Club Touareg Forum banner

1 - 20 of 32 Posts

·
Registered
Joined
·
9 Posts
Discussion Starter #1
The low oil pressure warning light came on and had noisy lifters on cyl's 5-8. I put in a mechanical oil pressure gauge and saw that I had 75 psi cold at idle and 50 psi after the car warms up a little. Pulled the valve cover off and noticed the cam chain was loose. I ran the engine w/ the valve cover off and saw oil squirting out of the chain tensioner, ( the orifice in the plastic guide) and the chain didn't tighten up. I assumed the chain tensioner failed and replaced it w/ a new one for $640 for the part alone. When I first started up the car the chain tightened right up and everything sounded great, no oil shooting out of the center hole. After it finished the cold start mode, I noticed the chain had slack again and started making they loud lifter noises and was squirting oil out the center hole again. Either I experienced infant mortality on the tensioner or there is something causing the tensioner to vent the oil and slacken the chain. Does the variable timing slacken the chain to retard or advance the timing? Could something like the cam position sensor be bad.

I am out of ideas, any thoughts would be appreciated.

Marc
 

·
Registered
Joined
·
20,430 Posts
I'm puzzled. The V8 has a timing belt not a chain.
 

·
Premium Member
Joined
·
287 Posts
From Bentley this is the oil pressure spec for the V8 engine oil over 80 degrees celcius.

  • Check oil pressure at different speeds: 2000 rpm: 3.0...5.5 bar over 2000 rpm: maximum 7.0 bar
So that's all the facts I have. From here on out its all random thoughts and guessing.

It looks like you are probably within that range, but I wanted you to see the spec.



I wonder if you are using the right viscosity oil.



I am almost thinking that squirting oil is the normal behavior of the part. I would also wonder whether there is some other problem that is causing the tensioner to back off too much such as a bad or no control signal or controller (whatever the heck controls the tensioner).


Do you have any codes?


Probably not much help. Good luck.
 

·
Banned
Joined
·
7,167 Posts

Attachments

·
Registered
Joined
·
9 Posts
Discussion Starter #7
So my problem with my cam chain tensioner is electrical at the plug not the unit itself. Cold start mode I have 12V going to the tensioner and have good tension. After the short warmup, the chain tensioner drops down. I unplugged the connector on the tensioner and put 12V from another power source to the contacts and the tensioner went right up and the engine sounded great. Take it away and the tensioner drops down and get the loud lifter noise. I measured the power at the connector and only had 10.5 volts.

Why do I have low voltage there? The only thing I can think of is a bad cam position sensor. I also have the low oil pressure warning after cold start mode. I am wondering if its low voltage to a bunch of things causing a bunch of problems.

Any thoughts?

Thanks,

Marc
 

·
Premium Member
Joined
·
287 Posts
To answer that question, you would have to take some voltage measurements and see. Assuming your voltage is OK, you might want also to check out some Audi forums for some input as the 4.2L V8 has been used in Audis.

Wild-a## guess time. Perhaps you have a bad oil pressure sensor. Perhaps its reading low puts the tensioner in a default mode to preserve oil pressure for lubrication.

I see that only one side is affected. Have you tried swapping the electrical connectors between sides to see if the behavior switches with it?
 

·
Registered
Joined
·
9 Posts
Discussion Starter #9
replaced the ecu

I replaced the ecu w/ one from a junkyard. I have the code 17978 engine start blocked by immobilizer p1570 - 008 implausible Signal. Does anyone know about recoding the ecu?
 

·
Registered
Joined
·
9 Posts
Discussion Starter #11
When I measured the voltage between to 2 pins on the cam chain tensioner, I only had 10 to 10.5V. But when I measured voltage between each pin and a real ground I had 14V on the plus pin but 4 or 5V on the ground pin and therefore only a 10V differential which was insufficient to drive the tensioner. So what I did was I terminated some speaker wire w/ mini faston terminals to plug into the pins of the cam chain tensioner and shoved one wire into the plug w/ 14V (w/ a fuse) and the other wire to a ground on the engine. The engine purred the a kitten. So I took it for a ride w/ the Ross Tech software going. There were a few things that didn't make sense. The ignition timing was all over the place but the engine was running as smooth as can be. I wasn't sure of the values I was getting for the knock sensors either. One thing to add which I am not sure if I said already is that the ecu controls the tension on the chain by varying the voltage to the ground. Since I wasn't getting the right ground from the computer, I just bypassed it. I called the dealer and talked to a VW tech and actually fooled them thinking I was an actual mechanic. :eek:) Anyway they were surprisingly very helpful but they did think it was the computer.

I got a ECU from the junkyard. Plugged it in and started the car. The message on the dash was "immobilization activated" and the car immediately turned off. Its an anti theft feature so you cant steel a car throw in a new ECU and be gone. The dealer is the only one that can reprogram the ECU to the keys. So you can't just get throw in a new ecu to see if the problem goes away.

So basically a trip to the dealer was inevitable. I gave them the rundown of what I did/found and asked them if they could do a quick check to verify that the computer is bad. I was told that the shop foreman was called in and VW is stumped and they think they may have to call VW headquarters and they need another day.

Now I feel better that I couldn't fix this problem. The dealer is having trouble w/ this also. But now if the dealer is stumped, them spending time on it is costing $$$$.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #13
The ECU from the junkyard didn't fix the problem (to my surprise). Now I think its a ground issue, but the grounds I checked didn't have any voltage on them. That is the voltage that I am seeing at the one tensioner. The car did have blocked drains where water was accumulating behind the firewall where the engine harness is and computer are. But I only see 2 ground connections by the computer and no others, and those 2 ground connections are fine.

So one more thing I tried was to put a separate ground wire through the back tensioner connector boot to the ground pin. I thought that since that pin had 3 to 4 volts on it that it might short out something or do something weird. Well it just made the tensioner work perfectly. I haven't gotten a chance to connect my computer to see if some of the other fault codes went away or are different. But again: I had my volt meter on the 2 pins of the tensioner connector when the engine was cold and it had 14 volts. As soon as the engine heated up the voltage in the tensioner dropped to 10 volts. This problem its driving me nuuuuuuts!!! Someone tell me what it is. :eek:)

I said ok let me take it to the dealer, I don't have the time and don't know the car well enough. The dealer experience was a joke. There lack of skill was blatant and they tried telling about other problems that had nothing to do with the problem at hand. When they realized how familiar I was with the car, I called them out their ridiculous suggestions, they didn't want to work on the car.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #15
2004 touareg tensioner problem

CGsnipe, do you have a Ross Tech vag tool? I am wondering if the timing in your car is all over the place like in mine. The update- Since the computer wasn't the problem and neither was the tensioner, I took a closer look at what was in between and couldn't find anything that would cause these problems. I thought it was the crankshaft position sensor but the other side was working fine. Since I was able to get the tensioner to work by grounding the ground pin on the tensioner, I wanted to see what would happen by plugging in the connector and putting a jumper wire into the back of the ground pin and grounding it. The tensioner went up and the noise went away but using my Ross Tech software, I got an error on my camshaft position sensor. I thought I was onto something but I as I was checking the cam shaft position sensor on the side that wasn't working, I realized the head on cylinders 5 thru 8 was the same just turned around on cylinders 1-4. I checked the tensioner on side that was working fine and it had the 10V that the side wasn't working had. I checked the voltages on the cam shaft position sensor on the side that was and wasn't working and couldn't find anything different. Unplugging the tensioner on the side that was working also didn't give me the same noisy lifter on the side that wasn't working (while the car was running). The only thing is, I didn't unplug the working side while the engine was in cold start mode only after the engine was warm. If I could reproduce the noise on the side that was working I would have been closer to the source of the problem. But I couldn't. I was doing this as a favor to a friend and couldn't spend anymore time on it. So I left in the ground jumper wire in the back of the ground pin on the tensioner and am hoping that the can drive the car like that for a few more years.
 

·
Registered
Joined
·
7 Posts
Gold unfortunately no I don't have it. But I might try that grounding trick and see if I can duplicate your results. Any chance of getting a photo of where you jumped?!
 

·
Registered
Joined
·
9 Posts
Discussion Starter #17
Since i was out of ideas on what was causing the chain tensioner to drop down after warming up, I did the following bypass to get the chain tensioner working. I gave up when I went to the cam tensioner on the other side of the engine and couldn't duplicate the problem.
First with the voltmeter check for the pin that has 12v and the one that has 4 volts on the chain tensioner conn. The ground is the one w/ 4 volts. What I did was pull the boot off the back of the chain tensioner connector. i put a stripped wire through the back of the boot to the back side of the ground contact making sure the strands of the wire were in contact w/ the ground pin. then i slid the boot back onto the connector and grounded the wire to a convenient bolt on the engine. I used one that was for the bracket for the engine cover. I thought grounding the wire w/ the 4v would blow the fuse but it didn't. It brought up the tensioner and quieted the engine.

Marc
 

·
Registered
Joined
·
4 Posts
I'm experiencing exact same issue on my 04 V8 after both timing chain tensioners replaced. Cold engine runs perfect, no noise, but as soon as it warms up, not the same at all. Grounding the 4volts on timing chain tensioner does not quiet the engine. Low Pressure red light is on when rpm a little bit up.
Can it be a bad oil pump not pressuring enough when Oil gets less fluid?
Hope it's not the Oil pump, I don't want to lift engine to access oil pan.
Any help welcome
 

·
Registered
Joined
·
129 Posts
This thread is over a year old, so I would not hold my breath for a magic fix. The first thing I would look at is that pin having 4volts when it shouldn't. Check the ground, clean it well, maybe add a jumper to a good ground. I would guess the oil pressure is based off that ground as well.
 
1 - 20 of 32 Posts
About this Discussion
31 Replies
15 Participants
73Will
Club Touareg Forum
We’re the online community for Volkswagen Touareg owners to share knowledge about their VW Touareg Sport Utility Vehicles and more!
Full Forum Listing
Top