Engine Noise. Please Help.
#1
Nordschleife Master
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Engine Noise. Please Help.
Below is a short video of a noise my 85 US is making.
The noise seems to get loudest when my ear is at the front of the fuel rail on either side.
The car was not making this noise before the below maintenance.
Maintenance: I just replaced plug wires, distributor caps and rotors. I also replaced the temp II sensor. While performing the work, I noticed an unplugged vacuum line. To access the lines, I removed the fuel rails and loosened the first three intake tubes to access the vacuum line.
Plug wires are used Magnecors. Caps and rotors are new Bosch. About 1000k mi. after intake refresh, timing belt and waterpump replacement
Symptoms: Besides the noise, the car is running excellent. However, it is running a little warmer than before I performed the above maintenance. Idling, it runs just above the halfway line and just above the first line while moving. Prior, it idled just above the first line.
The noise does not start up until the car is fully warmed and sometimes cuts out.
Your good advice is very appreciated. I can record a longer video if it helps.
The noise seems to get loudest when my ear is at the front of the fuel rail on either side.
The car was not making this noise before the below maintenance.
Maintenance: I just replaced plug wires, distributor caps and rotors. I also replaced the temp II sensor. While performing the work, I noticed an unplugged vacuum line. To access the lines, I removed the fuel rails and loosened the first three intake tubes to access the vacuum line.
Plug wires are used Magnecors. Caps and rotors are new Bosch. About 1000k mi. after intake refresh, timing belt and waterpump replacement
Symptoms: Besides the noise, the car is running excellent. However, it is running a little warmer than before I performed the above maintenance. Idling, it runs just above the halfway line and just above the first line while moving. Prior, it idled just above the first line.
The noise does not start up until the car is fully warmed and sometimes cuts out.
Your good advice is very appreciated. I can record a longer video if it helps.
Last edited by UncleMaz; 09-29-2011 at 12:55 AM.
#4
Nordschleife Master
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The engine noise is independent of RPM.
#5
Nordschleife Master
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#6
Under the Lift
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While performing the work, I noticed an unplugged vacuum line. To access the lines, I removed the fuel rails and loosed the first three intake tubes to access the vacuum line.
#7
Nordschleife Master
Thread Starter
Sounds like an air/vacuum leak. I recently did some repairs and attached vacuum that had come off the air pump diverter valve, among other things. After I finished I had a strange whistle noise on acceleration only after the engine warmed up. Pulled the vacuum off the diverter valve and plugged the vacuum line - strange whistle gone. Guess I need a new diverter valve. I'm not suggesting it is the diverter valve, but it could be whatever your detached vacuum line activates. Also, when doing intake refreshes, it's easy to knock a breather hose off the oil filler or throttle when reinstalling, causing a loud leak noise.
I guess my next move is to start removing the intake and check all of the tubes and such.
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#8
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I was going to say sounds like a vac leak to me also. small one drawing across an opening makes a whistling sound.
#10
Nordschleife Master
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#11
Team Owner
Michael it sounds like a vacuum leak I would test any parts that are operated with vacuum use a mytivac to see if they hold vacuum otherwise one of the fuel injectors lower seals may be leaking or the plenum hoses may have been mis fit
#12
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#13
Nordschleife Master
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I checked the vacuum lines and hoses and all are good. Since the injectors came out/went in so easily, I am thinking (also based on Mrmerlin's suggestion) it is time to reseal those. I did not do them when I did my intake refresh and it does sound somewhat like the whine/whistle before I did the injector seals on my VW Golf.
Anyone have a spare set of 85/86 injectors I can borrow or for sale for cheap for a WitchHunter core and service so my car is down minimally? Thanks.
Anyone have a spare set of 85/86 injectors I can borrow or for sale for cheap for a WitchHunter core and service so my car is down minimally? Thanks.
#14
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Oh, so you reused the injector seals. In that case, there is a good chance a divot was taken out of one of the old, weak compressed seals on reinsertion. You have to be careful even with new ones - lube them and watch that all the O goes in evenly and does not partially hang up on the injector hole lip.
#15
Nordschleife Master
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Oh, so you reused the injector seals. In that case, there is a good chance a divot was taken out of one of the old, weak compressed seals on reinsertion. You have to be careful even with new ones - lube them and watch that all the O goes in evenly and does not partially hang up on the injector hole lip.
I am going to pick up a reseal kit tomorrow and redo them over the weekend until I can afford a new set of injectors. I used a thin coating of silicone grease on the O-rings when I did the intake refresh and will be sure to do that when I redo the seals and caps.