Extracting broken head studs with the engine still in the car

[bkinghor]

Well, actually, I had the engine out while doing the gearbox, but I got the four broken head studs out and replaced without removing the cylinder heads – just the tappet covers off.

With the engine back in the car, and looking at spacing around the tappet covers, this method to extract and replace broken head studs should work with the engine still in the car. Not so comfortable, but likely do-able.

I made my extraction tool from an 8mm Koken nut twister, welded to a ¼ inch socket extension and turned down to just over 10mm outside diameter. I also had Plan B and Plan C, but didn’t need to use them. All described here:

https://www.youtube.com/watch?v=KQyXD_deDWA

Hopefully this saves some heartache for some of you!

Cheers, Brian

[Alan L]

Wow - great skills. Impressive. Didn't think it would be possible. Usually need gobs of heat.
Must buy some Mouse Milk :-)
So you were trying to freeze the stud down after heating the case area? That was the point of freezing the tool?
Alan

[icarp]

Brian, Thank you so much for making this video.
This is proof , the procedure can be done !!!
There are many people out there that argue that it can't be done


Ian

[Alan L]

Yes, the video is very helpful.
I orginally thought the title of the thread was really asking the Q. My answer would have been No.
If you had just said it was possible I still would have had trouble believing it.
Seeing the video was very instructive. Thanks for taking the time to make it.
Alan

[boyt911sc]

Originally Posted by icarp

Brian, Thank you so much for making this video.
This is proof , the procedure can be done !!!
There are many people out there that argue that it can't be done


Ian

Ian,

I was skeptical at first until I saw the tool successfully removed all 4 broken Dilavar cylinder head studs. This tool discovery is very beneficial for low mileage engines that don’t need a premature rebuild work. There are still many low mileage cars with Dilavar head studs in existence hidden some where.




Brian,

That’s a very impressive machine work. Wished you found this special technique much earlier like 2 or 3 decades ago. Nevertheless, this is an amazing discovery. Congratulations.

Tony

[bkinghor]

Thanks Alan!

That looks like a Mouse Milk advert indeed! But just passing on the info. It does seem to have high affinity to corroded parts, and penetrates very well when you squirt some on a rusty nut or so. But some other such products probably similar.

Indeed, it seems sensible to cool to tool, as long as you use it very quickly so that there is still some heat differential between the case and the stud itself. Else it just cools the whole area and you are better off not cooling the tool. The first crack is the hardest, but my studs continued to be very tight for many turns - so possibly good to keep up the heating as required. Hopefully others get the same good result as we did!

[Alan L]

You had a bunch of clever tricks in there. Impressed.
The way you fitted the new stud was clever too. I am not sure everyone will have a hollow socket set - but I am thinking a deep socket with a hex end (like a spark plug one) and a ring spanner, may suffice.
I also figure you need a nutcracker socket with the shallowest flutes you can find - that seemd to be your problem with the first attemot - not enough external meat on the tool.
I have welders and a lathe, so equipped for the next challenge - should it arise.
I love seeing new tricks applied to old dogs.
Well done.
Alan

[proporsche]

Very clever approach to the stud problem.You are crafty man...It helps to have the necessary machines around.Nicely done....
The only thing is ....if one or two are broken.....eventually you will ended up doing the others too...

Ivan

[Alan L]

So, Ivan, You could use the same technique to replace them all, at the same time?
Saves a lot of work pulling cylinders. If the engine was good and you loose one or two with corrosion (Dilavar), you could pull them all this way without splitting the engine.
The customer would be very pleased with you :-)
Regards
Alan

[proporsche]

Originally Posted by Alan L

So, Ivan, You could use the same technique to replace them all, at the same time?
Saves a lot of work pulling cylinders. If the engine was good and you loose one or two with corrosion (Dilavar), you could pull them all this way without splitting the engine.
The customer would be very pleased with you :-)
Regards
Alan

To be honest Alan..for me it is much quicker to take the heads off and do other necessary things than do all this work - to put it back together -if all is good -one day job for me, again very nice and crafty work by Brian

Ivan
if i work on engine they have to look like this


https://zupimages.net/up/24/17/bgfw.jpg

[shadowjack1]

Well done to say the least

[Porchdog]

As a guy who just found his first broken head stud this is very interesting to me!

That extractor is a Koken 2127-8? What the final diameter after turning?

Am I correct to assume that you replaced all the studs?

Thanks!

[shoooo32]

I agree, for an original, low mileage car where preservation is key, this is a great way to replace a few popped studs. Thanks for sharing this with us, Brian!

[Alan L]

Originally Posted by Porchdog

As a guy who just found his first broken head stud this is very interesting to me!

That extractor is a Koken 2127-8? What the final diameter after turning?

Am I correct to assume that you replaced all the studs?

Thanks!

Brian gives the dimensions in the Vid - but the Koken did not work. Not enough meat on it to turn down. Had a no-name brand.
There are a few skills in here not apparent in the Vid.
For instance, I would be keen to know how he welded the socket on to the bolt - which really had to be dead true to the bolt. Any out of round = loss in the socket when skimming to diameter. Since there is so little to play with, I am guessing he somehow used the lathe to get it true for welding.
Would be keen to know. Otherwise you are going to end up wasting sockets. Once made - another useful tool in the box.
Alan

[bkinghor]

Hello Alan! A correction to your post ... The Koken was the one that worked. The Mastercraft one did not work, but probably not its fault. The stud I tried it on had broken just below the cylinder head, where the rabbit hole narrows just a bit, in the cylinder. It was binding on the cylinder when I thought all my efforts were on the stud itself, so it must have been slipping.

Yes, getting the tool dead straight is dead right! If it wobbles then the gripping end will pull in and out of the broken stud at each point, as it turns.

However, the long hole in the Koken Nuttwister (picture below, from the vid) made that easy. Just turn down the end of your extension/shaft until it is a tight fit in that hole. Then it is dead straight and ready for a bit of MIG welding.


Hello Porchdog! Yes 2187-8 is OK, but better to get the long version that is in the video (pictures hopefully shown here), it has a nice long hole to tap it onto your shaft. I machined off the part number, but it looks like Koken 3128.80-8 ...
https://kokenusa.com/products/deep-nut-twister-3-8sq-dr-8mm-l-80 (~$35 most places. I found mine in a box of bits in a toolshop in Hong Kong!).

Final diameter is as big as possible while getting free turning down that rabbit hole. About 10.2mm for me. I actually tapered it off just a bit so that it is fattest (10.2mm) at the end, where the work is done, but a tad thinner (maybe 9.9mm) as of say 5mm from the end, to help not get snagged on any irregularities. I might not have needed to do that.

Once you know what you are doing, it should be under an hour to make your tool.

I only replaced the four broken studs. My reasoning was that in extracting all those sleeping dogs (unbroken studs), one or more could break, and possibly so near the crankcase that extraction might be difficult. Then you would have the big job to do. Easier to just look each time you adjust the valves, and replace as needed, engine in the car.

Cheers, Brian

[mepstein]

I learned my lesson about replacing broken studs about ten years ago. Had a customer who was very price conscious and only wanted the broken ones replaced. I obliged him and put the engine back together. The next day I come into the shop and see two broken studs on the ground. I figured they must have rolled off the work table. Just then, I hear a “ping”, a stud shoots up about two feet and falls to the floor. I learned my lesson and from then on, only replaced the entire set. No more onesie/twosie.

[bkinghor]

Hello mepstein,

I agree.

If you pull an engine down it makes good sense to replace all the Dilavar studs. Disturbing them twice (undo and redo) can obviously send them over the edge - and this seems apparent in your example with 2 or 3 pinging off just after the rebuild.

However, if the studs have lasted 50 years, and are left undisturbed, they are unlikely to ping for quite a while. If anything, replacing broken studs will lower the pressure on the remaining unbroken ones.

But in the end it is a personal choice. To avoid pulling down an otherwise sound engine would be attractive to many people, and once you are set up to replace a broken stud with the engine still in the car, there is little time and cost in doing that as required. If you have to end up removing the engine in order to twist out a stud, then of course that might alter the equation.

Cheers, Brian

[Porchdog]

I was thinking to replace all the studs, broken or not. I figured so long as I left at least two per cylinder in place on my remove and replace plan, I wouldn't be disturbing the fit at the spigot or head.

I further figured the intact studs would be easier to remove.

[boyt911sc]

Originally Posted by proporsche

To be honest Alan..for me it is much quicker to take the heads off and do other necessary things than do all this work - to put it back together -if all is good -one day job for me, again very nice and crafty work by Brian

Ivan
if i work on engine they have to look like this


https://zupimages.net/up/24/17/bgfw.jpg

Brian,

After watching the video of the broken head removal, all I could say was WOW! It is an incredible and amazing technique. Your title says broken head studs removal with engine in situ, that is not the case. But it should not deflect the credit and honor for this remarkable achievement.

However, as an engine rebuilder, engine removal is our way of life. And I tend to agree with Ivan about using this method versus the conventional procedure. Only time will tell us how practical and successful this could be done as well as Brian demonstrated.

Kudos to Brian!

Tony

[Rick Cabell]

In no way do I want to rain on the parade of this thread. Hats off to the clever work.
But, I don’t want anyone who is new to this to think it is this easy.
I have replacing broken Dilivar head studs since the 80’s. I would say only 5-10 % can be removed using this process. The rest are in tight with locktite from factory. Last week I took apart a 3.0 SC engine. All 12 lower studs were broken, never seen that before.
The typical method with engine disassembled without pistons and cylinders is patience.
First I cut the stud if needed to about 3-4 inches remaining, if you have that much. Then weld a 10mm nut over the top of the stud. Yes, you can weld to dilivar. Then take an acetylene torch with a rosebud tip and heat the bottom of the stud in the cylinder opening. I keep a temp gun handy to monitor the temp as if you melt the aluminum, you are done. Once about 275-290 degrees the locktite gives. Still you have the work the stud back and forth slowly u till you can see you are home free and back it out the rest of the way. That is with a long ratchet over the end of the 10mm nut.