I'm working on my 1926 TuDor engine, getting ready for the driving season. I have straightened my crankcase pan on a KRW jig. It was very close prior to the little straightening I did. A long time ago, in fact one of the first things I did after I purchased the car was to add an outside oil line. At that time I noticed that the bolt hole in the front dam of the crankcase pan where the outside oil line would fit, the threads are striped. The hole on the right in the picture.
The top 4 or 5 threads are damaged to the point where a bolt or the oil fitting will not snug up. In the past I just used a lot of permatex on it so it would not leak, but it still was loose. Now I'd like to repair it, while it's out. I'm looking for suggestions on how to repair this. I don't want to remove the dam to replace it. I had though of adding some braze to the hole and re tapping it. Any other ideas? Thanks, Mike
I would just heli-coil it and be done with it. They provide a strong thread if you follow the one major thing. The end of the coil should be half-one turn below the surface so the coil dosen't unwind. I also clean very well and add red loctitie to the coil. I have never had a stripped thread repair fail doing it this way.
I would for sure heli- coil it. I have used them on lots of different cars over the years and never had a problem. Just my thoughts!! Tim
If you install a Helicoil, be sure to read the directions, and be sure that the top of the insert sits a full thread or a bit more below the top of the hole once the insert is installed (trim it with a Dremel cutoff wheel if necessary). That way, the top of the Helicoil will "bite" into the top thread of the hole, keeping the insert from unscrewing when/if you ever remove the bolt.
Geez.... my old brain had forgotten about Helicoils. Thanks for helping me to remember. Mike
Helicoils will work fine, but for a more permanent fix, have you considered tapping the hole using a larger, fine thread tap for a larger bolt? Jim Patrick
Don't use a locking helicoil, it will eat the bolt threads .
If the area is thick enough, a Time Sert would be a better repair for this task. A slight counter sink may be needed for this application. It is something you don't want to have a problem with in the future.
Jim, I thought about using a large tap, but then I'd need a larger fitting for the outside oil line. Suppose I could make one, but then it's different for ever.
Ted, unsure of what a 'locking' helicoil is?
John, never seen a Time sert, looks interesting.
Before you start drilling a larger hole, whether for a larger fitting or some sort of insert, do take a peek at the rear surface of that front dam. You may find that there is less metal to work with than you need. You may be obliged to fill the hole, then drill and tap back to original. Good luck with your project. Bill
Permatex makes a stripped thread repair kit that works well, used it on a friends hogs head a few years back and when he re did his engine he couldn't remember which bolt hole we fixed so he's still running it. Will take more torque than you need. KGB
I have also used that Permatex thread repair kit with good results.
I'd take it to my local old time engine re-builder or machine shop for the repair. They deal with stripped threads every day. Your pan is too valuable to take a chance.
Mike, I've fixed that area on the pan in my coupe as well as the two bolt holes where the fourth main bolts are with heli coils without a problem.
Mike, you could buy a larger fitting and buy a tap to tap the threads of the larger fitting. Anyone who has the car after you will reuse the fitting you supply. Tapping the threads larger is not an uncommon occurrence on such an old car and is the most permanent and lasting repair. All of the fixes proposed, including the helicoil, require you to tap a larger set of threads, so instead of using an insert that, if not done right, could come out or fail, you might as well use the larger threads for a larger fitting. Jim Patrick
A larger fitting will require the casting to be drilled for an over sized clearance hole...do you want to do that?
an insert will require a considerably larger hole to be drilled and tapped in the pan, greatly reducing the cross section left in the dam.
A Heli-coil will require a very slightly larger tapped hole and will work just fine with minimal material removed (a locking helicoil is dyed red and has a tangent coil that presses on the fastener to keep it from rattling out). You want the plain vanilla "silver" colored coil.
Well.... I purchased a 3/8x24 Helicoil kit and installed it. Turned out well, the fitting works fine and I have a nice tight fit. Thanks for helping me to remember, Mike
Good Job, Mike
thanks for sharing the results