JimRockford

Hi,
I have a 1990 Pontiac Firebird with the 305 TBI V8 engine and automatic trans.
I just recently bought the car and love it,it was always adult owned and all stock.

The temp gauge seems to hover in the middle around 220 which seems high to me,I have had several 1970's Firebirds and a 1982 and 1983 Firebird and all of them stayed around 165-180 area at most.

I have checked and the electric fan does come on because when its in the 220 range and I shut off the motor and turn the ignition key on I can hear the fan running.

Can anyone here tell me where the gauge is supposed to run on the cars and what I can do to get it to run cooler?

I have also noticed slight "pinging" sounds upon acceleration once the car has reached the 220 range,I have read the owners manual that came with the car and it says the base V8 with TBI can be run with 87 octance fuel and that "some pinging upon acceleration is normal"...this is from the Pontiac owners manual!
I find that funny since they recommend 91 octane fuel for the the TBI motor but all the V8's have the same 9.3.1 compression.

evilemokid94

iTrader: (6)

220 is normal

JimRockford

Wow!,why do the later Firebirds run that hot?

Does your car "ping" on acceleration?

formula forever

my car runs that hot only on a hot summer day. use higher octane like 91 or 93. I have been using 93 for years and no pinging ever.

evilemokid94

iTrader: (6)

ever year thidgen run that hot, its just normal for these engines despite the thermostate, also without actually hearing the ping noise i wouldnt be able to tell you

bradley23150

iTrader: (10)

Mine hits 220 often and I also get "pinging" on acceleration, which I believe is spark knock.

JimRockford

Well,it's not summer,it's only been about 78 or so!
Where does your gauge normally read when it's not a summer day?

I'll try using 91 octane and see if that works,but according to the owners manual for the car its supposed to be fine with 87.

JimRockford

Thanks for the reply,I guess this is normal then,I just wasnt sure.
Isn't pinging supposed to be bad for the engine though?

bradley23150

iTrader: (10)

I wouldn't consider pinging or spark knock to be normal at all. My car is in a poor tune coupled with too far-advanced timing which I believe is causing my spark knock. The noise could be an exhaust leak, spark knock, lifter tick, etc.. You should really get that looked at.

formula forever

my gauge sits around 200 or so if its not hot outside. if my car is ideling and not moving it will go up to 220 and sit at 220 until i start moving.

JimRockford

I agree,I wouldn't either,even though the owners manual actually makes that statement.
The engine is in superb condition,no exhaust leaks,lifter noise,etc.
It only had one owner before me and was babied since new.

I am guessing perhaps the timing may be off since it was smogged right before I got it,however the car doesn't make the faint pinging noise until the car has reached the 220 temp and it is only heard under acceleration.

I will check the timing,I believe the factory spec is 0 degrees tdc.

the solitaire

Factory spec is 0°TDC indeed. Just as a small contrast to all previous posts, I do not have a 1990, but a 1989 TBI, and not a bird but a camaro. All of that shouldn´t change anything to the basic operating temperature of the engine however. My car generally runs between 140°F and 200°F. The fan never comes on, unless I deliberately switch it on. No pings, knocks or anythings in that regard under acceleration, WOT or at any other point during operation. Hearing your explanation I think something is not right. Check timing first as that might cause the engine to run hot. If not timing, connect ALDL to see if the car is running lean. If not running lean either check all the obvious cooling bits.

JimRockford

The thing is the car runs cool on the freeway,and stays at or below the first quarter mark from 100 degrees (which I am guessing is 190-200 mark)
It's only when I am sitting at stop lights and driving in city traffic after sitting that the temp gauge goes that high and the fan isn't coming on until after 220

JimRockford

How do I adjust the timing on my car anyway?
I've always worked on cars without emissions parts and computers before.

Dyno Don

iTrader: (7)

Change the fan temp switch, it's programed to come on at 225*.
Try to find one that comes on at 185*.

camaronewbie

Owner manual and pinging ...

Until recently (like last 15 years or so), the government mandated that all US cars have to be able to run 87 octane under federal law. Thus, good bad or indifferent to the engine, all manufactirers of cars to be sold in the US HAD to state in their owners manuals that 87 octane was fine, whether it was/is or not. Thus the statement in the owners manual.

"Pinging" is detonaton or spark knock, and is not good. Thus, if you experience it, I'd try higher octane gas, changes in timing, etc. to get rid of it. Just because the owner's manual says 87 and pinging is ok, doesn't make it so. It's 20 years later now, you can't sue GM and win because of their false statements in a 20 year old owners manual.

Yes, temps run higher in later model cars. It's part of the manufacturer trying to get better emissions numbers and better mileage numbers - hotter engine burns more of the gas and more of the emissions gases off. Again, like the "pinging" - not necessarily good for the car, but it's what it is. Every engine lives longer and runs better with lower temps, it's a fact of life. But keep in mind, by the time the 1980's were here, society in general became 'disposable' ... Bic lighters & razors, new computer tech every 3 months, etc.

Very few of us like the 220 temps, and most all of us change things to lower it - we know that it's too high, especially for 20+ year old parts. Lower temp fan switches, lower temp thermostats, etc. are all used to get the temps down closer to the 200 range where we feel is much better.

There's a thread around listing all the fan switch part numbers and what their ON temps are - search for "fan switch alternatives" and you should find it. Swap for a lower temp switch, try a 180 stat (no lower than 180), and you should be golden.

Also note - these gauges are far from accurate. Your car is not overheating by any means until the point where the coolant is boiling over into the overflow tank, regardless of what the gauge reads.

JimRockford

Thanks Camaronewbie,
So far the lowest temp fan switch ive seen in the thread is the Neihoff dr137x which supposedly turns the fan on at 204 degrees but I can't find any local parts house that can order it in.
Would the 204 degree fan switch keep the engine cool enough? or should I try the 185 switch and if so who makes it/ where can I buy it and is it an exact stock fit to work with the factory harness.

Regarding the pinging,I know it isn't good for the engine which is why o found it absurd that the owners manual said it was perfectly normal.
They do recommend premium 91 octane fuel for the TPI engine even though the TBI and TPI engines have the same compression.

I will try the higher octane fuel and see if it helps.

If you can provide me with any info on the switch please let me know.

Thanks.

JimRockford

Anyone here have any specs on a standard brand fan switch part number ts136 ?
The local auto parts store is saying this is the same as the dr137x but the don't have any specs as to when it turns on the fan.
Its also $44 Is this an exact fit?
Any help would be greatly appreciated.

Also regarding the hypertech switches will the fit the stock connector or do they require modifications?

Or maybe the 1987 Buick grand national switch I've heard talked about it supposedly comes on at 200 degrees.
My car still has the stock 195 thermostat,should I change it for the 180 when I change the switch?