Guys, had a bad day yesterday. When taking the bolt out of the oil pan for my oil change, the aluminum tread of the oil pan came with the bolt[&:]. So I went to Napa to get a tap and bigger bolt. They gave me what seemed to be bigger bolt and a 14mm X 1.5tap. After using the tap, I realised that the bolt they had given me was a 14mm bolt[:@]So of course it was too small.

It was then after dinner, so Napa was closed. I went to Canadian tire and they had a 16mmX1.5. That was too big, so I ended up getting those rubber insert with a bolt that fit real thight in the whole and is only a temporary fix, since it is not recommended to use a second time. I'd feel better knowing that I have the right bolt in place when I do my next oil change anyways.

My question here is: What size bolt do I need if I used a 14mmX1.5 tap ???

Thank you,

Darover

 

Ok, I could of course be wrong, but I do work in a hardware store, so take that into account. Your tap should be labeled for the size of bolt that it corresponds with. Hence, if you use a 14x1.5 tap, you should be able to thread in a bolt that is 14x1.5. Now, on a technical note, the 1.5 denotes the number of threads on the shaft within a certain measurement. For metric bolts, I believe it is the number of threads per millimeter.It is possible that you got a 14x1.5 tap and a 14x1 bolt. That would prevent the bolt from threading in properly. Or, alternatively, if you tapped it, and the new bolt is just sliding right in still, you may need a bigger tap AND bolt.

 

Mechanical Engineer in the house. What was the original size of the bolt? M14? what was the original pitch?

M14 has 2 different thread pitches

1.5 mm and 2 mm

With metric thread callouts the pitch refers to the actual measurement 1.5mm or 2mm (thread to thread).
With inch thread callouts it refers to thread per inch example; 1/2"-13 13 threads per inch

What you wanted to use was a helicoil insert.

You get a helicoil thread repair kit for the original thread specifications.

If a kit is not available you just get the individual stuff

It comes with the correct tap drill, helicoil tap (special for the insert!) and helicoil inserts to repair the oil pan.

I buy them for work thru: http://www.mcmaster.com/

 

Well, it said 14mmX1.5 on the tap and 14mmX1.5 on the package of the bolt ?!?

After noticing that in the kits the tap was a smaller size than the bolt it came with, I tried finding the right nut in which the tap would screw, in order to find the right bolt. They didn't have any 15mm nuts, but I tried a 16mm and the tap srewed in but not quite as snuggly as it should, telling me that a 16mm is too big.

Soooooo, I would think that I need either a 15mmX1.5, or the bigger equivalent between 14mm and 16mm in SAE.

 

15 mm is not a standard bolt size it jumps from 14 to 16mm.

14mm=.551"
15mm=.590"
16mm=.630"

SAE:

9/16-12 or -18 =.562" UNC course threads 12 threads per inch UNF fine thread 18 threads per inch
5/8-11 or -18 =.625

I still don't understand what you bought.

Was it a thread repair kit?

 

If you bought a "thread repair kit" the tap in the kit is for the helical insert.

The helical insert will have the thread you desire on the inside diameter and the larger "repair thread" on the outside.

This larger diameter "repair thread" does not match up with a standard bolt it is only for the insert.

 

You know what old gold, I think you may have nailed it right there. But the thing is that there was no insert. But the tap could have very well been meant to be accompanied with an insert which would explain why the hole is now just barely too big. So I guess that I now need either an insert, or a bigger bolt. 9/16 seems to be what I would need. Do you know if they make9/16 in 1.5 tread ??? cause the place I bought it from don't have the insert or helicoil which is what they called it...in that size.

 

Was it a "kit" you bought or the tap itself?

Look carefully at the tap.

What is written on it? (depending how good your eyes are you may need a magnifying glass)

You do not want to mix and match threads. Screw threads have a major and minor diameter plus the pitch or (threads per inch).

You might end up with a thread so weak you will strip it with your fingers. (especially in aluminum).

As far as 9/16" bolts as I mentioned earlier:

coarse thread is 12 thread per inch pitch=1"/12=.083"=.083/.03937=2.11mm too "course"
fine thread is 18 thread per inch pitch=1/18=.055"=.055/.03937=1.39mm a little too "fine"
9/16" is also a less common size especially in fine pitch

 

It wasn't a kit, it was 2 separate parts, and all it said on the tap was 14mm X1.5, same thing than on the package of the bolt. I guess I'll just have to go to an 16mm tap with proper 16mm bolt. This time I'll check the the size of both parts by using a 16mm nut to make sure that they match.

 

Here is a tap drill size chart.
http://www.lincolnmachine.com/tap%20drill%20chart.pdf

You can buy a oversized self tapping drain plug. Here is a 15mm

http://www.autozone.com/selectedZip,.../selectZip.htm

Willie