SAI check valve replacement - if you had to do it again
07-18-2007, 01:57 PM
#1
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SAI check valve replacement - if you had to do it again
I am getting ready to replace my SAI check valve.
I looked at some but far from all posts on this fun-filled topic and am hoping to benefit from the collective wisdom of the RL board.
Of the three commonly prescribed methods listed below, I am currently favoring STARTING with #2 - thoughts so far?
1) modified crow's foot
2) notch valve and chisel loose
3) cut off valve body and use wrench to unscrew
I favor #2 because I believe hard blows with a chisel will have the greatest likelihood of breaking loose the fasterner and also because there have been isolated reports of inadvertently cracking the air distributor housing with the crow's foot wrench.
On installation of the new valve, I intend to lube the threads with anti-seize. I have not seen much mention of doing this, but given the high potential for corrosion it seems prudent. Any reason NOT to use anti-seize.
TIA
I looked at some but far from all posts on this fun-filled topic and am hoping to benefit from the collective wisdom of the RL board.
Of the three commonly prescribed methods listed below, I am currently favoring STARTING with #2 - thoughts so far?
1) modified crow's foot
2) notch valve and chisel loose
3) cut off valve body and use wrench to unscrew
I favor #2 because I believe hard blows with a chisel will have the greatest likelihood of breaking loose the fasterner and also because there have been isolated reports of inadvertently cracking the air distributor housing with the crow's foot wrench.
On installation of the new valve, I intend to lube the threads with anti-seize. I have not seen much mention of doing this, but given the high potential for corrosion it seems prudent. Any reason NOT to use anti-seize.
TIA
07-18-2007, 02:06 PM
#2
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It seems to unscrew much easier when the engine is still warm. I smeared hi-temp grease on the SAI valve threads, no reason not to since the hose attached to it will keep it from turning. No problems with mine since I did this 15K ago.
07-19-2007, 03:26 AM
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While we're on the topic. Since my engine is out I decided to do it, BTW that check valve is soo easy to remove, can't understand what all the complaining is about. 
Anyway, all of my exhaust ports look super squeaky clean except for the right front, which has a little carbon build up. At 68K I am wondering if I am just lucky, or if it has been taken care of before. My car still likes to eat about a quart every 2500mi.
P.S. I put the carb cleaner where the check valve threads in and it just sat there, does the routing go back up somewhere? It kinda has me a little worried.
Anyway, all of my exhaust ports look super squeaky clean except for the right front, which has a little carbon build up. At 68K I am wondering if I am just lucky, or if it has been taken care of before. My car still likes to eat about a quart every 2500mi.
P.S. I put the carb cleaner where the check valve threads in and it just sat there, does the routing go back up somewhere? It kinda has me a little worried.
07-19-2007, 11:52 AM
#6
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I believe anti-seize iz very bad for o2 sensors. Since this system is pumping air in upstream of the o2 sensors, you would not want to use so much that it ended up getting pumped down stream.
I used anti seize on mine, but was very careful with the amount. Just a thin film on the threads.
The crows foot method worked for me.
Pete
I used anti seize on mine, but was very careful with the amount. Just a thin film on the threads.
The crows foot method worked for me.
Pete
07-19-2007, 03:58 PM
#7
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Crows foot here... it broke loose easily enough but made a loud noise when the threads gave up their hold. I checked everything to make sure I hadn't broken anything, and luckily all was well.
There's not alot of room in there, so while others have done approaches 2 and 3 I'm not certain my fat hands could accomplish it.
There's not alot of room in there, so while others have done approaches 2 and 3 I'm not certain my fat hands could accomplish it.
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07-19-2007, 11:12 PM
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Mid fluch update:
I pulled the exhaust manafolds on my almost 69K 993. and all but one showed absolutely no signs of any carbon whatsoever. The one that did have, had a totally insignificant amount.
I hooked up the little do-hickey, filled it with fuel system cleaner, and all ports flowed openly and easily on the first blast. I was baffled as to how clean my system is since it seems every one that comes through circle is 70K or less, and mine looks brand new. I am going to lend my advice to all who want to prolong the life of their SAI ports.
Use only Chevron gas: thats all I use because there really is a difference
Use that fuel system cleaner every 3K: well it seems to work
Use 15W-50 mobil 1 if thats your oil brand of choice: Thicker and thus is harder to get past guides
Drive it like you stole it: thats what I do 70% of the time.
I pulled the exhaust manafolds on my almost 69K 993. and all but one showed absolutely no signs of any carbon whatsoever. The one that did have, had a totally insignificant amount.
I hooked up the little do-hickey, filled it with fuel system cleaner, and all ports flowed openly and easily on the first blast. I was baffled as to how clean my system is since it seems every one that comes through circle is 70K or less, and mine looks brand new. I am going to lend my advice to all who want to prolong the life of their SAI ports.
Use only Chevron gas: thats all I use because there really is a difference
Use that fuel system cleaner every 3K: well it seems to work
Use 15W-50 mobil 1 if thats your oil brand of choice: Thicker and thus is harder to get past guides
Drive it like you stole it: thats what I do 70% of the time.
07-19-2007, 11:24 PM
#9
Race Car
Originally Posted by long_beach_968
Mid fluch update:
I pulled the exhaust manafolds on my almost 69K 993. and all but one showed absolutely no signs of any carbon whatsoever. The one that did have, had a totally insignificant amount.
I hooked up the little do-hickey, filled it with fuel system cleaner, and all ports flowed openly and easily on the first blast. I was baffled as to how clean my system is since it seems every one that comes through circle is 70K or less, and mine looks brand new. I am going to lend my advice to all who want to prolong the life of their SAI ports.
Use only Chevron gas: thats all I use because there really is a difference
Use that fuel system cleaner every 3K: well it seems to work
Use 15W-50 mobil 1 if thats your oil brand of choice: Thicker and thus is harder to get past guides
Drive it like you stole it: thats what I do 70% of the time.
I pulled the exhaust manafolds on my almost 69K 993. and all but one showed absolutely no signs of any carbon whatsoever. The one that did have, had a totally insignificant amount.
I hooked up the little do-hickey, filled it with fuel system cleaner, and all ports flowed openly and easily on the first blast. I was baffled as to how clean my system is since it seems every one that comes through circle is 70K or less, and mine looks brand new. I am going to lend my advice to all who want to prolong the life of their SAI ports.
Use only Chevron gas: thats all I use because there really is a difference
Use that fuel system cleaner every 3K: well it seems to work
Use 15W-50 mobil 1 if thats your oil brand of choice: Thicker and thus is harder to get past guides
Drive it like you stole it: thats what I do 70% of the time.
07-21-2007, 05:09 PM
#11
I would do it the same way that I did this spring - flex/break the valve body off and put a socket on the hex part that is left. Now that it has been out once, I may first try the customized wrench used to re-install. Wrench is available for 993 Rennlisters to borrow ! 
Having had the aluminum manifold out and seeing how it's mounted to the thin engine sheet metal, I don't like chisel method....
Answer to long_beach - the check valve screws into aluminum manifold, and then the two pipes exit upward to each bank of engine - so, if you pour in carb cleaner it will just sit there, that's why folks attach compressed air - see second picture - I took the hex portion of old valve and welded air compressor quick connect.
Be sure to read more of the posts on this topic to see about the potential rusted plugs in the SAI manifold. Once you've gone this far you don't want to have clean valve and ports only to still have insufficient flow due to the plugs leaking.... I posted good pics in my topic on this back in April.
Having had the aluminum manifold out and seeing how it's mounted to the thin engine sheet metal, I don't like chisel method....
Answer to long_beach - the check valve screws into aluminum manifold, and then the two pipes exit upward to each bank of engine - so, if you pour in carb cleaner it will just sit there, that's why folks attach compressed air - see second picture - I took the hex portion of old valve and welded air compressor quick connect.
Be sure to read more of the posts on this topic to see about the potential rusted plugs in the SAI manifold. Once you've gone this far you don't want to have clean valve and ports only to still have insufficient flow due to the plugs leaking.... I posted good pics in my topic on this back in April.
