cam sprocket bolts. It is not that hard of a procedure, provided you understand what you are supposed to do. But, many don't get it right.
I assume the engine is out of the car?
I assume the engine is out of the car?
03-25-2012, 04:55 AM
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Locked crank & camshaft timing
Yes, the engine is on an ATV jack, and the transmission is resting on my creeper. Once I have the crankshaft capable of turning, I would use the instructions in both Dempsey's "How to Rebuild & Modify Porsche 911 Engines" (Section 7 on Cam Timing), and Bentley's Chapter 152 "Camshaft Timing Chains".
The camshaft sprocket nuts, and camshaft sprocket lockpin/dowel pin are removed on both sides. Both spring tensioners are removed and the timing chain has lots of slack.
As mentioned earlier, when I try to rotate the crankshaft pulley using the special c-wrench on the alternator/fan - I only get about 15 degrees of movement before it won't budge. It can then be turned the same amount counter-clockwise.
Before I can do any timing - I need to somehow free up the crank. Any ideas? I've received the suggestion that maybe the gear in the distributor came loose, although this would have had to happen after I had dropped the engine, as the motor was still working when I originally dropped the engine.
Next, some felt the chain might be kinked or there is some debris preventing something from turning.
I will note, that the #6 intake valve rocker has no play or slack - even though I fully loosen the adjustment nut and screw. Is there any utility in removing the rocker arms on either the intakes and/or exhaust?
You thoughts and suggestions on how to get the crank to turn.....
The camshaft sprocket nuts, and camshaft sprocket lockpin/dowel pin are removed on both sides. Both spring tensioners are removed and the timing chain has lots of slack.
As mentioned earlier, when I try to rotate the crankshaft pulley using the special c-wrench on the alternator/fan - I only get about 15 degrees of movement before it won't budge. It can then be turned the same amount counter-clockwise.
Before I can do any timing - I need to somehow free up the crank. Any ideas? I've received the suggestion that maybe the gear in the distributor came loose, although this would have had to happen after I had dropped the engine, as the motor was still working when I originally dropped the engine.
Next, some felt the chain might be kinked or there is some debris preventing something from turning.
I will note, that the #6 intake valve rocker has no play or slack - even though I fully loosen the adjustment nut and screw. Is there any utility in removing the rocker arms on either the intakes and/or exhaust?
You thoughts and suggestions on how to get the crank to turn.....
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03-25-2012, 06:55 PM
#10
RL Technical Advisor
At this point, in looking at your questions, don't attempt this on your own. You don't loosen the crank to set cam timing-it is done with the dowel pins and the cam sprocket bolts. It is not that hard of a procedure, provided you understand what you are supposed to do. But, many don't get it right.
03-28-2012, 01:30 AM
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Free at last, free at last!!
With the expert house-call help of Richard Clewett of Clewett Engineering (http://www.clewett.com/, a Porsche specialty engineering company), the crank now turns!
Former PCA Grand Prix Section President Skip Carter gave me Richard's name and number. Richard lives nearby in Manhattan Beach. He came over today to look at the mess I was in. I explained the work I had done - replacing the clutch and replacing the chain ramps.
After inspecting engine and checking out the timing chain, he decided we needed to separate the transmission from the engine to see if the clutch was somehow binding the engine. He then had me remove the clutch plate. Eureka! I had interchanged two of the CV shaft allen bolts with the clutch bolts. The bolts are a few millimeters longer. He then tested the crank - it was able to spin.
Next, he helped me line up the two camshaft "dots" at 12 o'clock, and put the crank at TDC to enable me to set the camshaft timing.
I still need to put back the chain tensioners, and the #6 cylinder rocker pinch bolt. After that, I'll need to carefully read-through the steps to set the camshaft timing. If any readers have some good tips - I'm happy to listen.
Once that is done, I'll run a leak-down test to see of there was collateral damage. With some luck, I'll just have to suffer the embarrassment of "screwing" up the clutch work.
In any event, I very much appreciate the advice provided on the forum. And another big kudo to the great help that Richard provided (yes, I did compensate him for his time).
The fix came none too soon, as lack of work in Redondo Beach may force me to commute or relocate to San Diego to work on a different program with Northrop. Avoided the wave of layoffs, so far.
As for my latest Porsche experience, it goes back to the club adage,
"It's not just the cars, it's the people!"
Former PCA Grand Prix Section President Skip Carter gave me Richard's name and number. Richard lives nearby in Manhattan Beach. He came over today to look at the mess I was in. I explained the work I had done - replacing the clutch and replacing the chain ramps.
After inspecting engine and checking out the timing chain, he decided we needed to separate the transmission from the engine to see if the clutch was somehow binding the engine. He then had me remove the clutch plate. Eureka! I had interchanged two of the CV shaft allen bolts with the clutch bolts. The bolts are a few millimeters longer. He then tested the crank - it was able to spin.
Next, he helped me line up the two camshaft "dots" at 12 o'clock, and put the crank at TDC to enable me to set the camshaft timing.
I still need to put back the chain tensioners, and the #6 cylinder rocker pinch bolt. After that, I'll need to carefully read-through the steps to set the camshaft timing. If any readers have some good tips - I'm happy to listen.
Once that is done, I'll run a leak-down test to see of there was collateral damage. With some luck, I'll just have to suffer the embarrassment of "screwing" up the clutch work.
In any event, I very much appreciate the advice provided on the forum. And another big kudo to the great help that Richard provided (yes, I did compensate him for his time).
The fix came none too soon, as lack of work in Redondo Beach may force me to commute or relocate to San Diego to work on a different program with Northrop. Avoided the wave of layoffs, so far.
As for my latest Porsche experience, it goes back to the club adage,
"It's not just the cars, it's the people!"
03-28-2012, 02:21 AM
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Ed?
Sorry - is Ed local to Redondo Beach? I haven't met too many of the folks that work on the cars non-professionally. Back in the the Potomac Region, there used to be "drop parties" with pizza and beer. Here, I've been relying upon advice from Rob Wessels at Dutch Treat, and now Richard Clewett. Lately, the school of hard knocks.
Rick
Rick
03-28-2012, 03:26 PM
#15
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Nah, I'm in the San Diego area. If I didn't have projects on my boat on the weekends, and work travel during the week, a run up to RB would be fun. The only chance is I MAY have to make a call on LAX tomorrow or Friday, but I won't be dressed for car work.
You do need the Z-block and a dial indicator to set the cam timing. Neither of which will break the bank-Pelican would sell them to you, and probably has them in stock. If Richard got you poised with the cams in the proper position to start, you're ready to go with the aforementioned above. You do need to understand the process, and the fact that you will be dealing in two revolutions of the crank shaft to time both cams. I think that is where a lot of people get one cam out of whack.
I also assume you have the proper tools to hold the sprockets while you tighten the bolts?
You do need the Z-block and a dial indicator to set the cam timing. Neither of which will break the bank-Pelican would sell them to you, and probably has them in stock. If Richard got you poised with the cams in the proper position to start, you're ready to go with the aforementioned above. You do need to understand the process, and the fact that you will be dealing in two revolutions of the crank shaft to time both cams. I think that is where a lot of people get one cam out of whack.
I also assume you have the proper tools to hold the sprockets while you tighten the bolts?