You won't know for sure until you open it up. Until then, it's all speculation. If the current timing gear is around 100k and/or you've push-started it...you either have stretched chains or broken chain guides. Worn or jammed hydraulic tensioner could also be in there.
Skool's in session:
Works like this...Hydraulic (oil) pressure is what really keeps the tensioner bolt exerting the necessary tension against the upper timing chain. The bolt also has a spring in it but it does not keep anywhere near as much tension as 70+ psi of oil pressure.
Using the starter turns the engine over at an even conrolled rate whereas pushing it and 'popping' the clutch usually results in a very jerky start up which induces 'chain slap' since there is no pressure on the tensioner yet. This can be pretty severe inside the motor and finish-off your old, brittle plastic guides. It has also been known to cause the upper chain to jump teeth on the cam sprockets.
Push starting your car is bad for it.
k i could use a lil help..my chain seems to be at the right tension, my upper guides appear to be fine BUT my cams dont look like there aligned properly ie one is horizontal and the other is a few degrees off...what shuld i do
edit:nvm chaain is ddeff not as tight as it should be
Last edited by -..-; 03-03-2012 at 03:32 PM.
Before you assume one cam is off from the other, make sure the whole motor is set to TDC.
If it is set to TDC, and the cams are still off, then one cam may have jumped a tooth....possibly due to a worn or weak tensioner bolt. this is assuming, of course, that all your guides are in fact solid.
hey my new upper chain was shipped to me with the master link separate and I had too assemble chain together first before installing it. why would my upper chain come separated like this? so im thinking you could probably do your top chain, top guide & tensioner without dropping tranny. if you drop one end of chain down in there, fish it around the sproket and backout somehow. maybe with a string or something. you may need a special tool to install master link and rivet it together while its on cam sprokets though.
Last edited by heerschap; 03-17-2012 at 08:18 AM.
Remove the cam or cams that are not set in TDC position only. When you remove the bearing caps be sure to re-install them the same way you took them off. Use caution, the cams are under pressure.
Re-installing: Lubricate contact surfaces of camshafts and then re-install them into cylinder head so that camshaft sprocket alignment recesses are facing up. Check that cylinder #1 is at Top Dead Center (TDC) while you are doing this constantly. You will have to apply pressure to the cam while someone else installs the bearing caps. Install bearing caps 3 and 5 evenly then Install bearing caps 1 and 7 evenly then Install 2 and 6 evenly and then Install bearing cap 4.
Tightening torque Camshaft bearing caps to cylinder head....20Nm (15ft-lb)..Hope this helps...It worked for me
I replaced my upper chain guide last year as it had disintegrated. After buttoning it all back up, it was much quieter but still had a slap. I drove the car all summer and winter and this weekend decided to do something about it.
Pulled the transmission, took off the clutch, and removed the lower cover. Found out my lower guide rail was also broken into two pieces and parts of it and the original guide were wedged around the lower tensioner and in the nooks and crannies behind the chains. Pulled out two handfuls of plastic. Put new chains, tensioners and guide rails on and ran out of time last night to finish the job. I still need to put in the starter, hook up all the electrics, put the linkage on, battery, air cleaner, intake, throttle body, etc, and drain and refill the transmission and put another gallon or so of coolant in. IF I start right after work, I should be done in 2-3 hours hopefully. The worst part is those 6 bolts on front of the intake manifold.. finger crushers for sure!!
The real pita is the one on the passenger side near the AC port. I have to use a socketed allen wrench and put an open end wrench on the shaft to turn it.
While driving, I downshifted, felt a weird sluggish sensation in the motor and I get a low oil pressure warning stop vehicle immediately light. I was reluctant to put it back into gear so I popped the clutch immediately, coasted to the side, tried to start it for for one second, and gave up. It wouldn't crank, and sounded like it was just free spinning when I tried to crank. I pulled the following codes at the bottom.
The codes 16826, 16726, and 17796 are the only new ones.
I'm going to go ahead and replace every failure prone bit in the engine bay, fix all the stuff that wasn't working correctly since I'm down there anyway.
Tested compression, got 30 psi in one cylinder and none in all the others that we tested. I don't think we checked them all at this point and instead opted to take off the upper intake, valve cover, and timing chain inspection cover. Found a bunch of plastic bits inside from the leftmost upper guide (towards the nose of the car) and the tensioner was completely slack with a nice big groove worn into it. I'm sure that I've bent some valves, so I'm gonna take the head off. The camshaft lobes look a little "shiny" bug didn't look "wiped." Is this normal for 140k? How should I inspect them for wear? Inside the valve cover was free of gunk, I was surprised.
Also, isn't the oil pump driven by an intermediate shaft that's controlled by the timing chain? If the chain broke or at the very least lost timing, wouldn't the oil pump cease to pump and then trigger the light? The car ran for about 15-30 seconds after I felt the damage and then I shut it off. Just trying to get a clear picture in my head of what happened and document what happened to my car in the thread for anybody who experienced a failure rather than just doing the work as preventative maint. I'm going to pull the pan, check the pump as per manual, replace the pressure sender and inspect the rods.
VCDS Version: Release 11.11.0 (x64)
Data version: 20111111
Chassis Type: 1J - VW Golf/Bora IV
Scan: 01 02 03 08 15 16 17 19 22 29 35 36 37 39 46 47 55 56 57 75
Address 01: Engine Labels: 021-906-018-AFP.lbl
Part No: 021 906 018 M
Component: MOTRONIC ME7.1 G 6760
Shop #: WSC 07235
5 Faults Found:
17545 - Fuel Trim: Bank 1 (Add)
P1137 - 35-00 - System too Rich
16826 - EVAP Emission Control Sys
P0442 - 35-10 - Small Leak - Intermittent
16804 - Catalyst System; Bank 1
P0420 - 35-00 - Efficiency Below Threshold
16726 - Camshaft Position Sensor (G40)
P0342 - 35-00 - Signal too Low
17796 - Control Module Malfunction - DBW Throttle Monitoring
P1388 - 35-10 - - Intermittent
Readiness: 0000 0000
Some folks find it easier to remove the motor & tranny as an assembly to do the chains (me included), especially on Mk3's because the tranny mount is a PITA - during both removal and reinstallation of the tranny.
"OP sounds like a MKIV guy"
Thank you for this guide! My lower chain snapped. I guess all is well, this has given me the opportunity to create an enormous list of failure prone parts and bits to upgrade/replace, and allowed me to see many issues that need to be sorted before there are problems that I wouldn't have seen otherwise until it was too late. The list is so long I will have turned nearly every bolt on the car by the time I'm done. Kinda stoked, actually. I <3 my VW.
Gary, thanks for writing this. I am now looking at dropping my engine after seeing the lower timing chain snap and finding the guides broken and the oil pump pickup screen full of debris. I have been told by another member that I should inspect the intermediate shaft and replace the oil pump, replace the crank and rod bearings while I am down there. He thinks, and a couple things I've read verify this as a possibility, that the intermediate shaft may have seized with debris from the timing chain parts, causing the lower chain to snap, and that a rebuild of the motor is in order. Any insight, thoughts on the kinds of wear I am looking for and should expect? I am going to have the cyl head completely rebuilt because the valves are likely smashed. Hopefully the bores and pistons are okay.
I will pull the engine and then the cylinder head on Thursday and take pics.
Great DIY: Just did timing and chain stuff thanks to this thread, but have problem understanding this part, referring to Old Style Tensioner bolt re installment:
"NOTE: The above procedure is for the newer style tensioner only. To bleed the older style tensioner, insert a thing wire into the bleed hole in the end of the plunger to activate the check valve inside and then press down on the plunger to compress it fully."
Maybe it was asked here already but i couldn't find info
I have that old style bolt, I have drained it successfully using thin wire. It has no oil inside anymore but after bleed it popped up again, so now it has air inside, is it right??? shall i re install it that way ? is it normal way ?? doesn't it require to be compressed or something ? shouldn't i submerge it in oil like new style tensioner?
I have to install it today so please guide me with this old style bolt installation.
"OP sounds like a MKIV guy"
I have some newer tensioners here I can send you free of charge if you are interested.
"OP sounds like a MKIV guy"
Is it possible to replace the upper tensioner guide rail without removing the chain, I am trying to avoid removing my lower timing cover. I have a 95 jetta, with the old style setup. Any suggestions would be greatly appreciated.