Stripped/Cracked head bolt?

[Its_Always_T_Time]

Hello everyone, hope you and your cars are all well.

I was replacing Lizzie’s Kingston carburetor with a new Holley NH as the old Kingston was flooding badly and I figured I would pull it out and rebuild it and in the meantime use the rebuilt NH and in the end I’d have a spare carburetor ready to go.

As I got the new carburetor in, I noticed the horn bracket was loose and I decided I would retorque the head bolts to 55ftlbs (I think I have a steel head even though it does not say Ford MADE IN USA on it because it’s magnetized). Most were all up to snuff at about 55ftlbs.

Then I got to the center bolt just ahead of #4 plug, and it was only snugging to a point then becoming loose again. I snugged it down as much as it would go (about 25ftlbs) and I started the engine to see if the mixture was good. Oil began gurgling out of the bolt and I shut the engine down (it only ran for about 15 seconds). I began unscrewing the bolt while praying that it wasn’t cracked inside the block.

Turns out the bolt came out in one piece and the bottom most threads are all totally stripped. I’m going to pull the head off the engine tomorrow afternoon after work to see what’s going on inside the back two cylinders and see if the top of my block is good (hopefully it doesn’t need to be milled).

It looks like the bolts are missing some threads compared to pictures I see of other T head bolts, maybe it is cracked deep inside the head after all.

How do I measure the bolt to see if it’s missing the bottom?

How do I determine what bolts I need? Seems like there are different bolts for different heads.

Are the bolts supposed to bottom out?

How do I determine if I need to retap the block threads?

What thread tap and drill should I use to retap the block threads (if necessary)?

What should I do immediately to prevent any further damage to the engine? (Remove head, oil, and coolant?)

Here is a link with pictures of the stripped bolt. I’m not sure if it’s cracked. https://imgur.com/a/G0omH3a
How should I proceed?

[RajoRacer]

Just my opinion but 55 lbs. are a bit much in my shop - 45 lbs. is usually plenty - there will be more opinions than mine, I'm sure. It appears to be a stock head bolt and the threads are toast and more than likely the block bolts also. There are "high" & "low" head bolts - they're 7/16 - 14 x 3 & 1/4" long for the high head. And no, the bolts should not bottom out !

[Its_Always_T_Time]

How do I determine if my head is high or low?

[Allan]

Check the underside in the combustion chamber. On a low head there is cast in a raised ridge around the spark plug hole. On a high head the spark plug hole is drilled and tapped straight through. Others will be able to give you measurements for each.
Re fixes for the problem, I would,
*use a drill of appropriate size to clean out rust/carbon in each hole in the block.
*use a bottoming tap to clean up all the threads and blow out each hole.
* inspect all the cleaned out holes and helicoil any which are doubtful. I prefer threadserts to helicoils.
* Check each hole and each bolt for engagement prior to fitting the head.

We are fortunate to have a more modern GM product here that has better quality head bolts, which are also longer, so I use these to replace original T bolts. They give optimal depth of thread engagement.

Hope this helps.
Allan from down under.
*

[jiminbartow]

Recommended torque is 50lbs.
Since oil gurgled out, the leak is from the cylinder and not from the water jacket, so you have not punched through the bottom of the hole and entered the water jacket, which is a good thing.
1. Place the damaged bolt next to the other bolts. If it is shorter, you have a problem. When I worked for the Railcar repair industry, this was a common occurrence and our machinist had a special type of welding rod that he would slip into the hole and touch to the broken stud. The rod would weld to the top of the broken stud, but not the walls of the hole. He would then grab the rod with a pair of pliers and unscrew the stud out of the hole. I wish I could tell you more about this special rod.
2. Again. Compare the bolt with the other bolts. If the threads are the same, no one in the past has retapped it a different size or tap. It would be advisable to buy an entire new set of bolts, in case some of the other bolts are fatigued or stressed and about to break. I have never had trouble determining what head bolts to get. There is only one type for the Model T engine.
3. No, the bolts are not supposed to bottom out unless the holes are full of crud and rust. It would be a good idea to blow out all the holes with a high pressure air nozzle, but not before covering each cylinder hole to prevent the rust particles and crud from entering the cylinders. Clean off the head with lacquer thinner, and let dry, then tape over each cylinder hole with several strips of 2” wide clear packing tape or duck tape. Some would recommend stuffing rags into the cylinders, but small particles of rust could fall into the cylinders past the wrinkles of the rags and become lodged between the piston rings and the cylinder walls and badly score the smooth cylinder walls if allowed to remain. Tape over each blown out bolt hole as they are cleaned to prevent contamination by debris from the other holes.
4 and 5. Unless you discover that the female threads are damaged and plan to repair them using heli-couls, no drill will be needed. It is more likely that, after the holes are blown out, the threads will need to be chased with a bottoming tap (not tapered, so the threads will go all the way to the bottom of the hole). If you have a set of taps, the correct TPI (threads per inch) can be found by holding the tap up to the threads of the bolt. If the threads match and seat in eachother, you have the correct TPI. The tap with the correct TPI that will screw into the hole is the correct bolt size. It is possible that a past owner could have re-tapped the hole for a larger bolt.
6. See 4 and 5.
Good luck. Jim Patrick

F487B912-6A7F-4587-AAB6-FF51C4A2F2D6.jpeg (39.57 KiB) Viewed 5611 times

[Its_Always_T_Time]

How do I clean out the rust and carbon with a drill bit? Wouldn’t that damage the threads? Or am I supposed to use a bronze brush drill bit and spin it inside the threads?

[jiminbartow]

Do not use a drill bit. Use high pressure air then chase the threads with a bottoming tap. Only use a drill bit if the threads are destroyed and must be repaired with a helicoil. Jim Patrick

Here is a helicoil. You will need to drill and tap the hole bigger to accommodate a helicoil the proper size and TPI as the head bolt, you will need a special grooved tool that grabs the wire going through the center, to install it. The wire will break off when the helicoil bottoms out in the hole. In the picture, you can see a groove in the top wire to the left of the center wire where the break occurs.

D1CDA000-FE0A-4F02-A4B3-49611FE26BAD.png (88.29 KiB) Viewed 5594 times

[Its_Always_T_Time]

Thank you Jim, that was a lot of very helpful information. I appreciate you posting the picture from Imgur here, I tried posting it here but it was too large.

[Mark Gregush]

45-50 is fine. I tighten mine using the Ford head nut wrench. Some day I should check to see what it sets them at.

[Its_Always_T_Time]

I’ll pull the head next weekend when my final exams are over and I can put all of my attention towards Lizzie. I’ll see what those old threads are looking like after I clean them up and put put a bottom tap in them. Hopefully they are all ok and I don’t need to use helicoils.

[jiminbartow]

Keep us posted. Jim Patrick

[Dan Hatch]

Here is a link to Lock N Stitch. They make a product call Full Torque inserts check them out. Cost ,but they work. Dan
http://www.locknstitch.com/index.html

[Its_Always_T_Time]

I’ll definitely keep you all posted. I greatly appreciate all of your help and I can’t wait to get my hands oily again. If oil was coming out under the head of the bolt with the engine running, does that mean that #3 piston’s ring is blown? Or is that just because there was not enough pressure from the bolt to seal the head gasket and it allowed oil up into the combustion chamber?

I’m already thinking the back two bolts might be a bit of a challenge to clean since they are under the firewall. :/

[TXGOAT2]

The oil is probably a mix of oil, rust, and carbon that has accumulated in the narrow space around the head bolt over time. When the bolt failed, it allowed the accumulated stuff to escape, either due to heat expansion or slight leakage from the cylinder pressure or the water jacket. It's probably not an indication of a serious problem beyond the bolt thread issue. That's not to say you shouldn't check carefully for cracks, deep scratches or corrosion on gasket surfaces, or any other issue.

[John kuehn]

Cleaning out the head bolt holes in a Model T or any older flathead engine is often over looked. It’s nothing new and when not done it can cause a stripped out bolt hole and not getting the head down tight. And when you try to tighten the head bolt thats when it strips out the hole because the bolt bottoms out on the rust and gunk in the bottom of the hole.

Use a ice pick or a piece of stiff wire to break loose the rust and gunk and then use air to blow out the hole. That’s the easiest way to do it. It’s pretty simple to do and if you want use a tap to clean out the threads.
Another good tool to use is a wire brush used for cleaning out gun barrels. That can work also.

The back bolt holes in a T block is kind of hard to get to but using a stiff piece of wire bent at a angle can get the hardened rust out of the bottom of the hole. Just keep working at it and you can clean it out. Good Luck!

[jiminbartow]

Brendan. I would say, the latter. Probably because you could not get that bolt tight enough to seal the gasket around the bolt causing the oil to leak out under pressure. I may be mistaken, but isn’t the firewall on a ‘22, removable? If so, it would make getting to the back bolts, easier. Jim Patrick

[jiminbartow]

Regarding the special welding rods I mentioned above, I believe they were made by “Lincoln”. I seem to recall now, after thinking about it that the flux and wire of the rod was encased in a coating that enabled pinpoint welding, confining the weld to only the point of the rod, preventing the weld from extending to the threaded walls of the hole. Jim Patrick

[Allan]

I use the drill bit as digging tool, not a drill. Of course, the drill has to be smaller than the thread. It will quickly bottom out on the iron head without drilling in to it. The stuff loosened up at the bottom of the hole is broken up and will then blow out easily. If it is not cleaned out first, even a bottoming tap can be bottomed out on accumulated crud before reaching the bottom of the hole. The idea is to clean out as much as you can so you have as maximum useful thread available. The substitute bolts I mentioned are longer than standard T bolts, and make use of any thread not previously engaged. Some need a little ground off the end to prevent them bottoming out, even in the now deeper, cleaned thread.
Fitting Z heads led to the this procedure. With some variance in head height, and washers under the bolt heads, it is not difficult to pull threads in the block with reduced thread engagement. The longer bolts are a neat way to get around the problem.

Allan from down under.


Allan from down under.

[RajoRacer]

This is the best tool for cleaning the head bolt holes in the block - available through Goodson Products !

[Its_Always_T_Time]

Do I attach that cleaning tool to a drill and just slowly drive it in after cleaning the bolt holes? Then after that I put the bottom thread tap in? Or do it tap the threads then use the cleaning tool?

Hopefully I don’t have to put helicoils in but if that’s what I need to do then that’s what I shall do. When I take the head off I’ll post pictures of the underside of it and pictures of the top of the block. Any sort of brush that I use to clean the top of the block will be softer than iron (like a brass brush). I have a .45 caliber bore brush for my Model 1888 Springfield Trapdoor but that brush is too big to fit in the bolt holes. I’ll see if my nylon .30 caliber brush for my M1903A3 works. I’m imaging the bolt holes in my block are going to be quite dirty and require a good picking with a wire then blowing out before brushing the threads anyways. Going to be a good weekend next weekend.

[Mark Gregush]

I clean the hole out, vacuum, tap, vacuum then check with head on no gasket. If you use air, put the pistons at the halfway and use rags in the holes to keep the junk out from between the cylinder walls and pistons.

[Its_Always_T_Time]

Yes I’m going to cover the cylinders when they are all half down while cleaning the bolt holes so nothing gets inside and gets jammed between the pistons and cylinder walls and damages the cylinder walls.

[jiminbartow]

No. Clamp the fluted cleaning tap into a tap chuck and slowly turn it by hand. It is a good idea to dislodge the debris in the bottom of the holes with a small, long handled standard (not Phillips) screwdriver as you blow the holes out, as the accumulation of dirt, oil, gunk and rust might be compressed to a solid mass from the pressure of being mashed in the bottom by the tightened bolts, so it may require gently tapping and rotating the end of the screwdriver with a small hammer as you move it around in the bottom of the hole. Once everything is cleaned out, you may want to consider filling each hole with lacquer thinner and let stand to soften the oil and grease trapped in the threads, then do a final cleaning with a brass bottle cleaning brush, available in various sizes at Amazon. Most of the dirty lacquer thinner can be removed by pushing into the hole, a small strip of cloth twisted around a long wire or nail and blow the rest out. To avoid a mess, hold a rag lightly over the hole and allow the escaping debris to be caught in the rag. Be sure to wear goggles to keep the debris from blowing in your eyes. Jim Patrick

[George Mills]

For starters, I definitely think that 55 ft pounds is way too much for any T block be it early or late...but I'm not a boo-bird, dozens will tell you no problem, 100's are now heli-coil experts. ( I actually start at 35 myself after cleaning and chasing taps and have never gone over about 40 or so by the time I am done and I have a reason...the design and 'load' factor (read Hungarian hunch) for head bolts is based on 3/8-fine. In order to get the 7/16-14 at Rev 2 they had to cut off about 3 active threads, About 1/3 of the active threads on a head-bolt and still darn near bottom out...and were still doing it 15,000,000 copies later)

OK, back to your issue....

Cleanliness is next to Godliness....

I'd take stripped bolts as a good sign, not necessarily a guaranteed sign, but evidence of the way things are suppose to work! Bolts strip, tap threads are supposed to win 100% of the time. For those 100's who are now masters of hell-coil art...Grade 8 bolts work fine eh? Especially when torqued to 55-60. Modern wonders.

Here's a hint, a hack for the Model T tool box...we all wind up with a miscellaneous box of odd screwdrivers that just sit around forever and never get used again. I tend to repurpose mine, bench grinder and an oil dip! For the demount tranny clips? Anneal one of about the right width, bend over the tip in an L of maybe 3/16of an inch? Reharden and quench? Slickest tool ever invented to get those demount ends off...same thing on cotter pullers for the big pins...stick point in loop, rotate handle down, the pins walk right out.

Same thing for head bolts...oh, you can buy a pick but thats not fun...almost cheating. Grind a screwdriver to a point on about a 60 degree V, bend the point, file a v-shape on the bottom, harden and hone to a scraper edge? Gets the stuck on crud off of the bottom of the threads and the gunk that has been solid in the bottom of the tapped hole. I was too frugal to go buy a 7/16-14 bottoming tap as the second operation...but did have a spare 7/16-14 regular tap...bench grind, heat and quench time! That is now the bottom head bolt 'dresser as there is absolutely no lead on it.

Good luck....

[John Codman]

I confess that I have not read every post on this thread, so I apologize if this is a repeat of what someone else posted. Lang's catalog states that a low head bolt is 2 3/4" long, a high head bolt is 3 1/4".

[jiminbartow]

George, please correct me if I am wrong, but I always though that the 50 lb. torque for all the head bolts was meant to, not only prevent one from exceeding the breaking limit of the bolt, but to stagger torque all the bolts the same to prevent the cast iron head from breaking. If you torque all of the bolts to 50lbs. and one to 40, wouldn’t you risk cracking the head? The attached photo is the order in which the bolts should be tightened or loosened. This is just one illustration of many out there. There are other charts that show a different order, but they are all correct in that they all gradually spread out and increase the pressure on the head. Do not torque any one bolt all the way. This is a gradual process that takes several rounds, gradually tightening each bolt in increments of 5 to 10 lbs. Jim Patrick

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[George Mills]

Jim,

I was not advocating using that one lone one at 40 maybe I was not clear.

I do it all by hand and guess at the pull. I yes the ‘medium pull’ that I think is 35. Sometimes I don’t get a leaker! When I do it is the ‘medium tug’ all around which I think is just over I guess 40. Most don’t know it, but a mechanical torque wrench is only within 10% to begin with, yet was the standard, proving your point, whatever the reading, make them all the same

[Its_Always_T_Time]

So the threads on the bolt should be 7/16ths of an inch, 14 turns per inch. So that would be the bottoming tap and thread cleaning tip I should buy.

How should I tap the threads after cleaning the holes (if necessary)? Do I tap them with a ratchet or with a drill? I only have a weak cordless drill or a more powerful cordless impact drill. If I use the impact drill I think that would be a bad idea since it would put repeated shock loads on the tapping bit and potentially crack the brittle hardened steel bit. I take it a regular powerful cord drill would be ideal.

Edit: Seems like there is some sort of T handle tool you use to tap threads by hand with. You tap a few turns then remove the tap and take off the crud and re-oil it. I hope my block threads are alright, maybe I can just run the 7/16ths of and inch 14 turns per inch thread cleaner tool in them to get the remnants of the bolt out. When I take the head off I’ll post some pictures of the bolt holes before and after thorough cleaning before running any hardened steel cleaners or taps into the threads.

[Scott_Conger]

I have spent a bit of time trying to come up with the right words without sounding harsh...and in fact am giving this advice with the best wishes of success. That said, I think the following will still come off harsh, so my apologies in advance: based on some of your recent comments, I conclude that you really need some help from someone who has done this, or similar work; someone acquainted with taps, drills, and if it comes to it, the installation of helicoils. The only thing I am seeing is a project which is still headed in the "down-hill" phase of unhappy discovery at this point.

Please seek help and advice from someone on the ground, there with you. From your posted location, that really shouldn't be that difficult and will pay off in spades as you progress with your repair and further enjoyment of your T.

[Ed Fuller]

PLEASE take Scott’s advice and seek help first.

Using taps, thread chasers, helicoils, and drill bits can go from bad to ruined in a second.

[Its_Always_T_Time]

My friends and co-workers are going to help me with this, one is an experienced engine rebuilder. I’m just trying to learn as much as I can about all of this. Unfortunately when the head comes off I may indeed, and likely will, discover more issues such as sticky/burned valves or (god forbid) a warped head or worn block gasket surface.

[jiminbartow]

Yes, it is very hard to put into words how to perform complicated functions with tools that one has never used before. We try our best with words and pictures, but we cannot cover all aspects of the procedures, which must be frustrating for the questioner as well as for the person trying to help. To most of us who have been doing this for 40 or 50 years, the use of these tools is almost instinctual, but can be very confusing to those who have never done this type of work before. At one time, all of us have been new to the game and, growing up, most of us have been fortunate to have a mentor or mentors to give us hands on instruction, which is the best way to learn.

In 1970, when I bought my Model T, even though I was mechanically inclined and was a fast learner, like most kids in the 60’s, having worked on lawn mower engines and go cart engines, there was still a lot I did not know. Fortunately, in 1970, I had a 75 year old neighbor by the name of “Mr. Moore”, who, in his youth worked for Ford on the assembly line and was very familiar with my 1926 coupe, for he worked on them when they were new. Mr. Moore loved spending time helping me on my Model T and taught me a lot and I was fortunate to have him as a mentor at that time in my life. Not everyone is so fortunate. Fortunately, there are substitutes for those without mentors such as YouTube that has videos of how to do virtually everything from how to chase threads, how to use a tap and die, or how to install a helicoil. It is not hands on, but many of the videos are very well done, very explanatory and leave few questions unanswered. Jim Patrick

[RajoRacer]

My advice is when cleaning the block threads with either the proper "thread cleaner" tool like I posted a photo of above or a bottoming tap is by HAND USE ONLY - use your ratchet.

[TrentB]

You may want to take a look at this Youtube video for some ideas on how to remove broken bolts and studs from blind holes.

https://youtu.be/dJfkCj3FWBs

Respectfully submitted,

Trent Boggess