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Last Post:
Oct 14, 2009 9:18 PM
Last Post By: tcovenant2000
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Posts:
13
Registered:
01/24/06
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Jetta GLI Timing Issues
Posted:
Sep 7, 2009 2:36 AM
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Hi I have a 90 Jetta GLI and I have just the head rebuilt and installed on the car and I have a issue with the timing jumping. I checked the cam and crankshaft gear and the keys are not sheared, the belt is new and in good condition, and the tensioner is functioning properly. The engine is a 2.0Liter 16valve, the car ran perfectly before the head was replaced. I am out of answers any help is greatly appreciated?
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Posts:
5,903
Registered:
12/29/05
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Re: Jetta GLI Timing Issues
Posted:
Sep 7, 2009 12:17 PM
in response to: Jetta091
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Timing jumping how?
The mark is not steady when checking with a strobe light... or
the alignment marks (cam/crank) keep moving/are out of alignment
after the engine has run for a while?
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Posts:
13
Registered:
01/24/06
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Re: Jetta GLI Timing Issues
Posted:
Sep 7, 2009 5:20 PM
in response to: FKH161
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The marks on the cam and crank are moving out alignment after the car runs for a few minutes.
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Posts:
5,903
Registered:
12/29/05
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Re: Jetta GLI Timing Issues
Posted:
Sep 7, 2009 5:30 PM
in response to: Jetta091
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That is weird... the only thing that comes to mine is what
you already checked, the crank & cam keys, which only leaves
the belt tension and I doubt that you are leaving the adjustment
too loose.
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Posts:
13
Registered:
01/24/06
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Re: Jetta GLI Timing Issues
Posted:
Sep 7, 2009 7:51 PM
in response to: FKH161
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The belt is tight, do you recommend replacing the tensioner anyways?
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Posts:
175
Registered:
02/29/04
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Re: Jetta GLI Timing Issues
Posted:
Sep 7, 2009 7:56 PM
in response to: Jetta091
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What are the symptoms when this happens? Does the car start running noticeably worse? Do you hear any screeching, etc? Hard to imagine tensioner is at fault unless it is locking up, and even then, not sure belt would jump time. Are you sure the key/keyway in the crank and the crank pulley are not excessively worn?
Ray
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Posts:
5,903
Registered:
12/29/05
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Re: Jetta GLI Timing Issues
Posted:
Sep 7, 2009 7:58 PM
in response to: Jetta091
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Tensioner & belt should always be replaced as a set... but
the tensioner should not be the cause of the marks moving
(as long as the belt tension is correct).
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Posts:
13
Registered:
01/24/06
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Re: Jetta GLI Timing Issues
Posted:
Sep 7, 2009 10:55 PM
in response to: FKH161
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The only symptom that the car has jumped timing is the car begins to misfire and eventually die, and will not restart unless the I pull out one the injectors or pull the fuel pump relay and starve the engine of fuel?
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Posts:
13
Registered:
01/24/06
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Re: Jetta GLI Timing Issues
Posted:
Sep 7, 2009 10:56 PM
in response to: Jetta091
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Both key ways on the crank and cam look brand new and are not visibly worn considering the block was rebuilt in the last three years.
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Posts:
5,903
Registered:
12/29/05
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Re: Jetta GLI Timing Issues
Posted:
Sep 7, 2009 11:31 PM
in response to: Jetta091
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So when do you actually have to "re-adjust" the cam/crank
alignment (loosen belt etc)? Before or after you remove
a fuel Inj or the fuel pump relay?
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Posts:
13
Registered:
01/24/06
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Re: Jetta GLI Timing Issues
Posted:
Sep 8, 2009 2:17 AM
in response to: FKH161
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Hi that is after the engine jumps timing.
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Posts:
175
Registered:
02/29/04
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Re: Jetta GLI Timing Issues
Posted:
Sep 8, 2009 6:42 PM
in response to: Jetta091
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Are all pulleys(sprockets) correctly in line? Can you see any runout in any of the sprockets, ie does the cam sprocket look like it is wobbling while running? Does the belt seem to track on the center of the cam sprocket?
Ray
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Posts:
13
Registered:
01/24/06
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Re: Jetta GLI Timing Issues
Posted:
Sep 9, 2009 1:07 PM
in response to: RoboRay
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Hi Ray, all the pulleys are aligned correctly, the cam sprockets look good without any wobbling, and the belt is centered on the cam sprocket?
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Posts:
1,278
Registered:
12/09/03
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Re: Jetta GLI Timing Issues
Posted:
Sep 9, 2009 5:00 PM
in response to: Jetta091
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Wish I could actually add to this thread...but all I can say is I had a '79 Dodge Colt (Mitsubishi) that used to do this about once a month. No amount of swapping parts or visiting mechanics ever solved it.
Thomas
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Posts:
175
Registered:
02/29/04
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Re: Jetta GLI Timing Issues
Posted:
Sep 9, 2009 6:51 PM
in response to: tcovenant2000
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Well, the only thing I can come up with based on what you are saying is something suddenly becoming very difficult to turn, most likely the cam, and this causing the belt to jump. As I recall this symptom started to happen after the head was redone? Who bolted the cam in? Can't recall if it is possible to bolt the cam caps on backwards? I am wondering if one is on backwards and gets tight after heating up. Is there a time this seems more likely to happen, say after a drive of more than 15 minutes, when cold only, etc? Are you certain the belt is tensioned tightly enough? I always set mine by grabbing the belt in the center between the crank and cam and tried to twist it 90 degrees.
Ray
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Posts:
5,903
Registered:
12/29/05
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Re: Jetta GLI Timing Issues
Posted:
Sep 9, 2009 7:37 PM
in response to: RoboRay
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Good point Ray!
If that is the case, something is going to lock-up eventually
(in the head). A wide belt like the 16V shouldn't have any
issues maintaining grip.
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Posts:
13
Registered:
01/24/06
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Re: Jetta GLI Timing Issues
Posted:
Sep 10, 2009 2:07 AM
in response to: FKH161
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Thanks for the info, I am going to talk to my machinist tomorrow.
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Posts:
1,278
Registered:
12/09/03
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Re: Jetta GLI Timing Issues
Posted:
Sep 10, 2009 4:41 PM
in response to: RoboRay
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Good point. I had another car that I replaced the head on. It was a junkyard head. I didn't know that I was supposed to have the head and cam machined (since they were both used) before putting it together. <SIGH>
That car had an interference engine. The cam froze up and it jumped time and slagged valves.
Thomas
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Posts:
13
Registered:
01/24/06
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Re: Jetta GLI Timing Issues
Posted:
Sep 13, 2009 2:57 AM
in response to: tcovenant2000
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Well last night I re-checked the cam and crank gear and by accident broke the cam screw off in the head. However after setting the timing on the cam and crank and turning the engine by hand a couple of revolutions the timing was still TDC, will start car again let it run and warm up and see what happens. Again thanks for the help, will keep you updated.
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Posts:
13
Registered:
01/24/06
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Re: Jetta GLI Timing Issues
Posted:
Oct 12, 2009 3:02 AM
in response to: Jetta091
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Sorry for taking so long to update the post, however I have determined that I not having a timing issue but a motronic electronic nightmare. I have replaced the DPR, O2 sensor, and coolant temp senor and when I go to adjust the fuel mixture using an electric meter and the special tool the meter reads a constant 16ma letting me know the care is in limp mode. In addition, when the car warms up it runs rough, rich and back fires when you romp the throttle and its only running on cylinder 1 and 4, I pulled the spark plug wires on 2 and 3 while the car is running and no reaction, I was told this could be the ignition control module, please help I am desperate. Thanks.
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