964 Exhaust Port - Not Looking Good
 

Hi,

Found this tonight after removing headers. I was not expecting to see this. This is the worst one. What are my options? Thanks!

http://forums.pelicanparts.com/uploa...1487993930.jpg

Wow, did the guide start to walk out.

What is the history of the head work?

3.6
 

Where was the head work done & how long ago?Head looks pretty fresh.Fred

What is that surrounding the guide? It doesn't look like it belongs.

The PO had the heads rebuilt, but a long time ago. Engine did some racing, very low mileage.

Is the head junk? I am not sure what the other "stuff" is. It is very smooth.

Forgot to say - thanks for the replies.

The guide boss is not very large in that area and the ceramic liner looks intact you might be able to save it

https://uploads.tapatalk-cdn.com/201...2a0c181a83.jpg


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Thanks for the replies. I am not sure what the coating is. I have a feeling that the ceramic may be damaged. I will look again today.

It looks like the boss area around the guide has broken away, probably from when the guides were installed. Maybe the guide has walked but I don't think so, look at the back side of the guide and compare the exposed part of the guide to cgarr 's picture I don't know if this was a head that I would continue to use as is

Just experienced the same failure on number three intake. (97 3.6 L).
You said this is the worst one, are the other heads also damaged?
I am not sure how my damage occurred, whether it was a weakness at the valve guide on number three, a crooked valve guide, or the result of a failed O2 sensor.
Thinking this is beyond repair.

Dropped valve guide number 3 intake
 

Pics of my "head"ache ... no pun intended.
I'm not liking membership in the(TPHC)Thrashed Porsche Head Club

http://forums.pelicanparts.com/uploa...1488042648.jpg

OP, if anything send your heads to CGarr, he's the man :D

Valve guides are a press fit. Is it easy to use too much press and not enough fit? Seems like that could break the support part of the casting as shown. I've pulled some guides, but left the pressing (and the all important honing) to shops.

What to do may come down to economics - price of a good used head versus price of welding this up, reshaping, and reboring. An oversized hole for the guide in the head is not an issue - I know of shops which just make their own guides, so they can be any OD needed. Maybe that is what most shops do? Or they buy oversized guides and turn to fit?

Well, thanks again for the replies. I thought the smooth "stuff" was after market, however, I am guessing that it is the ceramic coating. I have pictures of all 6 of them. I am thinking that I may need to see what the intake valves look like.

http://forums.pelicanparts.com/uploa...1488053230.JPG
http://forums.pelicanparts.com/uploa...1488053230.JPG
http://forums.pelicanparts.com/uploa...1488053230.JPG
http://forums.pelicanparts.com/uploa...1488053230.JPG
http://forums.pelicanparts.com/uploa...1488053230.JPG
http://forums.pelicanparts.com/uploa...1488053230.JPG

Hmm

What is that Brown grease like Deposit on the stems?

Never seen something like that

Walte - I will need to determine what is the best in terms of quality, as well as cost. This is new territory for me.

betterair - TPHC- well, there was a time when something like this would have been VERY upsetting. This is a hobby, and this is part of that hobby. Don't get me wrong, I don't have the cash to fix this, in fact my car resembles more of a "dune buggy" then a 1977 Porsche 911S because of the cash shortage! Yes - I am now a member of the TPHC.

Not sure what the grease is. I assume an assembly lube?

Those guides look like they were just pressed in and the valves are clean and no carbon build up. Very strange.

Back in the day some racers would grind out the guide boss for better flow.

Someone was not very careful when they R & I'ed the exhaust guide and thats the result. I've seen a fair amount over the years and its due to not heating the head properly when extracting & installing the guides. Proper lubricants are also necessary when installing the new guides to prevent galling and cracking.

This could be repaired by removing the guide and TIG welding, then re-machining the guide bore, followed by a new guide and honing to fit. One also needs to be sure the guide is centered correctly as well.

Thanks for your contribution Steve...always appreciated.

It looks like all should be removed and inspected. I am not sure how important the ceramic covering is? It is not looking great in some spots.

Is a repair as good as finding better heads?