Cleaning up the Heads!
04-12-2003, 12:16 PM
#1
User
Thread Starter
Join Date: Oct 2001
Location: Cincinnati, Ohio
Posts: 380
Likes: 0
Received 0 Likes
on
0 Posts
Cleaning up the Heads!
Man, what a job! It took me 1/2 an hour just to get the valves out, then another 1.5 hours to clean out all the carbon. This is just one head!!!
I'm going to wet sand the gasket surfaces with 600/1000 grit paper. A cheap mans deck job. My head and block are flat, so this will work.
After that, re-seating the valves with a bit of lapping paste. I was amazed how much "wiggle" is allowed in the valve guides. A full 0.8 mm per the factory manual. I measured mine at 0.3 mm. The new valve guide seals will be a real help with oil consumption. The old ones were plastic, the new are a rubber or synthetic compound.
This is propably going to consume at least 5 hours of time for both heads. I think before I'm done, I'll have well over 100 hours into this engineb rebuild.
I'm going to wet sand the gasket surfaces with 600/1000 grit paper. A cheap mans deck job. My head and block are flat, so this will work.
After that, re-seating the valves with a bit of lapping paste. I was amazed how much "wiggle" is allowed in the valve guides. A full 0.8 mm per the factory manual. I measured mine at 0.3 mm. The new valve guide seals will be a real help with oil consumption. The old ones were plastic, the new are a rubber or synthetic compound.
This is propably going to consume at least 5 hours of time for both heads. I think before I'm done, I'll have well over 100 hours into this engineb rebuild.
04-13-2003, 08:37 AM
#3
Addict
Lifetime Rennlist
Member
Lifetime Rennlist
Member
</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica"> I'll have well over 100 hours into this engineb rebuild. </font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">No free lunch when doing it right <img border="0" title="" alt="[Wink]" src="wink.gif" />
04-13-2003, 10:32 AM
#4
User
Thread Starter
Join Date: Oct 2001
Location: Cincinnati, Ohio
Posts: 380
Likes: 0
Received 0 Likes
on
0 Posts
I finished up the pass. side head this AM. Up till midnight, cleaning off the carbon on the valves. Amazing how hard it sticks to the exhaust valves. Extra heat from turbocharging probably doesn't help any.
Everything lapped in real nice. Those valves should bite up real tight now. I had one slight exhaust leaker, but I think this was due to carbon build up.
If I see one more spring shim this weekend I am going to scream. Keeping all those parts straight was a pain. What would really suck would be realizing you forgot the stem seals after the engine was back together. Double check everything is my rule.
The head looks great....now I just need my block, pistons and turbos back.... tick tock!
Everything lapped in real nice. Those valves should bite up real tight now. I had one slight exhaust leaker, but I think this was due to carbon build up.
If I see one more spring shim this weekend I am going to scream. Keeping all those parts straight was a pain. What would really suck would be realizing you forgot the stem seals after the engine was back together. Double check everything is my rule.
The head looks great....now I just need my block, pistons and turbos back.... tick tock!
12-23-2003, 02:14 PM
#5
Drifting
How did it go John? Randy (tresamore) has given me loads of advice already, but wondered how you got on. Did you use the protective sheaths on the valve stems? My Official Porsche Centre doesn't seem to know that they exist!
12-23-2003, 03:00 PM
#6
Photoshop Bully
Rennlist Member
Rennlist Member
Hi Guys,
John,
I had the same problems cleaning the heads, I got a bucket close to the size of the head, put the bare head in the bucket and filled it w/ carb cleaner halfway up the head. Soak it for awhile and turn it over and soak the other end. It came out looking like new, no scrubbing. Same stuff to clean the valves.
Paul,
The sheath is to protect the valve seal surface from the grooves cut into the valve stem that the locks seat into. After the valve is reinstalled, the sheath is put over the valve stem, the seal then slides over the valve stem and down onto its seat. If the sheath was not there, the valve seal would have to go over the grooves which are sharp. It would cut or score the seal which will allow oil to leak past the seal into the path of the air/fuel on the way to the cylinder.
John,
I had the same problems cleaning the heads, I got a bucket close to the size of the head, put the bare head in the bucket and filled it w/ carb cleaner halfway up the head. Soak it for awhile and turn it over and soak the other end. It came out looking like new, no scrubbing. Same stuff to clean the valves.
Paul,
The sheath is to protect the valve seal surface from the grooves cut into the valve stem that the locks seat into. After the valve is reinstalled, the sheath is put over the valve stem, the seal then slides over the valve stem and down onto its seat. If the sheath was not there, the valve seal would have to go over the grooves which are sharp. It would cut or score the seal which will allow oil to leak past the seal into the path of the air/fuel on the way to the cylinder.
12-23-2003, 06:01 PM
#7
Drifting
Thanks Randy, I wasn't going to ignore your advice, but getting hold of these sheaths was proving difficult. 928 Int doesn't supply them, I described them to the OPC almost exactly as you said and they seemed puzzled, so I faxed the page from the WSM that mentions them. Fortunately a 928 buddy here has said he has some if I can't get them anywhere else, but how many times can you re-use them? I won't need 32 will I?
I've also ordered my gallon of carb cleaner (as you suggested) all I need now is that head shaped bucket...
I've also ordered my gallon of carb cleaner (as you suggested) all I need now is that head shaped bucket...
Trending Topics
12-23-2003, 07:11 PM
#8
Photoshop Bully
Rennlist Member
Rennlist Member
Paul,
Find some thin wall but stiff heat shrink tubing and put it on something slightly larger than the valve stem (Pin gages work nicely) leaving a 1/2" or so extended above the top. You don't want anything too thick. It may force the seal to open too far which might decrease its sealing grip or maybe damage it. Make sure its long enough to cover the valve lock grooves on the valve. Shrink it around whatever you use but do a gradual shrink above the top. You want a gradual taper on the tubing so your seal will slide on easy and open gradually. You don't want to be forcing the seal open over a 1/8" or so travel distance. After it shrinks you can remove it and there is your installation tool. If you can't find anything close to the valve size, the valve itself will do, you'll just have to stretch the heat shrink out a little after you remove it. It should look something like this (below) when your done. You'll only need 1 unless you damage it somehow. The one that came w/ the seal kit was pretty tough, but easily misplaced, hence the shrink tube ;-). 1 gallon probably won't be enough to do the buckethead thing. I think I used 3-4 g.
||
/ \
| |
| |
Find some thin wall but stiff heat shrink tubing and put it on something slightly larger than the valve stem (Pin gages work nicely) leaving a 1/2" or so extended above the top. You don't want anything too thick. It may force the seal to open too far which might decrease its sealing grip or maybe damage it. Make sure its long enough to cover the valve lock grooves on the valve. Shrink it around whatever you use but do a gradual shrink above the top. You want a gradual taper on the tubing so your seal will slide on easy and open gradually. You don't want to be forcing the seal open over a 1/8" or so travel distance. After it shrinks you can remove it and there is your installation tool. If you can't find anything close to the valve size, the valve itself will do, you'll just have to stretch the heat shrink out a little after you remove it. It should look something like this (below) when your done. You'll only need 1 unless you damage it somehow. The one that came w/ the seal kit was pretty tough, but easily misplaced, hence the shrink tube ;-). 1 gallon probably won't be enough to do the buckethead thing. I think I used 3-4 g.
||
/ \
| |
| |
12-24-2003, 10:36 AM
#9
Rennlist Member
Pardon my butting in, - if you plan to make a device, an inverted golf tee with the cup trimmed to the diameter of the stem followed with a sheath of shrink wrap will provide a gradual, smooth taper - plus a handle.
Or, at the throw away cost of shrink tube, with the hair dryer/heat gun, form a custom 'capote' (French style) over each stem - giving the tightest fit possible.
Or, at the throw away cost of shrink tube, with the hair dryer/heat gun, form a custom 'capote' (French style) over each stem - giving the tightest fit possible.
01-02-2004, 05:38 PM
#11
Drifting
Slow progress
I'm bored with working on these heads, so I thought I'd post some pics instead.
Head before starting
http://www.928.org.uk/~ukkid35/proje...ure%20060a.JPG
Close up
http://www.928.org.uk/~ukkid35/proje...ure%20058a.JPG
Valves removed, cleaning underway
http://www.928.org.uk/~ukkid35/proje...ure%20056a.JPG
My workshop
http://www.928.org.uk/~ukkid35/proje...ure%20057a.JPG
The Valve Stem Seals are a PITA to remove, even after spending yet another $30 on Seal Pliers. The valve guides have very little wear in them, certainly no where near 0.8mm at 10mm.
How John managed to remove all the valves in 30 minutes I have no idea, it took me forever.
I'm awaiting arrival of the valve sheaths so I can eventually reassemble them, eventually my OPC here in the UK managed to work out what I was talking about, I was so pleased they were only 30 cents that I ordered 32. Shame I didn't see all your helpful replies in time (I should have subscribed to the thread!).
Tried soaking a single exhaust valve in carb cleaner, but the white deposits are still there. Anyway since my bedroom is only a couple of feet away I can't really have buckets of carb cleaner sitting in the hall.
I think this is going to take me a while...
Head before starting
http://www.928.org.uk/~ukkid35/proje...ure%20060a.JPG
Close up
http://www.928.org.uk/~ukkid35/proje...ure%20058a.JPG
Valves removed, cleaning underway
http://www.928.org.uk/~ukkid35/proje...ure%20056a.JPG
My workshop
http://www.928.org.uk/~ukkid35/proje...ure%20057a.JPG
The Valve Stem Seals are a PITA to remove, even after spending yet another $30 on Seal Pliers. The valve guides have very little wear in them, certainly no where near 0.8mm at 10mm.
How John managed to remove all the valves in 30 minutes I have no idea, it took me forever.
I'm awaiting arrival of the valve sheaths so I can eventually reassemble them, eventually my OPC here in the UK managed to work out what I was talking about, I was so pleased they were only 30 cents that I ordered 32. Shame I didn't see all your helpful replies in time (I should have subscribed to the thread!).
Tried soaking a single exhaust valve in carb cleaner, but the white deposits are still there. Anyway since my bedroom is only a couple of feet away I can't really have buckets of carb cleaner sitting in the hall.
I think this is going to take me a while...
01-02-2004, 08:44 PM
#13
Rennlist Member
Rennlist Site Sponsor
By the way - you don't want a head or block surface to be really smooth - a little tooth from machining helps with gasket sealing. My machine shop uses something like 120 grit belts on their big flat-bed head surfacer.