Threads Popped Out Of The Block; YIKES!!

[jikelly]

So my roommate is dying to get my car running again. It's like he's more obsessed with my car than I am. So, while I was working on finishing the rebuild of my tremec 3550 transmission, which cost me like 1800 dollars , he got busy putting my engine back together.

I'd bought a windage tray which came with a stud kit. He pulled four of the main bearing bolts and started installing the studs in their place. I was struggling with my memory trying to figure out how the shifter assembly went back together. So I took a break and watched Heath work the torque wrench. He was straining trying to reach the 125Ftlbs on the studs when there was a loud pop and he almost fell over when the wrench went slack.

He pulled the stud out and it brought 4 of the threads out of the block with it. That's not good, not good at all, but what do you do about that?

We discovered that only those 3-4 threads were engaged when he started putting the pressure on the stud. The original main bolts went like three times farther down into the block. So we backed the nut on the stud off till they had the same number of threads engaging the block as the bolts did.

He retorqued the stud in the damaged hole and it held 100FTLBs (we figured we shouldn't try for the 125, and the manual says to do it between 95-105 so hopefully we are within tolerance). So, maybe we got lucky?? Or is it going to fail on us when we put the power down?

I'm kinda scared, but Heath said the look on my face never changed. It's because I was trying to remain calm for him. If he thought I was going to have to replace the block he would have freaked out considering how long it'd take to get another one.

What do you guys think? Is the block hosed?

 

[rbohm]

you should be fine.

 

[brianj5600]

Why 125ft#s? The extra torque may distort the bores. The main bores are honed round and to size with the caps torqued to specs. If the torque is not the same as it was during machining, the bore may not be round anymore. My machinist does not even recommend switching to studs w/o rehoning the main bores. He said bolts and studs vary the distortion when torqued. If your block was machined with 100ft#s on the mains you should assemble it that way.

 

[mrmustangman357]

if you cannot get the proper torque on the damaged main threads, you can drill out and helicoil, but this should be a last resort. and yes, helicoils hold up fine in the main stress area

 

[1320stang]

Studs should only be installed finger tight, only when you put the nuts on, do you torque to spec.

 

[bnickel]

you do know the studs should only be finger tight and then have the nut torqued to spec right? i've seen way too many people crack the block webbing by overtightening the studs. some 460 blocks are especially bad about this. i believe ARP has a special main cap bolt with a stud on top to attach the windage tray, i would personally use that style myself instead of a regular stud. i've never really been a fan of studs since there are so many ways to screw something up by using them, bolts don't seem to have that problem. yes, i know studs are supposed to be better because of more even clamping forces.

 

[180 Out]

I think with a windage tray, the "studs" are actually the bolts, with an extra bit of threaded shaft on top of the bolt for the tray to mount on. So they should be torqued to the main bearing spec.

If that's true, it would seem to negate the other criticism that studs should have a different align hone than bolts. They're really just a different kind of bolt.

I'm glad you guys posted, though, because I had always thought that, with true studs, you should only finger tighten them then depend on the nut to stretch the stud to the correct torque.

 

[Rusty67]

if you cannot get the proper torque on the damaged main threads, you can drill out and helicoil, but this should be a last resort. and yes, helicoils hold up fine in the main stress area

I agree, helicoiling the block would be what I would do. Just make sure you keep the internals clean when you do it. Get a lot of rags in the area and make sure none of the metal shavings get into the engine.

I think with a windage tray, the "studs" are actually the bolts, with an extra bit of threaded shaft on top of the bolt for the tray to mount on. So they should be torqued to the main bearing spec.

If that's true, it would seem to negate the other criticism that studs should have a different align hone than bolts. They're really just a different kind of bolt.

I'm glad you guys posted, though, because I had always thought that, with true studs, you should only finger tighten them then depend on the nut to stretch the stud to the correct torque.

I suppose this depends on the type of studs. The studs I used on my buddies Cougar were just long studs you screwed in by hand and then torqued down a nut to hold the main cap in.

 

[bnickel]

time-serts would be better for the main bolts than heli-coils.

 

[Rusty67]

time-serts would be better for the main bolts than heli-coils.

I've never seen those before. You ever use them ?

 

[jikelly]

The studs that came in the kit are just studs with nuts on them. We turned the studs down into the block using a couple nuts to get them to the right depth and then put a single nut on them and torqued them to specs.

So are you guys telling me I either shouldn't use the studs at all, or take the block to have the bores rehoned? I guess if I did that I could maybe see what they can do about those threads. Course it would really suck to do that though, cuz the heads are already on there.

Thanks for the replies!!

 

[brianj5600]

Maybe my machinist needed extra money. He builds mostly circle track engines, which is a rough environment, and he is very thorough. For a street motor he may have given a different answer. I told him I would be making up to 700hp so that may have made it different. I any case torque the rods, mains and heads to spec. Did you torque the rod bolts to spec? I would check with your machinist and see what he says.

 

[bnickel]

I've never seen those before. You ever use them ?

yes i have, they work much better than a helicoil, especially in a high torque enviornment. they are much like a threaded bushing only it's threaded internally AND externally and they are machined from steel.

 

[bnickel]

The studs that came in the kit are just studs with nuts on them. We turned the studs down into the block using a couple nuts to get them to the right depth and then put a single nut on them and torqued them to specs.

So are you guys telling me I either shouldn't use the studs at all, or take the block to have the bores rehoned? I guess if I did that I could maybe see what they can do about those threads. Course it would really suck to do that though, cuz the heads are already on there.

Thanks for the replies!!

no you'll be fine, i was just saying that i didn't like studs even though they are technically superior to bolts. if i was building an all out race engine i would use studs but for a mild street engine i prefer bolts.

 

[StangDreamin']

I've never seen those before. You ever use them ?

I've got some; haven't used them yet, I hope I don't have to. They seem to be the only thing that works when a pre-2003 Ford 2-valve 5.4 spits out a spark plug. Most garages charge $750 (local guy) to $3800 (Ford) to replace your heads with the same style so it can happen again The newer "Performance Improvement" heads are not the "three valve" heads; they just have more spark plug threads machined in. Of course they cost more!

(Obviously, I didn't know about this when I bought the truck.....)

Helicoils don't seem to work in this application, the only things that seem to work are Time-serts. I bought their "Ford Head Repair Kit" (install tool and four inserts) online for $170.00. Keep it in my toolbox, next to the "star" lug wrench and the jumper cables; in case I ever need it.

I'm not bad-mouthing Heli-Coils; but I think I'd use Time-serts instead if I was working down in the crank-gallery, as well.

 

[bnickel]

heli coils have their place, don't get me wrong, but some things are just too much for them, main bolt and spark plug threads being among them. they'll work fine for intakes, valve cover bolts, timing cover, stuff like that but some things are just a no go for them. the other cool thing about the time serts is you can also get them to adapt a large threaded hole to a smaller one, for instance late model ford heads have larger accessory mounting holes than early heads and you can use the time serts to adapt them down to the early size and run your original acessories.

 

[mrmustangman357]

I think this thread is betting too far off. Can you still get a good purchase on the remaining threads by screwing the stud in fully? For a milder engine the bore distortion of the mains isn't as critical. Studs don't distort the mains that much to matter with a mild engine (hell, think what distrotion is present when the motor's running). If you want to mess with having the thread-sets or whatever installed, go ahead but personally, I would helicoil it and thread and use it as is. To all those who are quick to comment saying the helicoil won't hold up, I worked at a major aerospace manufacturer where I actually studied thread inserts for quite some time. Trust me when I tell you, unless the original thread material is very resilient or tough (i.e. not cast iron like the block), the helicoil is actually stronger than the base material because of the increased surface area given the drill-out and threading of the base material. Plus the insert is stainless steel which is quite hard. I also have been to an auto tech school for 2 yrs and there are cases where cylinder heads have been held onto blocks with all helicoiled holes, and never popped a head gasket. So yes, if you don't want to spend an arm and a leg to repair the area, use a helicoil without worries, if you even need to repair the offending area.

P.S. make sure to check the rest of your studs to see if they pulled threads.

 

[Rusty67]

I think this thread is betting too far off. Can you still get a good purchase on the remaining threads by screwing the stud in fully? For a milder engine the bore distortion of the mains isn't as critical. Studs don't distort the mains that much to matter with a mild engine (hell, think what distrotion is present when the motor's running). If you want to mess with having the thread-sets or whatever installed, go ahead but personally, I would helicoil it and thread and use it as is. To all those who are quick to comment saying the helicoil won't hold up, I worked at a major aerospace manufacturer where I actually studied thread inserts for quite some time. Trust me when I tell you, unless the original thread material is very resilient or tough (i.e. not cast iron like the block), the helicoil is actually stronger than the base material because of the increased surface area given the drill-out and threading of the base material. Plus the insert is stainless steel which is quite hard. I also have been to an auto tech school for 2 yrs and there are cases where cylinder heads have been held onto blocks with all helicoiled holes, and never popped a head gasket. So yes, if you don't want to spend an arm and a leg to repair the area, use a helicoil without worries, if you even need to repair the offending area.

P.S. make sure to check the rest of your studs to see if they pulled threads.

I was starting to think I was the only one who knew that helicoils are stronger then just regular threads alone. For people who crave over kill, these time-serts are the hot ticket.

As for needing to helicoil the hole, I would do it just to be safe. If you have lost threads then you are loosing holding power on the stud. Again, I like over built stuff, but I think you should heli coil to the point where you have at least the same amount of threads as stock.

 

[jikelly]

Hum...

All the rest of the studs held. No more threads were pulled from the block.

We kinda continued on the next step, but no problem the oil is not in the block yet. I can pull the pan back off I recon. I've never done Heli coils before. How much material will fall into the block when I install them? How exactly do you install them?

Thanks for all the responses!!

 

[Rusty67]

You drill the hole with an off-sized drill and then tap it with a special size tap which should come with the helicoil kit. You don't want ANY metal falling into the block if you can avoid it. I recomend lots of rags and a vaccume when yer done.