I just got the low temp fan switch from MAD. This is the one that screws into the driver side head and turns the fans on at 200 deg. I'm stuck on the very first step of the install. There's a plug that I have to remove from the head to install the switch, but for the life of me I can't figure out how to get it out. It's square and it looks like a 3/8" drive should fit in, but 3/8 is a bit too big. No, problem I'll try 1/4" drive.......too small. I've tried every damn store in the are and no one has anything in between the two. What have you guys that have installed this type of switch used to get that damn plug out. I'm pulling my hair out. Thanks, Tom :crazy:

 

There was another post about that plug a while ago; it gave the owner fits getting it out. I think he was at the point of applying heat, etc to free it up.

I don't remember the outcome but you might check the archives.

You might take it to a Chevy dealer and ask them to install the switch. If they have the tool it shouldn't be over 1/2 hr of flat rate.

 

TA, you can remove the wire harness by squeezing the two sides together, then gently pull right off. It should come off easily.
As for the switch, I believe its 22mm. BE VERY CAREFUL WHEN INSTALLING! THE THREADS ON THE NEW SWITCH DO NOT GO TO THE TOP OF THE SWITCH!!!! IF YOU SCREW IT IN TILL THE NUT IS FLUSH WITH THE HEAD YOU WILL STRIP THE THREADS ON THE HEAD!!!!!!
Like I did.. :mad :mad :mad :mad :mad :mad :mad :mad :mad :mad

To top it all off, the switch didn't even work!!! I let it go to 250 before I shut it off. Yes the Aux fan does work. When the green wire was grounded manually with the key on, it went right on.
That was not a good day :cry

 

Thanks for the replies guys. I'm still having no luck, now I'm starting to wonder if a hex head socket might work in a square hole.

Tripple black 88, I'm not sure of the differences between 88 and 91, but I have no harness or wires of any kind at this location in the head....only this damn plug that I can't seem to get out. Thanks for the advice on the new switch install.

I'm calling it a night, I'll give it another try over the weekend

 

I believe I used some antiseize when I installed my low temp aux fan sw, instead of thread sealer, to assure a good electrical ground.

 

I have no experience trying to remove that plug, but I wonder if you could take a 3/8 extention, and slightly grind the sides so it would fit the plug.

 

*EDIT*
TA, can you possibly get a picture of that, so I know what you're talking about. I didn't know 91's had an aux fan temp switch in the drivers side head like previous years. (Cuz didn't they change the radiator/fan design in 90?)


[Modified by TIMSPEED, 3:41 AM 7/26/2002]

 

Good luck that thing is in there, I tried to get mine out, I ground an old extension down to fit and it just twisted the extension off. I tried
several times it did not budge. Another solution is to have your chip reprogrammed to have the fans come on sooner, thats what I did
works great.


[Modified by jeepie91, 7:41 AM 7/26/2002]


[Modified by jeepie91, 7:41 AM 7/26/2002]

 

I prefer the toggle switches I have........one for each fan .........they come on when I say the come on and if I forget they come on when GM says to come on ...........but I always remember ..............so far :seeya

 

I just removed the same plug on my new ZZ-4 motor. I had to grind down a 3/8" extension, it then came out. If you still have problems try soaking the outside of the plug with a penetrating oil to loosen up that offending plug. Once it starts breaking loose respay with the oil and lightly retighten and the loosen respray and so on and so on untill it is out.

 

Thanks for the replies. I'm probably going to try grinding down a 3/8" extension, but I want to try one more thing first. Sears sells some pretty heavy-duty looking flat bladed screwdriver sockets, and I'm thinking if I can find one the right size to fit across opposite corners of the square it might just work if the screwdriver bit holds up. Something just came up for the weekend so I'll give it a try on Monday. I'll let you guys know how it turns out.

Timspeed, I don't have pics, but you are correct on my '91 (and probably on the '90s also) there is no fan switch at this location on the head. The MAD switch simply threads into the head where this damn plug is and then you have to splice into the fan relays to make it operate. I'll try to take some pics on Monday.

 

You may not beleive this but when they remove these plugs in a machine shop they use hot wax................ but you cant do that if the heads are on the engine.............

 

I did the same install on my 91. The instructions should tell you to use a 5/8 square rod. See that anywhere? I got mine from Eckler's so your instruction sheet may be a little different. I'm prett sure 5/8 inch is the correct size. If you can wait until tonight I'll check my tool box and email you the size you need.

Here how i did it.

Got to hardware store, I went to HomeDepot.
Buy a section of 5/8 square rod about a foot long. You can find it in the asle that has the threaded rod lenghts.
Cut it down enough to fit in the area of the plug.
Stick the rod in the plug. Use Vise grips (Pressure Pliers) to turn the rod.
Be patient when trying to turn it. Put some liquid wrench on the plug threads, this should help loosen it. It takes some effort for it to come loose. Email me if you stiil want help.

 

Huh? :confused:

Guess me opening my hood at home and using a small section of 5/8 square rod to remove the plug was just my imagination :D :lol:

Don't need the hotwax. That may be the best way for them but it's not the only way.





[Modified by ConeKLR, 1:52 PM 7/26/2002]

 

The MAD instructions made no mention of that............only said to remove the plug, but didn't say how.

Thanks for the excellent tip, I'll give it a try on Monday :cool:

 

Okay. :cool:
One other tip for ya.
When you instal the new sensor put some thread sealant on it. Don't wrench down on it hard. Only tighten enough so that it is snug. Not really tight. Reason is you can break or damage the sensor if you try to make it super tight.



[Modified by ConeKLR, 1:58 PM 7/26/2002]

 

Just did the same thing a few weeks ago on a pair of Brodix heads. I first tried one of my short, generic 3/8" extensions ground down to fit. I chose it because it was expendable.

The metal was too soft and the extension barber polled.

I then did the same grinding act on a short, Craftsman extension and by appling force evenly and gradually, all four were removed.

I'm sure that someone sells the correct tool, but we couldn't find it and I made my own.

Hope this helps.

Jake

 

I found some time today so I gave it another shot using ConeKLR's advice. I went to Home Depot and bought a 36" length of 5/16" square steel rod. 5/16" is the correct size in case anyone in the future needs it, just hack it down to the size you need and you're in business. It was still a struggle to get the plug out because the steel rod is not hardened and tends to twist, but after about an hour of using rust penetrant, a little banging and some cuss words, I finally got the bugger out. A little word to the wise if your planning this project.......drain the coolant first! The directions stated you would only lose about a quart even if you don't drain the coolant............well after about a gallon and a half poured out I learned my lesson.

Anyway, the rest of the install was a piece of cake and the switch works perfectly. It was about 92 deg. out today and I let the car idle in the driveway for about 45 mins...............the temp never got hotter than 200, where it used to push 235 or so. I then took the car out for about a 45 min. cruise and again I never saw temps above 200. It stayed in the 175-200 range the entire time, just as the switch is supposed to operate. It is so nice now to not have to worry about getting caught in traffic.

I highly recommend this for any one that is having a problem with high temps. Its relatively easy (once you get that damn plug out..........but then again I think only 90-91 have it) and it works awesome, in my opinion. :cheers:

Thanks for everyone's help and advice :)


[Modified by TA, 9:47 PM 7/28/2002]


[Modified by TA, 9:49 PM 7/28/2002]

 

Congrats on getting the job done. Installing an aux fan sw to control the main fan is a lot cheaper than reprogramming your chip or buying an expensive aftermarket chip. And you can now change stats and fan sw to match, if you should so decide.

Actually I think anyone with a L98 that doesn't have the aux fan option will have that plug instead of the aux fan sw.

 

Glad you finally got the plug out and everything is working okay.

After the long 100+ degree heat spell we had here in Texas last year, I installed both a Derale oil cooler with integral fan AND a 16" Derale fan, both as pushers.

It was idle and low speed that caused my high heat problems, since once on the highway all the temps were fine. Now, with the extra airflow, even idle and low speed temps are under control.

Jake