I recently picked up a used AP1 short block for a really good price and was having trouble with a head gasket leak. We'll I finally pulled the head and I found a few aluminum threads left on one of the bolts. I know it was on the intake side (either between 1&2 or 2&3). I'm wondering now if that was the reason the short block that was in awesome condition was so cheap. I'm not sure how I could have stripped it but it's also a possibility.

Anyways I think that is why I may have had an issue with the head gasket leaking. I threaded a stud back into the holes and everything seams ok, no additional aluminum threads were on the stud. They were tight when removing them so I really don't know what to do in order to inspect or what type of repair, if any is needed.

Is there a way to tell if the threads are seriously damaged or if they will hold the torque properly? What alternatives do I have if the threads are damaged.

Thank you!
-Rob

 

I would lube up the thread of a new bolt and install a head/gasket and see if it will hold the required torque. If there is a problem with the thread it will spin round and round and not tighten up.

It could also be worth doing some measurements of the thread engagement as you may find an aftermarket stud like an ARP may wind in a lot more turns than a original bolt, plus the stud remains stationary when tightening as it has a nut on top.

If the thread is stuffed you may be able to get a timesert installed, just need a mill to make sure its all square when drilled and tapped.

 

Chris, I was using ARP head studs and every thing seamed fine.during install and removal. I was pulling the head to try to figure out why it was leaking... Warped head, block, or maybe I did something wrong on install.

I have a feeling that the few little thread I saw where nothing to worry about. I'll try to see if it hold torque with the old gasket before I use the new one.

Are you familiar with the ARPs? I don't have the instructions or the oil. I've seen figures between 80 - 100 lb ft for torque specs. I just used oil and followed manual with the 90 degree steps. Two steps seamed to be right about 90 lb ft.

-Rob



Thanks for the help!

 

I had to call ARP because mine kept losing their torque and blowing out head gaskets (I think I went through 3 or 4 of them ). This might have happened to you. I followed the torque instructions (provided by ARP) exactly each time. I believe ARP told me that I could bump up the torque to 95, but not to go much higher than that. I also used their liquid. They did finally get stretched like they are supposed to, and I've gone about 10k miles without them losing torque. It frustrated the hell out of me for about 2 months though, and I got real quick at swapping head gaskets

Not sure what to say about the threads coming off though. If they seem to hold torque, they should be ok since the studs themselves only torque to 25 or 30 IIRC.

If I were to do it again, I'd probably install them to spec, run the car to operating temp for ~10 minutes, then tear down and re-torque after it's cooled. Do that 2 or 3 times, increasing the run time each time, then go drive for a little bit, tear down and re-torque. It should heat cycle and stretch the studs enough to not blow the head gasket. When my ARP's were losing torque, the head gasket would pop as soon as I gave it some gas.

 

For ARP studs I would do the following.

Put ARP lube on the threads of the studs, and both sides of the washers under the nuts.

Make sure the holes in the head are free of oil/water by blowing them clean.

Wind the studs in till they just bottom out.

Install the gasket/head and apply sealant around the chain gallery.

Torque up the nuts in sequence to 40 ft/lb, then 60 ft/lb then 80 ft/lb.

Back off all nuts in reverse sequence approx 1/8 to 1/4 turn.

Torque up to 80 ft/lb,

Back off all nuts in reverse sequence approx 1/8 to 1/4 turn.

Torque up to 80 ft/lb.

When using a torque wrench, make sure you keep the wrench sweeping throughout the torque operation till it clicks. If you have to stop for some reason the torque required to get it moving again can be more than your target torque, if you unsure back it off and bring it up to the torque in a single sweep.

if the nuts start creaking, wind it off and reapply ARP lube to both sides of the washer and the thread of the but.

Finally, make sure your torque wrench is accurate, I have 3 precision units which I get calibrated every 2 years. I use them to check cheaper/basic units that some of our cars owners have and its scary how many of them are over 20% out.

 

I did test the studs and I don't think the block is stripped. I didn't see and more threads so hopefully it was a fluke.

I have a feeling that the reason I had a head gasket leak is because I did not use the ARP lube. I did not have the instructions and did not understand it's importance to the process and torque figures. Good news is that I was able to acquire some today so I can move forward once I double check the head and block for warpage.

I'm gonna get to work and follow these instructions to the last detail tomorrow and make sure I do it 100% right.

Thank a lot guy! This is a big help... I feel pretty confident I can get it done right this time around.

-Rob

 

[QUOTE=chris_barry,Mar 24 2010, 07:05 PM] For ARP studs I would do the following.

Put ARP lube on the threads of the studs, and both sides of the washers under the nuts.

Make sure the holes in the head are free of oil/water by blowing them clean.

Wind the studs in till they just bottom out.

Install the gasket/head and apply sealant around the chain gallery.

Torque up the nuts in sequence to 40 ft/lb, then 60 ft/lb then 80 ft/lb.

Back off all nuts in reverse sequence approx 1/8 to 1/4 turn.

Torque up to 80 ft/lb,

Back off all nuts in reverse sequence approx 1/8 to 1/4 turn.

Torque up to 80 ft/lb.

When using a torque wrench, make sure you keep the wrench sweeping throughout the torque operation till it clicks. If you have to stop for some reason the torque required to get it moving again can be more than your target torque, if you unsure back it off and bring it up to the torque in a single sweep.

if the nuts start creaking, wind it off and reapply ARP lube to both sides of the washer and the thread of the but.

Finally, make sure your torque wrench is accurate, I have 3 precision units which I get calibrated every 2 years.

 

These are used studs so I'm not all that worried about the stretch.


Once I got up to 60 ft/lb I could feel it slip or do something funny on a few random nuts and I couldn't hit my target on one sweep like I was with the other nuts. I backed them off and did it again. A few of them did this same thing when getting to 80 ft/lb....again I did the same thing.. backed them off and did it again till it was a smooth sweep.
Once they were all at 80 I backed them off and the same thing happened again on a few other random nuts. I ended up backing them off a 1/4 turn in the reverse pattern and taking them back up to 80 about 5 times in total (the 4th and 5th time all nuts were a smooth sweep to the target). No odd sounds for the entire process... I made sure to lube everything really well.

I'm not really sure what that was I was feeling but I didn't feel that the first time I did it. What ever it was I can definitely see how that could have lead to totally erratic numbers which was more than likely the cause of my head gasket leak.

Hopefully I should have it started up later tonight

-Rob

 

You were probably feeling the nuts/washers grabbing/sticking to each other and the head surface. As you go through the tightening cycles there is a burnishing process going on all the surfaces that are sliding across each other.

the ARP lube helps stop any localized micro welding of the metals and gets redistributed each cycle.

The process makes you feel like an obsessive compulsive, but is worth doing.

Once the studs have been used a few times the threads and washers are nicely burnished and torque up smoothly much earlier in the process.

 

Thanks a lot Chris! Your info was a big help! I really think that did the trick!

It's just my luck... I seam to learn everything the hard way and do it twice to get it right


-Rob