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DIY - SAI Port Clean-Out

 
Old 04-09-2013, 09:24 PM
  #1  
bruce7
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Default DIY - SAI Port Clean-Out

My CEL came on about 3 months ago and the code was P1411 (Secondary AIr
Injection for cylinders 3-6). The car had about 74k miles on it and had probably
never had any SAI-related servicing. I had the CEL reset but did nothing to address
the issue. About 3 months later, I replaced the SAI check valve, which I covered in a
DIY (https://rennlist.com/forums/993-foru...eck-valve.html). Two days later,
the CEL with code P1411 came back on. Time to dig in and deal with it - Part 2, the SAI port clean out.

So this writeup will be about how I did the SAI port clean out. Pictures to help illustrate
the steps can be found here:

https://picasaweb.google.com/bruce.c...jTir7UudXp-wE#

By the way I did this without the aid of a lift, lying flat on my back. So you can do it, but
man would it be nice to have a lift. I started about 10:30 am and finished about 7:30 pm. A long day.

In this procedure I did not use any carbon-cleaning chemicals, vacuum, or compressed
air.

I did a lot of research here on the forum and followed the suggestions of others especially with regard
to the bicycle cable technique. I found only one cylinder (#6) that was really
clogged up. Pretty sure it was the one responsible for setting the CEL.

I also noted that I need to replace the leaking lower valve cover gaskets and I plan to
check the resistance of the spark plug wires, especially for #6. Probably ready for new
wires.

Materials and Parts Needed

Copper Anti-Seize Paste (Lubro-Moly) forgot price but sourced from Steve Weiner at Rennsport Systems
Bike Cable Repair Kit $7 at Walmart
Nuts (18) 999-084-052-02 $46.08 at Sunset Porsche
Gaskets (2) 928-111-127-02 $26.50 at Sunset Porsche
Bolts (6) 999-217-167-01 $78.00 at Sunset Porsche


OK, here we go.

Steps to Clean-out SAI Ports

Note the mileage

Raise car onto jack stands and remove the rear wheels

Apply liquid penetrant to nuts and bolts that connect the heat exchanger with the catalytic converter

Remove the heater control box
7mm flexible nut driver

Loosen the heater supply hose clamp on top of the heat exchanger
7mm flexible nut driver

Remove heat exchanger to catalytic converter bolts/nuts and the gasket
13mm wrench, 13mm socket, 3/8 ratchet, 4 inch extension, 3/8 breaker bar

Break loose all the nuts holding the heat exchanger to the head
13mm socket, 10 inch extension, 3/8 breaker bar

Remove all the nuts completely. When the last one is free, be ready, the heat exchanger will come
down quickly and easily. The sealing rings for each cylinder on both sides of
my engine remained in the heads and I did not disturb them.

Prepare the cables to be used to clean out the ports according to the pictures for approximate lengths.
I started with a shorter one and then used a longer one. Plan on having to
make a few as sometimes you may wind one up on itself. The kit has more
than enough cable for this project.

Each port is cleaned out in 3 steps. Step 1 - push the shorter cable up into the SAI port
in the exhaust port as far as it will go, only about 2 inches and let it hang.

Step 2 - push on the appropriate sheath for the length of cable being used.

Step 3 - chuck up the cable and begin drilling out the passage with light pressure on
the cable until you can't push it in any farther. Then switch to a longer cable and repeat.

By the way, you can do this with a cordless drill like I did, but if I had to do it again I would use
a regular corded drill to eliminate the hassle with charging the batteries. I had to recharge a
few times to complete the project.

There is an obstacle to removing the left side heat exchanger. The front-most nut that
holds the heat exchanger to the head cannot be accessed without basically removing the anti-roll bar.
You need to push the anti-roll bar out of the way to get to the nut.
13mm socket/wrench, 15mm socket and 16mm open-end wrench

Re-Assembly

Put copper anti-seize paste on the studs before placing the heat exchanger into position.

Slip the heat exchanger into the black heater supply hose on top of the heat exchanger and then lift
the heat exchanger up to the head over the studs and loosely spin on new nuts to hold the
heat exchanger in place.

Insert a new gasket between the heat exchanger and the catalytic converter and insert new bolts and nuts
(also properly coated with copper anti-seize paste). Loosely tighten.

Now that everything is loosely connected, tighten everything up evenly then torque all the nuts and bolts to 23 Nm.

Reinstall the heater control boxes and tighten the heater supply hose clamp.

Reattach the anti-roll bar and torque the bushings to 23 Nm and the drop-links to 46 Nm.

Finish Up

Refit the wheels and lower the car. Torque wheel nuts to 130 Nm.

Using an OBD2 code reader, reset the CEL codes.

Start the car and check operation.

OK, so that's it. I'll check in tomarrow and see if anyone has questions I can answer.

-bruce

Last edited by bruce7; 04-10-2013 at 01:43 PM. Reason: added parts pricing information
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Old 04-09-2013, 09:43 PM
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Dryfly57
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Awesome write-up!!
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Old 04-09-2013, 10:34 PM
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Originally Posted by Dryfly57 View Post
Awesome write-up!!
As usual.
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Old 04-09-2013, 10:41 PM
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Thanks for your effort!
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Old 04-09-2013, 10:49 PM
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JB 911
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Excellent write up, again!

Couple questions.


Are you concerned that any debris got poked up into the horizontal portion of the passages and may have remained since you didn't use compressed air from the check valve down?

You said it was mostly # 6. How many inches would you say it was plugged up for? Any ideas why #6 was the culprit? I've seen others post that too.

Were you able to check your exhaust valve guides for play? And if so, was number 6 any different from the others?

Ok this might be a dumb question, but did you consider starting the car before reinstalling the heat exchangers? To allow the sai pump effectively to blow out any debris for you since you didn't used the compressed air method? I guess what little carbon was there probably not going to make an issue in the heat exchangers. Just I work on quite a bit of 2 cycle equipment, notorious for carbon clogging, no exhaust valve just a port on these, but after we clean them we always start the motor and let it blow out anything left in there before putting on the muffler. Here the motor obviously isnt goingto blow anything out but the sai pump might?


This way SURE is an easier method though. It will be interesting to see how long it lasts (hopefully a LONG time) especially since you just replaced the check valve. I hope you plan to keep and drive your car for another 30k mile at least , would be very interested in updates.

Thanks for posting.
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Old 04-09-2013, 11:16 PM
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Although its been done a number of times, great write-up and imagery! Thanks for taking the time. My SAI box of parts has been in my trunk about 2 months now. I'll get to it one of these days.
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Old 04-10-2013, 11:44 AM
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Bruce: Did you consider changing out the SAI valve behind the Varioram/airbox? This shoul dbe mandatory as well for future carbon build up.
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Old 04-10-2013, 01:38 PM
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bruce7
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Originally Posted by JB 911 View Post
Excellent write up, again!

Couple questions.


Are you concerned that any debris got poked up into the horizontal portion of the passages and may have remained since you didn't use compressed air from the check valve down?

You said it was mostly # 6. How many inches would you say it was plugged up for? Any ideas why #6 was the culprit? I've seen others post that too.

Were you able to check your exhaust valve guides for play? And if so, was number 6 any different from the others?

Ok this might be a dumb question, but did you consider starting the car before reinstalling the heat exchangers? To allow the sai pump effectively to blow out any debris for you since you didn't used the compressed air method? I guess what little carbon was there probably not going to make an issue in the heat exchangers. Just I work on quite a bit of 2 cycle equipment, notorious for carbon clogging, no exhaust valve just a port on these, but after we clean them we always start the motor and let it blow out anything left in there before putting on the muffler. Here the motor obviously isnt goingto blow anything out but the sai pump might?


This way SURE is an easier method though. It will be interesting to see how long it lasts (hopefully a LONG time) especially since you just replaced the check valve. I hope you plan to keep and drive your car for another 30k mile at least , would be very interested in updates.

Thanks for posting.
Hi, thanks for the questions.

I'm not too concerned with any debris that might have stayed in the air passages.
The carbon is brittle and breaks up into fine particles. I think that
the spinning cable breaks it up enough so that when the air pump runs it will
blow out any small particles that might be loose.

The resistance to the cable feels highest right at the start, about 2 inches in.
There may be a sharp bend there. Once past that there is very little resistance.

Cylinder #6 may have the highest temperature due to location and air flow.
That is why I think the spark plug wires for #6 fail sooner than the others.
The extra carbon buildup on #6 could be due to spark, cooling, failing valve guide
or something else. Not sure.

I did not try to check the valve guide for play. Is that possible with just this
amount of disassembly?

That's an interesting idea about starting the car before reinstalling the heat
exchangers. Don't know if that would be a good idea or not. I'd be interested
in getting opinions on that.

Hope this lasts a while, at least a couple of years.
I really would like to get to 125k+ miles before doing a valve job. As long as
the oil consumption does not get excessive, that is my plan.

-bruce
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Old 04-10-2013, 01:39 PM
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Originally Posted by osugasman View Post
Bruce: Did you consider changing out the SAI valve behind the Varioram/airbox? This shoul dbe mandatory as well for future carbon build up.
Hi,

I changed out the SAI check valve about 3 weeks ago and wrote up the DIY
for that. The link is in the first post of this thread.

-bruce
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Old 04-10-2013, 03:55 PM
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Originally Posted by bruce7 View Post
Hi,

I changed out the SAI check valve about 3 weeks ago and wrote up the DIY
for that. The link is in the first post of this thread.

-bruce
Bruce,

Sorry I missed the link when reading it the first time. I remember your write up now. My SAI valve required pulling the varioram and removing the aluminum bracket so as to put it in a vise to break the (factory original?) SAI valve free.

--Brian
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Old 12-28-2013, 06:25 PM
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I am looking up at 4-5-6 ports and I cannot see the SAI port. I feel a small hole behind the valve stem; is that the SAI port ? I ask as I am about to fish some gun cleaning cable up that hole in an effort to rid this '96 C4S of it's Check Engine Light (CEL). It has been 40k miles since last full split case rebuild and now it is back on (CEL). I do not want to damage ($$) the heads. Would carb cleaner be ok to use to clean off the surface carbon that I do see all around the port (?).
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Old 12-28-2013, 07:13 PM
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Yep that is the hole, as you will notice it is upstream of the valve guide. You may ask yourself as I did, how does leaking oil from a worn guide flow upstream against exhaust flow and gravity into the SAI port. My theory is worn valve guides have nothing to do with plugging the SAI ports. My photo above shows what worn valve guides look like. Interesting enough, those SAI ports were clear.
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Old 12-29-2013, 09:07 AM
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Originally Posted by Wolfk View Post



Yep that is the hole, as you will notice it is upstream of the valve guide. You may ask yourself as I did, how does leaking oil from a worn guide flow upstream against exhaust flow and gravity into the SAI port. My theory is worn valve guides have nothing to do with plugging the SAI ports. My photo above shows what worn valve guides look like. Interesting enough, those SAI ports were clear.
Thanks, I was afraid that hole I felt behind the valve stem was the spark plug hole. Today will be my first time going at the SAI hole (with fence wire).
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Old 12-29-2013, 12:09 PM
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Mike J
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Originally Posted by Wolfk View Post
Yep that is the hole, as you will notice it is upstream of the valve guide. You may ask yourself as I did, how does leaking oil from a worn guide flow upstream against exhaust flow and gravity into the SAI port. My theory is worn valve guides have nothing to do with plugging the SAI ports. My photo above shows what worn valve guides look like. Interesting enough, those SAI ports were clear.
That port is quite clean - a really worn valve guide would have the entire base of the valve crusted in black burned oil residue. There is a bit at the top of the stem, but it explains why the ports were clear.

Here are some shots from http://www.pcarworkshop.com that shows a worse condition example, this car was burning about 1 quart/700 miles, was misfiring, and had quite a bit of valve guide wear but not completely worn out (as measured using the Porsche specified techniques):



This has a bit more burnt material ...



Reaming the passage out:



Originally Posted by C4S993 View Post
Thanks, I was afraid that hole I felt behind the valve stem was the spark plug hole. Today will be my first time going at the SAI hole (with fence wire).
I hope you are just joking ....

Cheers,

Mike
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Old 12-29-2013, 06:30 PM
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Thanks for this thread. I had my car up on jackstands anyway and decided to go ahead and do this. Just spent about 2 hours and have the heat exchangers off and will finish tomorrow...or the next day...or the next day... after I go find some cable. I need to find the hole first......reminds me of high school Mine look pretty ugly. Ill take some pics as soon as I get back into it and finish. Is there any reason to do the SAI valve at the same time I have the HE's off or is it ok to just do it next after this is buttoned up? Thanks guys. I have been putting this off for about a year and this was my motivation
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