Antwans1990RS

so ive been having the typical overheating problems with my car, when i go at high speeds the car does fine, but when i slow down the engine temp spikes.
& my coolant boils
so heres what i have done,
i replased the thermostat and thermostat gasket
(boiled the thermostat it opens up)
cleaned the radiator of debris
checked the fan, it works kicks on at about 220 where its programed to
water pump works fine i checked that
its not having any steam come out the pipes
and im not loosing any coolant
electric fan not a clutch fan

My suspision:
the guy who had the car before me tried to lift it on the bar right below the radiator so its slightly bent up so the radiator leans back a little bit, its got two brackets that hold it in place though, when i got it i drove it around in traffic for about an hour then 3 hours home, and about another 23-30 min in town, and that worked fine so i think its something recently thats gone wrong, so im kinda at a loss.

Couple of questions
i saw the post about putting a lower thermostat in to help engine temp
so im thinking of getting a 180 it currently has a 192
and thinking about getting a lower temp fan switch
but i think thats just kinda putting a band aid on the problems isnt it? theres still some problem somewhere and i cant find it.

possible partially clogged radiator?
initial timing changed?
need a better fan?

i was also wondering if anyone knew what the initial BTDC timing on the 1990 305 was supposed to be as well?

spicyskater

das it go all the way up or just gous up to 3/4 of the temp scale and gous down when u start driving....if yes thats how every 3rd gen works stock...btdc is 0 whit the big wire socket unpluged from the distributor...if u have aftermarket distributor u need somwhere around 12 degrese advance

JamesC

iTrader: (5)

Welcome to TGO, Antwans.

Is the air dam in place?

JamesC

JimRockford

When you say you cleaned the radiator of debris do you mean you had it rodded out? An old radiator can be flushed and still be restricted inside. you can get a brand new radiator at Autozone or Kragen for $89.99 with a lifetime warranty.

I would definitely recommend a low temp fan switch,when I got my car it had the stock switch and the fan wouldn't turn on until 220 and the gauge would stay in the middle.I bought a low temp switch from TPI parts and it always runs cool now and the gauge never goes near the middle even in summer.

You can also check the air dam too as those are often damaged or missing,but it's only going to make a difference when the car is in motion,not at a stoplight.

Where is your gauge going to when you're at a stoplight?

Antwans1990RS

No no Air damn underneath,
Ive looked around heard some good things about those, ill invest in one of those next chance i get to
Im pretty sure for the most part at a stop light idleing it is fine, but between 10&25 mph it sky rockets well up past 260 if i dont keep an eye on it and get it up to speed.
and i didnt mean i had it rodded out, i just cleaned all the dirt and debris froum out of the front of it, there are a lot of dirt roads around here thinking that i could have an air build up.

has anyone had any problems running there car at around 180-195 rather than the normal 220? i know manufacturer says thats most efficient for burning fuel, but engine longevity says that around 180 is ideal.

JamesC

iTrader: (5)

Since the car is designed to use the air dam and baffle, I'd advise installing one before moving on to other possibilities. The thread below has some pics and an interesting dialogue about how the dam/baffle works:

https://www.thirdgen.org/forums/body...-plastics.html

JamesC

PUNISH3R

iTrader: (2)

Same problem. Yesterday I got stuck in traffic and it was hot and the temp spiked up. I always watch my gauges and the temp gauge was just below Red (danger zone) so I cranked the heat and it brought the temp down.

Prior to this, I redid my whole cooling system (New radiator, New hoses, New Thermostat, New Thermostat cover and new water pump). It doesn't leak and seemed to be working fine for about a month BUT I don't really drive it too far and wasn't in traffic. The Coolant fluid level is fine, it cycles and the oil level is fine (no leaks, nice and clean). But I've never ever witnessed my fan go on, EVER? Should'n't I hear it kick on at around 238 degrees? I popped the hood and it wasn't on. I've never seen or heard it working since I've owned the car. I replaced all fuses also last month. I did cut some of the coolant hoses shorter (that go over the right side/passenger side of the engine) to cut down on clutter in my engine bay after I did a full smog delete, everything. It made it way easier to do my plugs and wires (Did all MSD).

So my question is, Does this sound like a busted radiator fan? How do I test it? And what recommendations to fix it?

JimRockford

After installing a low temp fan switch my car runs at 180-195 all the time even in the summertime and I have had no problems at all.I just recently had it smogged and it passed with flying colors.

I would recommend the low temp fan switch.I see no reason for these cars to run that hot.Heat kills engines and transmissions.The stock switch lets the car get past 220 before turning the fan on.Seems like thats one of the biggest complaints around here and one I had too before I bought the fan switch.

JimRockford

Yes,it definetly sounds like a fan related problem.Your fan should come on in the 224 range.
Did you check the wire going to the fan switch? you can ground it and see if the fan comes on,that will at least let you know your fan motor is good.

I had a Formula 350 where the wire had actually fallen off the switch and once I reattached it,it was fine.

PUNISH3R

iTrader: (2)

That's what I thought. If it IS the fan. What normally needs to be replaced? The fan itself?

Antwans1990RS

im starting to think that im having the same problems as punish3r, i just went out and checked if im thinking right then it does in fact have an air dam, if thats that big piece of plastic that sticks out below the car right in front of the radiator that makes it hard to crawl underneath, then yeah ive got one haha.

PUNISH3R

iTrader: (2)

Dude, I'm in the same boat as you. I've changed out and upgraded almost all the major components. I'm just wondering if its the fan itself? Is there a sensor?

JimRockford

There is a temperature sensor switch that screws into the engine block,when the coolant reaches a certain temperature it grounds the fan and turns it on.

Check the connection on the switch.If its connected you can remove the wire and ground it to test the fan motor.The fan should turn on when the wire is grounded.

JimRockford

Is your fan coming on at all?

PUNISH3R

iTrader: (2)

If the fan goes on when I ground it, then its a sensor issue?

Antwans1990RS

Same here, my fan works, it comes on, but again not untill 220 where its programmed to, seems that. I should just change the fan temp switch

PUNISH3R

iTrader: (2)

Found this on another thread

my 86 z28 is running hot -

"The sensor for the thermostat is in the drivers side head between the #1 and #3 cylinders (near the front). this one you can change from the top of the car however you'll need to drain the cooling system first.

The sensor for the fan to turn on is on the passenger side between the #5 and #7 cylinders (the back two). This one you'll need to get at from under the car and again, you'll need to drain the coolant first.

Both of these have wire's going to them. It could be that the wires are bad and need to be replaced. I would however, go ahead and change the sensors just to be on the safe side. The sensors should have a pigtail that comes with them."

https://www.thirdgen.org/forums/cooling/643436-my-86-z28-running.html

PUNISH3R

iTrader: (2)

Ok, I'm going F**kn nuts! Fan STILL will not come on! It WILL come on when I turn the AC on so it works. Here is what I did:



1. Changed Radiator Fan Motor
2. Changed Fan Relay
3. Changed Coolant Temperature Sensor



Still won't go on!


Where the F%&K does the "Coolant (Thermo) Fan Switch" (O'Reilly's Auto parts # TFS1) go?!?!? I had the car on a lift and looked all over the bottom of the car. On the Manifold on the Driver's side is the Oxygen Sensor and some other sensor that looks nothing like the part in my hand.

I am about to rip this Chilton's manual in half, its not listed in here. I doubt it's an exotic part and sure does not sound like an uncommon problem. I hunted all over websites and it seems like everyone is asking the same F'n question. Some say screwed into the block above starter - NO! Others say Next to the Thermostat - NEGATIVE! Where does this thing go (description? Photos?) before I end up buying a new ECM when I don't need it. F#$K!

hydrolic144

iTrader: (2)

Either that's the wrong part or it goes in the driver side head where they mentioned above lol. OR, it's very possible it was removed and someone put a block off in it's place. Are you able to get a picture of between #1 and #3 cylinders on the underside of the car? That may help, but it'll point out any obvious wrongs for sure.

PUNISH3R

iTrader: (2)

There is something between 1 & 3 but looks nothing like this thing. I tried to get a pic with my phone but its too tight.

hydrolic144

iTrader: (2)

You may have the wrong part then

Antwans1990RS

Punish3r i found this online
on an 89 305 TBI
"It is on the pasanger side head between cylinders 8 and 6, has 1 wire pluged into it"
ha if its wrong dont judge me but thats what i have found

And i have made progres
So replaced the fan with a better one with a shroud, in the process i discovered that my fan switch is inconsistent, so i now have one of those drop in radiator thermomiters that goes to this beast fan that a friend gave me. and i noticed that it wasnt turning on consistently but when i turn my AC on the fan goes on, so i was driving around today engine was getting hot so i turned the heater on, and it stayed about 220 sometimes more. but then i turned my AC on then i heard the fan come on and my Temp dropped down like crazy and it was great. probabally sat about 190-200 ish.
Problem=solved

PUNISH3R

iTrader: (2)

I fixed it. Man, I was about to lose my mind. I took pics and everything, I'll post them when I get a chance to cover the part Chiltons forgot.

PUNISH3R

iTrader: (2)

Alright, after changing the Radiator Fan Motor (O'Reilly Part #PM517), Coolant Temperature Sensor/Sender (O'Reilly Part #WT3000) and Cooling Fan Motor Relay (O'Reilly Part #2DR1042) - they were all original and pretty beat up anyway - I still wasn't getting the radiator fan to kick on!

The last thing I through to change was something called the "Coolant (Thermo) Fan Switch" (Part #TFS1 www.oreillyauto.com/site/c/detail/BWD0/TFS1.oap?ck=Search_tfs1_-1_-1&keyword=tfs1 ). No worries but I COULD NOT FIND THIS THING on the car!

Chiltons DID NOT have it listed in the 82-92 Pontiac Firebird Manual and I read a ton of forums online where people couldn't find it, which was the Butterfly Effect of Chilton's not publishing it. To find it (in a 89 Pontiac Firebird Formula V8 5.0 305 TBI ), put the car on a lift, get underneath and shine a SureFire up where the oil dipstick is and you'll see it sticking out. Its SUPER hidden, you cannot see it from the top of the vehicle and it is practically touching the oil dip stick (See 2nd photo).

Then I saw my problem, wiring harness connector was broken off (See 3rd picture), and the switch itself was original, it was going to have to be changed eventually anyway (See 1st photo). All parts cost me less than $50 with lifetime warranties, why not replace everything?

I squeezed a ratchet in there, its tight up to the dipstick, and removed the old one. BE CAREFULFUL! ENGINE COOLANT CAN BE FRIGIN HOT so UNLIKE me, drain your coolant first! Remove old one, install new one. Easy.

Like I said the harness was just deteriorated so I crimped a blue wire connector on to it and it snapped right into the Coolant Fan Switch, PERFECT (See 2nd Photo again).

Lowered her off the lift, filled her with coolant, fired her up, let her run till about 236ish degrees and the car fan sputtered ON!