964-C2

Hi.
I could need some help understanding the engine problems I am experiencing..

I had one rod coming out the side of my engine block a while back, so I needed a new engine.
I do most of the work on my 951 my self , but I am not qualified to build / put together an engine, so I got help from an engine builder to build this:
S2-block with sleeves / wossner pistons and rods / piston squirters / windage tray / oil pick up brace / 2,7 liter cylinder head.

When I start the new built engine for the first time, everything seems ok, except I am experiencing more smoke (oil) from the exhaust than I like...
At first, we hoped it could be the rings (they might need to be broken in to seal better?), so I drive the car for a while, braking in the engine. The smoke did not get better. I also had high oil consumption.

I worked with my engine builder to find out what was causing the high oil consumption / smoke from exhaust, but we did no find out for sure what was causing it.
I did a leak down test - good result.
I had some traces of oil in the intake. But my intercooler / intercooler pipes were dry.
To my understanding the oil in the intake could not come from leaking turbo seals, or oil coming from the cranckase breather system (mounted like stock - before the turbo). If it was, I would have seen traces of oil in the intercooler and intercooler pipes.
One strange symptom, was that I had more smoke coming from the exhaust in left hand turns and less smoke in right hand turns...
Then, after about 500 miles I got this knocking sound from the rear of the engine:
I took the engine out of the car and sent it back to my engine builder.
When he opened it, this is what he found:
Carbon build up on top of pistons
http://i939.photobucket.com/albums/a...ikjel/9515.jpg
http://i939.photobucket.com/albums/a...ikjel/9512.jpg
The rings on #4 were stuck in the piston. It seems like carbon build up (burned oil?) caused the rings to get stuck.
http://i939.photobucket.com/albums/a...ikjel/9513.jpg
http://i939.photobucket.com/albums/a...ikjel/9511.jpg

The engine needs a rebuild again.
My engine builder hones the cylinders, install new pistons / rings, and puts the engine back together.
We were not sure what really caused the failure (how did oil enter the cylinders / combustion?), so everything was gone through and checked.
The 2,7-liter cylinder head had a few miles on it since rebuild before it was put on my engine. Just to be sure, the head was rebuilt again.
The turbo was also rebuilt again (although it had been rebuilt 500 miles ago).
We were really trying to make sure everything was in perfect condition.

So I install the "new" new built engine in my car, hoping there will be no problems this time.
When I start it, everything seems exactly like last time. The engine is running OK, but to much smoke from the exhaust...
I fear I have a problem again (same problem as last time??). We do not understand what can be causing the smoke, except the rings might need to be driven some miles to seal better. So we decide I should put a few miles on the engine, to see if the smoke gets less..
I drive the car about 40 miles. The smoke is still there, and I am beginning to hear a sound in the engine I do not like..
When I start the engine the next day (started cold), it sounds really bad:
It sounds very similar to my last engine failure. The engine is damaged again, after only 40 miles of driving. This time, it sounds like the knocking sound is coming from the front of the engine.

I take the intake off, and I see that all 4 intake runners in the cylinder head and the 4 "outlet runners" of the intake are wet with oil (brown color here is oil):
http://i939.photobucket.com/albums/a...l/IMG_4287.jpg
Oil in intake runners and oil on top of pistons
http://i939.photobucket.com/albums/a...l/IMG_4301.jpg

Outlet of the turbo is dry:
http://i939.photobucket.com/albums/a...l/IMG_4299.jpg
Intercooler + pipes are dry:
http://i939.photobucket.com/albums/a...l/IMG_4298.jpg
Inlet of intake is dry:
http://i939.photobucket.com/albums/a...l/IMG_4297.jpg

I do not understand where the oil in my 4 intake runners can come from when the rest of the intake system is dry. The head is just rebuilt, with new guides and seals.
It is alsmost like the oil is entering the intake from somewhere else, but that can not be possible, can it?
I have checked all vacuum lines, they are mounted correctly (like the 4th diagram here http://www.lindseyracing.com/lr/Parts/VACDIA.html ).
I did not swap the AOS-line and idle air controller line...

Is it possible that the oil can come FROM the cylinders (from the crankcase past the rings) up into the intake runners (I think not)?

I did a compression test and leakdown test (done on cold engine).
The compression was 135 psi on cylinder #1, and 130 psi on cylinder #2/3/4.
Leak down test was done with a low pressure tester like this:
http://images.carcraft.com/techartic...6_leak09_z.jpg
10% leak is supposed to be the best result you can get with this tester, and up to 40% leak is OK.
I have 15% leak on cylinder #1, and 20% leak on cylinder #2/3/4.
Both compression test and leakdown test show OK results.

I do not understand where the oil in my intake runners can be coming from and what is causing my engine failures.
Could it be that the pistons squirters are mounted wrong and are leaving to much oil on the cylinder walls for the rings to handle?

So this is where I am now.
I have not taken the head off (or taken the engine out of the car) to look at the damages yet, but looking down in the cylinders past the valves (when the intake was off), it looks like cylinder damage again.

I could really need some help understanding what is happening and where the oil in the intake runners are coming from. Rebuilding the engine one more time without understanding the cause of the failures, might not be a good idea.....

Thanks.


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Auto_Werks 3.6

the bad sounds in your latest video sound more like a loose timing belt slapping the inside of the cover, especially since you say it comes from the front. the balance belt is also SCREAMING for adjustment. now that is based on the speaker on my phone, so who knows what it actually sounds like. also does your turbo require an oiling restrictor, and is it in place of so?

Techno Duck

Cant comment on the rings but the knocking kinda sounds like a bad lifter to me. What was your oil pressure at idle in those videos? When the engine was reassembled the 2nd time did you keep the lifters in the same position or did they get moved around? That is one explanation as to why the sound moved from the rear to the front of the engine.

Humboldtgrin

That sounds like rod knock or piston slap almost. I agree with the oil feed line needing a restrictor to the turbo if it needs it, also did you plastic gage every rod and main bearings for clearance and check the bore and piston diameter size? There may be debree in one of the oil passages of the crackshaft so check that on tear down. Is the front crank bolt tight? Did you check the pick up tube for hair line cracks and replace the o-ring at the top? Is the check oil valve working? It's at the rear passanger side inside the block, that small round hole that feeds oil to the head. What's your oil pressure? Don't know if your piston squirts are any issue but may be, may want to plug them up. I would use an engine hanger to support the engine while the crossmember and steering rack was removed. Then remove the oil pan and start checking The rod bearings first. You may want to turn the engine by hand and see if you can see any problems first. Something is definitely wrong! I'm thinking something is blocking the crankshaft oil passage, or oil isn't reaching the rod bearings. But it may be other issues as well.
If it's a 104mm bore and custom Pistons then make sure that "if" the rings cross the piston pin opening that there is the proper spacer/support piece installed before the rings were installed. Check the piston pins as well. It realy sounds like a lack of oil to a few parts, if there was an oil block from debree in the block or crankshaft I would think that would cause all kinds of weird oil issues. A cracked head would cause problems also, although aluminum heads usually warps and doesn't usually crack I have seen cracked aluminum heads. Or if the block has a crack, but again not likely.

Now if you had a blockage at say just before the check valve but out of the way of the oil passage to the head and it made its way to #1 rod bearing, blocking the rod bearing oil passage and not able to escape, I could possibly by that idea. Now with the oil ring welded to the piston I have to ask, did you gap the rings before installing them? Meaning place them in the bore and push a piston upside down in the bore to line the ring up strait across in the bore and then use a feeler gage to measure the end gap? then use a fine file to set the proper gap? Did you use red rags to wipe the block down? I've seen red rag material in blown engines before.

964-C2

Thanks for your answers.
Sorry for my far from perfect writing, english is not my first language. But I hope you understand most of what I write..

The timing belt and balance belt are correctly adjusted (using my P9201 Porsche tool: 2,7 +/- 0,3 and 3,5 +/- 0,5).
The turbo I am using normally does not require a restrictor. But I tried putting in a restrictor to see if that helped reduce the exhaust smoke before I had the first failure. It did not help.
To my understanding a leaking turbo would either leak out the exhaust or into the intake through the intercooler + intercooler pipes. I have oil in the cylinders / combustion, but my intercooler and intercooler pipes are very dry. To my understanding, the problem can not be a leaking turbo then.

My oil pressure has always been good. About 2 bar at idle when the engine is hot (otherwise higher). We were also suspecting a bad lifter before I had my first failure. So I tried changing the location of the lifters to see if the sound would move from the back of the engine to the front of the engine. It did not.
I then swapped all 8 lifters with 8 lifters from another engine, no change in sound.
The knocking sound was not a lifter, but something coming from lower down i the engine (cylinder area).
When my engine builder opened the engine and I saw what the piston looked like, I thought it was clear what was making the knocking sound. To my understanding, the knocking was coming from cylinder / piston contact. Do you think this is not correct?
I did not build the engine or do any of the internal work on it. I had an engine builder do that (twice). I can not say exactly what he did, but he is experienced and should know how to do it right.

Im my mind, this is what has happened and what is causing the engine failures (but I could be very wrong, I have limited experience diagnosing failures like this):
1. The knocking sound is coming from cylinder / piston contact.
2. Cylinder / piston contact is possible because the rings was / is stuck in the pistons, caused by oil in the combustion / cylinders.

What I am trying to figure out, is how / from where is the oil entering the combustion. As I wrote in my first post, all my 4 intake runners are wet with oil. This is not normal, right?? I can not understand where this oil is coming from.
I believe understanding why my intake runners are wet with oil, will explain the failures.

gpr8er

wow, that's quite a mess.
I would suspect that the rings are wrong, cylinder clearances may be wrong (knocking), liners installed wrong...
Oil is being pushed in to the intake tract by the AOS vent line because the crankcase is being pressurized by the blow by. 2 bar oil pressure at hot idle seems a little low.

964-C2

Thanks for your input. If you were correct, shouldn't my turbo outlet / intercooler pipes / intercooler have traces of oil? They are very dry (AOS is attached at stock location).
Outlet of the turbo is dry:
http://i939.photobucket.com/albums/a...l/IMG_4299.jpg
Intercooler + pipes are dry:
http://i939.photobucket.com/albums/a...l/IMG_4298.jpg
Inlet of intake is dry:
http://i939.photobucket.com/albums/a...l/IMG_4297.jpg

Are you able to see the pics?

gpr8er

Well in that case I would suspect the valve guides or seals. Sadly this IMO is a complete teardown to zero, a do over.

964-C2

The cylinder head was rebuilt for the second rebuild. Did not make a difference (same problem before and after the second rebuild).
It will probably be a teardown to zero. But I would like to know why the failures are happening. Spending lots of money on a thrid build up of this engine without knowing why I have the failures, is not a good fealing (I fear I can have a failure once again).

gpr8er

There's some serious issues going on here. Hard to tell from sound on the computer but it sounds like rod knock. IMO all bets are off at this point. With this much is wrong I would consider a new builder. These motors are not rocket science but have some weird quirks and rules to follow. Where are you located?

lart951

Greg is on the right path wrong piston rings or sleeves compatibility, and tell me why do you think there should be oil on the pipes and turbo outlet? that is not entirely accurate but one thing for sure you MUST change the shop they obviously dont know what they are doing, failure after 40 miles seriously? who are these guys?

964-C2

Norway / Europe.

964-C2

Greg wrote that he thought:
"Oil is being pushed in to the intake tract by the AOS vent line because the crankcase is being pressurized by the blow by"
If that was correct, I think there should have been traces of oil in the intercooler, intercooler pipes and turbo outlet.

dizzyj

I had bad smoking and oil in the end of my intake runners. None at the throttle body/inter cooler

In my case it was improperly installed oil rings on the pistons. I had good compression and leak down

964-C2

Thank you very much for your input! That could be what is happening with my engine too, same symptoms.
So you think the oil in your intake runners was actually coming FROM the combustion chamber up into the intake runners?

I guess it is not possible to see from a picture if the oil rings are installed correctly or not, is it?
Pictures of my rings:
http://i939.photobucket.com/albums/a...ikjel/9511.jpg
http://i939.photobucket.com/albums/a...ikjel/9513.jpg