As Promised, Engine teardown pics.

[AFJuvat]

1998 Boxster with 5X,XXX miles. Car has been well maintained.

The original complaint was coolant spraying out of the coolant tank cap (valve in cap opens at 1.8 bar of pressure.) Eventually coolant level would drop, triggering the low coolant light.

Pressurizing the cooling system produced no detectable leaks. Dealer had replaced the following attempting to rectify the problem

Coolant tank cap replaced 4 times
Coolant tank replaced
Waterpump replaced.
Bleeder valve on coolant tank replaced.

Unfortunately, non of the above rectified the problem. Previously, my shop had filled, bled, and pressure tested the cooling system as well with no leaks detected and no "clues" as to what the problem may be.

The last time the car came into the shop for some routine maintenance, we finally detected a coolant smell coming out of the exhause (it was not there before)

Rotating the motor to TDC on all cylinders and then pressurizing each cylinder to 70 PSI indicated that air was leaking into the cooling system in #6 cyl. This indicated one of the following:

Bad head gasket
Cracked head
Cracked cylinder

After removing the motor, and removing the head, we found that the head gasket was indeed bad, but for a completely different reason: The cylinder sleeve had pulled. The total distance was less than 0.25mm - but just enough to break seal and allow combustion gasses to enter the cooling system, but not enough to allow coolant into the combustion chamber until the head gasket started to develop significant cracks in the sealing surfaces.

The first picture is cyl #6 - my thumbnail is resting on the split between the cylinder and the sleeve.



This next picture is #6 again, I ran a marker around the sealing surface of the cylinder - the white line you see is the area where the liner pulled away.



This next shot is #6 again - notice the concentric lines in the cylinder- that is where the piston "walked" across the face of the cylinder because the liner is actually pulled out more on the bottom that the top.



Here is Cyl 5 for comparison




Here is a shot of the head bolts - Difficult to see in this picture, but they are approximately 1 foot long.



And lastly, here is the engine compartment, without an engine.


Tomorrow, we order a new engine.

AFJuvat

[85percent]

nice pics. same thing happened to my 99 boxster.. what kind of engine is going to replace it?

i'm having a 996 3.4L installed in mine right now...

[AFJuvat]

It is a aftermarket warranty repair, so another boxster engine is going in.

AFJuvat

[85percent]

you're getting a warranty repair for a 98?? =o0

[Tool Pants]

Hard for me to figure out the pictures due to the slight damage. Was the cylinder bored out and a metal sleeve installed?

[AFJuvat]

No, that is the dreaded "cylinder liner pulling" problem that kills boxster motors.

It just pulled enough to blow a gasket, rahter than pull all the way into the motor and destroy it immediately.

AFJuvat

[trj911]

Nice pics and and description. I hope I never have to see it in person!

[Tool Pants]

What is the difference between a liner and a sleeve, or is it different words for the same thing. The thing in your picture that has pulled down a bit is made of what material and how did it get there?

http://www.pca.org/tech/tech_qa_question.asp?id={F3EA752A-E838-43E5-A43D-BB4F445F5A8F} This PCA article talks about a preformed silicon liner that is inserted into the block mold before the metal is cast. Then it talks about an out of spec block that has been bored and a liner pressed in. Which version is in your pictures?

I am use to the "slipped sleeve" problem of some 1998/1999 motors. To me this is when an out of spec block was bored out and a metal sleeve pressed in, like in the middle cylinder of my picture. Am I seeing something different in your pictures? Thanks. Jeff

http://www.pca.org/tech/tech_qa_question.asp?id={F3EA752A-E838-43E5-A43D-BB4F445F5A8F}

[Tool Pants]

The direct link to the PCA article does not work.

Try http://www.pca.org/tech/tech_qa.asp Select Boxster then, search on "MY99 Boxster cylinder liners" for a 6/14/2004 article by Scott.

[AFJuvat]

Sleeve = Liner. Talking about the LOKASIL liner. Same thing that is in your picture. The one in my picture didn't slip very far and it slipped at an angle.

One thing I've noticed as well - notice the green around the bad cylinder? The engine I took pictures of has the same thing - just around the bad cylinder. The other cylinders have a tan residue around them. Interesting, I wonder if it coorelates to something.

AFJuvat

[Tool Pants]

My picture is an engine that was bored out and a metal sleeve installed. The sleeve has a lip on the top that fits into a grove machined at the top of the cylinder. The lip keeps the sleeve from being pulled down. The sleeve can't move up because of the head. The sleeve looks like this.

|_ _|
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The lip breaks permitting the sleeve to be pulled down. Then the top of the now broken sleeve gets caught by the piston ring. This pic is the broken off lip from another sleeved engine.

I think the silicon liner/sleeve is very different and not a true sleeve. It is some fiber material with 25% silicon and the rest air. When the metal is poured in the mold the sleeve goes away and all that is left is the silicon that bonds to the cylinder wall and becomes part of the metal. I do not see how there is a "sleeve" that can move.



My drawing of a sleeve went out of wack when the message was posted. Looked good when I typed it.

[Tool Pants]

He is my drawing of the metal sleeve Porsche put into out of spec crankcases. A mechanic I know has taken at least 2 of these engines apart. The lip fractures off from the body of the sleeve thereby permitting the sleeve to be pulled down the cylinder. I put an arrow to where the fracture occurs. The lip is then just a ring of metal and that is what is in my second picture.

This is not related to the Lokasil sleeve that is placed in a mold when the crankcase is cast.

[eddieo]

I'm a 944 turbo owner who has been offered a 1997 boxster with a cylinder head gasket problem. How can I diagnose whether the engine is OK ? I assume the pistons will need to be removed if the liner you have been discussing has ruptured. How easy is it to remove the engine from a boxster - do you need to drop it onto the floor?
Sorry about all the questions

[HardDrive]

Wow, cool thread guys. Great photos and explantions. I hope I never have a conversation about this with my wrench!

[Britwrench]

Eddieo:

Do a leakdown and compression test. If it has internal problems, got to come out. Budget for a clutch, coolant tank and other external parts during the rebuild or replacment.

Call Josh Sadler at Autofarm as they can rebuild 987/996 motors.
I believe Autofarm also updates the intermediate shaft at the same time.

[village idiot]

Were these problems rectified in later models(2000 and later)??

[NOTASIX]

Our solution.

http://www.lnengineering.com/boxster.html

After two years of preparation and planning we have now teamed up with LN Engineering to create a true Boxster engine development program based on the original 2.5/2.7 engine.

Details to come later, the test car has been acquired and we are working to complete the first engine for field testing.

This process allows the use of Nikisil technology along with effective bore increases of up to 4mm a reality without losses of cylinder integrity.

Further upgrades including billet rods, coated bearings, and forged pistons along with both cam, head and ECU manipulation are just around the corner.

[ZoomGlide125]

Juvat, are you going to the PCA coffee clache' the 29th? If you are I'd like to talk to you more about this, I have a 2001 S and just would like to learn a bit more.

Merry Christmas!
v/r
Christian

[dweymer]

So what is the fix? New case or can it be re-sleeved?