ex-x-fire

Yeah, that looks like a lower hose. This is a better picture, Fords seem to use these tee or you could make one at a hardware store.

Joe C

you're not going to seriously try this, are you? just askin' -

WVZR-1

This is a "blunt tip" and you just use it with low air pressure to "aggravate" the bond of the dissimilar metals. With the OP having so much trouble it seems like maybe the heads have been done and someone got carried away with the tightening of the pipe plug. Many get carried away when securing NPT fittings and plugs.

Done this many times to loosen the "bond". Will it work for the OP? I'd think but if someone has over-tightened beyond spec the tapered plug maybe not.

If there's NOT a thread or a thread and one half visible on the plug it's most definitely been over-tightened.




There's absolutely no reason NOT to. NONE

mako41

Over-tightened??
If you have this plug in the aluminum head it was placed there by GM in the factory at Bowling Green. They were placed there if the HD cooling option was not ordered and an auxiliary cooling fan temp. switch wasn't required. I've never seen one of these pipe plugs with any thread showing on a Corvette head.

That being said if they were "over-tightened" that was done before anyone took delivery of a new 'vette. The problem as I see it, is years of galvanic corrosion over thousands of heat cycles between two dissimilar metals. I really don't see how the action of an air hammer is going to help break that bond. Heat and a turning force is probably the best way to get it done.

As I said in my first post, welding a bolt or nut to this pipe plug, something other forum members have successfully done, and then turning it out while still hot is probably the best way to remove this plug without f*cking up the head.

mako41

Not sure, if I think it might work I'd give it a shot. Why not?

I don't have a mig welder, but I do have air tools so I'd really like this to work...... Even though it's a long shot this might actually help....... it's worth a try??

8a8mfh

25 years is a long time, you sure GM touched it last?

Joe C

then I say, GO FOR IT, and good luck - something tells me you'll need it!

WVZR-1

I certainly hope it works for you. Good luck. I didn't realize you had a same situation, I thought you were commenting from previous experience. T.F.F.T is a spec for tightening plugs which generally will leave nearly a full thread exposed. You may only see the minor diameter of the fitting/plug but that's the way it's done. T.F.F.T. is Turns From Finger Tight and for a 3/8-18 plug I believe that's 2 - 3.

Since a square drive plug is all-thread there's nearly always a partial if not full thread visible. Who over-tightened? I can't argue that but on an original assemble it's usually controlled quite closely.

Were it here when it first failed to loosen the "blunt tip" would have been used so as NOT to demolish the female square of the plug.

Do you have any heat available? Have patience it's a low air pressure procedure and may take some time. AGAIN - GOOD LUCK - I'd like to see it work for you.

On a plug where a person has room we've used a large washer (not welded) with an ID of the plug surrounding the plug so that the "blunt tip" can be used on the OD of the plug with out damaging the part. A differential or transmission plug. You don't have the luxury of this with the location of the plug in the head.

antfarmer2

I would say the plug was there from the vendor if the option was ordered they would take the plug out for this they don't leave open holes when shipping

mako41

Well I've never touched it before I wanted to add an OEM auxiliary cooling fan. So yea I'm very sure that plug was installed by GM or their head manufacturer over 25 years ago!

There really is no reason to tighten one of these, most people probably don't even know it's there!

8a8mfh

You've owned the car since new? Heads never been off? Never had a valve job, nothing like that?

mako41

Yep, nope, nope, nothing...... Well to tell the complete truth I picked it up at a dealers only auction, as a repo, a couple of months and a couple of thousand miles old. But it was factory OEM and still looked and smelled brand new.

Why does that surprise you. This is a common issue when someone tries to remove that GM installed pipe plug after such a long time. If you do a search you'll find the same problem when these vette's were 12~16 years removed from the factory.

8a8mfh

yea I'll get right on that research.
My plug came right out after having not been touched in 22 years, guess you got to know what you're doing. Less internet time, more working on it.

TA

I posted a thread about the same issue almost 12 years ago.

https://www.corvetteforum.com/forums...ing-crazy.html

Joe C

when you guys start beating on that plug with your air chisel, take some pics and keep us updated. I like this "can't miss" idea!

seriously, I went out to my 90 to see what's involved in removing that plug. it took a minute or so to locate the thing, since it's somewhat buried in-between the #1 and #3 spark plug. it IS a straight shot, going in from the left, with a 1/2" drive impact wrench, a 1/2" to 3/8" adapter, and a 3/8" drive 5/16" pipe plug socket. I would personally crank in on the built in regulator to limit the torque/hammering action on the impact wrench, and gradually increase the air supply to the impact wrench until the thing broke loose - something like 3-5 second bursts. I have removed stubborn pipe plugs from aluminum with this method. my concern here is causing undo damage to the aluminum head and corresponding threads. this is just my opinion, and my 2-cents, but then again, WTF do I know....

WVZR-1

The OP hasn't posted back since his visit to HF and maybe he's absorbed enough "conventional wisdom" mentioned here to complete his project. The OP's car was also a '90 which generally speaking the fan control modifications aren't accomplished the same way as the '89 and earlier cars. It can be certainly, but generally not. I think switching/switches might be great but the quality of the required switches these days leaves maybe a good bit to be desired. Nearly everyone is sourcing the least expensive product with often very wide +/- % of accuracy. This type of switching isn't used industry wide any longer so quality will likely continue to get worse. Quality switches are available, they're not inexpensive and need to be sourced from specialty vendors and not the usual sources mentioned.

I thought initially "Mako41" was commenting on a previous experience and didn't realize his is also a current project. I believe that "Mako41" is talented enough to either accomplish the removal OR realize that there is always an exception where conventional methods for any project/operation doesn't and isn't going to work. There is always an "exception".

Does "Mako41" have one of these "exceptions"? It's maybe entirely possible that he does. I'd like to think NOT and wish him luck. I believe he'll post back with his solution.

Robert Perkins

After my attempt to remove the plug and breaking the tool and reading all the post. I have decided to pass on this project and not install the temp switch, just afraid of damaging the head. Thanks for all the responce.

mako41

Well good for you! I wish I could have been as lucky!

You must really "know what your doing" much better than the rest of us here that have had this problem.

Oh that's right you were the guy that claimed that this hi tech method worked for you;
"I used the square end of a thread tap. With vicegrips on the threaded end"
Really?...... The wrong tool with the least turning force, but your plug came right out!!!
Did you try a screwdriver first? You should have played lotto that day!

Do you have anything meaningful to add to this discussion?
If not find someplace else to practice being an a**hole!

You can go away now!

mako41

First off, thanks for your input.......I'm as skeptical as you on the "air chisel method" being discussed here. I agree it's not likely to work. But it can't hurt trying. Everything else I've tried hasn't worked at all.

Did you read where I posted about getting the right 5/16" snap-on pipe plug tool and a 1/2" drive impact gun and all that did was round the corners of the steel pipe plug? Using short bursts of air.

I think the only way I'm getting that plug out of my head without damaging it is going to be by carefully welding a grade 8 bolt into the square recess of the plug and turning it out after carefully applying some heat.

Joe C

good luck on any method or route you need to go at this point. not sure how you rounded the corners of the pipe plug - about the only thing I can think of is you were not squarely in the plug, or the tool was not in the full depth of the plug from the start, or both, but I'm just guessing here. if you're going to revert to welding, my suggestion is it's time to think about removing the head from the block. things are tight in there - maybe you can, maybe you can't pull this off with the head in place. anyway, again, good luck. I hope some of us were not too hard on you or anyone else on this thread.

edit - just throwing this out for a little FYI. I was doing pads and rotors on my 90, and one of the front caliper bracket mounting bolts in the front aluminum knuckle was frozen and driving me nuts. it seemed no way in hell that bolt was coming out. short bursts turned into long bursts, air pressure at max - that sucker was not coming out. I was starting to worry on how I was going to get the bolt out without completely removing the knuckle from the front suspension. the last thing I did was reverse the direction of the impact gun and gave it a quick burst - you know, right to tight. after that quick burst, back to reverse-removal mode, and the bolt came out on the next try slicker than s**t!" now maybe that helped, maybe not - I don't know, but the bolt did come out.