The Stovebolt Site Forums The Shop Area Engine Shop disaster!

Today I went out to do some more work on my engine. Started it up and ran it to get it warmed up. Then started on re torquing the bolts. Got the rocker arm bolts done, got the manifold bolts done, got most of the head bolts done, and then one of the head bolts snapped off!
Judging by the length of the piece I took out it must have snapped off right about at the block.

Now I'm going to have to pull the head, drill and re tap the hole, then put everything back together again.

Luckily I have a couple of spare head bolts to replace it with.

On the other hand, there were no oil or water leaks after running the engine for 10 minutes, so that's something!

I wish I could figure out a way to drill out the bolt and use an ez out without pulling the head, but it's so far down in there that nothing I have would reach.

Tim

Might be able to find a l.h. drill bit.

If you end up pulling the head, it might be worth your while to replace all of them, cheap at ARP. They won't have a set for your engine, just order by dimension.

Ed

I've thought about a left hand drill bit. If it were long enough to reach that might be good solution. I don't know what ARP is, but I have a local Fastenal store. I also think when I replace it I might use a heavy duty washer under it, just to make sure it isn't bottoming out.

I assume that it would require careful cleaning of the hole once I got it out. I don't think any of the head bolts go through into water or oil passages in this engine (1960 235).

Tim

Google ARP fasteners, Camarillo CA.

Ed

Clearly not the end of the world. No leaks. Woo Hoo!
What was your torque wrench set at? Did you chase all of the threads and blow them clean with compressed air prior to engine assembly? Machine shop procedures make a mess, and sometimes it gets in those holes.
Carl

Clearly not the end of the world. No leaks. Woo Hoo!
What was your torque wrench set at? Did you chase all of the threads and blow them clean with compressed air prior to engine assembly? Machine shop procedures make a mess, and sometimes it gets in those holes.
Carl

I broke one years ago on one of these sixes. I removed the head, took the top piece and inserted it into the hole and unscrewed the broken bolt from the hole. The threads were clean and oiled and the bolt threads had not become distorted. I would remove the head and try that first.

It would be fairly simple to weld an extension onto a LH drill bit and try backing the stub out that way. The back of a drill bit is tough, not hard, and I've welded plenty of them in the past when I needed a long bit. I can make you a drill guide from oil hardening drill rod that will keep the bit centered in the head bolt hole if you wish.
Jerry

I had my torque wrench set at 95 pounds, which is the top end of the recommendations. I probably should have used 90.
And I probably should have used new bolts, not reused the ones I had. Yes, they were well cleaned and oiled.
I don't think I will have a problem removing the bolt if I pull the head, I'm sure it is snapped off flush with the block measuring it using the piece I have against the head.
Just wish I didn't have to pull the head. I don't suppose it would run with one head bolt missing, huh?
And I am going to buy new bolts for reinstalling the head. Plus new head gasket, new manifold gaskets, and new water pump gasket. I think that's all I need to pull off to remove the head. And this time I'm going to get an assistant to help me drop the head in place. I mean gently lower it in place!
I tell myself that it is so much better for this to happen now rather than when I'm driving down the highway.
And it does run well, and no leaks!

As far as drilling it out in place, I think I could use a bit that just barely fit in the hole in the head to drill a dimple in the stub, so it's centered. I have a set of drill guides I use for wood working that should fit the hole. I also have an assortment of steel bushings that would serve the same purpose. I'm going to check around tomorrow and see what I can find in the way of drill bits and bolts.

More to come!

Tim

Working in my diesel shop we used remove broken bolts with head in place , put a piece of black pipe into the headbolt hole and weld the inside of the pipe to the top of the broken piece. The heat helps break the threads free, you leave about 4 inches above the head and use a pipe wrench to rotate the pipe . Did this several times and it works, I believe we used stainless rod so the weld would not stick to the cast iron. Be aware that if it doesn't come out drilling it later will be more difficult.I have also tried using the broken piece to twist it out like it was mentioned above it may come out easy. Good luck

Well, I went out this morning and managed to back the broken stub nearly all the way out. I took the broken piece I had, managed to get the sort of sharp edge where the bolt had broken aligned with the part in the block, and applied pressure while I slowly turned the bolt. It took an hour of carefully turning while maintaining pressure with a long screwdriver but as far as I can tell it is either unscrewed from the block or has one thread still in there. Now I have to see about actually pulling it out. I have some rare earth magnets, so I'm going to slip the bolt into the hole, the stick one of those on top and see if I can get the stub pulled with that.

Tim

I wonder if a very small dab of fast curing JB weld on the end of a 1/4 or 3/8 inch rod (being careful not to let it run beyond the diameter of the rod), might bond well enough for you to turn the broken piece?

You could place a circular piece of foam rubber around the end of the rod and put the dab of epoxy on the rod end, so when you push it down onto the broken bolt, the foam will create a wall to keep the epoxy from running out and contacting the block threads. Just an idea. If the broken piece is slanted, then you could slant the bottom of the foam ring to match the contour.

This would have to done carefully, of course.

You have got some good ideas going so far Bluesman. You got it almost out. Keep fiddling without JB or other for now. Don't loose a magnet down the hole, you will never get it out.
I reuse a lot of bolts when refreshing an old truck. Body and frame bolts. Screws and hardware. Just wire wheel and use. No problem. But old bolts on head or other critical motor parts, probably should not.
When torqueing, and there is a range, shoot for the middle. (This is called the nominal) Head bolts are usually re-torqued after a few runs. As mentioned, suck out all the holes. Be sure what the depth is of each hole so as not to bottom out. Torque in proper sequence at 3-5 times around. A third to a fifth of the torque at a time. Hold torque wrench ONLY at the end. If your torque wrench is a beam style, it has two problems. 1. Not as accurate as other. 2. Has a parallax distortion issue.

Well congratulations, you are almost there. Would a giant pair of needle nose pliers do it?

On my 216, the torque for the headbolts is 80 to 85. I guess you have a newer six.

As Truckernix posted, the torque spec for 235 changed in 1953 from 75-80 to 90-95 FT LBS. Be sure of your block year. However it should have nothing to do with the bolt breaking. If these are 1/2 Bolts, 90-95 is beyond the range of a Gr 5, even a fine. Maybe they are 9/16. The torque charts don't show that high but there are a lot of variables. Stay at 90.
You should have been able to use all the old bolts. However, especially with head bolts, PO's have "stretched"/overtorqued them, and when you re-torque it breaks.
This is not a disaster, as you can see, lots have done it. Be careful when a bolt gets a rubbery feeling from now on or something doesn't seem right. No jerking when tightening.

I'm using a new click type torque wrench, decided I no longer trusted my old beam style. I really like it. And I agree I probably should have run them to 90#.
One thing I'm wondering. I am replacing this bolt with a brand new one, and I will torque it in steps (I think I originally did 30, 60, 90).
If I want to replace the other bolts can I just remove them one at a time and replace and re-torque? I guess it's OK to do that, since the shop manual calls for removing two bolts to use as lift points.
I suppose I will have to re-torque the bolts after I replace them and run the engine. I was amazed just how much the bolts had loosened up after running the first time. Some of them I had to turn nearly a full turn to bring them back to torque.

Tim

Yes one at a time is OK. Just do it per the pattern. Then re torque later. If you loosen them all, you will loose gasket compression/seal.

Needing to make that much of a turn is a big red flag- - - - -the bolts are stretching way too much. The one that broke just might be the tip of the iceberg, or you could be way over the proper torque specification. I'd recommend replacing all the bolts, one at a time.
Jerry

A 3/4 to full turn to re-torque???

+1 on what Jerry said.

Bluesman, 3/4 turn is 1/16 linear travel on a 1/2-13. Don't think so. Hope not. Red flag indeed.

1. What could possibly make it stick up 1/16? Heat and torqueing should only stretch it .005-.010. You are talking .063-.078. At least it seems that way.
2. Maybe it was much less than 3/4-1 turn.
3. Maybe wrong bolts and bottoming out and twisting off.
4. Maybe correct bolts with gunk in bottom of hole or wrong washers, if any were used.
5. Assuming a 1/2-13 thread.

My 2 cents:
Threads in block not clean or liquid (i.e. coolant, oil) in threads or how about head not properly centered on block pulling bolts at angle. With no locating pins the bolts will try to center the head as tightened.

Related note, I did the reinsert the broken bolt to remove the remander on an 5.7 diesel I had for many years. Boy, those were the days!

Interesting BC59. I wonder if a bolt will hydraulic lock with fluid/oil down in hole? Never thought of that. I think it could.

Bluesman, you said bolts were cleaned and oiled. We are asking if threaded hole was cleaned out. Threads chased? Vacuumed out the debris?
Are all the original bolts the same length? I would check the total depth of each bolt hole against the bolt with washer length; and be sure there is space at bottom before bolting.

Hardware stores don't have the proper lengths for many of our automotive bolts. Weird but true. If you saw extra washers on the bolts, that would be a PO's remedy.

As Jerry said, you are in a red zone with this broken bolt mystery. Somebody did something wrong..... hard to break a 1/2" bolt.

Possible the new torque wrench not calibrated properly?

I went out today and bought new head bolts and will replace all of them.
None of them had washers when I tore apart the engine, and I didn't use washers when I assembled. How ever I bought some thick heavy washers when I got the bolts.
I thought I had cleaned the holes well enough before assembly, but I will check each hole when I swap bolts to make sure.
I used short lengths of all thread in two holes to align the head during assembly, and hand tightened each bolt before I did any torquing, so they must have been pretty well lined up, I would think.
I will measure the depth of each hole to make sure there is no bottoming out. I suppose there might have been some oil in the holes, but only what might have been on the bolt when I installed them. And I didn't use much oil, just dipped them in some oil then wiped them by turning through a clean shop rag.
I think it is possible that these old bolts have been used for a couple of rebuilds, and might have gotten too stretched out, maybe weakened from being torqued down many times. It was obvious when I tore apart the engine that someone had done some work inside before, so I know of at least one rebuild.

I'm going to replace every bolt, being very careful on inspection of the hole in the block, and hope for the best.

Tim

I got a call from one of my round track competitors about some stripped threads in a small block Chevy race engine he was assembling. It seems that in the process of installing the heads, he had stripped the threads on 10 of the head bolts. "Can you fix it?" I ended up installing heli-coils in ALL the head bolt holes on both sides of the block, since the holes that weren't stripped were badly damaged. Two questions- - - -why didn't he stop when the first bolt stripped, and just what happened in the first place? It seems he had made a 20-pound error in setting his click-stop torque wrench, and he had a bad habit of working on his race car while suffering from a bad case of Budweiser Fever!

A few months later, he was "testing" the race car on the road in front of his house, broke a piece of steering linkage he had been welding on, and ran the car through his neighbor's bedroom. Nobody was home, but he had to sell the car to pay for the damage he caused! The guy was definitely not the sharpest knife in the drawer!
Jerry

Well, even I would probably stopped after the second or third stripped bolt. And I admit that my eyes aren't what they used to be (in fact not much is), but I know enough to double check after I set the wrench, just in case.

I took out one bolt, just to see where I was, and measuring the bolt and the hole I found the hole is just about 1/16" deeper than the length of the bolt. So I am going to be using thick washers on all of the bolts.

Tim

My '60 235 did not have washers and I did not add them when I had the head off. With only a 1/16th difference, I'm wondering if you have the right bolts to start with. I did not do that check on mine when I took off the head off so not sure if it is normal. Someone with that knowledge will probably chime in. Also on the use of washers, I've always used special hardened precisely flat flat washers on heads that call for washers so you get a more precise torque. Again others more familiar with the 235 can agree or refute that. What are the markings on the top of the bolts?

Dennis

1/16 is very bad. Wrong length bolts. If your measurements are off 1/32 on each piece or bolt length tolerance, you will bottom out, bad bad bad. Very bad. Holes could be different depths. Not familiar with that. Betting you snapped the bolt because it was bottomed out.

Over 2 1/2 length, the tolerance is +.06/-.08. That will bite you. A bolt maker will not shoot for the minus side. If the threaded hole is a blind hole, it probably DOES NOT have thread all the way to bottom. Even using a bottom tap. And you may be measuring depth to the point of the tap drill. That will throw you off with a false depth.
You don't need a massive amount of thread engagement. You do need 1/4 inch gap at bottom, minimum.
If bolt and mating threads are same material, 4 threads engagement is as strong as the bolt. Some designers have a 1D engagement standard. (in your case: 1/2")

It's possible that the wrong bolts were in the engine when I bought it. I do know that one head bolt was not there! The washers I bought today are hardened, 1/4" thick, and very flat. The edges look like they have been machined. They look like grade 8.

I am planing on measuring each bolt and each hole as I go along replacing bolts. I haven't measured the hole and bolt that snapped off because I'm still working on getting that out. And I will clean out each hole as I go along. Don't know what else I can do.

Tim

You are now on a winning track. Probably giving you TMI.

What are the washers for? I have never seen them on head bolts.

.."possible wrong bolts were in engine"

That is absolutely correct. I may add that for many years in my youth I watched as a lot of folks, including my daddy, did not own a torque wrench or could afford one, or knew anyone that had one to loan.
Therefore I'll guarantee you that many bolts were "under" and many "over" torque.

Its just my opinion but I think I'd have bought a new set of head bolts instead of washers.....
Still, hope all goes well and let us know how things go on getting the broken one out.

OK now lets throw another wrench in the spokes. The original head bolts seem to have a pilot shoulder under the head. A diameter larger than the shank. This would be your centering feature. If they all go in before any are tight, then this would align the head to whatever they wanted aligned. (for the gasket, passages and mechanical features). So actual 235 bolts should be used, I think, for this alignment feature and they would be correct lengths. However they do not seem to be available except used. Don't think original used washers with the shoulder bolt.. They will not hurt anything if you are using them as spacers, and a normal bolt.

Problem solved!

I went out an bought an extendable magnetic pick up tool at O'Reilly's this morning, with a rare earth magnet on it. slipped it into the hole, gave it a turn to make sure the stub was really out of the block, and it slipped right out. I put in a new bolt with the special washer, torqued it to 30, 60, 90, no problem. I'll recheck the torque next time I have the engine running.
I've seen these washers before, I remember using them on VW engines, I assume to protect the aluminum heads. And I think the Jeep straight six I rebuilt had them. I am guessing that these spread out the pressure, they are about 1/4" thick and I think grade 8.
Now on to the next challenge!

Tim

Yes they are used on Aluminum heads. Tim, you are a master mechanic. Seriously! BUT..........you are going to damage the fingers and nails you need for pickin the blues.

I think I qualify as jack of all trades and master of none.
I built my own house, do all of my mechanical repairs, grade the roads, play music, build observatories, and cook. Sort of like the old Amphibicar, as a car it was a great boat, as a boat it was a great car.

Right now my ambition is to get this truck driveable before my 70th birthday. Of course, that gives me nearly two years, but at the rate I'm going ...

Tim

take a week off for good luck, then I am sure all the starts will align up just right..

..I know you will sleep good tonight! Congrats on the job well done.