4.2 timing slip still runs, but poorly

[jeffyallroad]

So this 2005 4.2 I've owned for a total of 3 months jumped time and now runs really poorly. I don't know how to know if valve met piston or not, but when I looked at the multiple MIL with the vagcom this is what I saw:

8 Faults Found:
17748 - Camshaft Position Sensor (G40) / Engine Speed Sensor (G28)
P1340 - 001 - Incor. Correlation - Intermittent
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 001 - - MIL ON
16687 - Cylinder 3
P0303 - 001 - Misfire Detected - MIL ON
16688 - Cylinder 4
P0304 - 001 - Misfire Detected - MIL ON
16685 - Cylinder 1
P0301 - 001 - Misfire Detected
16689 - Cylinder 5
P0305 - 001 - Misfire Detected
16691 - Cylinder 7
P0307 - 001 - Misfire Detected
16686 - Cylinder 2
P0302 - 001 - Misfire Detected
Readiness: 0000 1100

How would I determine if I have valve damage without removing the engine? If this motor is savable I would entertain having someone do the updated timing chain kit and would give it to my kid as his first car, but I am also of the mind to just donate this thing to some charity and move on.

I love this car and am so disappointed this has gone this way. I had a 6 speed swap in mind but now I'm tempted to just dump it for a 1.8t A4 or something along those lines.

Thanks for any advice.

[chris86vw]

compression test or leak down test would tell you for sure it isn't broken but not necessarily for sure that it is broken.

If you get compression or do a leak down and aren't showing issues then for sure it is good.

however if it is off enough that it isn't building compression or no longer has a valve closed at TDC for a given cylinder then failing one of those tests would not conclusively tell you it is damaged.


A leak down test would be the safer option if it isn't damaged yet since you would be turning the engine by hand not cranking it over. It shouldn't suddenly make valve contact if it didn't at high rpms, but just a possibility.

[jeffyallroad]

compression test or leak down test would tell you for sure it isn't broken but not necessarily for sure that it is broken.


I do have an allroad buddy that can help me with this, and just spoke with another mechanic friend that pointed me in the direction of a local mechanic that just did a timing job on an S4 variant of one of these so all is not lost.

I have run the vehicle at low rpms once just to move it from one spot to another in my driveway so that's something, I'm not sure if it'd run with a bunch of bent valves or not. This is a first for me.

Thanks for the advice.

[rollerton]

I do have an allroad buddy that can help me with this, and just spoke with another mechanic friend that pointed me in the direction of a local mechanic that just did a timing job on an S4 variant of one of these so all is not lost.

I have run the vehicle at low rpms once just to move it from one spot to another in my driveway so that's something, I'm not sure if it'd run with a bunch of bent valves or not. This is a first for me.

Thanks for the advice.

It would NOT run with more than a couple bent valves. Hopefully it did not jump timing. It's an 05' 4.2 ----Allroad...or is it a sedan? If it's the 4.2 Allroad and it has timing chain issues it's somewhat of a project to get repaired. You probably know that. I don't think the Allroad 4.2 can technically 'jump timing' and still run, that would be catastrophic. The belt driven engine could slip a tooth or two, but after that you get bent valves- and usually several +/ - the engine locks up if the belt doesn't snap.

You can tell by ear how bad it is to some extent: when you turn the key and the engine turns over listen for the: wrrr-wrrr-wrrr-wrrr-wrrr- sound of the pistons moving as it cranks over. If it sounds obviously uneven - wrr-wrr-wrr- WEEER-wrr-wrr- ....go crack open a beer...or one of those men-in-black memory erasers. You're gonna want to erase the memory of that sound.

[JTown77]

Mine costs 7k to pull the engine and replace all the chains and tensioners.

[Scotty@Advanced]

You probably have some valves that are bent slightly. Don't worry however continued operation will result in the heads snapping off.