Stripped drain plug in aluminum pan

Motherberkeleying neon.....

Drain plug was tightening fine until it didn't. Pulled the threads out of the aluminum pan with almost no effort. 

Before I go through the effort to change pan, is there a simple permanent solution? Ive actually never had this happen. Its a car i actually care about, so good solution. I know replacement pan is the best option, but...

Sounds like pretty much of a text book application for a helicoil.

Time- Sert makes stuff, probably pricey.  Check your local auto parts store.   Tap and go a size bigger?  By the way, weren't you looking for a tap & die set recently?

I've had reasonable success with oil-pan specific drain plug repair kits.  You drill the old threads out, tap the new larger hole and replace the drain plug with a larger one.  You need to be very careful to tap the new hole exactly perpendicular to the mating surface so that the drain plug seals correctly.

I have seen a threaded insert in an aluminum pan and it didn't leak at the plug.

BUT I also bought the car for the engine block and having I purchased it from the 'Nth' owner who said it 'always had a tick since he bought it' and he parked it when the battery froze and then he stripped parts from the suspension to fix a different car, and when pulling the engine block apart I discovered it had at least 2 rod bearings that spun and a main bearing that was trashed, no idea if there is any correlation between the two incidents.

I only noticed because when pulling the pan, the excess threads were still attached inside the pan.

Safest bet may be a thread repair and engine flush to keep oil inside it while shopping for a new pan?

Drilling or tapping is a huge pain because the drain plug threads are tangent to the bottom of the pan.

This means that when you get past the end, such as when you are running the Heli-Coil tap through, it walks it up and gives you a cockeyed oval hole.

Your best bet is a self tapping oversized drain plug and a lot of patience to install them.  They usually come in .4 and .8mm oversizes.

And use a captivated O ring style gasket if the drain plug doesn't come with one.  They are much more tolerant of the drain plug not being perfectly square to the face, and they only need just enough torque to keep from backing out.

Berck said:

I've had reasonable success with oil-pan specific drain plug repair kits.  You drill the old threads out, tap the new larger hole and replace the drain plug with a larger one.  You need to be very careful to tap the new hole exactly perpendicular to the mating surface so that the drain plug seals correctly.

May be time for a new tool Michael.  A hand drill jig might be something to consider.  Can be used in other projects too.

Go to napa and get a repair plug. They come in a variety of sizes and will cut their own threads as you wind them in. Simple and effective.

I cam close on my cayman a couple years ago. I did not pull threads but had a hell of a time getting that stripped plug out in front of 8+ quarts of oil in an aluminum semi-dry sump.

A while back I had an Integra that the oil change place stripped the treads on the aluminum pan. IIRC they fixed it with a helicoil and probably lots of loctite.

I've done several re-threads in aluminum pans back when I was working in shops.  We were a cut-rate shop and by the time these people brought their wasted-ass hoopties to us they had already undergone 30 oil changes so it was inevitable that some would fail.

They sometimes go crooked.  It's a thing.  Just get a kit with the right drill bit and you should be fine

While I love helicoils (by type/brand) the way they install includes a cross-piece at the bottom (or in this case the top) of the threads which sometimes limits how deep the bolt can go, especially if it has a magnet nub on it.

Having said that, if it's deep enough, I really like the concept of how they work.  A helicoil in aluminum is far stronger than the aluminum ever was.  The steel threads alone are stronger, but by design, the coiled wire design of the threads causes them to exert radial pressure out as you tighten the bolt.  Stronger even than regular threads tapped in steel.  Install with green or red loctite.  The other thing I like about helicoils (even without loctite) is that because they are coils and the individual threads are not connected to each other, during the un-torquing process of the bolt for future draining, the helicoil is exerting expansion force on the aluminum threads meaning that the possibility of the helicoil coming out is next to zero.

This is something many people don't understand about helicoils.  The coiled insert itself is slightly too big for the threads you just cut.  The installation tool fits down in and engages that tang at the base of the threads.  When you twist it to thread it in, it tightens the spring reducing it's diameter allowing it to fit in the hole.  Once it's installed and you remove the pressure on the tool, the whole thing is pressing out on the aluminum.  If you tried to reverse that action (like when removing the drain bolt) you are effectively trying to expand the spring which adds radial force to the aluminum around it.  It's not coming out without a drill bit.  This is why I prefer helicoils.  The physics involved cause the torque forces to work in your favor.  Think of it kind of like a press-fit where the entire length of the coiled insert is actively engaging the substrate around it.

Timeserts are great, but they are a solid collar.  They're a bolt inside of a hollow bolt. This means that the only thing holding it in is torque and/or loctite.  I like Timeserts for more permanent applications like an intake manifold, or an alternator bolt.  It might never back out, or it might back out the next time you use it.  There will always be one time in the future though, that the friction between the bolt and timesert is greater than the friction between the time sert and the aluminum pan, and the timesert will give up the ghost.

Pete. (l33t FS) said:

Your best bet is a self tapping oversized drain plug and a lot of patience to install them.  They usually come in .4 and .8mm oversizes.

And use a captivated O ring style gasket if the drain plug doesn't come with one.  They are much more tolerant of the drain plug not being perfectly square to the face, and they only need just enough torque to keep from backing out.

What he said. I've used them successfully several times

Thanks everyone. 

I'm grabbing an oversized plug when the roads clear. At the moment, i have the stripped bolt snug enough it doesn't leak and i can heat cycle the engine swap and check everything else. It'll need an oil change immediately anyway, so its a good time to change the plug. If it doesn't work, or i hate it, or whatever, ill look at swapping the pan for a new one. Dorman apparently makes one. 

The captured o ring gasket: any pictures? 

Neon oil pans are pretty easy to change.

Look for bonded sealing washers. Frequently used in AC systems. I have seen them used on oil pans as well. I keep an assortment in the shop. 

In reply to Toyman! :

I usually raid the A/C kit, too.

Very common in industrial hydraulics as well

However, if your Time-Sert fails I have the $400 oversize Time-Sert kit (don't ask).

Call me if you get stuck.

I ordered the pan since i have to drop it to diagnose a low oil pressure issue that didn't exist previously. 

This car has seriously pissed me off. Time to walk away. 

When I think about "captive O-ring" this is what I picture.

Underneath the flange of the head there is a groove with an o-ring embedded in it, much like this:

Helicoil. Done dozens of them in aluminum neons pans. 

Hope the low oil pressure issue turns out to not be a problem.  Incant remember what it was called, but my Neon used a plug that was made for pans that had been partially stripped before.  Threads were just a bit bigger than stock, and it held fine.

My temporary fix, going on three years. 

Dusterbd13-michael said:

I ordered the pan since i have to drop it to diagnose a low oil pressure issue that didn't exist previously. 

 

This car has seriously pissed me off. Time to walk away. 

Yup!  Take a break.  Hug your wife and kid.  Look at the bright side, maybe that stripped plug prevented something catastrophic from happening.  

Dirtydog (Forum Supporter) said:

Dusterbd13-michael said:

I ordered the pan since i have to drop it to diagnose a low oil pressure issue that didn't exist previously. 

 

This car has seriously pissed me off. Time to walk away. 

Yup!  Take a break.  Hug your wife and kid.  Look at the bright side, maybe that stripped plug prevented something catastrophic from happening.  

Exactly!

Clean the shop, read my book. Fix the attic door. Go sledding. 

Walk away, figure it out next week or two 

Oil pressure is over rated. I drove a Triumph Spitfire for two years with zero. It would come up to five pounds or so and then drop back to nothing as it warmed up. When I finally rebuilt the motor I found the oil pump was split open. But the bearings and top end were still fine.