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Clutch, AOS, Water Pump, Thermostat DIY Questions

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I am presently in the disassembly stage to replace the clutch, AOS, water pump and thermostat on my 2006 C2S. I am having real trouble finding good accurate DIY instructions on the parting of the trans-axle/transmission from the bell housing for the 997.1. All that I can find are DIY bits and pieces on the 996 which are often inaccurate (one refers to the IMS as the "balance shaft"...hmmm..) or they refer to the 996 GT3's and 996tt's which appear to be different from the 997.1.

I have already removed much of the bolt-ons and connections from the trans-axle/trani. I have also loosened the all bolts to the bell housing except the top one which will require dropping the front of the motor just a bit. Man, these bolts needed over 100 ft/lb to loosen. Hopefully the top one will be easier!

I have a number of questions for our member experts out there that I would appreciate answers on:

1. If I am not replacing the RMS (which was done 3 1/2 years ago on warranty), do I need to replace the casing bolts above and below the RMS?

2. The coolant capacity from "dry" is 8.45 gallons according to the manual. Dealer says that I will need two gallons of coolant and another 2 of distilled water which means that half the old coolant will remain in the car-kind off unacceptable. How much could I reasonably be able to drain as a result of opening up the water pump, thermostat, the bottom drains on the motor, the tubes around the trani and the bottom hoses on the two front rads?

3. What would be a good replacement transmission oil (other than what Porsche supplies)?

4. I am only familiar with the old style clutch fork/release bearing from the pre-hydraulic Porsche era. Is there a specific trick to lining up the clutch release lever and release bearing on re-assembly of the 997.1?

5.There is a big variance in values in DIY threads on the web and none that I could find specific to the 997.1.

I would welcome factory torque values for the following bolts:

a. Water pump

b. Thermostat

c. Bell housing to trans-axle

d. Fly-wheel

e. Clutch housing to flywheel

f. IMS bearing cover

g. Case bolts around RMS

I would appreciate any help, past experience, threads and suggestions.

Thanks in advance.

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1. Do not touch the case bolts above and below the RMS unless you intend to split the cases for some reason.

2. You will only get about 90% of the coolant out of the car.

3. Do not use any other gear oil but the OEM stuff, we are constantly draining transmissions of "lube experiments" gone bad. Simply ain't worth it. The Porsche product is a full synthetic designed for Porsche, which has no true aftermarket equivalent.

4. Not really, you just line them up

5. Nearly all, if not all of these torque specs can be found by conducting a quick search. In most cases, they are the same as 996 values, but do not use the values for the Metzger design engined cars you mentioned (GT, Turbo), those are different as the engine is completely different.

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Here are my tips on replacing the AOS.

I followed this DIY thread found over on 6speed: AOS DIYand also consulted the Porsche workshop manual.
Here are a couple tips, to add to the DIY.
- You can take off the entire throttle body including the middle section as one piece.
- Both coolant hose connections located on the left side of the AOS have the same clip system. The first clip is visible, the second clip is facing down and not visible. These are the hardest to take off.
- You will need to take off the second plenum to allow for ample room to take out the AOS and to install the new AOS.
- Be careful working with the breather hoses since they can be brittle since they've dealt with ample heat and dirt oil over time.
- Use a heater to warm up the rubber seals on the side of each plenum. This will make them more flexible and much easier to re-install.
- Apply some white lithium grease to the clips for lubrication if they are hard to turn.
- Purchase pentosin 202 power steering fluid so that you can refill the power steering fluid reservoir after the car is back in one piece.
On a scale from 1-10 in terms of difficulty I would rate this a 6 or a 7. Mostly because of the AOS location and all of the hoses which need to be disconnected.
Pictures during and after.
My AOS was quite filthy and had a fair amount of dirt and oil residue built up on it.
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Thanks JFP, death and Loren.

I searched and found all the torque specs here except for the bolts that hold the transaxle to the motor.

Can anyone help?

Also, if I R&R the AOS from the trani side, I do not touch the P/S reservoir, right?

Edited by Uwon
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Thanks JFP, death and Loren.I searched and found all the torque specs here except for the bolts that hold the transaxle to the motor.Can anyone help?Also, if I R&R the AOS from the trani side, I do not touch the P/S reservoir, right?

The M12 bolts are 63 ft. lb; the hex head M10 bolt is 33 ft. lb.; and the M10 multi tooth bolt is also 33 ft. lb.

If you do the AOS while the gearbox it out, it is out in the open.

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Thanks JFP for those specs.

Well, it is now Saturday evening hoping that I would have the transaxle/trani out but no such luck. The assembly comes out about 3/4" and no more in spite rocking the assembly gently, changing the angle of the trani and motor and even pushing the trani back in. I have disconnected and moved out of the way the plug on top of the trani, the slave cylinder, the half shafts, two shifter cables, electrical wires on top right and front right of trani, and the 9 bell housing bolts. The bell housing is clearing the suspension cross member. Front horseshoe trani mount and lateral braces have been removed been. I have rechecked my steps and have run my hands over and under without any obstruction. I am now at my wits end.

How much prodding/ force should I use? Crow bar? Any suggestions would be welcomed.

Edited by Uwon
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+1 to JFP comment, if the engine and trans are not balanced or aligned together when removing, for example if the trans is at an angle it may not slide out easily because the weight of the transmission is on the shaft.

You can use a crow bar but do so ever so gently and put something in between the mating surfaces like a thin metal plate or wood to protect from damage. It should not need excessive force.

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Well, 8 bolts on the bench and 9 in the picture. I get the dummy award this weekend. Must have got distracted and not retreived the top bolt . Back to mechanics 101. LOL trani slid out without much effort.

Tomorrow, the clutch and flywheel comes out. Can already see trace of oil inside the bell housing.....

Keep you posted. Thanks for your help JFP and logray.

Edited by Uwon
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Yep that top bolt is a PITA. You can lower the engine and trans down a few turns to give more access. I use a several foot long 1/2" extension w/wobble socket to get up there and it works great. Next time I'm in there though I think I'll just drop the engine. Makes reinstalling the trans easier and you can also get to other bits on the engine much easier.

The oil in the housing is pretty normal. With the PTFE RMS is installed correctly and a new bearing flange goes in (with a little flange sealant) usually the only thing you'll see in there after cracking it open is clutch dust.

When you do the bearing cover DO follow procedure. You must lock the cams and release tension on the chains (i.e. remove tensioners) otherwise you'll have a big timing mess to deal with.

Also with the question of how many gallons of coolant will I get out, if you are only draining from the rear, you might only get 2-3 gallons out.

And lastly I know JFP said don't touch the case bolts, if you have a 997 you should not touch them but early 996 engines used non micro encapsualted bolts in that area that were prone to leaking, which is why you read in many places they need to be replaced

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Hi logray,

Reference your third paragraph. Are you saying that if I open the IMS cover, I first have to lock the cams and release tension on the chains? Looks like it's a 22mm nut on the end of the IMS cover, consistent with the 2006 C2S.

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Hi logray,

Reference your third paragraph. Are you saying that if I open the IMS cover, I first have to lock the cams and release tension on the chains? Looks like it's a 22mm nut on the end of the IMS cover, consistent with the 2006 C2S.

If you intend to remove the IMS cover flange, you need to prep the engine as though you were going to remove the bearing itself (crank locked at TDC, cams locked, tensioners removed, etc.). If you do not do this and remove the cover flange, the shaft will be pulled to one side and you will never get the flange back on again. If the cover flange shows no signs of leakage, I'd leave it alone.

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You definately need to read the workshop manual &/or procedures before you just start unbolting stuff.

Even if you aren't replacing the bearing (which you can't unless you tear apart the engine), you still need to follow the complete bearing replacement procedure anytime you deal with the IMS flange otherwise your timing WILL be compromised and your engine will explode!

Here is a link:


The end of the IMS tube that you are going to be looking at is held in position by the IMS flange (what you refer to as cover).

When you remove the IMS flange there is nothing to hold the tube in place, it will just sorta "float" around below the oil scraper.

There are drive chains forward and aft on the tube, and normally they are under tension by springs via several chain tensioners, and then even more tension once there is oil pressure.

Lets say you don't remove the tensioners. You may find it difficult to remove the IMS flange because of the tension on the tube by the chains. Then when you do remove it (if you are able to), the tube will slam HARD against the oil scraper and you will find it impossible to put the new flange in place because of the tension on the chains is pushing the tube to one side.

So, I won't get into the part about the cams, but you should lock those in place too along with placing the engine at TDC and locking the underdrive pulley as well.

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I do remember now that I saw a video, which I cannot find now, on locking the cams, etc. I think, but I am not sure, that it was posted by LN Engineering but may have been pulled as they appear to have changed their web site. The link http://www.lnengineering.com/imsretrofit.pdf is not descriptive enough for someone like me that has only worked on air cooled Porsche motors.

I'll only pull the clutch/flywheel and inspect today. Then I will have a better idea whether I have to learn about locking the cams, etc.

Keep you guys posted. Thanks for all the advice.

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Both LN Engineering and Jake Raby have moved away from direct support of the aftermarket (read DIY), primarily due to the simple fact that even though they supplied fully detailed instructions and specialized tooling, there are simply too many ways to screw up and only one way to do this correctly. And as nature always sides with the hidden flaw, which is this case tends to be those that either cannot, or will not, read and follow directions; they found themselves spending 90% of their time trying to unravel 10% of the IMS installs that went south. So they now tend to be less forth coming on information.

Get the correct instructions, read them, and follow them. To do otherwise may be to dig yourself a hole that maybe difficult to get out of…………..

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So here are some relevant pics.

Bolts above RMS are slightly dirty.

RMS looks really clean.

IMS flange is dirty.

Clutch disk is evenly worn. Measures 8.39 mm total thickness. all rivets are at least 2 mm deep.

Clutch assembly is smooth as new.

Flywheel is smooth as new. there is no ridge where my finger is pointing.

My first thought is that I will not replace the clutch. Traditionally, I have never been hard on them even at the track. I learned to double clutch on a Model A that I restored in my teenage years and a continue to double clutch to this day.

However, I do not know how to read the dirt and slight moisture around the IMS flange.

Any thoughts?








Edited by Uwon
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Thanks logray and JFP for the link and blunt advice. I have now had a chance to review and I understand the seriousness of not following to a tee, if indeed I open up the IMS flange.I forgot to add in my previous post that the motor and clutch have 58,000 miles.Any thoughts on the prognosis of my IMS flange would be welcome.

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Nice work. I would clean the area on the case, but not go further. Unless you have compelling evidence to the contrary, now you have the peace of mind to know your rear engine seals look good. Reinstall the flywheel usuing new bolts in the correct sequence and angle. Then replace what clutch parts you want and reassemble the transmission. I would not touch the ims or rms, what you see in the pictures is totally normal and not a reason to tear into the motor.

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Thanks logray and JFP for the link and blunt advice. I have now had a chance to review and I understand the seriousness of not following to a tee, if indeed I open up the IMS flange. I forgot to add in my previous post that the motor and clutch have 58,000 miles. Any thoughts on the prognosis of my IMS flange would be welcome.

If the dust collected around the IMS flange is dry, just clean it off and leave the flange alone. If that is all the crud built up in 58K miles, the IMS seals are doing OK.

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Thanks guys.

I am probably suffering a bit from IMS/oil leak paranoia so I have to apologize if I seem overly cautious.

I have now started to clean the IMS flange and found that the small amount of crud at the bottom is a bit wet with oil residue. See pic attached. The blob at the end of the small screwdriver is definitely wet/shiny. Now, this could be the result of a leftover from when the dealer replaced the RMS on warranty in December 2009 at 13,000 miles. What is bothersome is that the rest of the housing is so darn clean that I would have surmised that the technician would have cleaned up any oil residue prior to reassembly. There is no apparent other source for the small oil residue-I have checked under and around the bottom of the motor. So, the pendulum in my mind is swinging form leave it alone to go further.

I will, however, pull the oil pan and split the oil filter to make sure that there is nothing foreign there. (I regularly split the filter and get an oil analysis done by Blackstone Labs.)

I am replacing the pilot and clutch release bearings on reassembly despite the fact that the current ones appear to be OK.

I am planning to lightly smear the splines on reassembly with Lucas X-tra Heavy Duty Wheel Bearing Grease rather than a lighter grease that may spray or drip. Any opinions?

Also, any particular disadvantage in using Hylomar Universal Blue Racing Formula gasket sealant (good to 500 degrees F.) for the oil pan rather than the Porsche stuff?


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That really is not a lot of gunk there... the seals look to be doing reasonably well.

If you had done the flange replacement procedure many times before and had the cam lock tools, etc, I would say go for it. But there really is potential to do much more harm than good just to fix a little oil leak, which in that quantity of leaking oil over that amount of time is not going to cause a problem other than making a small mess when the transmission is removed. It has no "bearing" on the health of your IMS bearing or anything else. It is basically treated as just another engine leak, which I'm certain there are more on your engine right now that will probably be there for the life of the car and no-one will ever notice them and they will never cause any problems.

The thing is, a leak on the IMS flange is really secondary (and a very minor problem) compared with the actual problem of the IMS bearing itself. However, you should have nothing to worry about in that department because your engine has the larger IMS bearing which is about as strong as the original dual row, and the occurrences of failures in these two designs is small compared with the cars that have single row bearings.

I would not use any other sealant except drei-bond for the sump plate. You can pick a tube up at your local Porsche dealer for about $15-20.

I would not use anything on the splines, but if you do use something, use it very very sparingly.

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Thanks logray.

New flywheel bolts, clutch bolts and drie-bond ordered. Already have the bearings.

I have a friend of mine who has an auto mechanic shop who is interested in purchasing the LN Pro Kit as he is starting to have a number of 996 customers....hmmm. Having said that, I think that your suggestion to leave the seal alone is a prudent one.

Keep you posted.

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