Urgent: AWM 1.8t Engine Question

[ZXERT]

Hey friends. My brothers b5.5 VW Passat which is a 2005 model year with a 1.8t AWM engine broke down on the freeway. We pulled it apart to find a siezed waterpump with a frayed timing belt. He turned the car off while it was running well and we believe the toe truck driver cranked it twice. We were able to order and install a metal impeller water pump, new tensioner which are installed and correctly tensioned. The belt is on, the marks line up to TDC after 2 full rotates which is one compression cycle.

The issue and question I have is about turning the engine over by hand. We have a 19mm 12 point socket connected to a breaker bar but it doesn't turn over as easily as I think it should. It turns in a inconsistent manner. At points it take 5ft lbs of torque which is smooth and at one point I measured 25ft lbs was required to turn it over. Im worried that there are bent valves which could amplify in damage once we button in up and start it.


Is it typical that turning it over by hand isnt exactly butter smooth?

I realize we dont deal with AWMs too much in this forum but I also realize that the AWM isnt too different from our b6 1.8ts.


Thank you for any help/advice.

[Jflow23]

Turning by hand is not smooth, compression requires more torque to turn crank. You still may have bent valves, compression test will let you know.

[MikTip]

Pull the intake manifold and visually inspect the valves....or take a chance.

Got a borescope?

[diagnosticator]

As long as the timing marks align properly now, turning the engine cannot cause any valve bending, but since the engine was cranked before the damaged belt was replaced, the chance for bent valves is very high. Do a compression test to determine if/what cylinders have bent valves. Normally, the effort to turn the engine over by hand, varies with the pressure development during the stroke of the piston, of the cylinder/s on the compression stroke. With 4 cylinder engines, one of the four cylinders is on one of the four operating strokes. Therefore, there is a power stroke occurring every 180 crankshaft degrees of rotation, in the firing order. The other piston strokes of the four stroke cycle occur in the standard sequence, at each cylinder in the firing order. Pistons 1+4 move up and down together, and pistons 2+3 move up and down together, 180 degrees away from 1+4. For the two pairs of pistons moving together, each cylinder in the pair is on a different stoke of the cycle. One piston/cylinder of the four cylinders, is on one of the four strokes of the cycle, Intake, Compression, Power, Exhaust. If you remove the spark plugs, there will be no compression of air in the cyliners during the compression stroke, so you can turn the engine with the plugs removed, to evaluate the turning resistance of the engine without the compression resistance occurring. With the plugs removed, the turning effort should be uniform with a minor variation from the valve springs pressing on the cam followers, but that resistance should be fairly constant considering all of the valves being somewhere between open and closed. If an angle of higher turning resistance occurs with the plugs removed then the only likely cause considering the recent history of the engine, is a bent valve sticking in the valve guide somewhere in the valve opening closing cycle. It is possible for more than one valve to be bent. A compression test with the plugs removed will comfirm bent valves.

[ZXERT]

Thank you all so much for your assistance. We did I compression test to find 0 psi. I pulled the upper timing cover to find the belt working correctly and rotating the cam pulley smoothly. It appears to be bent valves. I only tested cylinders 1&2 but didnt ever see the needle move. The engine also sounds much different when cranking. Is there any way I could be doing the compression test wrong. We pulled the plug in each cylinder and installed the test gauge and fired the engine via the key. After 4 entire combustion cycles the needle did not move.

From what I understand, the engine should show some compression if its being turned over. In my head the only explanation is the worst.

Bent valves.

I took a video of the noise when the engine is attempting to start. Will upload it and post soon.

Sent from my SAMSUNG-SGH-I317 using Tapatalk

[ZXERT]

Please have a look at the video below. Let me know what you think. After watching the video its more apparent there is a larger issue. That is also the same noise that it made when the tow truck driver turned it over.

www.youtube.com/embed/RAPiTB_PTjQ

[ZXERT]

This thread might be better off going to the b5 forum.

[customa4]

Here ya go. You should definitely be seeing some type of numbers when cranking.

Compression Check
Engine oil temperature at least 30°C
Battery voltage at least 12.7 V
Remove engine cover
Switch off ignition
Disconnect coil pack harness'
Pull out ignition coils
Remove spark plugs
Disconnect connectors from all injectors
Fully open throttle valve
Check compression with the compression tester
Using the compression tester-Operate starter until tester shows no further pressure increase

Max difference between cylinders-43.51 psi

Someone else will chime in with the which numbers are acceptable unless you've already found them.

[walky_talky20]

That is the sound of no compression. You've got some bent valves there.

But hey, at least it didn't happen during a blizzard.