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Stuart Boblett

82 Water Temperature sending unit.

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Is the water temperature sending unit the unit in the picture on what I think is thermostat housing and has a  beige body that is underneath the air cleaner hose opening. What I have does not seem to match up with any wiring diagrams I have but I think they were for the early cars. I just want to confirm before I start yanking wires and pulling senders. Thanks.

water temperature.jpg

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Mine is different it’s in/on the drivers side cylinder head, but mine had a replacement 350 ci. Installed to replace the 305 ci. That being said it looks like a sender to me.

Merry Christmas to all.

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That is a temperature sending unit, but it only sends a signal to the ECM. The one for your temperature gauge should be in the driver's side cylinder head between #1 and #3 spark plugs.

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I don't have an '82, but I would expect the temperature sending unit to be on the driver side near the rear and look similar to this one...

432835839_tempsendingunit.jpeg.0dd43f612b0168d3e7fff2ac68839d6a.jpeg

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I do have a 1982, still with all the original stuff under the hood. The temperature sending unit for the gauge is impossible to see from above, since it is hidden by the exhaust manifold A/C compressor mounting bracket and the sheet metal spark plug heat shielding. The sensor is the standard one as you have shown.

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The sender in your photo, (sometimes called a thermal switch) and its 'brother' hidden under the fuel bowl vent hose, are parts of the GM 'Computer Command Control' system which was used on '81-'85 Avantis.

This rather complicated system really did not age well....and can sometimes be a real headache to deal with.  (Sometimes a very expensive headache!!:o)

The computer controlled Quadrajet carburetor occasionally can have a mind all its own!!

Hopefully, your Avanti's CCM system is functioning correctly.......however, if it isn't, consider eliminating the computer control entirely and replacing the CCM Quadrajet with an earlier version (say,1979) mechanical (vacuum) controlled Quadrajet, and a non-CCM vacuum advance distributor....(An Edelbrock carb is another good choice!)

Doing this can sometimes make a 'balky' Avanti a much more pleasant automobile to own and drive!:)

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On 12/24/2018 at 5:43 PM, popeyesteve said:

I do have a 1982, still with all the original stuff under the hood. The temperature sending unit for the gauge is impossible to see from above, since it is hidden by the exhaust manifold A/C compressor mounting bracket and the sheet metal spark plug heat shielding. The sensor is the standard one as you have shown.

Thanks Popeyesteve, I am still trying to get a handle on my newly acquired car. Does yours have all the anti smog "junk" with a zillion hoses, tubes plumbed into the exhaust and many valves throughout the firewall? I bought my car from the original owner and think he acquired it from a Virginia Dealer who got it from a California dealer. Thanks.

On 12/24/2018 at 6:24 PM, mfg said:

The sender in your photo, (sometimes called a thermal switch) and its 'brother' hidden under the fuel bowl vent hose, are parts of the GM 'Computer Command Control' system which was used on '81-'85 Avantis.

This rather complicated system really did not age well....and can sometimes be a real headache to deal with.  (Sometimes a very expensive headache!!:o)

The computer controlled Quadrajet carburetor occasionally can have a mind all its own!!

Hopefully, your Avanti's CCM system is functioning correctly.......however, if it isn't, consider eliminating the computer control entirely and replacing the CCM Quadrajet with an earlier version (say,1979) mechanical (vacuum) controlled Quadrajet, and a non-CCM vacuum advance distributor....(An Edelbrock carb is another good choice!)

Doing this can sometimes make a 'balky' Avanti a much more pleasant automobile to own and drive!:)

Thanks mfg, I appreciate your input. I was just contemplating that very thing today. Do you know if there is a good description on here or elsewhere describing the best way to eliminate all that CCM stuff as well as all the smog pump and related junk. I cannot even find a systemic drawing on either system for my year car.

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When I replaced the 305 in my 83 with a 355 roller cam engine I eliminated the entire system including the wiring, carb, distributor, ECM and sensors.. What I found interesting was the wiring harness was totally separate from all the other wiring in the Avanti. It was strung all over but as I removed it the rest of the harnesses stayed in place.

I'm not recommending you remove yours unless you really just want the mess gone but it worked form me. Be aware, I'm driven to get crap like that out of my cars and have been doing it for many years so be advised.

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9 minutes ago, Stuart Boblett said:

Thanks Popeyesteve, I am still trying to get a handle on my newly acquired car. Does yours have all the anti smog "junk" with a zillion hoses, tubes plumbed into the exhaust and many valves throughout the firewall? I bought my car from the original owner and think he acquired it from a Virginia Dealer who got it from a California dealer. Thanks.

Thanks mfg, I appreciate your input. I was just contemplating that very thing today. Do you know if there is a good description on here or elsewhere describing the best way to eliminate all that CCM stuff as well as all the smog pump and related junk. I cannot even find a systemic drawing on either system for my year car.

As far as eliminating the 'Computer Command' GM Quadrajet carb, the easiest way to do that is seek out an earlier GM non-computer controlled Quadrajet of the '75-'79 vintage.

If you find one made for a Chevy, it will be a direct fit. (linkage,etc)

You'll also need the earlier, vacuum advance type, Chevy V8 distributor of the '75-'79 vintage, as your Avanti now has a computer controlled advance distributor which will not advance once you remove the CCM carb.

The CCM harness itself can actually be left in place on your Avanti, just wire-tie the various leads out of the way.

Eliminating the smog pump is really just removing nuts and bolts.....The air injection tubes sticking out of your Avanti's exhaust manifolds can be unscrewed (they're stainless steel) and replaced with brass or steel plugs.

If your restrictive 'catalytic converter type' exhaust system has seen better days, remove everything and order a true dual exhaust system for a 1968 model Avanti ll...it will fit up perfectly!:)

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Thanks again, mfg. I have already eliminated the cat and plan to get rid of all the other junk I can. I will get a carb and distributor for a late 70s 305 chevy, hopefully that will really clean things up and make everything more tune-able  for this old shade tree mechanic. This stuff looks like the typical knee jerk reaction to more bureaucratic  government mandates. Your responses are really appreciated.

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3 minutes ago, Stuart Boblett said:

Thanks again, mfg. I have already eliminated the cat and plan to get rid of all the other junk I can. I will get a carb and distributor for a late 70s 305 chevy, hopefully that will really clean things up and make everything more tune-able  for this old shade tree mechanic. This stuff looks like the typical knee jerk reaction to more bureaucratic  government mandates. Your responses are really appreciated.

You're welcome!....and I do think you will enjoy being able to 'tune' your Avanti with a screwdriver, timing light, and perhaps a vacuum gauge again!!....Take care:D

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My car does indeed have all that mess still installed. It ran fine...until it didn't. I have been chasing a rich running condition for a while, which has led to just parking it for a few years in disgust. I am no neophyte with these CCC things either. I have a 1987 El Camino with a GMPP 350HO (330HP) running an electronic Quadrajet, AIR headers and all CCC/ECM systems functional which has run perfectly since I set it up 18 years ago. Meanwhile, I am trying to get myself motivated to start over and quit pursuing the "fix" to the CCC/ECM system and just retrograde the whole Avanti system back to conventional old-school carburetor and distributor. I have a spare distributor and Quadrajet for my 1979 Barth motorhome I can use, except the choke is a hot stove type incompatible with the Avanti intake manifold. If I were to buy an electric choke Quadrajet (not cheap) and put on my stock intake (with the EGR plugged), it could still be used later on an upgraded 350-383 crate engine, but would then require a new spread bore intake manifold for the new engine. MOST aftermarket intake manifolds will present a hood clearance problem in the Avanti. See the problem? One thing leads to the next and the next. This is just to get it to the everyday driver reliability stage. If I were to go ahead and upgrade to a compatible low profile square bore dual plane intake manifold for the hood clearance now (Weiand 8120?)  I would need a new carburetor (square bore). Edelbrock (glorified Carter AVS), Holley 4150, Quick Fuel 600-680 or Demon 650? Would need to be forward compatible with a larger engine without being too big for the 305. and this is the EASY stuff. The problem is how best to make the upgrades now which you wouldn't have to do-over at a later date. 

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Sorry, didn't mean to highjack your thread. I am just saying that the simplest things can lead to more complexity (and cost) than it seems like at first. And don't forget that eliminating the ECM means you have to come up with a new way to control your torque convertor clutch (TCC). Your car SHOULD have a 200R4 or 700R4 transmission (mine is a 200R4).

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The more I see and hear the more I think I will try to keep all the junk for a while since it is not running bad. When the original wimpy motor gives up the ghost or all the stuff becomes more of a problem, I will probably replace the whole thing but hopefully that will be a while. I will try to just drive and enjoy it for a while. I did find the water temp sending unit hidden right where you all said it was, right under the exhaust manifold.  Now to figure out the best way to get to it, probably from underneath. I am a life long Chevy guy but they sure seem to not like people working on their SB engines with stuff like this sender, the spark plugs, the distributor etc being in very difficult locations especially for these old antique hands and body.

 

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If it's where they are usually, front left side, a deep socket (about 3'4" or so) and a short extension should work. It'll be messy if you haven't drained anything but not bad. Check the socket size of the replacement.

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3 hours ago, Avanti83 said:

If it's where they are usually, front left side, a deep socket (about 3'4" or so) and a short extension should work. It'll be messy if you haven't drained anything but not bad. Check the socket size of the replacement.

I believe that you are referring to the temperature sending unit for the computer.  I believe that the OP is looking to change the temperature sending unit for the temperature gauge.  

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1 hour ago, studegary said:

I believe that you are referring to the temperature sending unit for the computer.  I believe that the OP is looking to change the temperature sending unit for the temperature gauge.  

Stuart B said he found the unit under the exhaust manifold where they usually screwed into the head. That unit will come out the way I described, I can't speak to what it connects to but I usually use that location for my temp sender when I ashcan all the pollution equipment.

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23 hours ago, popeyesteve said:

Sorry, didn't mean to highjack your thread. I am just saying that the simplest things can lead to more complexity (and cost) than it seems like at first. And don't forget that eliminating the ECM means you have to come up with a new way to control your torque convertor clutch (TCC). Your car SHOULD have a 200R4 or 700R4 transmission (mine is a 200R4).

For me , engaging the lockup clutch in the torque converter works out better when the CCC system, computer included, is removed.

What the computer does is provide a ground for the TC lockup circuit .....and many folks feel it usually does this WAY TO EARLY!:o....'loading' the engine.

Installing a simple toggle switch (mine is on the driver's side of the console in my '83 Avanti), allows me to 'ground out' and activate the torque converter's lockup clutch when I decide it's needed....usually when I'm on a main road or on the highway.

I could double check, but I believe it's the brown wire on the computer plug-in that needs to be snipped,  ran to a toggle switch, then to a convenient ground.:)

 

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Good Idea, Did the same thing on my 2004R. Just switch it on when traveling on the highway. If they don't want to futz with the computer wiring, the plug is on the drivers side of the trans that needs the connection IIRC. The wiring diagram is easily available on the WWW.

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On 12/31/2018 at 7:38 PM, Avanti83 said:

Good Idea, Did the same thing on my 2004R. Just switch it on when traveling on the highway. If they don't want to futz with the computer wiring, the plug is on the drivers side of the trans that needs the connection IIRC. The wiring diagram is easily available on the WWW.

 

There was a very well written article in the Summer/Fall 2018 issue of the AVANTI Magazine that details a relatively simple, but effective method of providing automatic control of the lock-up feature on the GM overdrive transmissions. 

Edited by Jim78

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13 hours ago, Avanti83 said:

Good Idea, Did the same thing on my 2004R. Just switch it on when traveling on the highway. If they don't want to futz with the computer wiring, the plug is on the drivers side of the trans that needs the connection IIRC. The wiring diagram is easily available on the WWW.

Yes, removing the CCC system, which came stock on my '83 Avanti, (RQB3655), has worked out well for me.....I purchased this Avanti from its original owner in January of 1994....Around the year 2000, after dealing with the onboard CCC system for six years, I decided to 'revert' to a non-computer controlled Quadrajet carb, a vacuum advance type distributor, and manual (toggle switch) control of the torque converter lockup feature. (700R4 tranny)

This Avanti had 94K on it when I purchased it....It now has a shade under 380K....a true 'daily driver', which has gotten me to work (and everywhere else) over all these years!:)

I really doubt I'd have been able to depend on this Avanti as I have if I were still trying to deal with that General Motors Computer Command Control system!:o

 

PS....For Avanti owners whose car is equipped with the CCC system and are sticking with it, I suggest purchasing a copy of an '81-'84 General Motors (Chev, Olds, Pontiac) shop manual.

These manuals give highly detailed info on the 'ins & outs' of the GM CCC system........HAPPY NEW YEAR!!!!:D

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Popeye Steve,

     A rich running condition on Quadrajet (even the CCC one) is usually due to a saturated float.  Get a fresh float and it should fix the problem.

chuck

RQB-3553

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21 hours ago, chuck said:

Popeye Steve,

     A rich running condition on Quadrajet (even the CCC one) is usually due to a saturated float.  Get a fresh float and it should fix the problem.

chuck

RQB-3553

Very true!:o....The composite floats used in those carbs often absorb fuel and become 'heavy'.....Only cure there is to replace with new float   (Replacing those composite floats is inexpensive and 'good practice' during a Quadrajet carb overhaul).

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Normally I would agree, but I have used two different E4ME Quadrajets with the same running condition. So I believe it is a mixture control issue. Funny that it doesn’t set any trouble codes. 

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