Temp. sending unit placement
 

Hi everyone. I'm in the process of putting my '71 GTO back together and I'm using the factory intake manifold. I want to run the red temp. idiot light and also an electrical temp. gauge at the same time. The red temp. light is already operating from a sending unit in the front of the intake. Across from that, there is another identical threaded hole that has a pipe plug in it. I tried my best to free this plug, but no way. I used the biggest breaker bar I had. The plug is in there. Other then heat, which I prefer not to do, is there a way to remove this plug?? Is there any other area on this motor that I can use for a temp. sending unit?? I know on my sbc, I was able to use a drain plug hole with an adapter. I haven't seen any on this engine. Has anyone had this problem before and how did you resolve it?? Thank you, Carmine.

You could drill it out, drill it large enough to fit a small hacksaw blade in it and cut pieces of it out. There should be a temp sending unit port in each cylinder head.

Do you have compressor and impact wrench? Most times the vibration from the impact will break stuff loose. If that didn't work, I'd go with heat even though you say you don't want to do that.

I don't know why this works but I have melted candle wax onto the exposed threads and gently heated with a heat gun. Broke loose some rusted together parts on my 69 Corvette that nothing else would touch.

Some good ideas and suggestions here. Thank you everyone. I will look for those ports in the cylinder heads. I have a pretty heavy duty and powerful electric impact gun/wrench. I'm afraid of cracking the cast iron manifold by using it. It's old and brittle to begin with and I think the vibration might be too much. At least that is what I think. I don't want to use the heat because the manifold has been redone and looks great. I see a mess, but maybe I can't have it both ways, Carmine.

My apologies for being a pain with this, but I just looked at some #96 heads, which are what I have, and I didn't see any ports for a temp. sending unit. All I saw were spark plug holes, freeze out plugs, holes for head bolts and other taped holes. I must be totally blind because I didn't see anything resembling something to do with a coolant port. Can someone kindly give me a clue as to where to look?? Thank you, Carmine.

Doesnt have one. I have 96's as well. (D-Ports) maybe round ports do? I converted to rally gauges and just use the intake port.you could do the same for the idiot light.

I believe those extra holes (one in each head) came out in the '72 year heads.. what type of plug do you have/ is it the 1/2 inch square or a hex type?...

I believe you are correct Forrest. The heads i took off my 72 Lemans did have a port for a sending unit,pass side.it also had a 3wire temp unit if i remember right. Big If...
Carmine, i wouldnt worry about breaking the intake with an impact to get that plug out.
Has anyone here actually broke an intake trying to remove that plug?

The best way to get a NPT threaded fitting loose is to tighten it before you try to loosen it. That helps break the threads loose. If that doesn't work then worst case drill and cold chisel it out. I assume you already have the water drained from the radiator and the block. Once you've done this, and as you are doing this, use a magnet to get all the filings out of the intake and otherwise cleaned up. It sucks, but it's just time intensive with little skill required. You can do it.

http://i1285.photobucket.com/albums/...psiuloafoj.jpg

http://i1285.photobucket.com/albums/...pspqw1yg42.jpg

The plug is identical to the ones in the pic; thread #10. It would be the one on the driver side. Definitely some different ways to approach this issue. I just wish I had taken this plug out when the manifold was off the car and before I restored and painted it nicely. I would have used the acetylene torches for this. They would have humbled that plug in a heartbeat. I was thinking about this and I recall having the same issue with my '62 409 where I wanted to keep the red temp. idiot light and used a mechanical gauge also. Went to my local speed shop and they came up with some type of thermo housing adapter block. Not sure of the technical name. It is about 1" thick, taped for a sending unit and sits on the intake. The thermostat goes in the top and the housing on top of that. Works quite well and almost looks like it belongs there. Certainly satisfied my need. Not sure the thermo housing size and bolt pattern would be the same between Chevy and Pontiac. Guess this might be another option, Carmine.

You might want to try that wax idea. I've never used it but I've heard of it being the way to do it many times to get the oil passage plug out back by the distributor. .
I was thinking you had a hex head brass plug or something like that in there when I recommended the impact...although, I would not think that an impact is going to break your intake!

I'm going to try this wax approach. So, what is it exactly that I do?? Take a candle and melt some wax above and around the plug threads. Then possibly using a hair dryer, I keep the wax warm and try to remove the plug. Is that how it's done??
Went to my speed shop today and bought a thermostat spacer that gives access to 4 ports around it for a sending unit. Problem is, it's designed for a Chevy although it looks identical to the Pontiac one. The Chevy bolt holes are about 1/4" longer, center to center across the top, then the Pontiac housing. I can take this to the machine shop and have them drill each hole 1/8" closer and that should do it. Everything else should line up fine. But first, I'm going to try the wax approach, Carmine.

I tried the wax and other methods to remove this plug. It's not coming out. Does anyone know of a "t" that is made that can be screwed into the manifold to accommodate two sending units?? The thermostat spacer will not work. It won't fit under the fuel line and I'm not going to bend it. The spacer is 1" thick and I only have 3/4 of an inch room available, Carmine.

Use Bentwheelbob's suggestion. Just drill it and break it. Use a magnet to pick out the pieces. Sometimes after struggling with something like that for a while, breaking the crap out of it is therapeutic!

That was my suggestion. Bentwheel's method was to chisel...

Correction...77 Canamman's AND Betwheelbob's suggestion..lol

Update. The thermostat spacer was a great idea, but it sets the thermo housing 1" higher on the manifold, which isn't too bad, except it comes in contact with the fuel line. I'm not going to even think about bending that line. So what I did, is removed the old sending unit and began installing the new one for the Auto Meter gauge. I'll be without the red idiot light, which I wanted, for now. I just can't bring myself to go pounding on that frozen plug in the manifold. I have visions of the manifold cracking/breaking. I can't get past the idea the manifold was designed to transfer liquid and vapor. I don't know how much pounding it could take, Carmine.

A lot more than that plug can I'll bet.

If it was me...I'd get another intake that you can just add new stuff.. Those can be found in reasonable price range at swaps and here I bet.