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Carbon Emitter
 
jkarolyi's Avatar
 
Join Date: Feb 2004
Location: Socialist Republic of California
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911E valve adjustment gone bad...help!

Hi All,

As a new 1971 911E owner, I was reffered to Pelican from some people at Rennlist, and found it to be a great place for ordering parts and for tech articles.

I bought the book "101 projects" and all the parts needed for a valve job and oil change. All went smoothly (I've adjusted valves for years on my 1971 BMW) until I started her up. Feels like it's running on five cylinders.

Thinking it might be an electrical problem, I pulled plug wires one at a time and ran the engine. Each time it ran even rougher than with all of them connected, so I'm assuming I'm getting good spark. Wouldn't this point to a misadjusted valve?

I bought the special "question mark" feeler guage and even went through the cycle a second time to check the clearance. I followed the 101 Projects instructions and removed the spark plugs while checking clearance, but looking at the Pelican website today I noticed a tech article that said you should leave them in, lest carbon shake loose and prevent the valves from sealing. DOH!

Questions:

1. When checking valve clearance, do you err on the "can barely move it in" or "moves in easily but has some resistance". I did the latter, which always worked fine on my BMWs.

2. Should I check compression on all cylinders...would that reveal a misadjusted or carbon-blocked valve?

3. If a valve is blocked by carbon, how can I clean it out? Some kind of engine cleaner flush?

4. If you lift the car on one side only, can I remove one lower valve cover without losing all my nice, fresh oil?

5. Where would you start to diagnose the problem? I've considered towing to a mechanic, but they just LOVE fixing other people's "repairs" . Any good 911 mechanics in the Redlands or Riverside, CA area?

A frustrated new 911E owner,

Jay Karolyi

Old 02-02-2004, 04:20 PM
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Sure you reconnected the ignition wires in the correct firing order?
Old 02-02-2004, 04:34 PM
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Carbon Emitter
 
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Yep, I labelled them, and after I had problems I traced the wires to the cap and made sure they were in the correct firing order.
Old 02-02-2004, 04:37 PM
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Jay, you post is almost identical to one I posted when I first got a '72 E a few years back. Exact same symptoms. I did the same thing you did, took the plugs out before adjusting the valves. When I was done seemed to run terrible. Did a compression test, no compression on #1 cylinder and I went running for advice to this board. The advice was recheck my vavle adjustments. Now I don't know if there was carbon in the valve or not, but I reajusted the valves on #1 and all was well. If you did have a piece of carbon sticking one of your valves open, just running the car should have removed it. Go ahead and do your valve adjustment again, but leave the plugs in this time!
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Old 02-02-2004, 05:03 PM
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Jay,

1. Either way works, and any such variation in gap will only cause a slight ticking noise, not roughness in running.

2. & 4. If carbon was the problem ... it has probably been moved, crushed, or blown out by now, so a compression test would probably not find a problem now! The excessive clearance after you adjusted is probably the only problem, now, so just go through the valves again to find the one loose one ... yes, you can jack up one side to minimize oil loss on that side.

3. If still causing a problem, carbon can be cleared by pouring an ounce of liquid Berryman's B-12 Chemtool down an injector stack and letting the engine sit for an hour. Several Pelicanheads have cleared up major compression loss problems cause by carbon by using my "B-12 treatment" procedure. It is the solvent recommended by the factory [in the "blue book," a.k.a. Check, Measure, Adjust] for cleaning the warm-up thermostat, idle passages in injector stacks, etc. You will find the documents at the following Pelican page useful in learning and adjusting the MFI system:

http://www.pelicanparts.com/techarticles/911_MFI/TipMFI.htm

5. You don't need to worry about having to take the car to a shop ...

Good luck!
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Last edited by Early_S_Man; 02-02-2004 at 06:20 PM..
Old 02-02-2004, 06:17 PM
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Thanks Kurt and Warren for your advice. I think I will try the compression test. If the valves are out of adjustment, that will tell me which one to re-adjust.

If there was carbon holding a valve open, wouldn't I have adjusted the valves too TIGHT, not too loose? Hopefully I didn't burn a valve by running it for 10 minutes on five cylinders.
Old 02-03-2004, 10:30 AM
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I adjusted my valves for the first time this weekend, and I got lucky, it seems to run just fine. If carbon blocked a valve from closing then you would have adjusted it too tight so it would be a bit open during the compression stroke which would cause problems.

Did you get the feeler guage tool from PP? What did you think about it? I thought it was very difficult to use. The tool I've seen in the past the screws were threaded into the body of the tool and this one used nuts and bolts. I had problems with the nuts and/or bolt heads interfereing with getting it in deep enough. I had to bend the dang thing around before I got it to work.
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Old 02-03-2004, 11:14 AM
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Quote:
Originally posted by jkarolyi
Thanks Kurt and Warren for your advice. I think I will try the compression test. If the valves are out of adjustment, that will tell me which one to re-adjust.

If there was carbon holding a valve open, wouldn't I have adjusted the valves too TIGHT, not too loose? Hopefully I didn't burn a valve by running it for 10 minutes on five cylinders.
Like Mike said, yes they would be too tight, keeping the valve from shutting completely resulting in low or no compression and a bad running car.
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Old 02-03-2004, 12:04 PM
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Don't tow it to your mechanic's place, I'm sure it's just a small oversight. I would recheck all of the adjustments again. Run through the cycle of rotating the engine, and wiggle the rockers to check for clearance. This is a quick and dirty way to tell if something went wrong...

The carbon thing is not a very common occurance...

-Wayne
Old 02-03-2004, 12:13 PM
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The cylinder that runs less rough when you disconnect its plug wire is the weak cylinder. Concentrate your diagnosis on that one (open circuit in plug wire, spark plug gap, crack in distributor cap, etc.).

Sherwood
Old 02-03-2004, 12:58 PM
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Quote:
Originally posted by 911pcars
The cylinder that runs less rough when you disconnect its plug wire is the weak cylinder. Concentrate your diagnosis on that one (open circuit in plug wire, spark plug gap, crack in distributor cap, etc.).

Sherwood
If the compression check out okay follow Sherwood advice.

Check the wire to the weak cylinder. Pulling the spark plug cable from a spark plug can sometime cause an open circuit in the plug wire.

Use an ohm meter to check the resistance in the wire.
Old 02-03-2004, 07:16 PM
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Maybe you have all 6 plug wires in the proper relation to themselves ( 1-6-2-4-3-5)..but all are "off-position" by one or more plug spot. Possible?
---Wil Ferch

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Last edited by Wil Ferch; 02-04-2004 at 08:28 AM..
Old 02-04-2004, 07:03 AM
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