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My block has broken threads for the head studs between #4 & 5 cylinders, bummer! So I'm looking for a block or whole engine to rebuild. What years are the 6 cylinder blocks interchangeable? I'm mid east coast in Delaware.

Hi 2dayistheday,

Would it not be possible to drill out the 'broken threads' and put inserts in, then replace your head bolts?? When I had my engine rebuilt the machine shop found that a previous 'mechanic' had applied Loctite to all the head studs. Some came out and some broke off, but they were able to use inserts in the sheared off holes and I have not had any issues related to this since. Might be easier than replacing the entire motor, unless, of course, yours are such that they are allowing coolant and oil to mix, or coolant to get into your cylinders. Chris.

Home away,

Good idea, but... I tried to install a Heli-coil into the hole, the tap only required light figure pressure to thread it. The "repaired" hole is very loose. I've put it bask together trying to get some driving in during the summer. But it does not hold a torque (will take 60 lbs, but is soft and loosens with use). The engine was sleeved back in the '80's and my belief is that the block is fractured in that area between the water jacket and head and sleeves. Not much material at all there to put a thicker thread sleeve, even if the block is whole!

If you read the instructions, red Loctite will be rendered inactive by careful application of heat. Even if they go ahead and break off a stud welding a bolt to the stud should shrink it enough to come out. As well, simply putting some weld onto a frozen stud will heat it enough to neutralize red Loctite.

These methods are a lot safer than risking cracking the block using back yard methods.

Tim, Sorry I didn't respond to your comments on Red Thread Locke, they are 100 % correct, I totally agree. I've been away from my account and lost track of a couple of requests for help I had posted.

I was able to get the block repaired. I used Time-Sert inserts and some Big-Sert inserts (a 2nd oversize by Time-Sert). Unlike Helicoils these are a continuous sleeve, not a wound spring. I had a couple of issues with them, but overall like them. I did find a small crack, but since the cylinders had been sleeved the crack went from the head stud hole to the cylinder sleeve (but not to the bore). I pulled the iron block and had the crack repaired by having it stitched, a very interesting process. If you are not familiar with it; google “stitch repairs to cracked cast iron”. In the end I got it repaired! A lot of work, but she's running well. Thanks again, sorry for not getting back.