j.kenzie@sbcglobal.net

It won't be m6 x 20. Metric threads are diameter x thread pitch, both in mm. Probably m6 x 1. The 1 mm is the distance between each thread, while English threads are called out in threads per inch.
Taps are available at big hardware stores or Amazon. I bought a metric set years ago, very cheap, and it has saved my bacon many times.
Good luck,
Dave

dr bob

M6 1.0 is the size for the tap/chaser. The 20 in te bolt spec is the length.

Stan hinted at a problem you'll face, and that's management of chips from any tooling you'll use. For sure drain the oil and clean/flush the sump, particularly in that area under where you are working. Then, you'll want to build a dam underneath, inside the sump. that will keep anty cuttings from escaping into the sump as you tap, chase, or drill. This is extremely important! --Any-- oil remaining under where you are working will grab chips and hold them, so it must be clean clean clean. Tap/chase with a greased tool, cutting 1/8 of a turn at a time, remove and clean the chips off, regrease the tool, repeat, until the threads are cleared. Then carefully vacuum out the area inside the dam you made, using a keyboard-vac crevice tool (about 3/8" diameter). A regular vacuum will suck the dam out and spill chips into the rest of the sump, so go slowly, inspect carefully to make sure you have all the chips before you extract the dam. --DO NOT-- use compressed air or sprays like brake-cleaner to flush or clear the chips, since the high velocity spray risks pushing chips past the dam into the still-oily part of the sump and the bottom of the crank area in the block.


Were it mine... I'd try carefully fitting new M6 capscrews in the existing holes, and see if the remaining threads are sufficient to hold the gasket in place. I'd use a film of Honda/Yama/Drei-bond or Hylomar on the gasket and probably the bolt threads, and torque it very lightly (like maybe 5 lbs/ft at most) and see if it holds. If it didn't, I'd pull the sump and repair it correctly. The cobbiest emergency repair I'd consider is a couple studs in the holes with red Loctite, and use nuts to hold the tube flange in place.

Five-8

Dave ..thanks for the clarification, that makes sense to me.

Dr Bob...thanks for the excellent specifics regarding what perils lurk in this particular adventure.I had considered just trying to see if replacement bolts would find the threads, but was/am fearful of doing further damage, but i suppose i still would have recourse if they won't go/hold.

I REALLY appreciate all the advice!

Thanks,

Steen Jensen

If the thread chaser doesn't work it looks like there is enough material there to drill oversize and use a tap to create a new thread.

To prevent any metal debris getting in the hole , just clean the surface with laquer thinner and place tape over the whole area and then do your repair on the two damaged threads.

Randy V

That's what I would do.

No need to drain the oil if you can effectively prevent debris from entering the pan in the first place.

Koenig-Specials 928

Try Princess Auto. They have those tools. Or Crappy Tire/HD as a last resort

Five-8

Taking Dr Bob's advice to heart...i contrived this cunning plan...fresh piece of hose going spare from the intake refresh...fits VERY snuggly...should keep all the nasties out.
If this is flawed thinking...i give you permission to hurl insults at me :-)

Cheers,

dr bob

You can make a "thread chaser" from a new bolt, cutting a groove up one side with a grinder or Dremel. The groove, with grease in it, catches the chips, so you still need to use the 1/8 turn forward, pull to clear chips method, do again method so chips don't get wound back into cleaned threads.

Otherwise, there is little difference between a thread chaser and a "bottoming" or "plug" tap. Taps for blind holes come in a set of three. The first is the standard atp you see on the shelf someplace. The middle one looks the same minus about half of the tapered end. The thirs has virtually no taper on the end, and is used to get the last few threads in a hole where there's no pass-through and therefore the standard taps couldn't get those last bottom threads cut completely. Sometimes you can fudge a bit by cutting the tapered end off a longer tap and get similar results. Be Sure you have a tap wrench that will get to the holes. I use an extension to get to stuff like this, but they are not something you find at common hardware stores or home centers.

dr bob

Now you just need to expand the hose inside the sump, so it's big enough to catch any chips that drop from the tap/chaser through the threaded holes.


Clean completely inside the sump under that area after draining the oil out. Build a dam out of a rag section, rolled and then passed through the bigger hole. Use forceps to place it around the whole area to contain any droppings. You'll be able to see anything that falls in, and remove it through the big hole before extracting the dam. Think about forming a donut out of rolled rag, with the hole not going all the way through the middle. Push it through the hole and reform it inside like a bowl. Your cuttings should fall into the bowl. recover the cuttings before you recover the bowl from inside.

Five-8

Ahhh...NOW i get it!

Thank you Sir!

Randy V

Do those threaded holes go all the way through the flange into the pan?

Seems they wouldn't.

dr bob

Pretty sure they do, although it's been a few years now since I had James' '85Euro project car here for some recovry work around there.

928Myles

If it was me (my recollection is also that the bolt holes go all the way through) I would use the following to catch & remove any metal pieces while repairing & cleaning the thread:
1 - Find a 1/2" deep bottle cap that just fits through the large hole.
2 - Attach a piece of steel wire to one side of the cap. You could do this on the inside or outside depending on how tight a fit it is through the hole.
3 - Lightly smear the inside of the cap with grease.
4 - Insert cap with wire down through the hole and rotate until the cap is below the hole you are about to work on.
5 - Pull cap up to base of hole & use vise-grips or similar to hold cap, via wire, in place.
6 - Repair threads & clean.
7 - Move & rotate cap to below other bolt hole.
8 - Repeat step 6.
9 - Remove cap and debris back up through hole and throw away.

Myles

Rotmilky

If you've got an Autozone local to you, they should have a set of chasers for loan. Generally, the non metric chasers are all beaten up, but I find the metric to be basically unused.

As Kevin said previously, make sure you get a chaser and not a tap. Taps are designed to cut new threads. Chasers are designed to reform threads with the existing metal there. Basiclly unbooger the boogered up threads.

Five-8

You Guys have all been a tremendous help...I'll post the outcome once i get there.

Thanks All,