Need advice from those knowledgeable.

[Roll]

1997 B7300

While the HST continued to drain I started on the crankcase oil change.

First I noticed the pan plug was leaking; an occasional drip. On removing the plug, it had to be wrenched out for several threads then, it easily came out by hand. I had expected it to spin out easily after initially wrenching it loose but it did not.

I've replaced the filter and I'm ready to replace the plug (with a new copper gasket). I can screw the drain plug in 7-8 turns but then it gets tight, some 4 threads before the base of the plug contacts the pan.

It feels as if I am screwing the plug into a nylon lock nut. If feels just like that, it goes in easy until I hit the "nylon" at the end of the nut and then it stiffens up. I don't imagine there is nylon at the end of the threads in the pan but that's what if feels like.

I tried taking it up a 1/4 turn and backing it off, then a bit farther and backing it off again, as if I was using a tap to cut new threads, (or repair damaged threads). But I stopped because it doesn't seem to be loosening up. I also stuck a rod gently up into the hole to see if the oil pick up or screen might be sitting over the hole and I was bumping into that with the drain plug but no, there is nothing for at least an inch over the hole.

I have a set of taps and dies but they are American fine, not metric. The bolt checks to 20 count NF 1/2 inch perfectly but the 20 count NF tap won't start in the hole. Odd.

I'm now wondering if the drain plug was originally metric and someone jammed an SAE 1/2 in plug into the hole.

Any thoughts or recommendations? Can anyone say if the original plug is SAE or metric? Is there by any twilight-zone chance a nylon lock at the top of the drain hole? (LOL)

Thanks for any help,

Mystified in central Ohio, Roll

I really don't want to pull the pan but .....

 

[BroncoRN]

Pick up a metric tap from Harbor freight?

 

[North Idaho Wolfman]

I would first buy a new drain plug.
And then as BroncoRN said, get a tap for the hole.
No need to pull the pan yet.

If you can, post a picture of the plug you have and we might be able to tell you if it's the right one or not.

 

[Bobjones]

If you do run a tap, make sure you stick a magnet in the drain hole after. A quart of solvent to wash debris out wouldn't be a waste.

 

[Tooljunkie]

There is a good chance the threads on plug are pulled. Have seen it many times. Take plug to dealer to compare. If its a match,buy it.
Then get a tap to match new plug. You may not even need it. Plug is softer than nut in pan.
Grease tap and carefully recut the threads. Only a little bit at a time,cleaning chips from tap frequently.

 

[Kubota Newbie]

Yeah, plug stretched. Get a new one, bet it'll thread right in. I've had it happen too, but not on my Kubota.

 

[Roll]

Thanks gents.

I did find a 12mm 1.25 die and tap this afternoon. I also ordered a new drain plug.

Interesting... I intended to tap the pan tomorrow after running a magnet round the hole. But for whatever reason I took the die out of the package and since I had the drain plug in my hand I screwed the plug into the die. What a surprise when I found it went in nicely for a half inch or so and then bound up. Just like what it does in the pan, (meaning roughly the same number of threads showing when the plug binds up in the pan).

I've never seen a drain plug "stretched" but that fits my symptoms exactly. The new plug won't be here until next week but in the mean time I'll fish for metal fragments and gently run the tap into the hole. I hope it will go smoothly since it seems the plug is the problem.

Assuming the tap runs cleanly through the hole do you still recommend running a cleaner through the pan (would have to pour it in through the fill hole on top). Also can you recommend a cleaner (brand and name).

Thanks for the help Gentlemen,

Roll

Pics attached. The plug is about 15/16 in long; the threaded portion is about 5/8 in. The picture with the plug screwed into the die shows about how far in it is when the threads start to bind up

 

[D2Cat]

Roll, do you have any kind of small hand pump? Just rig up something to squirt a cup or two of diesel in the hole and let the fluid run out taking any cutting with it.

Do as Tooljunkie suggested, put some axle grease on the tap. It will collect pretty much all the metal if you go slow and wipe the grease and re-apply if/when you get much on it. Then you might try a small magnet pushed up in the hole and possibly pick up a crumb. Then if you flush it you're good to go for sure.

 

[Tooljunkie]

A new die nut on a new bolt will do the same thing, bind up.
Thread old plug and see how it fits.

 

[Roll]

update on oil pan hole

I loaded the tap up with carriage grease and gently started it into the pan hole. After a few tries it caught and started in. It started to bind up after a few revolutions. By hand I gently advanced it a 1/8 turn, backed it off, and continued until it became easy to turn. I never had to put much strength to it, ( rotated the tap by hand with a short T handle) making me wonder if the threads were clogged up rather than stripped.

I examined the tap and grease for metal fragments and found none. I measured the point I stopped and then checked the tap after I pulled it out. I had screwed it into the pan 1/2 inch.

I put a handle on the die and a socket on the drain plug and worked it through the die to the base. It took a little more pressure than the pan but I can't say it felt like I was cutting new thread. I did have some metal fragments left in the die when I was done. Not a lot but some.

I then tried the plug in the pan and it ran all the way in by hand with little or no effort. I did not try to tighten it up against the pan. It screwed out just as easily as it went in. One spot gave me some slight resistance but I was able to unscrew it without using a tool.

I have not tried rinsing out the pan with diesel yet but that sounds like a good idea and I'll give it a try. I have some concern about any remaining diesel left in the pan and mixing with the new oil. This is not an issue?

I am thinking that rather than "go for it" with the old plug I'll wait for the new drain plug coming next week. This one is working fine now, or it seems that way.

Suggestions?

Thanks again for the assistance, I read every post.

Roll

 

[D2Cat]

Roll, maybe you can do this. Forget the diesel flush. Go to your local hardware store and they probably have similar magnets. Buy one that fits on the end of you drain plug (so it fit's in the tapped hole).

When you get your new drain plug, put the magnet on the end and screw it in. Done!

Don't order magnets on Ebay. They come from China and you may be mowing grass before they arrive.

http://www.ebay.com/itm/S-Chic-12-X...124211?hash=item2a7a7525f3:g:BQYAAOSw241YlDpI

 

[North Idaho Wolfman]

I think your fine, any small amount of metal that is left in the pan will either stay on the bottom or get picked up and shoved into the filter.

 

[clay45]

Re: update on oil pan hole

I am thinking that rather than "go for it" with the old plug I'll wait for the new drain plug coming next week.
Suggestions?

Thanks again for the assistance, I read every post.

Roll

I did too. Learned something new and I agree you should wait for the new plug and crush washer?. Why lose another crankcase of oil by getting in a hurry over the drain plug?

 

[Tooljunkie]

Just had a for escape on shop. Aluminniun oil pan. Threads pulled and stuck on plug. Rethreaded from 12 mm to 1/2" and there were few cuttings on the greased tap. 1/2 plug was loose and went to 1st oversize. You can never overtighten an oil plug if you pull hard in a standard length wrench. Destruction occurs when you start using long ratchets and dont know when to stop.

 

[Roll]

Just had a for escape on shop. Aluminniun oil pan. Threads pulled and stuck on plug. Rethreaded from 12 mm to 1/2" and there were few cuttings on the greased tap. 1/2 plug was loose and went to 1st oversize. You can never overtighten an oil plug if you pull hard in a standard length wrench. Destruction occurs when you start using long ratchets and dont know when to stop.

As an 18 year old learning about servicing cars and some repair work, my boss watched me tighten up the drain plug on a vehicle I was working on. He stepped over and explained something to me that I have never forgotten.

"This" he said, pointing to the drain plug, "is not the bolt that holds the car together. So go easy on it".

LOL Roll

 

[Roll]

Finally got the replacement drain plug. It's different in that at the base of the thread, the shaft tapers out. I noticed the oil pan had a slight taper in where the thread starts but didn't think much about it. Now I wonder if someone lost the original drain plug and stuck that flat plug in. It probably leaked and so they put a little extra effort into tightening it up.

That might explain the leaking pan, the stretched threads and the difference in the new plug. I'm done for the night so that will be tomorrows work.

 

[Tooljunkie]

Funny you mention that,i use that comment quite often. Or the one bolt they build the entire car around. Had one of them today.

 

[Roll]

Funny you mention that,i use that comment quite often. Or the one bolt they build the entire car around. Had one of them today.

LOL Well that's a new one to me, "The bolt they built the car around". I like that.

Roll and by the way for you young folks still working....keep at it and save your money every chance you get, because I can tell you from experience, retirement is absolutely outstanding. ;-) (But you will want a little money to spend when you get there.)

 

[North Idaho Wolfman]

retirement is absolutely outstanding. ;-)

What is this retirement B.S. everyone keeps chatting about?

 

[nickelplated5s]

when you're done working for the day and you 'retire' to the couch or what not.