M20 Oil Pan Threads Stripped. How to fix?

[bigredguy]

I have a 1987 325 with the m20b27 motor and the threads on the pan have become stripped, which I believe happened the one time I let a shop change my oil. I have been doing research on if this is fixable or not without removing the pan and replacing it which is not really an option for me as I work full time and dont have a place nor the time for that fix. Now through my research I have found several options that would be possible for me to do and I would like opinions on which is the best and why.

Option 1: Expanding rubber plug. This is a plug that will go into the oil drain and when it is tightened the rubber is compressed and expands filling in the threads and making a tight seal. This would only be used for one maybe two oil changes which is not a problem, but I cant seem to find any metric sizes and the smallest one I can find is 1/2 inch which is bigger than the drain.

Option 2: Drill the hole out to 15/32 of an inch and then tap it to 1/2-20 threads. With this option after the hole is tapped I would be able to use the expanding rubber plug, and if that doesnt work I could just use that size oil drain plug.

Option 3: Liquid Thread? I have never heard of this, but I was talking to a buddy today who recommended it and said they use it on machines where he works if the threads are bad. I will be looking into it because I am looking for the easiest fix for now. Any opinions or information on this would be helpful.

Those are the 3 options I have found in my research so far and will continue to search it up. I am just asking for people who have experience with these particular oil pans because most of my research was for other cars and not e30s, so all different sizes of drains and types of pans.

I am looking for any pros/con s of any of these 3 methods along with any other information you may have.

I also have a black gasket maker/rtv sealant that I have a little left over from sealing my new wheels that I thought about using with the first 2 options just to ensure that the pan would no longer leak, so any opinions on that would be helpful too.

[blazinxpk]

i stripped the oil pan drain on my b25 a few months ago. what i ended up doing was install a over sized piggyback bolt.

i believe it was a single over size. (they make single/double/triple)

the oversize bolt basically cuts through the pan and makes a new thread as you tighten it down. the addition of the piggyback allows you to open the smaller bolt every time you change your oil, instead of having you take out the whole bolt that is now screwed into the pan.

mine has been holding up fine since march or so.

you can also add jb weld to this procedure, you will basically permanently screw in the big bolt and then only use the piggyback to drain the oil.

might sound sketch but it works.....

[bigredguy]

i stripped the oil pan drain on my b25 a few months ago. what i ended up doing was install a over sized piggyback bolt.

i believe it was a single over size. (they make single/double/triple)

the oversize bolt basically cuts through the pan and makes a new thread as you tighten it down. the addition of the piggyback allows you to open the smaller bolt every time you change your oil, instead of having you take out the whole bolt that is now screwed into the pan.

mine has been holding up fine since march or so.

you can also add jb weld to this procedure, you will basically permanently screw in the big bolt and then only use the piggyback to drain the oil.

might sound sketch but it works.....

Thanks, that does sound like it works well. Does the smaller bolt require a gasket? And would you happen to have a link to the product you purchased?

[blazinxpk]

the smaller bolt does not come with a gasket. (i didnt use one, but i dont think you have to)

i actually got the bolt from a friend of mine who worked at a mechanics shop. they had drawers full of various oil pan drain plugs, i just picked one that looked like it would fit.

here is a basic procedure to the fix:

http://www.mtsac.edu/~cliff/storage/gs/Stripped-Oil-Drain-Plug-Repair.pdf

quick google search found this:

http://www.cgenterprises.com/drain_plugs_oversize_repair.htm

[bigredguy]

ok, thanks alot. I will most likely be going this route, and I also have the black permatex sealant they used so hopefully it will work. I just need to find one with the right threads. I have already looked online a little and cant seem to find any in our M12x1.5 thread size. There are some in M14, but so far havent found and M12. I will continue looking tonight and tomorrow I will call around to the local auto parts stores.

[jlevie]

The ideal fix, which can be done without removing the pan, is to install a Timesert.

[bigredguy]

I am not a fan of inserts like that. I have used helicoils in the past with no luck. Any reasons you have for this method as opposed to the method listed above?

[SpecM]

^ I did this. I used 1/2 - 20 timesert. it is much stronger than the original threaded aluminum

[dnguyen1963]

Timesert is your best bet. Otherwise, you can buy this drain plug and JB weld it into the existing hole.

http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

[bigredguy]

^ I did this. I used 1/2 - 20 timesert. it is much stronger than the original threaded aluminum

Alright, I will be looking into the timesert. Correct me if I am wrong, but then I will have to drill and tap the hole out to 1/2-20 thread and then insert the timesert? Could I also use a gasket maker to ensure that the outer part does not leak? What does that make the inner thread?

Timesert is your best bet. Otherwise, you can buy this drain plug and JB weld it into the existing hole.

http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

I thought about using one of these, but I am worried that if I bottom out I would mess up the drain and wouldnt be able to use it, and then if its secured in the hole then I have no more options.

[dnguyen1963]

It is actually pretty short. You can't hit it even if you lose air in both front tires. However, it you drive over a big bump (like a man hole), you can damage your oil pan big time.

[bigredguy]

It is actually pretty short. You can't hit it even if you lose air in both front tires. However, it you drive over a big bump (like a man hole), you can damage your oil pan big time.

yeah, I think thats how the oil pan got to the condition its in now. The little bump on the bottom of the pan that the gasket seals up against is worn completely flat, so even if the threads were not messed up it still would leak slowly, but with the threads being stripped as well it leaks pretty bad.

That is why I was trying to go with a piggyback plug and then would just use a gasket maker on the outside plug to seal it in place so that the outer plug wouldnt leak and I would no longer have to worry about that anymore, but unfortunately I cannot find an m12x1.5 single oversized piggyback plug. they make them in a ton of other sizes, but not the size I need. :hitler: It seems like anything in m12x1.5 is pretty hard to find around me, or even online for that matter.

[richard.bratton]

+1 for Timesert!

[bigredguy]

Timesert is now my second option behind a piggyback bolt, which I cannot seem to find anywhere.

If I do go with a timesert could I just buy the m12x1.5 one and seal it with jb weld or gasket maker? Also when buying them when they advertise m12x1.5 is that the outer thread? if so what is the inner thread then?

[jlevie]

A Timesert is specified by the thread diameter and pitch of the threads it replaces. Red Locktite is a suitable sealant between the insert and the pan.