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Unable to Remove Oil Drain Pan

2K views 16 replies 7 participants last post by  rumb 
#1 ·
On my '86 560SEL, the previous owner stripped the drain plug bolt on the oil pan, causing me to be unable to remove it. I purchased a new oil pan with plans to replace the old one. I extracted all of the oil and began removing the oil pan screws. Well, only about 1/3 of them were removable. The rest wouldn't loosen at all. They're rusted to hell. I blasted them with a type of WD40 made specifically for rusty parts and still no luck. Does anybody have any advice on how I could go about removing these? I can't even fit a socket around these screws either as the raised lip around the drain pan prevents a socket from being able to fit firmly around the heads. I tried turning them with a pair of pliers and they couldn't grip properly either.
 
#2 ·
One word: Kroil.

Penetrating-Lubricating Oils

If this stuff won't loosen them, you're done.

In the roughly 40 years I have been wrenching on cars, I've never found something that did what this stuff can do.

I'm not sure if the bolts for the pan are exposed on the top edge or are blind holes in the bottom of the block, but if they're exposed on the top be sure to get some of the penetrant up there so it can soak down into the holes.

Good luck,

Dan
 
#5 ·
I do plan on ordering that stuff actually but I don't think it will help me in this particular situation. The insides of the heads are stripped so the bit just spins around inside of them when I try to loosen them.

One word: Mityvac.

Getting under a car to do an oil change is for Honda owners.
I already have a topsider that works great but I also want to replace the oil pan simply because it's rusted and ugly.
 
#3 ·
One word: Mityvac.

Getting under a car to do an oil change is for Honda owners.
 
#8 ·
Mityvac does make oil extractors, I have one and it works fine BTW.

Back to the screws in question: a penetrator will do little to help in this case because the screws are inverted, witch means the penetrator would have to go up against gravity to reach the threads. I also understand that the heads of the screws are somewhat stripped, so grabbing them is not so easy.

If I would be in this situation, this is what I would try:

1) I would come up with a way to grab those heads as well as I can so I can turn them. Next I would raise the engine a bit with a jack under the oil pan, putting pressure upright on the oil pan with intention to decrease some of the tension on the screws. While the pan is pushed up, I would try to get the screws to turn. I am not expecting a success for all screws, but you never know, is worth a try. I do expect however that the pan will deform, but it does not count much anymore because you are going to replace it anyway.

2) IIRC the screws require an alen wrench. If the hex hole is rounded, that means it will guide a drill bit to the center of the screw. Use a drill to get the heads off and the pan will drop. Then you deal with the headless screws left. I used this procedure and worked on other stubborn alen head screws.

While you are there, do yourself a favor: replace the pump's rubber sump. I think is PN 1021860007
 
#9 · (Edited)
You can also dremel a slot and use a screw driver. Used a light film of blue hylomar on my gasket to pan and to clean fastening surface. Not enough to seep but enough for me as a solo to get things started without cussing.
 
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#10 ·
To remove socket head bolts made of steel and installed in aluminum I have used this method with great success,
1 take a drift or punch place in socket head and give one or three good raps with a hammer, this helps shock the threads ,

2 take a oversized torx bit and drive it into the socket head with said hammer as far as it will go .

3 attach ratchet to bit and with a quick loosening motion remove bolt .

good luck
 
#17 · (Edited)
weld another bolt onto the one stuck in the drain hole. the heat does wonders and gives you a fresh bolt to put a wrench on.

you local muffler shop can do this very easy.

For allen bolts I always insert the allen wrench socket on an extension and then give the end about 3-4 good hard raps. that helps loosen the threads. Make sure the allen is inserted all the way in. good steady preasure with a breaker bar is good, dont try to snap the wrench against the bolt. The extra length of the breaker provides a high amount of torque to the bolt.


bolt vs screw:
 

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