I'm searching for a place to put a new electric water temp sensor and my eyes are on the pipe plug at the back of the driver side head just above the intake manifold. Could this be a coolant plug? If so, I'm having a terrible time trying to remove it. And what do you guys think about using the engine coolant drain plug on the side of the block between the started and engine mount as a temp source instead. Just asking. Dave
Dave - because the heads are cast to go on either side of the engine, thats the same spot the factory temp sensor goes on the passenger side head. It's a great spot for your sensor, I did the same thing. And yes, It's a bear to get out. When I did it, I would heat it only to lose the heat as the coolant was in contact with the back side of the plug. Drain a little coolant, use something as hot as at least MAP gas and try to wick some wax/parrafin into the threads. I also had good luck wicking in some PB Blaster by spraying the hot plug with it too. Just be careful not to strip square face of the plug. I almost did. Heat, penetrant and patience are your friends here........ Good luck, and keep us posted
Don't some early 455's have the second-stage temp sensor there too? The stop engine light, right beside the HOT light on the dash?
Not that I know of. The '67 & up big cars that had the hot & cold lights used a dual terminal sender on intake's front water crossover. Devon
Yes, as Adam said, the "stop engine" light cyl head temp sender was in one of the cylinder head accessory bolt holes. Apparently installed for the folks that ignored the "hot" light, or the gauge. Big car only, I have for sure seen it on '73 up motors, might have been there earlier, I don't recall. Never seen one in a 70 455 head. Two wire switch that activated 240-250* if I recall the specs correctly. As Devon stated, this was not in the earlier big cars.. Apparently Buick engineering realized that a good portion of the population may have damaged some Brain cells in the 60's. :Brow: JW
Do you mean the plug at the back of the block on the driver side head? I'm using the front passenger side plug for my electric fan switch so I need another port.
My 70 Wildcat had two separate senders: That would make a fine place to add a temp gauge, as long as it is deep enough.
That is a very poor location for a temp sensor. For practical purposes, you'd be measuring the temperature of the incoming coolant from the radiator, not the heated coolant that's passed through the engine. Your temp gauge will read very low. Heat the plug HOT. I use oxy-acetylene, and make them cherry-red. As it increases in temperature, it becomes more malleable and also grows from heat expansion. The heated plug becomes soft, tries to expand radially but cannot because it's trapped in the casting. It expands axially instead. When it cools again, it contracts and becomes microscopically smaller radially, having distorted axially. Makes the threads "looser", and the plug unscrews readily. For the record, some pipe plugs have a female square wrenching surface of 1/4", 3/8", or 1/2" internal size. RESIST THE TEMPTATION TO USE A SOCKET EXTENSION OR THE SQUARE DRIVE OF YOUR RATCHET in the pipe plug. Particularly with extensions, you'll break the square tip of the extension right at the point where it's drilled and fitted with the spring and ball that retains the socket. Use a male-square pipe plug socket, which won't be drilled for that spring-ball or retaining pin that holds a socket in place on extension bars.
Hey Frank, Where is that extra sender at?.. the later Big cars have them on the DS cylinder head rear, in the outer top accessory bolt hole. I have taken apart quite a few 70 Wildcat, Riv and Electra motors, and I don't recall seeing that extra switch.. Then again, maybe I have seen too much of this stuff to keep it all straight.. JW ---------- Post added at 03:02 PM ---------- Previous post was at 03:00 PM ---------- Sorry to muddy your thread up.. we were talking about the later 400/430/455 motors.. Yes, get that plug out and you can use that for your temp sender-- follow the instructions provided to get it out. Good luck JW
In that spot. Will someone please post a pic of the back of a 70 Wildcat DS head? I could not find one, and I R & R'ed my engine to clean up the under hood area. No pics of that.ou:
Still working on it guys... I tried using a socket extension on a breaker bar, lots of penetrant, and heat from a propane torch. Started this a day ago and no luck yet. I'm learning the hard way not to use a socket extension as mentioned above. Its rounded the square hole a fair bit and now I think I'm into a whole lotta pain now. I'm going to look for a pipe plug socket and/or some hardened square stock I may weld to a socket. At some point I might even try to whack a large allen wrench into the hole depending on how bad it gets. My advice to everyone is if you ever have the engine out of the car, remove these plugs and replace them with brass plugs with sealant or never seize. Its much harder to do this with the engine in place. Thanks for all your advice. Will keep you posted. Dave
if you strip it.. take a 3/8 bolt 1" long and grind it to a 5/16 taper. sit it in the square drive and weld it in the plug. set your wire speed low so it starts to ball at the end of the wire and you hear a slight hiss when welding. this will heat the plug real good and take it off with a 9/16 socket on the head of the bolt. I have done this multiple times with broken head bolts in the blocks too.. Paul turbo nailhead
Back end of the LH head will look the same as the front end of the RH head. RH mounts the AC & alt. brackets. Rear of the LH side had a switch mounted in the 3/8 threaded hole (5/16 maybe ?). The switch was a delay for the passenger heating system. Kept the heater fan off until the engine hit XX temp.. Don't want to be blowing cold air on passengers in your new Electra.
You need much more heat than you can get from propane - go to home depot and get a MAP gas set up. Not kidding.
Still working on it...Today I tried pipe nipple extractors from Harbor Freight. Good tools, but I've stripped it just a bit too far for them to be useful. I also welded a 3/8" bolt to it and sheared the head off the bolt when trying to remove. I stepped it up to a 1/2" bolt that I tapered to fit, welded it up, but this time it sheared off at the weld. I don't think I had a good bead on it and will try again one last time. If this doesn't work, I'm giving up. It will stay in there until I pull the motor again. Probably needs to be drilled out now. Its a streetrod, so its easy to pull the motor, just a PITA. I wish the engine builder had done this. No idea why anyone would replace the coolant plugs during a build. Dave
As others have said, heat is your friend here. If you have the money, a good oxy-acetylene cutting torch is a tool you will use forever. Now is a good opportunity!
grind it down get it good and clean.. heat it up than weld it. Try welding a flat washer to the plug and than a 1/2 nut to the washer.. don't give up, you will get it! I spent a whole day working on a head bolt in a block.. what a pia but felt great when I got it. good luck
