Tips on valve guide removal

[SteveCarr]

Yesterday I removed all of the valve guides from the cylinder heads from my 1985 930 Turbo. I did it like this.

I have a special drift that fits the valve guide that I made from 1/2 inch steel rod. I made this on a lathe about 20 years ago when I did my last engine re-build on a 911.

After de-greasing all six heads I put them in my wifes lovely convector oven and set the temperature to 230 degrees C.

After "cooking" them for approx 45 minutes I took each head from the oven and placed it on a peice of wood on the kitchen floor.

I carefully used some wet kitchen roll to poke down the centre of the guide to cool it a little then I used my special drift and a 4lb lump hammer to remove the guide.

Each and every one came out with no problems or damage to the heads.

When I fit the new guides I will put the new guides in my freezer overnight then heat the heads in the oven again then use another drift with a collar on it to insert the new guide to exactly the correct depth.

When I get my digital camera back I will post some photographs of the drifts I made.

I hope that this information is useful and if anybody has any other tips or advice it would be nice to hear.

Regards

Steve in the sunny UK!

[neilca]

Steve,

I just put new guides in my heads. I used dry ice to chill the new guides and heated the heads to 400F. Went in without a hitch. The dry ice will chill the guides to a lower temp then the freezer.

Good luck,
neil

[davidppp]

Hello, Steve.

I like to drill them guides first: 12mm is good..I believe this allows them to collapse a little thus reducing the broaching effect in the head..I leave the last 1/2 inch undrilled to seat the drift on and drive them out cold..

Kind regards
David

[Henry Schmidt]

If you do enough heads you will find that pushing the guides out will only work if the guides have very little wear.

What we do is run a 10 mm tap in the spring end of the guide and then screw a 10 mm bolt in the threaded hole 15-20 mm.
Next you push the guide out with the appropriate valve guide tool by pushing on the bolt.
If you just beat ( wack-it, wack-it, wack-it) on the valve seat end of the valve guide you may get lucky on a few but eventually you are going to mushroom the end and as the guide moves it will split the boss on the inside of the port.

[SteveCarr]

Hi Henry,

I did not make myself clear in my first post.

I used a drift from the valve spring end and NOT the valve seat end. My exhaust valve guides were shot so it would have been impossible to get them out by trying to drive them from the valve seat end as you rightly say.

Best Regards

Steve in the sunny UK!

[Henry Schmidt]

That won't work with most valve guides. Most valve guides have a lip or collar to seat the guide again during installation.
The racing guides have a 5-6mm lip.

[rvanderpyl]

Just put your drift in the freezer. That is how the small aircraft engine rebuilding place I worked at for a few summers did it. They also had a real nice fixture that held up to 8 cylinders in a steel plate with holes cut out to seat the cylinders, it was fixed at both ends so it could be flipped, and then they had gas torchs that heated each cylinder up, the engine guy would throw all the cylinders on the fixture, fire up the torches and 10 minutes later turn them off, flip the cylinders over, grab a handul of drifts out of a freezer and knock each guide out. Did a very similiar thing to put the new ones back in. He then used the same fixture to hold the cylinders as he reamd the guides to size, cut the valve seats and and then honed the cylinders. He used to redo a complete set of 6 cylinders in about an hour.

[cgarr]

If you thread and plug one end as Henry does, that works great but I also drill out 90% of the old guide and it pushes out real nice. No heat or cold needed..

[Henry Schmidt]

Originally posted by cgarr
If you thread and plug one end as Henry does, that works great but I also drill out 90% of the old guide and it pushes out real nice. No heat or cold needed..

It is an extra step but it does help.
If you have the correct size core drill you are ahead of the game.

[SteveCarr]

It seems that running a drill down the old guides to weaken them is popular but I was wondering if this is difficult to do in case the drill grabbed?

If the guide has a lip or collar then you are of course right Henry you can't drive it out like I said. My technique worked on my first 1978 3.0 911 SC for the old guides and the new ones and it will also be OK for my current project but I guess looking carefully at the type of guide that is installed is recommended before you try to get it out.

Nice tips and advice!

Regards

Steve

[cgarr]

A stock bit will grab real bad, I sharpen the bit real shallow, much like a bit used for plastic, otherwise it bites too hard

[john walker's workshop]

i use a step drill and drill 1/2 to 2/3 through the guide and then run it out with a special homemade bit in an air hammer. very gentle on the trigger! i always eyeball the valve spring end for a possible lip and run one out in the direction of the spring seat first to be sure there is no lip. sometimes it's hard to tell. ya don't want to run a lip through the guide bore! proper size step drills are available through baum tools. no heat necessary. never had any issues doing it this way. we used to get vw guides out with the thread tap and bolt method, but on 911 heads, step drilling is so much easier, and faster. mic the old guide and be sure the new one is the same size, or no more than a couple hundredths ofa MM oversize. spray the guide and guide bore with WD40 or the like and run them in. for installation i use the airhammer again, real light on the trigger, and a bit that fits the guide, with a fat washer slipped over it so not to damage the guide.

[SteveCarr]

Here is a photo of the old valve guides and the tools I used to remove them. You can also see the drift with the collar used to fit the new guides.

Hope this is of interest...

Steve

[shbop]

Anyone using Neway cutters on their seats? Manual or air? Thank you!

[cgarr]

I used the manual cutters for both 2.7 and 3.2 heads, worked great #642 #272 and the 9.0mm pilot

[john walker's workshop]

step drill to bore about 1/2 way through, the long bit to run them out, and the bit with the washer to install. no heating or cooling needed.

[tony77targa]

anyone point in the direction to buy a step drill bit online like the one in John Walkers post above... Ive searched for about 4 hours now and ready to give up....
Thnaks
Tony

[shbop]

Go to Baum Tools and type "step drill" in the search box. It will pop right up.

[tony77targa]

Thanks John ... I tried that and am getting nothing ... I must be on the wrong site or something... care to post a link???
Thnaks
Tony

[tony77targa]

Hey John I found it ... thanks for the help ... much appreciated... Tony