epj993

My rationale regarding injecting upstream of the check valve was that it is really an air valve, not a fluid valve. If you look into it, you'll see what appears to be a rubber flap or membrane to allow the air to flow in one direction. I'm not sure if a carb cleaner would be harmful to the flap/membrane or not.

Joel's info is great feedback for this concept - and important to consider. I had the same concerns. I wasn't sure whether a small amount, e.g. 1/2-ounce, used over an extended period would be an issue. If such an amount would not vaporize and burn in the cats, it's not worth it.

On the last paragraph, I believe that's the idea. However, my old check valve was quite rusty yet still seemed to work. But I agree, regular replacement would still be necessary.

Olav A.

Sorry to ask a dumb question but where is the check valve located?

thanks.

tessicini

Eric,

When you say the check valve "seemed to work" .....did you check to see that it sealed against flow in one direction or that it just seemed OK. My guess is that if it leaks at all it will end up causing the problem. This stuff can't flow up the passages if the check valve seals, except for a small amount of compression of the gas caught in the dead end passage there should be no way to go back from the exhaust port up the SAI passages toward the check valve.

..Tony

epj993

No dumb questions here. On my 1997 it's located under the airbox behind the VarioRam tube for cylinder six (i.e. right-side toward front of car). To see it, you'll need to remove the airbox.

epj993

I was able to blow air both ways. My guess is that over time, stuff does flow back up into ports but not past the valve. But, I'm just speculating on this.

tessicini

Eric,

Somebody jump in if you think I'm off base here, but my take is that once the check valve flows in both directions SAI "nasal congestion" is on the way. If these valves are susceptible to leakage from contamination or condensation (rust?) maybe a more reliable valve is required. There are other ways to perform this function.

..Tony

epj993

I agree, I'm just reporting what may valve was doing. Although, my simple blow test probably didn't duplicate the pressures within the engine. So my valve may not have been working when under stress.

kkim

My old valve still operated as a one way valve and I still had blocked passages. I made sure to check the valve's ability to seal in one direction as I was sure I was going to find it flowing both ways, but it worked just like it was designed.

As far as the T idea, I think the T should be above the valve... easier to design and I'm pretty sure the liquid would flow past the flap w/o problems. As an added benefit, flowing a cleaning agent through that valve may prevent rust buildup, though I don't know which of the solvents would have adverse effects on the flapper material.

Finding a higher quality valve to work as a substitute may be difficult... seems easier to just change it out at regular maintenance intervals.

As an aside... I did notice a lot of moisture in the rubber tube leading to the SAI valve, which I assume is what is causing the valve to rust... does anyone know where the source of air that the pump uses comes from? If it's just a tube sticking out somewhere, maybe a better, drier location can be found for it so not as much moisture gets into the system to begin with.

Laura

Eric,
We have spent considerable time researching, testing and diagnosing these cars with the SAI problem. We have been forced into it because so many of our customers are faced with the problem of passing emissions here in CA. We have developed a method by using the PST to look at specific values in the computer that allow us to determine, with a great deal of accuracy, the amount of blockage on each bank of the engine. We can not determine the amount of blockage on each specific cylinder without physical testing. The overall bank efficiency determines the failure for emissions and triggering of fault code.
We have not had to reflush any systems. We have not had any SA codes codes reappear on any cars that have had flushes.

Other shops and dealers have their own method of dealing with this problem, This is about as much info as I can give without the "boss" giving me the talk about proprietary "stuff".

Laura
Hergesheimer MotorSports

kkim

Laura,

I thought you were the boss... or doesn't he know it, yet?

Hope the goodies got there in one piece... mahalo.

epj993

So once flushed, regular replacement (e.g. every 10-15K miles) of the check valve has prevented the problem from reoccurring (per your previous post)?

If so, that would be great!

epj993

Well, just a quick update on my SAI flush progress. It's been 6 days and 5 ports are clear using 6 bottles of carb cleaner. Originally 4 were clear, then suddenly only 3 were clear.

For 4 days I couldn't get the other 3 to clear. I'm using the "Kelly Plug" method with the air connect. Out of frustration, I fashioned yet another tool to assist in this SAI enema. See the attached pic.

This is a 3/16" copper tube with the appropriate flair nut screwed into the air nozzle (available at your local hardware). A small rubber plug with a small hole drilled through it attached to the end. While not shown in the picture, you'll need to trim the end to narrow the angle so that it can fit as tight as possible into the SAI port hole.

With some gentle bending, you can the tube to insert into the SAI hole. I squirt some carb cleaner in the SAI hole through the straw, fit this device, get my fingers up in there to press on the rubber plug and blow.

This worked well on 2 of the 3. I'm still fighting cylinder 3. Oddly, this is probably the shortest port on that side, based on where the air distribution tube attached. But, being short it is probably more prone to cake up.

Cylinder 2 has stopped in such a position that both the intake and exhaust valves are open. So I'm getting some blow-through up thru the VairoRam - thus, not getting the max pressure. I may have to turn the crank to get these to close.

Lastly (and sorry for the long post), any issues with those carbon deposits possibly getting in the cylinders? My guess it they will just blow out.

epj993

I goofed - here's the pic.

kkim

Eric,

Outstanding w/ the 3/16" tubing and rubber stopper idea! I guess "frustration" is the real mother of invention, huh?

I, too, had the engine stopped in such a position that the valves were not sealed at times. I noticed that depending on which of the plugs were removed, the pressure from the air being injected would actually turn the engine a bit so at times other cylinders would have the intake/ex valves "opened". I was afraid to bump the the engine w/ the starter to try and move the position, so I tried putting the car in gear and rocking the wheels by hand to try and turn the engine... no luck.

I also was concerned about cleaner going into the "open" valve cylinder, but it didn't prove to be a problem when I was done and restarted the engine. Lots of neat smoke in the garage, but it fired right back up and idled like normal.

Perhaps there is a way to turn the engine by hand using the alt shaft nut 24mm nut when the trans is in neutral? Picture from Robin's belt change DIY... http://p-car.com/diy/vbelt/



Good luck... please keep us informed as you make progress to free the last port. This stuck port is exactly the reason I advised for allowing at least a couple of days to do this flush. Are you getting excellent flow through the other 5 of 6 ports?

Take your time and have a few while you wait for the clog to soften up.

JasonAndreas

That is the way we have to do it when adjusting the valves on a 964. Sometimes the belts will slip so you just squeeze them a little (with your hands) and the motor will turn over fairly easy.