Alum. Oil Pan Repair

[cubs-n-bxrs]

Originally Posted by young enthusiest

I had an aluminum pan with 3 stripped holed. I drilled and tapped all 4 holes 7/16 Nf. I don't hsve a bottoming tap so I slugged the bolts the last 1/8th inch or so with the impact. They aren't comin out

Couple things come to mind here 1. Not a good idea bottoming bolts out in hole that is not tapped all the way to the bottom. If you ever remove them bolts the aluminum threads are coming out with the bolt. 2 You must have had to drill out the frame to put the 7/16 bolts into the pan which will cause a problem if you ever decide to go back to a correct oil pan. You will have quite a bit of slop there causing alignment problems.

[clint]

The procedure mat used with a pressed in threaded plug is by far the best/strongest for this fix. I have used this fix many times in all types of metals, plastics, etc.. I'm not sure the welding the threaded bushing in was needed, I probably would have cut a coarse thread on the outside of the threaded bushing, and used a high temp lock type with at or just below max press fit spec for material used... I'm not trying to take away from matt's idea here, just another way to skin a cat... and the thread on outside of bushing is to hold the locktite, or whatever you use, a max fit pressed in plug is not going to come out anyway... but I would have used a high strength locker for that feel good feeling.

Another method I have used... make the plug your going to use, thread the outside of the plug, drill tap the hole your repairing, then thread plug into tapped hole to be fixed using high strength locktite.. If you can drill a hole to get a set screw to lock the threaded bushing in that's even better

I agree with the others jbweld alone will not hold up at the engine is heat cycled along with the vibration. Mcmaster and other places sell threaded bushings, they come as a standards, this would give an option to those without a lathe, mill etc.. Just read the directions careful when drilling the hole size for the threaded bushing as to much press fit and you will reduce the ID of threaded bushing causing your bolt not to fit.

I have not run into the problems with fine threads on aluminum, I have witnesses galvanic corrosion of aluminum threads (car engine brackets seem to be the worse) mostly from the elements kicking off the reaction.

[rmidgett]

I recently had to repair two of the engine mounting bolt holes in the oil pan of my 1250. Both were on the left side. The pair of holes on the right side are in good shape, and I don't like to fix what isn't broken.

I bought a Power Coil thread repair kit a a local bolt supplier. The kit didn't come with coils long enough for the hole depth (~.975"), so I purchased additional coils that were too long & cut them off flush with a Dremel cutting wheel after installing them. I applied blue thread locking compound on the coils as I threaded them in. I'll let the thread locker cure before putting bolts in the new holes.

I have access to a vertical milling machine at work, so I used it to center the drill bit & tap to repair the holes & threads. In the process, I carefully measured the dimensions & documented them overlaid on a photo of the oil pan. I hope this information is helpful to others reading this thread.

[finsruskw]

Pitch the aluminum POS and grab a cast iron pan.
Picked one up off e-bay the other day for $17.
If Ya have to pay someone to screw around w/the alum one, it's gonna cost a heck of a lot more.

I have 5 QL's and just swapped out the last alum pan for a CI one.
PLUS, in really cold weather, you can slap a magnetic heater on 'em!

[Nailhead]

I've heard quite a few times that Time-Sert is the thread repair system to use, although I've used Heli=Coils several times with good results.

[corporalk]

Hello RMidgett,

Was the hole pattern truly not rectangular? I find that VERY odd and wonder if it is supposed to be 4.875 x 7.625. I want to make a fixture to mount the engine cradle rails to perform the modification with the cross member welded in.

How did the helicoils hold up? I'm about to do the same.

Thanks,
Kevin

Originally Posted by rmidgett

I recently had to repair two of the engine mounting bolt holes in the oil pan of my 1250. Both were on the left side. The pair of holes on the right side are in good shape, and I don't like to fix what isn't broken.

I bought a Power Coil thread repair kit a a local bolt supplier. The kit didn't come with coils long enough for the hole depth (~.975"), so I purchased additional coils that were too long & cut them off flush with a Dremel cutting wheel after installing them. I applied blue thread locking compound on the coils as I threaded them in. I'll let the thread locker cure before putting bolts in the new holes.

I have access to a vertical milling machine at work, so I used it to center the drill bit & tap to repair the holes & threads. In the process, I carefully measured the dimensions & documented them overlaid on a photo of the oil pan. I hope this information is helpful to others reading this thread.

[rmidgett]

Hi Kevin,
I'm sorry for the slow response.
I was surprised by it, too. I was very careful making the measurements. I used digital calipers to measure each hole diameter, then the inside to inside distance between holes, and then added one diameter to arrive at the center to center distances. This is the only time I've done this job, so I'm sorry I don't have an average of several to draw conclusions from. I suppose it's possible mine is odd.

The helicoils are working fine, no problems yet. Time will tell, though..the machine shakes like a Harley-Davidson now, whereas it was smooth prior to the repair job. I've tried tightening the bolts and ended up loosening them to minimize the vibration.

I tack welded my cross member in, then had to move it forward..something bumped into it while putting the engine back in..don't recall exactly what, but it did fit in the end.