How to remove pipe plug in driver side head
Thread Starter
Racer
Joined: Sep 2014
Posts: 429
Likes: 29
From: Brooklyn, MI
How to remove pipe plug in driver side head
I am trying to remove the pipe plug in the drivers side head between 1 and 3 cylinder. It is square recess 3/8 extension to large 1/4 inch to small. I am trying to remove the plug to install a fan temp sensor. 1990 L98 engine
Instructor
Joined: Dec 2004
Posts: 217
Likes: 1
From: Drums PA
Regards, Chris.
Pro
Joined: Sep 2008
Posts: 694
Likes: 27
From: St James New York
That plug is a nightmare to remove! I think the 3/8" NPT steel pipe plug has a 5/16" square female recess.
Snapon makes an external pipe plug socket that fits into the square recess of that plug and even with the right tool I couldn't get it out..... all I did was round out the square recess.
https://store.snapon.com/Pipe-Plug-i...--P641829.aspx
The only members here with success removing that plug have mig welded a bolt or nut to that plug and then turned it out while still hot from the weld. Check out this thread; and good luck!
https://www.corvetteforum.com/forums...lant-plug.html
Snapon makes an external pipe plug socket that fits into the square recess of that plug and even with the right tool I couldn't get it out..... all I did was round out the square recess.
https://store.snapon.com/Pipe-Plug-i...--P641829.aspx
The only members here with success removing that plug have mig welded a bolt or nut to that plug and then turned it out while still hot from the weld. Check out this thread; and good luck!
https://www.corvetteforum.com/forums...lant-plug.html
Last edited by mako41; Mar 29, 2015 at 10:58 AM.
Melting Slicks
Joined: Dec 2009
Posts: 2,236
Likes: 286
Harbor freight has a plug socket set that has all square sizes, I use them daily at work (esp. the 3/8 square & 10mm hex) & haven't broken one yet.
Sometimes adding some heat to a plug then cooling it quick will cause the grip to loosen. It works on rear end plugs great.
Sometimes adding some heat to a plug then cooling it quick will cause the grip to loosen. It works on rear end plugs great.
Thread Starter
Racer
Joined: Sep 2014
Posts: 429
Likes: 29
From: Brooklyn, MI
Harbor freight has a plug socket set that has all square sizes, I use them daily at work (esp. the 3/8 square & 10mm hex) & haven't broken one yet.
Sometimes adding some heat to a plug then cooling it quick will cause the grip to loosen. It works on rear end plugs great.
Sometimes adding some heat to a plug then cooling it quick will cause the grip to loosen. It works on rear end plugs great.
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
If you have access to air an impact will work well and you could likely avoid the heating thing, if you don't a hand impact driver could also work well providing you've got access and a BFH.
I believe that an unmolested square on a 3/8-18 recess plug is .324 so if there weren't that particular size in the package I'd avoid a complete kit buy. I'd work with maybe the suggested "file to fit" 3/8 square drive, an air impact or hand hammer impact. It's a tough job no doubt.
HF would have a 67011 square drive to hex wrench kit. You could use the 3/8 - 9/16 knock out the ball and file/grind to fit, grind the end to flat to allow deeper penetration. That's only $4 and the rest that you don't need to file/grind could be used occasionally. If you thought that it were going to be a waste then the 3/8 square drive would be very useful when servicing the rear.
If you've already attempted and have maybe destroyed the square then maybe the file to fit is required anyway.
I believe that an unmolested square on a 3/8-18 recess plug is .324 so if there weren't that particular size in the package I'd avoid a complete kit buy. I'd work with maybe the suggested "file to fit" 3/8 square drive, an air impact or hand hammer impact. It's a tough job no doubt.
HF would have a 67011 square drive to hex wrench kit. You could use the 3/8 - 9/16 knock out the ball and file/grind to fit, grind the end to flat to allow deeper penetration. That's only $4 and the rest that you don't need to file/grind could be used occasionally. If you thought that it were going to be a waste then the 3/8 square drive would be very useful when servicing the rear.
If you've already attempted and have maybe destroyed the square then maybe the file to fit is required anyway.
Last edited by WVZR-1; Mar 28, 2015 at 08:02 PM.
Pro
Joined: Sep 2008
Posts: 694
Likes: 27
From: St James New York
If you have access to air an impact will work well and you could likely avoid the heating thing, if you don't a hand impact driver could also work well providing you've got access and a BFH.
I believe that an unmolested square on a 3/8-18 recess plug is .324 so if there weren't that particular size in the package I'd avoid a complete kit buy. I'd work with maybe the suggested "file to fit" 3/8 square drive, an air impact or hand hammer impact. It's a tough job no doubt.
I believe that an unmolested square on a 3/8-18 recess plug is .324 so if there weren't that particular size in the package I'd avoid a complete kit buy. I'd work with maybe the suggested "file to fit" 3/8 square drive, an air impact or hand hammer impact. It's a tough job no doubt.
After 20+ years of galvanic corrosion between the steel pipe plug and the aluminum head along with thousands of heat cycles from engine operation that plug was literally welded in place. No way to remove it without adding some carefully placed heat before mechanical manipulation.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
I tried the correct snap-on tool with an air impact gun..... No dice!
After 20+ years of galvanic corrosion between the steel pipe plug and the aluminum head along with thousands of heat cycles from engine operation that plug was literally welded in place. No way to remove it without adding some carefully placed heat before mechanical manipulation.
After 20+ years of galvanic corrosion between the steel pipe plug and the aluminum head along with thousands of heat cycles from engine operation that plug was literally welded in place. No way to remove it without adding some carefully placed heat before mechanical manipulation.
If the OP has air it could be an excuse to buy something that's actually quite useful.
Last edited by WVZR-1; Mar 28, 2015 at 08:14 PM.
Racer
Joined: Dec 2007
Posts: 416
Likes: 3
Well I would have said anything if it didn't 
I was relocating the factory temp sender to the driver side head, just a coincidence I had a 14mm tap forever that I never used and it fit right in. I thought it would be too brittle and break, but it didn't even ruin the tap.
I was relocating the factory temp sender to the driver side head, just a coincidence I had a 14mm tap forever that I never used and it fit right in. I thought it would be too brittle and break, but it didn't even ruin the tap.
Thread Starter
Racer
Joined: Sep 2014
Posts: 429
Likes: 29
From: Brooklyn, MI
I went to Harbor Freight and they no longer sell the square pipe plug sockets. I ground down a 3/8 extention and got it fit fine however the plug was so tight I snapped off the end of the extention were I ground to fit.
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
There's multiple size blunt tips.
Race Director
Joined: Aug 2000
Posts: 11,470
Likes: 764
I went to Harbor Freight and they no longer sell the square pipe plug sockets. I ground down a 3/8 extension and got it fit fine however the plug was so tight I snapped off the end of the extension were I ground to fit.
again, CAUTION NEEDS TO BE EXERCISED HERE!
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
Certainly an alternative that maybe could/should be considered. A quality Tee could be an issue and then there's the determining the sizes of the male aspects of the Tee and the placement.
Team Owner
Joined: Dec 2000
Posts: 21,094
Likes: 282
From: Phila., PA burbs
When I removed mine many years ago I went through the same issues. I ended up buying a section of 5/16" steel rod from Home Depot. I cut a section to make a "bit" and then found a 12 point socket to fit. IIRC it was still a bit of pain due to the unhardened rod twisting, but the plug eventually gave way.
Race Director
Joined: Aug 2000
Posts: 11,470
Likes: 764
Pro
Joined: Sep 2008
Posts: 694
Likes: 27
From: St James New York
Could you elaborate more on what exactly you mean by doing this. Maybe a pic of the tip. I have an air hammer but I'm not really sure what procedure one would use to loosen this plug. Are you just impacting the plug w/the air hammer tip to break the bond w/ the aluminum head without using heat, or are you referring to something else?