Terry L

I must decide whether to bear the cost of replacing the valve guides or sell the car (1996 polar silver C4S with 71,000 miles - beautiful). I don't think the cleanout will work for long. What kind of prices are you getting to do the job and how much do you think it will affect resale? Can a car with a CEL even be sold for a fair price? I will not consider just disabling the light or something like that.

kkim

How much oil is your car consuming per 1000 miles?

Terry L

Maybe a quart - not terrible at all, but evidently enough to clog the SAI ports and trigger the computer.

Terry Adams

I would spend the approx. $1K on the cleanout before I spent $6.5K for a top end w/valve guides. Or DIY the cleanout.

kkim

Just because you have clogged SAI ports, doesn't mean you need a valve job to fix it. What makes you think you need a valve job?

Of the people that have cleaned their SAI ports, very few, if any, have reported reoccurring of the problem. I assume you have been getting CEL codes? Do you happen to know what those codes are? Has the SAI check valve ever been replaced?

There will undoubtedly be others jumping in on this thread to help you. Don't think of selling the car because of this problem... it can be fixed.

trojanman

Hey Terry,

Take Kelly's advice... determine the root of your problem before you stress out about the top end rebuild. My story is well documented here on Rennlist, but in summary I had a CEL for SAI ports that I learned later had been chronic for some 15k miles. I needed a top end because my guides were shot, but there wasn't necessarily a correlation between the ports and the guides.

If your oil consumption is within spec (mine wasn't... I was burning a quart every 500 miles), deal with the SAI ports and forget about the valve guides. Just my $.02.

Good luck...

tam993

Right, before you go off on a tangent, check a couple of things first. My 96 had CEL issues and I flushed the ports at 74K. Some were pretty blocked. But I was able to clear the ports out very well, thanks to a lot of the people on this list.
When I opened the exhaust ports there was very little carbon build up on the exhaust valves. Some none at all. The oil consumption on my car is nowhere near the limit Porsche specs.

Honestly I think this valve guide replacement when there is a SAI CEL fault code is a bunch of crap.
Sounds like people are gettting screwed big time. I'd seriously think about checking oil consumption before cracking open an engine.

By the way the check valve on my car was the original and it was stuck WIDE open..... I believe if that system is working properly there should be NO exhaust flow back up in to those ports. I think if the check valve fails your using those ports as and exhaust when the blower motor is not running.

inspect the SAI system, determine oil consumption, oh yeah don't sweat the small stuff

epj993

I think the correlation between SAI and valve guides is that *if* you have bad guides it may contribute to the clogging of the ports - not clogged ports = bad valve guides. If oil use is within spec, guides are most likely OK. As others have said, do the port flush first (DIY: ~$250 in parts and several days time) & replace the check valve every 10-15K thereafter. The best long term evidence to date shows this to be very effective.

As always, there's plenty of assistance when you undertake this project. Good luck!

Terry L

Maybe I'm wrong, but I was under the impression that many of the guys who did the DIY ended up having the same problem a short time later. To answer a few questions, the codes show SAI and the CEL will retrigger within a few days or a week after reset. The scan tool shows that the airflow problem is on the right side only (IIRC). I thought oil consumption was high but when I actually clocked it, it wasn't bad. The smell of burning oil, however, is always there on shutoff.
So, how many people who did the cleanout had a problem later?

kkim

From the posts here, I have not seen one with a reoccurring SAI problem after doing a flush that I have read. Care to post threads that gave you the impression of the problem returning?

Your first job would be to determine if you have a valve guide problem, which would be indicated by high oil consumption, or just having clogged SAI ports. If the latter, your problem can be solved at a mechanic with a flush for 1k or at home for about $200 in parts.

Doesn't that sound better than a 6k valve job?

tam993

Yeah, I guess bad valve guides could contribute to the problem.
But I think if the system is working correctly there shouldn't be any exhaust flow into those ports.
I would think it would be like trying to blow into a straw with your finger blocking the other end.
kind of like what that check valve does. Not sure how true that is though.

vjd3

If the car runs well and pulls hard, I wouldn't bother with the valve guides. A quart per 1000 miles is not unusual for a 911; most of them are all over the map. Changing oil brands and/or weights can also have a big effect on usage. I think it really depends on how the car was initially broken in, particularly on the 993. When it starts really drinking oil and/or fouling the plugs, that's when it's time to do the guides. That's the advice I've gotten over the years from two friends who are both Porsche master technicians ... just drive it, they both say. They had the same advice for other problems that weren't really affecting performance ... broken head stud on a 1980 911SC which still ran perfectly and had fine compression, minor oil leak that was a cheap part but huge labor to repair, and so forth. The car will let you know when it really wants you to do something.

If the SAI flush will get you through emissions, why spend all that money to fix something that only affects the car on a cold start for a minute or two?

Terry L

OK, I'm convinced. My eyes went bleary trying to read all of the SAI/CEL/valve guide threads. I'll do the flush and let you know if I don't live happily forever after. Thanks for everyone's input.