Not 911 but close.....
 

I wrote this article for our local PCA newsletter what do you guy's think??

In this article we will show how to disassemble a 2.5 Boxster engine and show a lot of things that unique about its inner workings. This engine has suffered from a intermediate shaft failure we will look into seeing why it failed. Of course this will be a broad article and will not touch on all aspects of engine disassembly and reassembly

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We start with engine out of the car and all accessories’ removed like A/c compressor and Alternator etc. The first thing we remove is the valve covers from the motor. The valve covers are not movable from side to side or from one engine to another as the cam bearings are made into the cover it’s self and cannot be replaced with out replacement of the cylinder head. Also there are two pumps one on each cylinder head that run’s off the camshaft the pump’s are the same but must be indexed to the correct head or they will not work correctly. These pumps are used to return oil to the sump under extreme use when all of the oil can end up in the head and not in the sump where it belongs

The next step is to remove the camshafts from the head along with the camshaft adjuster. Now there is also two other bearing caps that now must also be removed. The camshaft is turned by a timing chain which is secured by four bolts. Remove the four bolts and the two bearing caps there is also three bolts
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Now you can see the cams and adjuster removed from the motor you will also notice how the adjuster works. The solenoid is controlled by the ECM to allow oil to flow into the adjuster which in turn moves in and out causing the camshafts to advance
Now on the Boxster engine the chains run on chain rails which are controlled by chain tensioners Note that there are three different tensioners on the engine Two separate tensioners for Bank 1 and Bank 2 and another for the chain between the crankshaft and the intermediate shaft. These must be installed in the correct location for proper chain tension.

After removal of the cams you can remove the lifters and the holder for the lifters you must keep each lifter with its cam lobe. The holder can be removed by removing the bolts holding it to the head and it then it simply comes out. You will notice that not all bolt’s you remove are the same take note of this so that they can be installed back into the correct location I removed everything at on time for ease.


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Now you can see the lifters removed from the head take note of the valve springs shape they are not straight up and down they are cone shaped this gives them a strong spring rate but with less weight as using dual valve springs which in turn allows the motor to rev more freely and be more efficient. The Cylinder head is secured to the motor with six TORX bolts you must be careful and use a quality socket to remove these as they will strip out easily. There are also four bolts on the perimeter of the head that must be removed also.
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Feed back welcome guy's

Pulling back the veil of mystery around the water cooled cars...LOVE IT.

Interesting. I'm glad I'm rebuilding an '84 air-cooled motor.

Is it normal for the camshafts to be rusty like that, or is that a sign that things weren't sealed properly or something? I only ask because I'm used to seeing wear and/or pitting in disassembly pics, but not rust.

No the rust isn't normal this is just an old core engine that I got just to do the article and some tech stuff with it sat outdsde for a couple months.

Here are some more picture's of the bottom end I will finish up the rest of the article

Are those ball bearings??? I'd hate to see those ejected at speed!! Can you say shrapnel?

-michael

fairly deep valve pockets in those piston domes!!! Must be an aggressive cam used in these engines? What is the compression ratio and fuel requirement for this boxer?
Cool stuff!!!
Bob

Those are ball bearings the intermediate shaft is supported in the rear by roller bearings.

The engine does have 11.0 to 1 compression

Hello 911quest
I’m interesting by how to disassemble a 2.5 Boxster engine
How can I read more of 11-20-2007, 04:46 AM
I live in Belgium (Europe) Thanks Pimpon21lg
Sorry translation Google

YAY, Hans. F'n Torx head bolts. AS if the 12pts weren't bad enough. I see some head studs replacing those. Open deck block, damn won't like much boost. We could fill it with Hard Block. No hope of pinning the block, coolant passages right smack in the middle of the cylinders.

I could see pistons making a decent increase. The heads will definitely need work. I already see some shrouding in the chambers. Wonder what the ports look like.

What drives the two oil pumps in the sump? No way to dry sump it and set it lower in the chassis.. What do the freeze plugs on the bottom of the sump go to? How tall is the whole engine with the sump on?

Thanks for the pics.

Yeah! Me too.

Theres only one oil pump the other two parts are oil/air seperators the sump just has a flat cover I would say it was 6-8 inchs deep.

The crappy thing was I took the motor out to some property I own to store it out there and some meth head stole the dam thing for scrap.:mad:

Here you can see where the noise is coming from in this motor. The rear intermediate shaft bearing Porsche uses is a ball bearing similar to a wheel bearing this is what came apart in this motor probably due to lubrication problems this is one of the weak points in the water cooled motors. This area is also one of the culprits of the notorious oil leaks and of course the rear main seal more on that later.

In the other picture you can see more damage from the bearing coming apart. Fragments of the chain rails and shards of metal from the bearings. Also not shown in the pictures is the sump cover it is unique in it’s design as if has a flap on each side of the oil pump pick up to help keep the pick up submerged in oil during cornering.


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You can see the oil pump pick up screen and the two other parts on each side of the sump are the air-oil separators these are used to keep the oil foaming to a minimal which could lead to a loss in oil pressure. Porsche went to great lengths to keep these motors from starving for oil as these motors don’t incorporate an oil tank like the air cooled 911’s.

In the next step is to separate the case half’s once you remove the perimeter bolts there is only three remaining bolts that hold the case half’s to the crankshaft assembly one on one side and two on the opposite side. Now the way I took the motor apart is different then the way you would if you where actually on planning on reassembling this motor. There is an access hole on the 4-6 cylinder side of the motor so that you can pull out the wrist pins and remove that case half with the pistons staying with that case half. The way I did it was just to leave the pistons attached to the crankshaft.

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Now you can see the crank shaft assembly and below that is the intermediate shaft once you get to this part you can see how the RMS could become a problem as the whole crankshaft sits in a cradle and what happens is the cradle can shift and move inside the motor no longer allowing the seal to correctly do it’s job.http://forums.pelicanparts.com/uploa...1201143534.jpg

Now there is a special fixture that is supposed to be used to lift the crankshaft assembly from the case it is heavy, it is basically a plate that bolts to the assembly that allows you to use an engine host to lift up and out of the case. Here is another photo showing the relation between the crankshaft assembly and the case also in the photo you can see the access plug used to get to the wrist pins.

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This is what the crankshaft and its housing look like once removed from the engine. Now you can remove the main bearing bolts used to hold the housing together to service the crank and the rod bearings.

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Here are some of the special tools needed to reset the cam timing during reassembly of the motor

A) Fixing pin for the crank pulley 9595 allows rotate the motor over
B) Auxiliary chain tensioner 9599 used to set the proper tension on the chains during timing
C) Locking device for camshafts 9612 Locks camshafts in timing position
D) Ring wrench no tool number used to tighten the tensioners
E) Holding device 9634 holds the camshafts down
F) Holding device 9611 holds cam shaft down (not shown but similar to 9634)

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It shares a lot with the water-cooled 911 engines also. One major difference is the way the Vario-cam plus works. It uses a locking style lifter that basically two parts as the cam has two separate lobe profiles. As you can see in the diagram above when the engine desires low camshaft lift the small lobes open the valve and when more valve lift is needed the locking pin is actuated and the lifter locks allow the valve to open further.

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