Stripped oil pan drain bolt thread

[George Hill]

The threads IN the oil pan are likely NOT damaged. What usually happens is the bolt fails, it is hollow and when over torqued it usually stretches or breaks the head off. If the bolt is stretched it will show as a being easy to turn then get hard, then get easy again. If its broken then remaining bolt threads will be damaged in a way that makes them more "round" than spiral and as such it just spins and doesn't unscrew.

*EDIT: brain fart, the non-m bolts are hollow and stretch and pop the head off, m bolts I still see stretch in a similar fashion. I still stand behind my recommendation above and since people own non-m's I'll leave the info posted as well.

Don't try to cut the head off at the base, you will certainly damage the pan surface. But cut the head off by grinding it down with a grinder on its end. If you get lucky you don't damage the threads in this process (the head will be spinning at times) if you do, you are still repairing the threads anyways.

This is likely a lazy or CYA situation. If they say they can fix it and it leaks then the customer wants them to fix it which at that point is likely a pan that the shop would likely have to eat. They just don't want to commit to a repair they can't pull off. Either way if the pan comes off there is no reason why they shouldn't be able to fix it on the ground, but still a CYA situation. Bummer if you were in central Texas I'd have it fix in no time as I repair these frequently.

[scubastove]

Cut the head off with a grinder, then hammer the threaded shaft "up" into the the crankcase. Remove the oil pump pickup strainer and fish it out.

Repair with a time sert.

They couldn't even get a razor blade between the bolt and the drain hole, let alone a grinder. Using a grinder and hammering away into the oil pan/drilling the bolt out would cause severe damage to the pan, according to the shop.

[sapote]

It's hard to believe one cannot pull/turn the stripped bolt out. What was stripped, the steel bolt or the aluminum threads? One would guess the soft aluminum threads stripped, the the bolt still has good threads so why it cannot be turned out with decent pulling force? I mean, one can drill and tap threads on the drain bolt for threading a long M5 bolt, then use a metal bar under this long bolt to pull the drain bolt out while turning the it CCW, and it should COME OUT!

[eacmen]

Cut the head off with a grinder, then hammer the threaded shaft "up" into the the crankcase. Remove the oil pump pickup strainer and fish it out.

Repair with a time sert.

This.

Might need new gasket for that oil pump strainer.

[George Hill]

Cut the head off with a grinder, then hammer the threaded shaft "up" into the the crankcase. Remove the oil pump pickup strainer and fish it out.

Repair with a time sert.

[Da Jemster]

spot weld a longer bolt and see if you can get leverage

[Halftim3]

My oil pan bolt/threads also kept spinning freely on a previous oil change so I plugged it with some RTV and would do oil changes through the strainer area for about 3 oil changes and timed it with my local shop to do my rod bearing job, oil change, and oil pan drain bolt repair. He repaired it by welding a bung which works perfectly and is IMO way better than buying a new oil pan. It doesn't look good, but no one sees it anyway.

[Da Jemster]

I "3rd" on Time-Sert. I've used it on 3 cars now. No leaks.

[scubastove]

I did this same thing due to a bad magnetic drain plug. I was able to remove the bolt, but I did use a Time-Sert oil pan repair kit. The repair was fantastic and very solid, it uses a steel insert that mechanically locks into the oil pan. It also retains the OEM threads and you can use the original drain plug.

Coming from an engineer, this the best solution short of oil pan replacement.

according to the shop they are unable to remove the plug. That is the main issue in the way

[JayVee]

I did this same thing due to a bad magnetic drain plug. I was able to remove the bolt, but I did use a Time-Sert oil pan repair kit. The repair was fantastic and very solid, it uses a steel insert that mechanically locks into the oil pan. It also retains the OEM threads and you can use the original drain plug.

Coming from an engineer, this is the best solution short of oil pan replacement.

[heinzboehmer]

So you're saying they should be able to remove (and likely destroy) the drain plug but leave the oil pan intact?

I think so, pan is aluminum so it shouldn't be too hard to force the drain plug out. I would at least try

Is there anything I can recommend the shop try specifically?

Sapote's recommendations are what I would do too. Just be careful if drilling into the bolt. There isn't too much stuff above it, but you don't want them to hit an oil line or connecting rod. Oil pan is for sure coming out if they do.

[scubastove]

You can definitely get the drain plug out without removing the pan, even if it means drilling it out or otherwise destroying it.

Repairing the pan with a time sert is the way to go btw, much better than a helicoil. Just make sure you get the appropriate length inserts (9.2 mm). Had to do this myself not too long ago: https://nam3forum.com/forums/forum/m...162#post156162

I did see your thread for this while looking up my issue. But I think you were able to get your bolt plug out without issue? I just don't have the tools/place to do this myself right now. So you're saying they should be able to remove (and likely destroy) the drain plug but leave the oil pan intact? Is there anything I can recommend the shop try specifically?

[heinzboehmer]

You can definitely get the drain plug out without removing the pan, even if it means drilling it out or otherwise destroying it.

Repairing the pan with a time sert is the way to go btw, much better than a helicoil. Just make sure you get the appropriate length inserts (9.2 mm). Had to do this myself not too long ago: https://nam3forum.com/forums/forum/m...162#post156162

[sapote]

The shop informed me that they could not back the drain bolt out, it just freely spins and will not catch a thread. The only way to get the bolt out would be destructive to the oil pan, so they recommended oil pan replacement

Shop didn't offer any creative ideas. I would try these before the removing the pan:
1. Grip vise on the drain bolt, then while pulling the bolt out HARD, like lifting 20 lbs weight, turn the bolt CCW to catch the threads. This should work but if after 10 minutes and not work, then next
2. Drill the bolt at perfect center (keep it from rotating with other nose pliers or something) start with small bit, then get to larger bit and do this careful then the bolt reduced to thin sleeve, then with pliers crush it inward and turn it out or pull out. Try to drill to the pan threads.

[scubastove]

honestly, it doesn't hurt to bring this to the attention of the reputable shop? Reputation goes a long way, and while you might be right about them not honoring their work, the worst place you get is back where you started.

I did call them up about this last year when I found the drain bolt was spinning. They mentioned I could bring it in and they would take a look/helicoil it there, but the shop is a few hours away from home and my car is on a lift local to me. And it's not like the reputable shop will front the bill for this parts/labor without them seeing it, and determining if it is something they would cover. I feel a little cornered and wasn't sure the best route to go.