What caused my 3.0 to seize?

[6speedman]

Hi guys,
I just bought a 02 A6 with the 3.0 and 128,000 it was showing misfires on all cylinders so I replaced all plugs and coils.That improved it but then i got a 17930 code for exhaust cam position sensor bank 2 so while I was waiting for the sensor to arrive i pulled the old one out and cleaned it up and swapped it with the intake sensor. Fired it up and it ran great so I decided to run it a few miles, after about 10 miles of cruising at 60mph I noticed it downshift and lose power, it shuddered slightly about like a misfire and had a bit of rattle. before I got stopped it had died. It did no over heat, there are no codes and the timing belt is good and tight oil level is good.
A 2ft bar on the crank will not turn it over.
Any ideas to what happened would be appreciated.

[RAF_S7]

Try taking the plugs out and turning the engine manually.

What happens when you try and start it normally?

[6speedman]

Try taking the plugs out and turning the engine manually.

What happens when you try and start it normally?

Starter engages but stalls. I tried turning it with a two foot breaker on the crank but it's tight.


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[lyates1987]

Not doubting that you did check this but how much oil is in it?

[6speedman]

Not doubting that you did check this but how much oil is in it?

It's full I just changed the oil a week ago.


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[lyates1987]

Man that's weird, Not sure where to start if you don't get any codes or a CEL. I assume you had correct amount of coolant in it as well.

[john_gonzo]

Damn, horrible story.

Maybe the engine is fine and the auto trans is holding the crank in one position. Seems like a long shot but I thought I'd throw that out there.

[6speedman]

Fluid levels are good temps where good and it was running strong till the last 10 seconds.


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[6speedman]

Good idea I'll scan the tranny see if there's any codes there.


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[lyates1987]

AAAAhhhhhhh auto trans.................

[john_gonzo]

Were the plugs out as suggested above when you tried turning the engine with the two foot bar?

[john_gonzo]

AAAAhhhhhhh auto trans.................

Oh shit, is this really a failure mode for these auto boxes? Does the torque converter get locked up somehow?

[6speedman]

Were the plugs out as suggested above when you tried turning the engine with the two foot bar?

They were not out but a bar will easily overcome the compression and it won't turn backwards either.


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[john_gonzo]

They were not out but a bar will easily overcome the compression and it won't turn backwards either.

Compression of air. If the cylinders are full of liquid....

[lyates1987]

You try to put the tranny in neutral then turn the engine?

[lyates1987]

Oh shit, is this really a failure mode for these auto boxes? Does the torque converter get locked up somehow?

You can't turn the engine unless it's in neutral. If it's in park then it won't turn.

[john_gonzo]

You can't turn the engine unless it's in neutral. If it's in park then it won't turn.

Right, of course. Thanks for spelling that out. Thought I had missed a thread about death of a transmission.

EDIT: This was not one of my more lucid moments. Came here to correct this but I see diagnosticator is already on the job here: Post #20.

[AudiA4_20T]

Most likely your cams wore down and led to something worse. They're notorious on those cars. Pull the valve covers

[6speedman]

You try to put the tranny in neutral then turn the engine?

Park locks the engine?? Car aways starts in park.


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[diagnosticator]

You can't turn the engine unless it's in neutral. If it's in park then it won't turn.

The engine must be free to rotate regardless of the trans shifter lever gear position. There is nothing associated with the trans that can lock the crankshaft preventing engine rotation. Apparently, this has been confused with the trans Park lock that locks the trans output shaft to prevent the car from rolling with the shifter lever in Park.

[diagnosticator]

It's full I just changed the oil a week ago.

How do you know the engine oil is still full, have you actually checked it after this happened? It would be a one in a million event for the low oil pressure and low oil level warnings to be inoperative when the oil was somehow lost from the engine while driving. It is possible also that the oil pressure warning is inoperative when the oil pump stopped pumping engine oil and there was no oil pressure and nothing to warn you that was happening, even with a full oil level. Also a one in a million event.

The ECU OBD II diagnostics does not monitor the low oil pressure/low oil level warning system and does not monitor engine oil pressure.

A seized camshaft is the most likely result, because the oil pressure in the heads is always the lowest, and will go to zero before oil pressure to the crankshaft and rod bearings and oil spray from the bottom end bearings lubing the pistons and cylinders falls to zero.

[6speedman]

How do you know the engine oil is still full, have you actually checked it after this happened? It would be a one in a million event for the low oil pressure and low oil level warnings to be inoperative when the oil was somehow lost from the engine while driving. It is possible also that the oil pressure warning is inoperative when the oil pump stopped pumping engine oil and there was no oil pressure and nothing to warn you that was happening, even with a full oil level. Also a one in a million event.

The ECU OBD II diagnostics does not monitor the low oil pressure/low oil level warning system and does not monitor engine oil pressure.

A seized camshaft is the most likely result, because the oil pressure in the heads is always the lowest, and will go to zero before oil pressure to the crankshaft and rod bearings and oil spray from the bottom end bearings lubing the pistons and cylinders falls to zero.

Yeah checked it about 10 times after it happened. Low oil pressure seems to be the only explanation so I guess I'll pop the valve covers off and see what I find. Would a seized cam lock the engine up without jumping the tbelt?


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[RAF_S7]

If the cam locks up for whatever reason, your either going to strip the cam belt, or throw it off.

Id still pop the plugs then try turning the engine, the point john_gonzo makes about cylinders full of water is a good one....

[crazyquik22023]

Since you were throwing a 17930 fault I am betting that there was/is a problem with the cam to cam timing or crank to cam timing. A fault code for cam position is almost never a bad sensor. On rare occasions it is but 99% of the time when a cam fault pops up it is related to timing in some way. I am guessing that unfortunately you have bent valves now and they are interfering with the pistons which is not letting the engine rotate.

[6speedman]

If the cam locks up for whatever reason, your either going to strip the cam belt, or throw it off.

Id still pop the plugs then try turning the engine, the point john_gonzo makes about cylinders full of water is a good one....

I'll pop the plugs out first thing this morning. The belt is still tight and not stripped looking at it from the top covers. But can't see down to the crank. Although if it did strip from a locked cam the crank should still turn till it hits a valve unless the pistons/ rings are seized to??


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[SJorge3442]

Was there any noise associated with this occurring? Any screeching or screaming? i wonder if some how there is an issue with the crank or a rod. I'm thinking this is a bottom end issue, but we wont know until you're able to pop the valve covers and then check the timing belt.

[deyrag]

On the 3.0 it is a 10 minute job to drop the lower oil pan. You won't be able to see the bottom end (crank and bearings) but you will be able to see if there are any chunks of shiny bits sitting there.

[6speedman]

Was there any noise associated with this occurring? Any screeching or screaming? i wonder if some how there is an issue with the crank or a rod. I'm thinking this is a bottom end issue, but we wont know until you're able to pop the valve covers and then check the timing belt.

There was just a gradual loss of power almost like running out of fuel accompanied by misfires and then a faint metallic ticking in the last few seconds.


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[SJorge3442]

There was just a gradual loss of power almost like running out of fuel accompanied by misfires and then a faint metallic ticking in the last few seconds.


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I'm sure you already know this, but 2002's and early 2003's were plagued with cam issues because of issues with the hardening process that makes the cams strong. Usually this results in rounded cam lobes (sometimes broken), which causes the cams to not properly operating the valves, thus causing a collision with the pistons and major internal damage. First things first, you need to try to get both heads to TDC (remove T-belt and manually rotate cams by hand, then insert cam lock tools in head bank), then see if the bottom end spins freely. If so, the issue is likely valve related, which means both the heads need to removed and rebuilt. On the bright side, you'll have 2 fresh head gaskets.

[diagnosticator]

If the cam locks up for whatever reason, your either going to strip the cam belt, or throw it off.

Id still pop the plugs then try turning the engine, the point john_gonzo makes about cylinders full of water is a good one....

That is certainly true if the cam stops suddenly. If the seizure is more gradual, it conceivably could stall the engine without stripping teeth off the timing belt

[6speedman]

I just picked up a complete engine semi locally for$300 so I have something to work with.


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[SJorge3442]

I just picked up a complete engine semi locally for$300 so I have something to work with.


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Cant beat that. While its out, I'd recommend replacing the O-Rings on the hard pipe on the rear of the motor. They are bitch to get to with the engine installed. I'd probably give it a good steam wash if you can too, but hey, thats just me

[diagnosticator]

Yeah checked it about 10 times after it happened. Low oil pressure seems to be the only explanation so I guess I'll pop the valve covers off and see what I find. Would a seized cam lock the engine up without jumping the tbelt?


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Intuitively, that seems almost impossible. However actual chances for stripping/throwing the belt really depends on how quickly the cam seizure progresses before it finally locks up.
Each cam seizure event is unique regarding initial conditions and progression variations.

[deyrag]

At least satisfy everyone voyeuristic urges and post up the gory pictures once you figure out what happened

[6speedman]

At least satisfy everyone voyeuristic urges and post up the gory pictures once you figure out what happened

I'll try to do that. It may be a week or two till I get time to dig into it.


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[6speedman]

The fun has begun. Looking at the bellhousing bolts downpipe to manifold bolts it would look like this engine was pulled previously also the ac had no charge. So the story on this engine is anyone's guess.


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[deyrag]

Nice work area.

[jayiszraw]

I heard driving on no A/C charge is bad for the compressor.



What O-rings?

With out adequate pressure in the system the compressor will not cycle unless the fail safe is somehow bypassed

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[SJorge3442]

I heard driving on no A/C charge is bad for the compressor.



What O-rings?

Im refering to the hard pipe that crosses that back of the engine. There is an o-ring on either side. I doubt they would ever start leaking, but with an unknown engine, you never know.

[diagnosticator]

With out adequate pressure in the system the compressor will not cycle unless the fail safe is somehow bypassed

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Yes, that is true. However, the A/C compressor is always turning, driven by the engine 100 percent of the time the engine is running. Consequently, the compressor needs refrigerant charge to distribute compressor oil to lubricate the compressor. If there is no refrigerant in the system the compressor won't be lubricated properly and will eventually be damaged from no lubrication. It could seize up without proper lubrication.

The compressor is a variable displacement type compressor, it does not cycle ON and OFF during operation, it varies the amount of refrigerant pumped depending on compressor suction and discharge pressures to regulate A/C cooling power, anywhere from 0% to 100%.