yelcab

I am about to yank out the cam shafts on a 2007 Turbo engine. I do not have the factory cam set up tools to put the cams back, but I do have the ability to do cam timing IF I know what the overlap specifications are.

Can someone post the overlap cam specs for a 2007 Turbo engine?

yelcab

So no published cam setting specificaitons? Just the $1,000 tools?

Catorce

Yup, you need the tools. You can't easily time these like you can a 2 cam motor. Which is why there are tools.

Kevin

yelcab,

What are you trying to fix with your engine?

Did you get your answer from this Thread/Post?

https://rennlist.com/forums/996-gt2-...-or-right.html

Fix your issue>>cam sleeve failure, inlet tappet, bent valve or head gasket.

Then find a Porsche dealer or Indy that will cam time your engine.

As you know the tools are engine specific. You need different "LOCKS" for every 4 cam engine(GT3 vs Turbo). The vario cam wrench and exhaust cam wrench is a must have "even" if you are tearing the top end apart.

Goodluck

o7silverturbo

There is no overlap cam specs. These engine are not like timing a regular engine. there is no mark for TDC you have to find true TDC

I was going to buy the tools for when I got the camshafts pinned but I talked to a local Porsche performance shop here in new jersey and they would charge me between 6-8 hours to take the engine apart pin the cams and re-time everything. I would be pulling the engine and undressing it.

So even at 200 dollars an hour (which they are not) it would be 1600 dollars. The tools cost between 4-5 thousand. Doesnt make sense to buy them, id have to have the engine apart and re-time four times to make them worth it

yelcab

I have a 997 turbo that is making a very scary noise that seems like it is coming from the vicinity of the IMS. It is definitely chain noise. So the guesses are stretched chain, bad (brand new) chain tensioner, IMS sprockets, about to break chains, or ramps. To properly fix this, the engine has to be split which means the cams have to be timed on the way back.

I have timed over twenty Ferrari 4 cam engines so I know what I am doing when it comes to cam timing with degree wheel and precision gauges, I just need the specs. If there are no specs, what I am thinking of doing before disassembling, I will find CYl 1 TDC with a degree wheel, then measure the overlap specs of both the intake and exhaust cams and put the engine back to the exact same specs.

I might need to scribe or somehow make my own assembly marks as starting point.

Does that sound like a good plan?

Catorce

Yelcab,

I applaud you for trying to work on this yourself; that's my biggest complaint in this subforum, that few do their own work.

However, and I say this respectfully, it doesn't sound like you know what you are talking about with regards to this repair. And that's OK, that 's what we are here for.

I am an engine builder and a manufacturer of the Mezger case. Needless to say I know a lot about these motors.

Your classic 2 cam motor is timed using dial gauges and factory specs based on what cam you use, probably a lot like the Ferraris you are talking about. It's not hard, but it also requires a handful of special tools, not to mention dial gauges and Z blocks.

Your 4 cam motor is very different, mainly because of that extra cam on each side and the variocam nature of the intake cams. The exhaust cams are basically normal cams on these motors.

You need special tools to do this job; that is the procedure depicted in the WSM, which brings me to my next point.....I would not tear down a 997TT motor without a PIWIS 2 tester and WSM. I have both, which is why I work on these motors.

Lastly, if your problem was purely chain related (which I doubt), there would almost always be no need to split the case; you could replace both chains with master link chains without touching the case. You can see enough of the layshaft on a Mezger motor to determine if everything looks OK down there.

I am not sure where you live, but if I was doing the job you are doing, I might consider getting a WSM at the very least, tearing it down, finding the problem, then having someone time the cams for me with the tool.

I have 2 997TT so for me the tools to fix them make sense, I buy them as I need them.

For stock cams its just way easier to use the tools. Once you see the pictures in the WSM you will know why you cannot just degree wheel them or dial gauge them like you would on other cars.

yelcab

Thank you Catorce

In my stable: Ferrari 328, Ferrari 348 Challenge, Ferrari 355 Berlinetta, Ferrari 355 Spider, Porsche 997S, Porsche 2005 GT3, and I have torn down more Ferrari motors and aircool Porsches than I really remember. All Ferraris I worked on are 4 cam motors.

Cam timing of a 4 cam overhead cam motor is a walk in the park for me. I have all special equipment needed for the job. I just don't have the Porsche tools.

I will admit that this will be the first Mezger engine I tear down. Maybe it is designed such that my indicator cannot touch the valve tappet. If that is the case, then OK, buy / rent / beg / borrow or steal the tools it will be. Speaking of tool rental, would you care to rent them?

But, variocam engines (a Ferrari 360) can be timed with the varator off. I assume a mezger engine can be timed with the variocam off too.

Finally, I suppose I can take the motor to someone with the tool, but ... that sounds so unprofessional. I have not seen a mechanic in 25 years. Why start now? It's a hunk of metal, I can beat it.

Catorce

Well you can see what is in my stable in my sig. I get, it you are handy with a wrench. I understand.

HOWEVER, you need to get it through your head that the TT and GT3 motors are NOT TIMED LIKE THE OTHER CARS.

Every Porsche manual that I have, from the 944 to the 928 to the 1965-1998 911 - every single one of them describes the cam timing that you and I are used to, the same kind you have undoubtedly done on Ferraris and such.

Then, starting with the GT3 and 996TT, they do away with that method and use this tool instead. They do not provide any sort of spec, they just tell you to align the cam lobes with this tool.

If you want to keep working on your cars, like you have been, you're going to need to pony up and buy it. And like I stated, you are going to need the WSM and almost certainly a PIWIS unless you want to make a trip to the dealer to clear codes.

Of all the cars you listed, the TT is by far the most complex, certainly electronically.

Catorce

Also I wanted to give you a feel for how this is done. Here is a page from the manual to illustrate this.

Kevin

Have you seen alot of metal or chain rail plastic in your oil filter?

Have you viewed your camshaft deviation and checked the vario cam module angle at idle and low RPM.

In a few 996TT engines, I have seen a loose crankshaft intermediate shaft drive gear. This will create noise. Also, the drive sleeve between the intermediate shaft and oil pump can make alot of nose. If you search on Rennlist, you will see the intermediate shaft GEAR failure (loosen/wobbles). It's a rare failure.

The 996TT and 997TT chain tensioners are actually from the 959.. They are market left and right, top and bottom. Basically the oil supply ports are 180 degrees apart due to one being installed on the top Bank 1 and bottom Bank 2..

I also read a few years ago that the brake vacuum assist pump that is mounted on bank 1 exhaust cam can fail and make a racket.

Thinking outside the box, if you can monitor your knock retard, high knock at low RPM's will point to loose chains, worn chain rails or failing tensioners.

yelcab

OK, buying the tool it will be.

I tore into the engine and found that I was able to measure the valve overlap but it is useless because with the oil pumps and cam variator attached to the end of the cam shafts, there is no easy way to finely adjust the cam timing. I think that is why Porsche went to a fix tool in the first place.

The Turbo engine is complex in the sense of its having a lot of stuff, but it is not complicated in the sense that nothing is really a mystery. In fact the chain / variator set up looks remarkably like the BMW Vanos system. Which, by the way, also requires cam timing tools.

And the TDC mark on the crank pulley is at least 3 degrees off from true TDC... go figure that !

Catorce

I personally never use the TDC marks for cam timing. I always use a dial gauge and holder touching the crown of piston number one.

I think in that manual if I recall it wants you to use a dial gauge which makes sense.

Oh, and if you are working on engines at this level....nothing should be a mystery, LOL :-)

Keep us posted and good luck!