nine9six

Did you watch him do the port cleaning? A true port cleaning is a fair amount of work, and $500 is a fraction of the cost.
I would imagine a check valve R&R might be $300 itself (including valve).

goldcountryboy

I did not watch him do the work. He did say my ports were not too bad to begin with. I supplied the new check valve. Who knows? After my debacle with my monitors and dealer / independent mechanics I do not have much faith in any so called Porsche air cooled shops any more.

David Schiff

listen to Richarddew
don't monkey with it unless mandatory.
sometimes its best to stay away from healthcare….
david schiff MD

Quadcammer

the only trouble running around with a CE light on is that you may have other issues that you won't know about because you think its just an SAI code. If you wanna check every once in a while with a code scanner, I think it will give you some piece of mind.

myflat6

I just read in Adrian Streather's 993 book that the SAI port clogging issue could be influenced by high phosphorous content found in some motor oils. not sure if I had seen this in any of the threads here before (but I am new). just wanted to get the reaction/thoughts from the group.

Steve Weiner-Rennsport Systems

Nossir,....not based on everything I've seen to date.

IMHO, hogwash.

nine9six

Steve,
Your response leads me to believe that most if not all clogged SAI ports you come in contact with; you have chemical analysis performed on the percentages of contents found in the carbon/soot. Is this true?

I am trying to correlate comments, less analytical proof to the contrary; and cost effectiveness of having said analysis performed.

If high ZDDP oils like Mobile 1-V2, are known to be detrimental in premature clogging of cats, it would seem to promote some possible validity to the posted comment in question.

Just thinking out loud here...

Quadcammer

catalytic converters and sai passages are pretty different. Not sure you can make any correlations from these vague comments.

nine9six

Firstly, we are not talking about passage configuration, but rather chemical components that may promote CLOGGING!

Vague?
Comments made without chemical analysis support, seem to epitomize the definition of vague! ...But thank you for your typically informative insight...

I look forward to further discussion once some viable hard data is available to examine.

Steve's knowledge on the subject is considerable, to be sure. However, comment based upon, "what I've seen", without chemical analysis data to support conclusions, are nothing more than unsubstantiated observations.

Surely non-technical people can understand the logic being applied here.

P.S. I have no idea if any hard data was used in support of the contents of Adrian Streather's 993 book.

Quadcammer

oh please.

Please explain how you correlate what happens inside a catalytic converter to an sai port?

oh thats right, you have no idea.

do your own chemical compositions of carbon deposits.

Steve Weiner-Rennsport Systems

All I can offer is an opinion based on experience so anyone should read it just like any other.

I've been doing 911 heads for a very long time and plenty of ones with SAI passages (over 1000 sets). While I've no time to have a chemical analysis of the carbon (I have to make a living), its pretty obvious to this 67 year fellow who has been working on engines my whole life, that the deposits are mainly soft & hard carbon. You can also tell during the cleaning process by what comes out and how much effort is required to thoroughly clean the passageways in the heads and cam housings.

Oil chemistries OTOH and phosphorus in particular, do affect the rare-metal substrates in the cats, rendering them less effective but this is completely different subject.

I've never seen any evidence that ANY oil additives played a role in how fast the SAI passages become obstructed; its just due to the excess consumption of oil and you also see the effects all over the port surfaces, guide bosses, and valves.

Talk to any shop specializing in 911 engine machine work and they will tell you the same things.

nine9six

Steve,
Thank you for your articulate, intelligent and rational response.

This is most likely due to the fact that such analysis has probably never been conducted to this level of analysis. Additionally, nobody could possibly predict the future formulations of oil and its potential effects on a 20 year old system.

I knew when I wrote this there'd be a lack of comprehension...

Steve Weiner-Rennsport Systems

Always a pleasure,...

I think you're right about that. Before SAI, the vast majority of port and valve deposits were from fuel formulations and I was always surprised to see how much that varied.

In an otherwise healthy engine, you will not find the soft carbon buildups due to oil consumption in the exhaust ports.

richardew

313,000 miles and still cruising along with clogged SAI ports.