How many head bolts do you REALLY need?

Long back story short- I have a 88 Wrangler with a 4 year old reman 258 motor. The motor was dropped in around winter 2009. Due to a out-of-state move and motivation issue it sat for awhile. I recently have got it running and driving.

While doing some of the final underhood clean up I notice a head bolt missing. Funny. I dont remember removing it. I dont know why I would have. I look through all my stuff and cant find it. I see know reason one of my buddies that helped me drop it in would have taken the bolt out. Wierd stuff. It has obviously came out since I painted it. I poke a screwdriver in the hole and it goes way down so I source a new bolt.

I go to install the new bolt and it wont thread in. Wierd. So I grab the boroscope that has saved my keister a few times when I was a tech and take a peek. Its broken in the block. Great.

My current theory is whatever low buck remanfacturer OReillys uses broke it and installed some gunk to hold it in place. But that doest explain where the 3+ inches of bolt went that should still be in the hole. I dont see how it would have bounced out on one of my test drives in the pasture.

So I have 13 out of 14 headbolts on a cast iron head and block I6. I am going to run it and see what happens.

Just how many head bolts do you actually need anyway. I like to think I have added lightness

I will post a pic once the Photobucket App starts playing nice.

Look up an image of the head gasket. Does it look like it will leak water into a cylinder if it fails? If not, drive it. You could try a reverse drill bit. If its loose, it will back itself out. If its not, drill it. I can't say this is the right fix, but here is how i fixed my SBC's busted exhaust manifold bolt when it snapped of flush with the block:

They are 3/8" bolts. With the manifold still in place, I stuck a 3/8" drill bit in there and started drilling just enough to center a chamfer in the frozen bolt. Then I drilled and tapped for a 5/16" bolt directly into the old frozen bolt shank.

Just don't ask how many 9/32" drill bits I had to buy or how many times I had to go back and forth with the tap.

The broken part is a good 3 1/2 inches down the hole. I dont think I am getting to it while the head is on. It is by coolant but at least its on the long side instead of an end. These are not exactly high compression engines so I am curious how long it will take for a problem to arise. If it was aluminum and high reving I would be more concerned.

Iron is pretty flexible and iron blocks/heads are thin lattices of iron. An aluminum high-revving situation would probably stress it less. (Aluminum heads' main head gasket issue is the difference of thermal expansion - it's easy to make the bolts TOO tight)

I'd be happier if it WAS on an end. That has two cylinders pushing on it, not just one.

Well, philosophically, it has to come apart to fix it, right? Might as well wait and see how long you can put it off, as long as the broken bolt doesn't rust itself to the threads to prevent removal.

If that hasn't happened already. Who knows how long it's been?

In answer to your question: one more.
Quit your belly aching and get the bolt out.
BTW, the price has gone much, much lower......

I wouldn't be too surprised if it never gave you trouble. Drive it until it does. David's 911 had a broken head bolt too, but no one knew until the engine came apart.

Rover v8s used to have 14 head bolts. Then they figured out the the bottom 4 helped to contribute to premature head gasket failure. The 4.0 and 4.6 versions did away with the whole row and only used 10 per side.

Alan Cesar wrote: I wouldn't be too surprised if it never gave you trouble. Drive it until it does. David's 911 had a broken head bolt too, but no one knew until the engine came apart.

This. Lot's of Porsche's are driving around every day with multiple broken studs. Mine has three broken studs (I know, I'll fix it). You'd never know it by how it runs, and it doesn't leak.

DrBoost wrote: In answer to your question: one more. Quit your belly aching and get the bolt out. BTW, the price has gone much, much lower......

You wanna pull the head? Sounds like a good job for a play date.

Nathan JansenvanDoorn wrote:

Alan Cesar wrote: I wouldn't be too surprised if it never gave you trouble. Drive it until it does. David's 911 had a broken head bolt too, but no one knew until the engine came apart.

This. Lot's of Porsche's are driving around every day with multiple broken studs. Mine has three broken studs (I know, I'll fix it). You'd never know it by how it runs, and it doesn't leak.

The plan is to see how long it goes. I have a trailer if it does decide to blow while I am far from home.

Duct tape it.

Go find a left hand twist drill bit long enough to get to the remainder of the bolt, and commence drilling. I'd be very surprised if it didn't turn out of there easily.

Streetwiseguy wrote: Go find a left hand twist drill bit long enough to get to the remainder of the bolt, and commence drilling. I'd be very surprised if it didn't turn out of there easily.

Easiest and cheapest! And imagine how you'll smile when it works!

Its a jeep, they leak and they run.

I would center mark it with a bit the size of the hole, then attack it with a left hand bit a touch smaller than the minor diameter of the threads. If it doesn't come out, open that up with the tap drill and chase it.

Way back in the Dark Ages the GM Iron Puke used to break head bolts like that. GM came out with a kit that had a long drill bit, a guide bushing and a bolt extractor. You dropped the guide bushing in the hole, dropped the drill in the guide, drilled it about 3/4". Yank out the guide bushing and the drill bit, then the bolt extractor went in this little adaptor thingy that snapped onto a 1/4" extension, back out the broken bolt.

I had a broken head bolt on my TR-3. They left the broken top end stuck in the hole and I didn't find out until I went to pull the head to figure out why I was getting coolant into my oil sump. The TR-3 engne is wet liner and it was allowing the liner to ride up just enough to get a little weeping of coolant. I ended up towing it to an aircraft mechanic who did the dirty work and charged around $100 in 1977 dollars. He also tapped it a little askew.

Curmudgeon wrote: Way back in the Dark Ages the GM Iron Puke used to break head bolts like that. GM came out with a kit that had a long drill bit, a guide bushing and a bolt extractor. You dropped the guide bushing in the hole, dropped the drill in the guide, drilled it about 3/4". Yank out the guide bushing and the drill bit, then the bolt extractor went in this little adaptor thingy that snapped onto a 1/4" extension, back out the broken bolt.

I wouldnt trust myself to try and repair it with the head on the block unless I had a kit like that. I see myself makeing it worse trying to drill out an inch of bolt at the bottom of a 3+ inch hole. I always sucked at drilling out bolts in the field. Broken 7/16 headbolts seem a little common when I did a quick interwebs search.

pinchvalve wrote: Duct tape it.

I prefer zip ties. They work better in grease.

Update- I have a few all day trips to a local offroad park and hours of it running with no issues so far. Knock on wood!

When a head bolt breaks it can launch itself in projectile fashion out of the bolt hole with enough force to leave a dent in the tin shed roof!

Inline six? You'll likely never have a problem. I've had and still have a number of engines missing various head bolts.

As for drilling, it's easy with the head on. Makes a nice guide and keeps the chips from going anywhere they could cause problems. But do check on the guide kit curmudgeon mentioned. Sounds like a generically usefull bit of kit.

Ther is also a kit of goo similar to jb weld that I've used to make perfectly serviceable repairs using wrong bolts. You squirt the goo into the hole. Coat the bolt with the anti-stick, and shove it in. Let it sit and cure. Unthread the bolt and install a slightly shorter one. You can torque it even! The next person behind you will hate you, I suppose.

Run it until it dies and then drop in a torquey 383 SBC

Can you get a C-clamp on it? Or Vise-grips?