Hello Cayenne community. I picked up a non running project car and am beginning to dig away at the issues. It came to me on a flatbed so it should be an interesting can of worms. I have researched the web for a month or so looking for a similar situation to mine but have not found one. Lot's of documentation on the cylinder scoring but none that have led to a locked engine.


2005 Cayenne S 240xxxKMs

First worm = No crank

1. Check battery, installed a new battery
2. Check power to starter, ground to starter, power to starter solenoid. No pulse from starter so replaced. Old starter looked dry, engine has had coolant pipe upgrade.
3. Installed new starter. Starter engages but cannot spin ring gear. Too much resistance
4. Turn engine by crank bolt. Engine seems seized but start to free up when moving crank bolt back and forth 1/4 turn.
5. Pull plugs and inject oil into cylinders.
6. After much wiggling the engine becomes free to turn and the starter seems to be able to spin the crank without plugs installed
7. Reinstalled the spark plugs. Engine still cranks but does not catch. There is fuel pressure in the fuel rail. After killing the battery trying to start and only getting an occasional single piston fire I put the charger on the battery and give up for the day.
8. Next attempt and the engine is tight again. Pulled serpentine belt and found no dragging components. Pulled plugs again but still no crank. The starter gets power but cannot turn the crank. After a few tries you can smell the starter heating up.
9. Use the crank pulley again to work the engine free. Engine will turn in one direction but not the other. Once the engine is freed again it turns but with some clatter from parts collision.
10. Put the cover back on the car and consider the options.


This is a project for me and more of a learning opportunity than a car that need to get on the road anytime soon. If I do put the time and money in to get it road worthy it won't see pavement until the spring. Does an initial root causes jump out at anyone? I know that these engines suffer from piston scoring but that usually leads to oil consumption, clicking, and misfires. So unless the last owner drove it to this condition I am not sure that this would be the cause. How is the oil pump driven? I can't imagine a piston / valve collision as I did have it cranking smoothly for some time. Could it be a really work cylinder and a piston skirt binding on a cylinder wall on the full down during crank? Camshafts binding?

I just find it odd that it would go from locked to free and then to locked again.

All suggestions with the exception of "walk away" appreciated. Again, no time pressures, so more of a hobby project for now.

 

Good luck with the project.

This thread
https://rennlist.com/forums/cayenne-...n-the-oil.html

is for the 2004 S that I currently own. Fuzzy on memory a little here, but I do remember doing tests before he took it in to the dealer for diagnosis and engine replacement. The engine was seized as I recall. But the info in the posts in that thread is probably better than my memory is now.

But I think it suggests that cylinder scoring can lead to engine seizure. Hopefully something easier for your case.

 

Thanks for the fast reply @oldskewel . I reviewed you thread. I still can't cannot connect the low coolant, wet plugs on 5 and 6 and wet 5 and 6 cylinders with scoring. Maybe there were multiple engines issues and Porsche just dealt with the obvious and most common?

 

Regarding the oil pump, its chain driven. Chain goes from crank to oil pump behind the timing chain.

Sounds like an interference issue due to item #9 in your first post. Without plugs, the engine should be relatively easy to turn by hand as only things giving any resistance are the valve springs. Take the oil fill cap out and look, is the chain still in place? I'd lift the cam covers and inspect the chain and camshafts. You can get a pretty good look at the timing too.

 

Great. Will do @hopsis Thanks!

 

If you disconnected the accessory belt and the engine is seizing internally, you'll be taking it apart one way or another. The question is whether the block is salvageable or not.
I'd start with a boroscope of the cylinders. You can get a USB one for like $10, or handheld one with a camera for under $50 easily. If the scoring is severe enough to cause bonding, you'll see it from the top through the spark plug holes.
Only if there are no scored cylinders would I consider going any further with that engine. Next would be dropping of the oil pan to inspect the bores from the bottom, that would confirm 100% whether bores are good (scoring starts from the bottom).
If it's scored, which I highly suspect it is, then your most economical course of action would be a new engine. If a project is what you want, go ahead and rebuild it.

 

Thanks @slavie . If I were a betting man my money would be on wall scoring as well. I just find it interesting that the engine can go from tight to cranking well to tight again. Amazon will deliver a borescope for me tomorrow so when I get some time I'll have a peek. Still hoping it's seething else though. Can a torque converter behave like this?

 

Oh, another quick and dirty test - take the oil filter out and inspect for metals. If there's nothing but glitter, you can stop right there...

In theory, maybe the Torque Converter could lose balance and get bent out of shape internally and start seizing, but I have no idea how that could possibly happen in practice. The outside of the TC is also spinning the oil pump in the transmission, maybe something could've gone sour there.
Your best case scenario is that the oil pump is seized somehow - but oil pumps usually seize because debris gets in them, and wherever the debris comes from is nothing good.
Maybe a valve got stuck and bent and when you turn over the engine you're hitting the stuck valve? Maybe, but head rebuild is still a job in itself.

 

Thanks @slavie . It's an odd one. The first time I turned it over by the crank bolt it was very tight in both directions. Then after a bunch of fussing it was cranking like a champ. Then, tight again. Then clanking when cranking. Something is worn or broken that I am sure of. Our early snow is supposed to melt away this weekend so maybe I'll get time to get under the hood and follow some of the tips I have so far. The fact that I can turn in one direction but only so far in the other indicated to me a piston binding. When the connecting rod pushes up it's pushing offside one way and when it pulls down it's pulling the other direction. Could be just so bad it digs in and locks up. Borescope arrives tomorrow so I'll post pictures of what I find.

 

Turning the engine in the reverse direction to normal rotation is likely the cause of your now clanking engine. That's a NEVER DO THAT thing with these engines. The timing chains and tensioners get very unhappy when turned the wrong way.

The engine is likely economically infeasible to repair. A used engine is in your future if you want to proceed with the project.

 

Or an engine-trans swap to a 600 HP crate Chev with a trans that can shift quicker than 1.5 seconds.

 

@ScootCherHienie I would convert to a Teslafranken cayenne before I would do that:
@deilenberger that makes sense. Would the engine bind if you tried to turn it backwards? And assuming the crank bolt is right hand thread is it safe to assume that the engine normally turns CCW looking from the front?

 

Scope the cylinders .... Most likely the engine is toast .

 

That clockwise/counterclockwise looking at engine from left or behind or passenger side is just confusing. Imagine You want to tighten the crankshaft end bolt. That's the correct way to turn the engine.

 

Okay, got it. Thanks @hopsis . Either way, I just purchased an engine off of eBay. Came from a southern dismantler so should not be a "cold start" engine. The seller will let me scope the cylinders before we load it into my van anyhow. I will scope my engine tonight and share photos anyhow to see where we are at with this one. And if I ever do drive this Cayenne in cold weather I'll fit it with an oil heater first. Any suggestions for the best heater technology for this engine?