Pinhole in steel oilpan: weld or epoxy or...?

Streetwiseguy said:

Mig will blow through the rust, ignite the vapors and blow the valve cover off. 

And how!

Had to chop and channel a deep/wide sump oil pan to clear the headers. It's a Ford thing.  Well, the welds leaked, but only with the engine running.  Removing the pan was a 10 hour ordeal involving pulling the engine after pulling the exhaust, transmission, headers, and bellhousing all individually.  So, I drained the oil.  Hosed out the inside of the pan as much as possible with carb clean.  Angled the car on the lift so the area I had to weld was elevated.  Forgot to blow out the carb clean vapors and fill the oil pan with argon before welding.

I got a half inch of weld bead before it blew the (rubber) gaskets out from under the valve covers, and blew the breathers out hard enough that one landed 30 feet away, and the other was never found.  It also added a good amount of capacity to the pan as all of the straight sections were now bowed out 

It also made the crack much more visible, and it welded up nicely  after that.

02Pilot said:

Any thoughts on welding or epoxying a small (quarter-sized?) metal patch over the hole, rather than just attempting to fill the hole itself?

Fuel tank repair kit.  The kind that comes as a two part liquid epoxy that you squeeze the container to break the seal between the two for mixing.

You will have about 30-40 seconds to mix it before you apply it.  It will start to get very... exothermic as it sets.

Have successfully used it many times on oil pans to limp something along.

Helpful info. I have an oil pan with a slight leak by the drain bolt from taking some kind of hit,I wasn't sure best way to address it. 

I got ten years (until sold) out of a JB Weld repair on the bottom of my gas tank. I enlarged the pinhole and let it drain for a week,  sanded the surface and cleaned it with acetone, followed by canned compressed air. 
 

I would expect good results from your last repair. 

Oh, it just got so much worse.

I stuck my head under there to look things over once more and noticed a little oil seeping from the OQS gasket. I just replaced it, and made sure the sealing surface was clean, so I figured I hadn't tightened the three M6 nuts enough. I backed them off and pulled the sensor out to double-check that everything was in place and correct (it was) and reinstalled. As I snugged down the nuts, one of the studs decided it had had enough and snapped. No good deed goes unpunished. Studs were not rusted or compromised in any way that I could see (these are steel, not the stupid aluminum ones BMW uses (those I didn't break when I did the oil filter housing earlier today)).

Now I have to cut off and drill out the stud, and fish a bolt in there and hope it seals. And I won't be able to do this until Friday at the earliest. berkeley me.

It looks to me that those studs are the reason the rust starts. Probably dissimilar metals or some other reason. 

I went through this on my Dad's E90 330i, it had the same rust around the sensor just like Slippery shows. I did pretty much the same as you, cleaned up all the loose rust, treated it and used JB Weld to seal everything up (no patch but I didn't open things up trying to weld it). It held fine for over a year before he bit the bullet and got a new pan installed for peace of mind.

If it were today with the price of pans now (supply and demand I guess) I'd pull the pan off and then weld in a patch and a new stud for a permanent fix to avoid buying the new pan. My welding skills (and equipment, I'd TIG it now) have improved a lot since the JB weld repair though.

I don't know if it's dissimilar metals, or that the OQS doesn't sit quite flush to the pan, and as a result that water gets trapped between the pan and the body of the sensor. The studs themselves were totally clean.

I'm dreading having to deal with the broken stud. I wish I could just pony up and pay to have the pan replaced, but that's not possible right now, nor is taking the time to do it myself, so I'm going to have to suck it up and try to make it work. The stud doesn't back out with some moderate hammer taps, so it's probably pressed in there with some special jig to seal properly. How I'm going to get a new bolt to do that, I have no idea. I considered a rivnut, but I think that would leave too much of a gap between the sensor body and the seal.

In reply to 02Pilot :

I would think that stud is welded to the pan. 

I thought that too, but I can feel the head of it inside the pan, and I don't feel any sign of welding. I suppose it might be some sort of spot-weld arrangement. I should stick a borescope in there and see exactly what it looks like.

An alternate solution for the broken stud came to me in the middle of the night. Rather than drilling out the broken one and replacing it, I could clock the sensor differently and simply drill three new holes into solid metal, install three bolts (I'm thinking with O-rings inside the pan to help them seal), and install the sensor. The orientation makes no difference to operation, there are no locating tabs or pins to worry about, and the wiring harness has a little slack. I would also avoid having to rely on the remaining two studs, which I don't entirely trust at this point. Of course, it's higher risk - I'm drilling three holes in the oil pan, after all. Good idea? Bad idea? Anyone got something better?

FWIW, I would simply plate off the hole for the OQS if I could, since I don't use the condition-based service intervals for oil changes, but with no dipstick, it's the only way to monitor oil level.

In reply to 02Pilot :

I would go and do what you said and reclock the sensor. 

Just for the hell of it, I would create a paper template and make sure you have all the clearance you need before drilling as to me it looks like you might steel need to cutoff the old studs but might be a perspective thing with that picture. 

Does you car have an oil temperature gauge? That sensor on my e46 gives both the level and temperature, I just had to change it as the gauge stopped working. 

Also, you can buy bolts with o-rings built in. I used to use those to seal in gas applications. McMaster should have them. 

One more thing. Any concern of the new bolt turning while you are trying to tighten it?

Just bite the bullet and get a new pan or a used pan from a Southern junkyard.    Its cheap insurance if you are planning on keeping the car with a running engine.  

If it has one rust hole there are others lurking elsewhere just waiting to open up.

Will the auto transmission pan fit on that car?  Just wondering...

In reply to jharry3 :

Auto pan fits with some mods, that's what I would do. The process is outlined in the thread I linked. 

Can you removethe sensor and seal it? Just use some sort of wiring/resistor to replicate the signal and be out of there? 

If this thing is rusting holes in the oil pan, think you should revise the approach on spending hours drilling/tapping if possible....

Slippery said:

In reply to jharry3 :

Auto pan fits with some mods, that's what I would do. The process is outlined in the thread I linked. 

I missed that link the first time around. If all it takes to adapt the aluminum pan is making a few relief cuts in a piece of sheet metal, I think that's probably the best long-term solution. Unfortunately, it also means I have to wait for parts and buy an engine-hanging tool, and probably another torque wrench to deal with the ridiculous low torque aluminum bolts.

In reply to 02Pilot :

You should be able to rent an engine hanging tool from AutoZone depending on how long you expect to take to swap the pans out. 

Slippery said:

It looks to me that those studs are the reason the rust starts. Probably dissimilar metals or some other reason. 

Oh, eew!!  Yeah, now I see what you mean.  

Why is a manual pan even steel?  Seems like a lot of work for no real benefit.

02Pilot said:

Slippery said:

In reply to jharry3 :

Auto pan fits with some mods, that's what I would do. The process is outlined in the thread I linked. 

I missed that link the first time around. If all it takes to adapt the aluminum pan is making a few relief cuts in a piece of sheet metal, I think that's probably the best long-term solution. Unfortunately, it also means I have to wait for parts and buy an engine-hanging tool, and probably another torque wrench to deal with the ridiculous low torque aluminum bolts.

If you were down here I'd offer to do it in my garage. We can knock that out in an afternoon. 

In reply to Pete. (l33t FS) :

The advantages of a steel pan, regardless of gearbox type, are supposed to be lower cost and increased survivability in case of impacts. This one is madly expensive and rusts like an old Subie's fenders in salt country though, so I don't think it's delivering on those advantages...

In reply to Slippery :

Thanks. Unfortunately, I don't think it will make it that far without oil...

I'm going to go talk to my indy tomorrow and assess my options. Looking more closely at the DIY link posted, it seems I need to lift the engine rather than just hang it, so that means I need an engine hoist. Great....

In reply to GameboyRMH :

That all would make sense were it not for the automatics getting an aluminum pan.

GameboyRMH said:

 This one...rusts like an old Subie's fenders in salt country though.

That's just the result of an oil pan gasket that lacked sufficient leakage.