Engine Rebuilt Part III - Heads and SAI passages
01-09-2006 | 01:18 PM
#16
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Originally Posted by tam993
So wait a minute, I'm confused here.
Does the air from the SAI pump come throught the cam carriers or what ever they are?
it appears to be so... or am I wrong.
I'd like to know the routing of those passages. I'm doing a flush on my car. PITA. First they are flowing
well, the next day they're clogged. Must be that carbon carp up in there.
Does the air from the SAI pump come throught the cam carriers or what ever they are?
it appears to be so... or am I wrong.
I'd like to know the routing of those passages. I'm doing a flush on my car. PITA. First they are flowing
well, the next day they're clogged. Must be that carbon carp up in there.
The air pump sucks the air through a rubber hose from the air cleaner. It passed through the pump, a controled valve and into the famous one way valve on the top of a air distribution manifold. This manifold splits the air into two metal lines, each going to the back of each cam tower. At the cam tower the air is received and routed through a passage in the cam tower to each head. The air passes through the interface between the cam tower (carrier) and the head into the passage down through the head into the exhaust chamber...**whew***
There is not trace of carbon at the entrance to the cam towers so its all down below there. You can see the significant crap buildup in the cam towers where they meet the heads above.
Maybe you are getting some of the carbon loosened and its plugging the hole...notice how small these holes are...
BTW mine all flowed fine...its was worn valve guides that triggered the rebuild.
Cheers,
Mike
01-09-2006 | 01:29 PM
#17
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From: Vancouver, BC
Originally Posted by Toga
But to my opinion, with about 75k mi, my engine doesn't need it yet.
Cheers
Cheers
- With 75,000 miles all the wear surfaces (rings, bearings, etc) will have wear, not significant but still there
- I do not know what the PO did to the car so I feel much better taking it down to the bare bones and then I know what I have
- Its not that much extra work and cost once you are down to the head.
- Its best to catch any problems before anything wears out. I have finished the dissassembly (I need to get to posting) and there was a bit of wear on some of the bearings...nothing to worry about but it had started to wear at the bearing shells
- It good to replace the Rod bolts since they have a history of stretching if an overrev happens (like on the track with a missed shift). Replacing them with ARP or Raceware is a very good idea (I am using ARP on mine).
So that was the idea behind it...peace of mind and a fresh engine from top to bottom. While you can argue that the bottom ends can last 200.000miles + since I did not control the first 80% of the car's life I can't say what the internal condition was. Most people argue the average bottom ends seem to go 120,000 miles. If I do the whole thing I should have another 100,000+ miles from the engine without having to rip into it again...
Turns out i my case that it was marginal to do this but I have seen some wear and now I will feel much better about the engine overall.
Cheers,
Mike
01-09-2006 | 04:02 PM
#18
Three Wheelin'
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Mike,
A tech at my Porsche dealer (Boardwalk in Plano, TX) mentioned when they do an SAI job they bore out certain passages to eliminate the problem or make it less likely in the future. I don't know the details but have you heard about that?
A tech at my Porsche dealer (Boardwalk in Plano, TX) mentioned when they do an SAI job they bore out certain passages to eliminate the problem or make it less likely in the future. I don't know the details but have you heard about that?
01-09-2006 | 04:11 PM
#19
Burning Brakes
Joined: Apr 2005
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From: Raleigh, NC
Originally Posted by Dr. P
Hello there. I've been lurking here for about 2 months now. I don't even have one of these cars but I do plan on getting one in next year or so....anyways, to get to the point....excellent work you are doing here Mike, but I decided to chime in with a chance to give you a piece of advice.
I know I'm a total stranger here but for some legibility, I'm a quattro guy and have had Audis and worked on them myself for 6-8yrs now, but its totally up to you to accept this or not. perhaps cosult others. So, by looking at that SAI port, I would suggest, once you clean it real well, you take the grinder in your hands and polish that port to a mirror-like finnish. Even better yet, if you could have it lined with Teflon coating it would be the best. The reason I suggest this, unless there is already a better method for preventing this clogging, is that I and many other have had had a bad experience on Audis V6 12V engines. The EGR(exhaust gas recirculation) port that goes from EGR valve through intake manifold and exits just after the throttle body was so small that often got clogged with carbon buildup, which would throw a CEL(check engine light) and help you fail emissions. The best solution was to take IM off and polish that port to a mirror finish. When I did so, it was good for next 3 years, after which i sold the car but even the guy that bought it never had problems to date. Mind you, it used to clogg every year or so if cleaned and left as is(abrasive alluminum).
Hope this helps and good luck with the rebuild, its quite an experience and you'll find so much more joy in driving the car afterwards!
I know I'm a total stranger here but for some legibility, I'm a quattro guy and have had Audis and worked on them myself for 6-8yrs now, but its totally up to you to accept this or not. perhaps cosult others. So, by looking at that SAI port, I would suggest, once you clean it real well, you take the grinder in your hands and polish that port to a mirror-like finnish. Even better yet, if you could have it lined with Teflon coating it would be the best. The reason I suggest this, unless there is already a better method for preventing this clogging, is that I and many other have had had a bad experience on Audis V6 12V engines. The EGR(exhaust gas recirculation) port that goes from EGR valve through intake manifold and exits just after the throttle body was so small that often got clogged with carbon buildup, which would throw a CEL(check engine light) and help you fail emissions. The best solution was to take IM off and polish that port to a mirror finish. When I did so, it was good for next 3 years, after which i sold the car but even the guy that bought it never had problems to date. Mind you, it used to clogg every year or so if cleaned and left as is(abrasive alluminum).
Hope this helps and good luck with the rebuild, its quite an experience and you'll find so much more joy in driving the car afterwards!
Would this be Dr. Phil? If so, welcome to the board! Great first post...
01-09-2006 | 04:29 PM
#20
Track Day
Joined: Dec 2005
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Thanks for the welcome, but I'm not by any means a doctor, let alone Dr. Phill. My first name is Peter, but Dr. P was a quick handle pick and references to Dr. Ferdinand Porsche
I'm sure I'll change it to something more apropriate in the future, I'm still in the process of learning about these cars and doing something more than a basic research before I'm ready to buy the most beautiful 911, that is 993, ever made. And being the last air-cooled I believe it will keep its values high.
I'm sure I'll change it to something more apropriate in the future, I'm still in the process of learning about these cars and doing something more than a basic research before I'm ready to buy the most beautiful 911, that is 993, ever made. And being the last air-cooled I believe it will keep its values high.
01-09-2006 | 05:51 PM
#21
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Thanks for the explaination of the air passages,for the SAI crap, makes sense now.
I had 5 of the 6 flowing like they were wide open and the next day nothing.
I have another question, evidently there is one gallery for the air the "T"s off for each exhaust port right?
I had 5 of the 6 flowing like they were wide open and the next day nothing.
I have another question, evidently there is one gallery for the air the "T"s off for each exhaust port right?
01-09-2006 | 06:09 PM
#22
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From: Reno, NV
Great pics again, Mike. I'm thoroughly enjoying keeping up with your saga. Just FYI...your SAI ports look only slightly cleaner than mine were at 110k miles. I'll not bother posting the pics here, but mine were almost completely clogged. It took many expensive hours for the shop to clean them. Not a fun task.
01-09-2006 | 09:36 PM
#23
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From: Vancouver, BC
Originally Posted by Jastx
Mike,
A tech at my Porsche dealer (Boardwalk in Plano, TX) mentioned when they do an SAI job they bore out certain passages to eliminate the problem or make it less likely in the future. I don't know the details but have you heard about that?
A tech at my Porsche dealer (Boardwalk in Plano, TX) mentioned when they do an SAI job they bore out certain passages to eliminate the problem or make it less likely in the future. I don't know the details but have you heard about that?
Can you find out more (like do they bore the heads and to what extent? I am hoping that with the new guides etc. I will not have any problems with SAI...yeah right....
Cheers,
Mike
01-09-2006 | 09:38 PM
#24
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From: Vancouver, BC
Originally Posted by tam993
I have another question, evidently there is one gallery for the air the "T"s off for each exhaust port right?
Cheers,
Mike
01-09-2006 | 09:39 PM
#25
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Originally Posted by Toga
: I hope my 96 4s have them too, because I'd really like to make that valve timing adujstment mods
Cheers
Cheers
What was the build date on your car? Mine was Jan/96. If its before that that its very likely you have the keyways. How much longer after that date I do not know.
Cheers,
Mike
01-10-2006 | 09:43 AM
#27
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From: Belgium
Originally Posted by Mike J
Hi JP,
What was the build date on your car? Mine was Jan/96. If its before that that its very likely you have the keyways. How much longer after that date I do not know.
Cheers,
Mike
What was the build date on your car? Mine was Jan/96. If its before that that its very likely you have the keyways. How much longer after that date I do not know.
Cheers,
Mike
01-10-2006 | 11:01 AM
#28
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yes, that answers my question, I suspected that. I suspect the port to the exhaust is a straight drill too. (from the top of the head to the exhaust port).
what happened on my car was the check valve failed and allowed the exhaust to blow back up in the ports... I guess.
Regardless, I was cleaning them via the flush method and basically made things worst. I would have been ahead of the game if I just dropped the engine and pulled the cam carrier off and cleaned them that way.
I don't think my SAI ports were clogged from bad valve guides, there was little to no build up on the exhaust valves or exhaust ports.
Lame design.... Are only US versions of this engine doing this sort of thing. Like to people in Eroupe have these issues?
thanks
what happened on my car was the check valve failed and allowed the exhaust to blow back up in the ports... I guess.
Regardless, I was cleaning them via the flush method and basically made things worst. I would have been ahead of the game if I just dropped the engine and pulled the cam carrier off and cleaned them that way.
I don't think my SAI ports were clogged from bad valve guides, there was little to no build up on the exhaust valves or exhaust ports.
Lame design.... Are only US versions of this engine doing this sort of thing. Like to people in Eroupe have these issues?
thanks
