2003 Dodge Ram 1500 4X4
Engine: 4.7L

Has anyone ever drilled out and installed a helicoil on the bottom of the engine block before, specifically a oil pan screw hole?

If so, what general steps did you take? Did you have to pull the engine or simply raise it? Did you do it by hand or make use of a jig to get the right perpendicular angle?

Long story short, an initial cross threaded hole required a retapping to repair the threads, but that tap broke off in the block and was since removed. A final running of a different tap realigned those threads, but the initially damaged threads have lost a lot of their strength to tightly hold a bolt and will require the hole to be drilled out so that a helicoil can be inserted.

The particular screw hole I'm referring to is hole 11, as shown in the diagram below:


This hole is about an inch or slightly less from the transmission dust cover. Does anyone have any knowledge of using longer taps or drill bits (>> 6") to overcome the dust cover clearance, which extends down at least 6 inches?

There's no hurry and plenty of time, so I'm trying to figure out the best idea.

Thanks,
John

 

Not sure if you have the space or not as I haven't been there. Just some shooting from the hip here............
There are kits that come with extensions as I understand.
But for one hole??


OK...........
For the drill maybe use one with the hex drive and an extension. The bit should tend to follow the hole that's there already. You will need a stop for the drill. Figure out the depth of the the hole and cut a piece of tubing that fits over the drill bit to keep it from going too deep.
For the tap you might try a 6" X 1/4" drive extension and square drive socket.
Same deal with the driver figure out an extension. Don't forget to break the end off the helicoil.

 

Use a 12 pt socket on the end of a 1/4" x 12" extension on the end of the tap. Make sure you use some type of tapping fluid. Chamfer the the edge of the hole after drilling and prior to tapping, makes starting the tap much easier. If you're worried about getting the hole and tapping straight, drill a block that can be laid against the oil pan flange to hold the drill and tap straight while you get the hole drilled and the first few threads started. I'm assuming the pan is removed. Hope you're doing this in a warm dry garage!!

 

Good ideas! I was initially concerned about drilling the hole at the right angle, but I didn't realize the existing hole would act as a pilot hole. I think I'll try using a longer drill extension to clear the transmission dust plate. What do you think about using a pulley tap?

 

I'll likely have to use a tap extension, which will make aligning the tap straight a little tricky, but still doable. The block sounds like a good idea. Do you think a simple block with a hole would work or one that has a flange cut out?

 

"What do you think about using a pulley tap?"


As long as it's the correct size for the helicoil, sure.

 

Have you thought about using a timesert and maybe a slightly smaller bolt?

You've got to be EXTRA careful going with either option b/c if you drill too large you might end up cracking the block inside and then you'll have larger issues on your hands.

You also have to make sure you don't drill too deep, so measure, measure and measure again... I suggest using a depth-gauge (not the back end of a caliper)

If you like the idea of a timesert make sure you get one that will not overlap on the outside of the hole so that you still get a nice flush mating surface.

I've seen it done before, but not on a Dodge Motor... I've had to do some exhaust manifold bolts on my last car (that sucked), you've just gotta be VERY careful, and use lots of Thread Tapping Lubricant...