I originally posted this on the racing times thread and Zap suggested I move it to a new thread.

It might be interesting to have a local discussion on this (and other subjects) since we now know what kind of setup a lot of us are running. Also since we are familar with a lot of the cars, we might make suggestions that we wouldn't get on the big subject specific boards.

So here goes the copy and paste.

Last week my car started running hot (around 240) so I decided to put it on the ramps in the garage and replace the cheap/easy parts and see what happened. I researched a little and decided to replaced the coolant temp switch. I researched a little more and found out that 240 degrees was the normal point when the 2nd cooling fan kicked in.
This got me wondering if the guys that run at the track, have made any mods to get the fans to kick on sooner?
I ordered the hypercrap fan switch that kicks the primary on at 200 and off at 185. I may have the chip modded to kick the secondary fan on lower than 240 (1bad91z?).

Anybody made any changes in the fan department to get your engine to cool sooner?

Don't dump on the fan switch because I already ordered it. $52.70 from Summit.

(Zap and Wheelspin, copy and paste your response on this thread?)
Also, any guys who are really new to this want to go into this in detail at the monthly meet on Sunday. I could save old parts or pictures of the new parts. Lets find something constructive to do at our monthlys. (I know the dyno is pretty cool but I am talking about the future ones.)

 

That's where thse cars are designed to run. Wait till August with th AC on, and your in stop and go traffic. If you want the car to run cooler, you WILL have to change the radiator and fan set-up.

 

Yeah, last summer when I was on a section of the beltway that was surrounded by concrete barriers, the thermometer in my truck said it was 101.

 

Yeah, that temp thingis what GM had to do for emissions. Sucks! That's too hot for our engines to run efficently. Street or Strip!

Second, the temp switch control, is one of the best things U can do, except U really need to order a second switch--same type_ and replace the secondary temp switch as well. Otherwise the only time it comes on is with the AC or when it gets to 240.

Yes there are other ways to control the cooling fans. Mainly the fans are controlled by a power relay, usually up by the battery (depending on what year it is). When the temp switch reaches the correct temp, it closes, and completes a ground circuit that grounds the activation side of the relay.

It is possible to put a toggle on the relay either with or wothout the temp switches still in line.

U can also (like mine has been since about 45 minutes after I bought it and brought it home), ground the signal/activation wire to the relay/relays, and they fans will run whenever the key is on. I still have the temp switches in the circuit, but the grounding the relay overides the switch.

AS far as how the other guys in Hou have theirs set-up --not sure. I know I have told a lot of people about doing this--be interesting to see how many do have something other than OEM stock.

 

Had 1bad91z reset my temp thresholds when he burned my chip. Also have some info on re-wiring I got from a guy on the board here. I'll see if I can find it. (I didn't do it).

 

From the tech boards: https://www.thirdgen.org/cool

It's a pretty good write-up. I contacted the guy (William Weissman?) and he sent me a .pdf for the dual-fan setup mod. Pretty sure I have that somewhere if you want it.

If you're car is running fine (and I don't doubt it is), you'll have no problems leaving it all stock. HOWEVER, GM did design them to run hotter than desireable. A cooling mod would do you a lot of good, and would never be noticed if that is what you want.

I'm happy with the chip / tune I got from Mike.

 

Yeah, I read that post already. Well, I read until he started discussing how to hook up the add on switch and my head started to hurt. We sure are lucky to have people like that figuring this stuff out.

I know the secondary fan can be controled by the chip. But the primary fan is controled by the fan switch located in the block right in front of #8 cylinder (passenger side).

I was wondering if anybody has tried the fan switches that kick on around 200 or the one that kicks on at 185. It might help keep the cars cooler at the track.

It would also be cool to get one of the add on fan switches that will continue to run even after the car is turned off.

I was in the garage last night installing some of the new hoses and I noticed a 'boss' (I think is the word for it) on the radator about 5-6 inches above the lower hose connection. Is this where people are drilling, taping and installing these add on fan switches?

Who is running a 160 degree 'stat? I chickened out and went with the 180 stat and the on at 200 and off at 185 fan switch.

 

If I'm not mistaken, the primary fan (drivers side) is controlled by the computer. The secondary (passenger side) is controlled by one of several things--ac being on (not sure if it's going thru pooter or not) and the temp switch in front of #8.

I noticed a 'boss' (I think is the word for it) on the radator about 5-6 inches above the lower hose connection. Is this where people are drilling, taping and installing these add on fan switches?

No--not sure what that is-- first thought is one of the tranny cooling lines to internal cooler in rad, but if U have a 700, that port should be already being used. Would have to see it-regardless of what it is--no it is NOT where U would add a switch. There is 3 spots accesable for water temp sensors--on the head where U described (both heads) and in front of intake below top of manifold, above timing cover.

Running a 160 stat unless U change the chip--it screws up the pooter timing table and other junk the pooter controls. 185 is as low as I would go for a stat.

 

Here are some pics of what I was looking at. I'll look for ports on the drivers side of the block when I install the lower hose tonight.
(I'll clean that spot by the lower hose opening too!)

BTW, anybody changed the hose on the right that comes out of the heater core? What a biatch. I think it took me 2 hrs to get it off and 2 hrs to get it on. Good thing I don't do this for a living!

Also, can you buy new oem clamps? I changed to regular over the counter hose clamps but I don't really like the way they look. I was always told not to reused the oem clamps.

 

Not sure what that is--have to see it in person. excellent quality pics though!!Do U have 2 lines from tranny going into the passenger side of rad? If not that may be what those are, if U do then I have no clue.

Get OEM clamps from the dealership? of maybe like Hawks or one of the board sponsers

 

I got a manual trans. I shouldn't have cooling lines, would I?

 

For some reason I was thinking U had a 700r4--see what I get for thinking.

Yeah, that's probably what those are then--U should have one the same, close to the top?

 

i would have to checking a wiring diagram to be sure about the second fan, but im pretty sure it is controlled by the ECM on a 92, other wise i don't think i would have changed the on & off temps of it in the chip on my car.
the fan switch is used as a backup on a stock car. even if the fan switch is used only as a backup, i think its a good ideal to run one thats colder than the stock one.

i run a 180 T-stat. i think i set the primary fan set to come on around 195~200 & off around 192 or so, the secondary fan is set to come on about 205 & off about 200, i would have to look in my bin to be sure.

i feel a 160 T-stat is too cold, you want the oil to get hot enough to burn the moisture & unburned fuel out of it. if you always drive it for a long time each time you start it a 160 would probably be fine, but my drive to work is only about 20 minutes or so & thats not long enough to really get everything good & hot, plus i don't change my oil quite as often as i should, 4~5000 miles is normal for me between oil changes.

 

Well, I went back and reread Willie's article about cooling fans. It does not say which fan is primary or secondary..The more i think about it, the more I think Chris was right and I have it backwrds.

If U really need to know go to the cooling tech board and ask.

 

In my effort's to keep my car cool over the years I have tried LOTS of combinations. The most effective way to keep it cool was the origional SC front bumber. It allowed direct frontal exposure for the radiator. Switching to the Z-28 style front end made it run 40 degrees hotter under all circumstances. Adding the lower air-deflector lowered the temp by 20 degrees when driving on the freeway.

Switching from a mechanical fan to a dual electric set up (from a 91 Z-28) (both running all the time) let it run 5 degrees cooler when stopped (it would eventually overheat anyway), but 20-30 degrees hotter on the freeway. I went back to a mechanical flex fan.

I now use a dual 1.5" core aluminum radiator with an 18.5" diameter flex fan. It will eventually over heat at an idle (about 45 minutes) but if I am moving at least 40 MPH it will sit on the thermatsat all day. I expect to get the AC working soon. I hope it will not make a big difference.

 

Williams Dad here.
The factory design for the original 305 ran hotter than I like to run motors, especially in traffic. Since it is a TBI car, we only have one fan, which is controlled by the switch in the block. When we put in the 350 Vortec, I installed a 170 deg stat and changed the fan switch to a "supposedly" on at 200, off at 180 hypertech. The vortec blocks do not have an internal bypass so you must find one yourself. Since we were eliminating the heater system as well, we did not have the bypass valve to use. The GMPP TBI intake has provisions for the bypass on the front of it, and we first used a line from here to the old heater return to the radiator. This seemed to take the engine longer to warm up than I liked so I re-routed the line back to the water pump. I had enough forethought on this to have installed an early vortec pump that had threaded provisions for connecting extra lines. We installed 1/4" flex line at this location, with a "T", where we have the temperature sensor for the computer located. The car never gets hot at all, even with the stop and go traffic during the Rita evacuation to North Texas. On very cold mornings, which we seldom have, it takes a few minutes to warm up for closed loop, but 99% of the time it works great. The fan comes on sooner than it should though, I believe we actually got the "on at 180 off at 170" switch. It isnt marked. We may change it out again one of these days.

 

From what everyone has said, it looks like the 180 was a better choice than the 160 tstat. Although ***** states he has no problem with his 160, I wanted to stear clear of any problems.

The switch should come in tomorrow so I should be able to get everything back together for Dyno Day.

It would be cool to hook up a separate switch like Willie mentioned. I found one at the parts store that the 'on' temp was controled via a rotary dial. I think the range was 160-220ish. With this you could control the secondary fan without monkeying with the chip. (I think!)

 

Here is the .pdf Wilie sent me for his "Option 1". I have the 1989, dual-electric fan setup. I have NOT installed any switches, 1bad91z's tune brings my secondary fan on much earlier now (I forget the temp*). To note, my primary (first on) fan is the drivers side. I still may do the manual switch, idling in the staging lanes still gets too warm for my liking. I am running the 180* thermostat, but I agree the 160* is not hot enough.

 

It makes a difference in my car . Temp goes up 20 degrees. But I have the stock 2-fan set-up. I'm switching to something after-market soon. Your mechanical fan may be better w/ AC.

 

I have cooling to spare when I'm moving, but at an idle it's just a matter of time till it starts boiling. I may hook up an electric fan in addition to the mechanical, if I have too. I have a few laying around. I might as well use them.

 

My switch came in a day early. So, I went to work putting everything back together. Everything went together just fine. I noticed the 90 degree vacume line that plugs into the throttle body was cracked, so back to the parts store. (I think I have been about 6 times.)

I took a meat thermometer from the kitchen and put it in the radiator when I cranked it up. Pretty uneventful thank goodness. The fan came on at about 200. The thermometer was only marked to 190 but I could tell it was about 200. The upper radiator hose was warm at about 160 so it was hard to tell when it opened up. No leaks (yet) and the gauge in the car is slightly below the first mark on an 80 degree day. It used to stay exactly on the first mark. I think the previous t stat was a 180 also.

So, I guess some of my last questions are;
1. Anybody know how to get the thermostat out without taking off the throttle body.(I had to take it off to get to one of the bolts.)
2. Anybody know how to clean the inside and outside of the TB and plenum? They were very dirty when I had it apart.
3. Do you think it is safe to use the meat thermometer now for its intended purpose.
D. When I take the intake apart to try and get the dents out of my runners, should I grind down the casting ridge that is right behind the plenum bores.

 

1. No- I don't

2. Carb cleaner or brake cleaner and one of those green scratchy pads or steel wool

3. Yes--boil it on stove top and clean--LOL

4. Not sure what U are referring to--but if it has to do with ir flow--yes--if U don't have already get the piece that bolts on the front that has a smoother surface-- forget what the name of it is--maybe somebody will jump in here.

 

Has anyone had their headers ceramic coated and has it helped with your cooling problems???

 

I have read some threads in other tech columns on TGO--supposedly, a good ceramic header coating WILL reduce the under hood temps, and U might see a 10* reduction in water temp becuse of that, but I'm not sure it would do much more than that, according to what I read.

 

The biggest thing that I am getting from this thread is that if U are running a stock engine or very little mods, the OEM fans system will keep your ride cool, ONLY if u do the mods to the fans where they come earlier--either thru a lower temp control switch or by grounding the fan relays, where one or both are on when everthe key is on.

If U have some heavy mods, U need to go with a better aluminum radiator and better fans. The A rad is not enough by itself. Yes, it will help some, but drawing the air across the rad is the most important thing. In fact, in my research U would be better off with the OEM rdiator and better fans, than a better rad and OEM fans.

The bigest thing when upgrading fans, is to get a set up with a fan shroud. The OEM fans for thirdgens because they do NOT use a shroud does a very poor job in drawing the air across the rad.

 

forget cooler thermostats, and temp switches! go straight to the source of the problem and get a radiator! i got the summit brand aluminum 4 core (direct fit for our cars) for 250 dollars. that was the best 250 dollars ive ever spent on my car. my temp used to stay at 220, now it doesnt get over 200 unless i let it. normal driving conditions it stays at 160 which is what my t-stat is.
kent

 

I disagree. Radiators are a pain to change in our cars as the aftermarket one never fit without grinding, building brackets, new fan mounting setup etc.

I say keep it simple. I run the stock radiator, stock dual fans. 180° thermostat, 1st fan on/off at 190/185 and the fan switch for the second fan is 200/185. 1 jug of water wetter. That's it.

Runs about 185-190 while driving around town. 180 on the highway. 200 in heavy traffic.

Things I would do differently? Maybe switch to a 25% antifreeze amount rather than the 50/50 I have right now. Might do a 170° thermostat instead of the 180°. But either is going to do the same on a hot day. For those rare rare cool days, the 180 gives good gas mileage, great heater output, and keeps the engine warm enough for moisture issues.

I did bypass the radiator with the transmission cooler. But that's more to protect the transmission fluid from nuking itself during a rare overheating of the radiator.

 

I am currently trying to install a fan switch in my 85 and my biggest problem is getting the plug in the passenger side head out! It is not a 3/8'" square opening but a bit smaller. Had to grind a 3/8" extension to fit. Using PB and a lot of cussing has had no results. Any ideas on how I might get this plug out. I want to run the switch to make the one fan come on sooner. Also,TPI parts has the 170 degree thermostat which I feel is a good compromise for our cars.

 

I would go with a better aluminum radiator as well, they cool so much better than the brass radiators. I got a good deal on a Modine from NAPA (stock fit) and that thing cools better than any other radiator I had in there before, including the GM Harrison aluminum radiator and a 3 row brass radiator.

Its pretty common for people to have problems getting that plug out of the head.

What I did on my dual fan TPI setup is to lower the fan on temp for Fan 1 (I have a MAF car so you can only control Fan1) and then I jumpered the relay for Fan 2 to come on when the ECM energizes the relay for Fan 1.

I stripped the insulation off of a jumper wire, slipped the wire inside the terminal in the connector and pushed the relay over the connector (pinning the wire in place). I did this for both relays and when the ECM turns on the primary fan, the second fan comes on as well, bypassing the factory temp switch in the head.

Now you can go through the trouble of installing a Scotchtite connector or soldering the wire to the factory harness, but that little rigging saved my engine during this summer heat.

I'm too lazy to change the temp switch in the head, and this way would provide extra protection: if the wire were to come loose, the factory temp switch would still energize the fan relay anyway at 245 million degrees.

I have the fan coming on at 225 (via the chip) with the factory 195 thermostat installed and the stock radiator. It rarely gets over 220 degrees, even with a leak at the intake gasket that causes it to lose pressure.