Day in a life of a 996TT motor build.
10-05-2004, 01:55 AM
#1
Rennlist Lifetime Member
Thread Starter
Day in a life of a 996TT motor build.
I thought I would share with you the typical day in an engine build. Not many people have dove into the TTs motors for several reasons. One I think because most are still under warranty. The need will arise sooner than later. There are some natural wear items and as the HP goes up so should the insurance policies. AKA, rods, studs etc. Everything has a purpose and a goal in mind. The one thing unlike the motors from years past is the 996TT motor is old and new technology combined. When that happens there is always a different way of doing things. This means a battery of tools that is required. We have always been able to slip by on the old stuff with very little mandatory tools. If you plan on building a 996TT motor be prepared to spend 3-4K in tools alone. This is if you already have the equipment for the older motors. I will out line as I go along the newer procedures and things that require a different tool.
Removing the motor is not any more difficult than any 993TT motor. More wires, more lines, more weight and coolant. Be prepared for one heck of a mess. I rarely make a mess, all bets are off on these motors. Even for me.
The amount of crap on the top of these motors is amazing. The maze of lines, additions and supports is staggering. The 993TT is nothing. It will take you a day if you are familiar with them just to clear the motor to the long block. Keep a keen eye out for the order that you removed things. If you go to assemble and do not reverse the order you will spend the next 2 days trying to figure out how in the heck the lines went under all the crap. I will post pictures of the motor on the table when I find what I did with them.
Once you have cleared the motor of the intake etc then you can start into the meat of the motor. You will remove the valve covers to expose the cams.
Notice the mess of coolant and oil draining, even 3 days later!
The next step is to remove tensioners, holders and cams. You will want to invest in the manuals. If you do not follow the order you run the risk of damaging the cams and or sprockets.
Notice the center of the top tappets. There are two sections to these tappets. The center section and the out edges. As computer deems necessary based on load, TPS, RPM etc the cams will switch from 3mm lift to 10 mm lift. If you look at the picture above you will notice the 3 sections to each lobe. This is the equivalent of 2 cams in one. The sections of the tappet will drop out exposing the desired section to achieve a specific lift. At the same time the cams are also advancing from the sprocket on the nose of the intake cams. It is a very elaborate system that relies on oil to act as a hydraulic coupler. This is what activates and moves these items. Never use anything other than the weight the factory recommends.
The next step is to remove the housing and remove the cylinder assembly. These items will simply pull off exposing the pistons and head studs only.
From here the motor splits like any other 911 case. The 14 case studs and a nut. The outer bolts and the case splits in half exposing the crank, oil pump intermediate shaft and chains.
This picture shows the original pump compared to the new GTIIIR pump to be installed. Notice the second pick up on the bottom. The new pump goes in without modification to the case. If you use high performance rods you WILL need to profile the pump 20 thousands. Notice the red ink on the installed GTIIIR pump. This is the profiling area. If you don’t profile the pump expect to be back in there. The rods will hit the pump as the big end passes on the stroke.
The newest gig from Porsche is a clear silicone that sets in 10 minutes. I am not and never have been a fan of silicone in any Porsche motor. I cleaned the case halves with a soft wire brush, steamed the cases then applied loctite 574 to the case halves. Notice the case through bolts on the lower channels. These are now sealed with O rings and the case has a beveled edge to seat the rings down when the case halves are closed. Also never forget the orings on the oil pump. For those of you reading, notice the oil pump bolts?
Next is the assembly of the head studs. I have chosen to go with an updated heavy duty version. These are not available from Porsche. These are aircraft strength and quality. Notice the coating.
Once the head studs are installed and set to 150mm from spigot you can preassemble and set the cylinder assembly. This is were things get very different from the past. In the older motors each cylinder was separate and assembly could be done in any order. In the new setup there is no way to install the pistons of you do not follow the order and have the special tools. You will want to press the liners out of the block and install new seals. I replaced the old style rubber ones on the liner with Viton, while the others remain a different compound. The liners must be pressed in. Keep in mind for final assembly the center liner has to be pressed in on the car with the special tools. I will post those tomorrow. For those that think you can buck the system and do it without. Forget it. Not happening. I promise. BTDT.
Removing the motor is not any more difficult than any 993TT motor. More wires, more lines, more weight and coolant. Be prepared for one heck of a mess. I rarely make a mess, all bets are off on these motors. Even for me.
The amount of crap on the top of these motors is amazing. The maze of lines, additions and supports is staggering. The 993TT is nothing. It will take you a day if you are familiar with them just to clear the motor to the long block. Keep a keen eye out for the order that you removed things. If you go to assemble and do not reverse the order you will spend the next 2 days trying to figure out how in the heck the lines went under all the crap. I will post pictures of the motor on the table when I find what I did with them.
Once you have cleared the motor of the intake etc then you can start into the meat of the motor. You will remove the valve covers to expose the cams.
Notice the mess of coolant and oil draining, even 3 days later!
The next step is to remove tensioners, holders and cams. You will want to invest in the manuals. If you do not follow the order you run the risk of damaging the cams and or sprockets.
Notice the center of the top tappets. There are two sections to these tappets. The center section and the out edges. As computer deems necessary based on load, TPS, RPM etc the cams will switch from 3mm lift to 10 mm lift. If you look at the picture above you will notice the 3 sections to each lobe. This is the equivalent of 2 cams in one. The sections of the tappet will drop out exposing the desired section to achieve a specific lift. At the same time the cams are also advancing from the sprocket on the nose of the intake cams. It is a very elaborate system that relies on oil to act as a hydraulic coupler. This is what activates and moves these items. Never use anything other than the weight the factory recommends.
The next step is to remove the housing and remove the cylinder assembly. These items will simply pull off exposing the pistons and head studs only.
From here the motor splits like any other 911 case. The 14 case studs and a nut. The outer bolts and the case splits in half exposing the crank, oil pump intermediate shaft and chains.
This picture shows the original pump compared to the new GTIIIR pump to be installed. Notice the second pick up on the bottom. The new pump goes in without modification to the case. If you use high performance rods you WILL need to profile the pump 20 thousands. Notice the red ink on the installed GTIIIR pump. This is the profiling area. If you don’t profile the pump expect to be back in there. The rods will hit the pump as the big end passes on the stroke.
The newest gig from Porsche is a clear silicone that sets in 10 minutes. I am not and never have been a fan of silicone in any Porsche motor. I cleaned the case halves with a soft wire brush, steamed the cases then applied loctite 574 to the case halves. Notice the case through bolts on the lower channels. These are now sealed with O rings and the case has a beveled edge to seat the rings down when the case halves are closed. Also never forget the orings on the oil pump. For those of you reading, notice the oil pump bolts?
Next is the assembly of the head studs. I have chosen to go with an updated heavy duty version. These are not available from Porsche. These are aircraft strength and quality. Notice the coating.
Once the head studs are installed and set to 150mm from spigot you can preassemble and set the cylinder assembly. This is were things get very different from the past. In the older motors each cylinder was separate and assembly could be done in any order. In the new setup there is no way to install the pistons of you do not follow the order and have the special tools. You will want to press the liners out of the block and install new seals. I replaced the old style rubber ones on the liner with Viton, while the others remain a different compound. The liners must be pressed in. Keep in mind for final assembly the center liner has to be pressed in on the car with the special tools. I will post those tomorrow. For those that think you can buck the system and do it without. Forget it. Not happening. I promise. BTDT.
10-05-2004, 01:56 AM
#2
Rennlist Lifetime Member
Thread Starter
This is the cylinder assembly with the center liner out.
This is a liner out of the block. Notice the updated seal.
Install the base gasket.
Number 2 and 5 preset ready for the cylinder assembly to be placed on.
I will continue with more pictures tomorrow. I don’t want to bore anyone. I do however want to share a few more things. I had mentioned premature wear on the thrust bearing and on the intermediate shaft thrust. The picture here shows at 40K miles the brass is visible on the thrust collar. Odd to say the least.
Here are a few of the cam tools need for the cams. Special holders and wrenches.
Heads, cam housing, cylinder assembly, valve covers and more. I have a high pressure steamer that will clean anything. Notice no cosmline on this motor.
This is a liner out of the block. Notice the updated seal.
Install the base gasket.
Number 2 and 5 preset ready for the cylinder assembly to be placed on.
I will continue with more pictures tomorrow. I don’t want to bore anyone. I do however want to share a few more things. I had mentioned premature wear on the thrust bearing and on the intermediate shaft thrust. The picture here shows at 40K miles the brass is visible on the thrust collar. Odd to say the least.
Here are a few of the cam tools need for the cams. Special holders and wrenches.
Heads, cam housing, cylinder assembly, valve covers and more. I have a high pressure steamer that will clean anything. Notice no cosmline on this motor.
Last edited by PorschePhD; 10-05-2004 at 02:11 AM.
10-05-2004, 11:02 AM
#6
Rennlist Lifetime Member
Thread Starter
I wouldn't be too concerned. We are seeing more and more small issues. It is hard to confirm 100% if it was component failure or user error. Compared to the number of cars verses failures in the industry the ratio is very small. The TT is a wonderfully built car!
10-05-2004, 12:19 PM
#7
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Great read and great pictures...if this motor work is an interesting/frustrating exploration to you, I can't imagine what anything on this motor would be to we mere mortals...
Keep us posted...we are very interested~!!!
Keep us posted...we are very interested~!!!
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10-05-2004, 02:16 PM
#9
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Stephen ---
Ditto on the above comments, awesome effort and great images/descriptions!
As much time as I've spent intently perusing your pictures of the various stages of disassembly, my wife likely assumes that I'm surfing illicit websites. This is far better than that (from what other people tell me, of course). Keep on going with this excellent contribution to the forum!
PS - is there an OEM P/N for those rubber bands? they sure don't look like a German elastomer!
Jeff
Ditto on the above comments, awesome effort and great images/descriptions!
As much time as I've spent intently perusing your pictures of the various stages of disassembly, my wife likely assumes that I'm surfing illicit websites. This is far better than that (from what other people tell me, of course). Keep on going with this excellent contribution to the forum! PS - is there an OEM P/N for those rubber bands? they sure don't look like a German elastomer!
Jeff
10-05-2004, 05:57 PM
#11
Professor of Pending Projects
Rennlist Member
Rennlist Member
The information you are posting and the images are priceless. Thank you for going to the trouble of documenting most of the process. The mention of the tools required is great.
Again, thanks for the extra effort on keeping us informed of the process and the photos of the internals.
Awesome!
Again, thanks for the extra effort on keeping us informed of the process and the photos of the internals.
Awesome!
10-06-2004, 01:49 AM
#15
Rennlist Lifetime Member
Thread Starter
Ok, time for more pics…
We talked about the pressing in and out of the liners. Below is a picture of the procedure for pressing it out. I use a hydraulic press to do this. Notice part of the Porsche tool in the liner.
The next picture show the liners on the outer cylinders and the factory spacer tool behind the cylinder block.
This is a picture of one of the two circlip tools you will need. There is an art to using these and making them help rather than hurt. Install it wrong and the circlip will pop off and roll into the newly sealed case. You guess it, hope you are good at fishing.
Next is the picture of the piston being compressed in the ring and supported by the Porsche OEM tool.
There are other ways to do this procedure, but to be honest the OEM tool keeps it simple. You will not loose time by continuously slipping past the rings.
One of the interesting things about the 996TT pistons that is unlike any Porsche piston from the past is the second ring land. The groove has a dowel as seen in the picture that prevents the ring from spinning in the cylinder. When reringing the piston I highly recommend you place the oil scraper ring away from the bottom of the cylinder. This will prevent unnecessary smoking from time to time.
Once the cylinder assembly is installed on the spacers you will need one of these. Once again this is about an 800.00 tool.
Here is the tool installed and live at work.
This picture shows the headgasket. When installing notice the orientation. There is a face of the gasket. The gasket is a three part gasket riveted together. There is only one way to install this.
Here are the heads back on the motor and torques to spec.
One nice upgrade is the use of the older style chain housing gaskets. The 993 style has about a .5mm more rubber on it than its newer brother for the 996TT. The gasket on the left is the 993 version, the gasket on the right is the 996TT gasket. They are interchangeable. I also suggest this to the chain tensioner gaskets.
We talked about the pressing in and out of the liners. Below is a picture of the procedure for pressing it out. I use a hydraulic press to do this. Notice part of the Porsche tool in the liner.
The next picture show the liners on the outer cylinders and the factory spacer tool behind the cylinder block.
This is a picture of one of the two circlip tools you will need. There is an art to using these and making them help rather than hurt. Install it wrong and the circlip will pop off and roll into the newly sealed case. You guess it, hope you are good at fishing.
Next is the picture of the piston being compressed in the ring and supported by the Porsche OEM tool.
There are other ways to do this procedure, but to be honest the OEM tool keeps it simple. You will not loose time by continuously slipping past the rings.
One of the interesting things about the 996TT pistons that is unlike any Porsche piston from the past is the second ring land. The groove has a dowel as seen in the picture that prevents the ring from spinning in the cylinder. When reringing the piston I highly recommend you place the oil scraper ring away from the bottom of the cylinder. This will prevent unnecessary smoking from time to time.
Once the cylinder assembly is installed on the spacers you will need one of these. Once again this is about an 800.00 tool.
Here is the tool installed and live at work.
This picture shows the headgasket. When installing notice the orientation. There is a face of the gasket. The gasket is a three part gasket riveted together. There is only one way to install this.
Here are the heads back on the motor and torques to spec.
One nice upgrade is the use of the older style chain housing gaskets. The 993 style has about a .5mm more rubber on it than its newer brother for the 996TT. The gasket on the left is the 993 version, the gasket on the right is the 996TT gasket. They are interchangeable. I also suggest this to the chain tensioner gaskets.
Last edited by PorschePhD; 10-06-2004 at 10:06 AM.