myturn89

Since all of the cars that i owned only had a dial gauge for engine temperature, i have no idea with my 89 what the normal operating temperature. Mine runs right around 200 but that seems high. Plus on a very hot day i am running well into 225 so i turn the heat on full blast because i am concerned of where the top end is. Any help would be great.

Thanks!!!

jimg's'93

Your primary should be turning on right at 225 so that sounds about right.

There's a thread started earlier you should read (1990 Temperature):

http://forums.corvetteforum.com/c4-t...mperature.html

vader86

Thats normal, you dont have to turn your heater on.

The danger zone with aluminum heads is the 250-260F coolant range.

Sam Lam

I bought a stock 89 a few years back and agree with the above threads. As I recall, the ECM turned on the main cooling fan at about 226 deg F and the stock thermostat is a 195 deg F part. I did not like the high temps and installed a 180 deg F thermostat. In addition, I installed a manual switch to turn on the main fan during stops for traffic issues. The switch is hidden under the dash but convenient for use. Later, a friend reprogrammed my ECM to turn on the main fan at 195 deg F. These changes have cooled down my engine and it rarely gets to 200 deg F. I hope you find this info useful.

samsonb

Does anyone use a Robertshaw thermostat? I read they give better flow, so the car tends to run cooler than the typical poppet style thermostat.

TJM

Your welcome......

My ’89 runs at that temp, as a max.. 190 - 230 or so, never seen it much higher.

If you have a model with the Aux fan, you can install toggle sw. in the Aux circuit, easy to do, and then manually turn on that fan when paranoia creeps in?

Beats the heck out of turning on the Heater!!

Unless you live Washington State or something?????

Fill out your profile, it will help getting advice. ’89 covers a lot of technical ground.

TJM

Z51L9889

That's just about right for a stock cooling system on the '89. I've owned my car since new, and it ran about 202-203 on the freeway and about 210 in traffic. These cars tend to run hot -- 230 when sitting in traffic on a hot day with the A/C on is not unusual at all but it should cool down very quickly once you start moving again. In my 89, the primary fan comes on at 227 and turns off at 210, and the secondary fan doesn't kick in until almost 240 with the stock switch.

BADDUCK

That's perfect don't f**K with it. Your fan doesn't even come on until 228*.

SunCr

'89 Specs: 226 Main - ECM driven; 228 Aux - Left Head Switch. A/c: ECM grounds the main relay at 228 psi from the pressure sensor on the high side line. Off at 190 psi.

Aux fan became a Dealer installed option in '85 following field complaints that the cars overheated with spirited driving or while ascending long grades. It was never intended for controlling coolant temps at idle, even after it became a Factory Option. Frankly, it should never come on.

A/c coolant temps should be 5 to 10 degrees lower as the fan will come on sooner and stay on longer. A/c operation is exempt from emissions and needs to maintain a condensor temp of 80 to 100 degrees for cold air. That's far less anything flowing through the radiator.

If your '89 can't maintain coolant temps within specs (and the only way to check it out is with a Scanner and Manifold Gage Set), something else is wrong.

Demonic85

On my '85, thermo opens at 205 (not sure why) then goes down to ~195. Normal temps while driving should be around 190-210, while sitting in traffic the coolant temp should go no higher than 232, thats when the fan kicks on and drops the temp to ~210.

BADDUCK

Sun CR, the aux fan on my 1989 came on at 236*. I don't believe the specs you are quoting are correct. Why have the aux fan kick in at just 2* more than the main fan?

SunCr

Specs are from the Service Manual. Aux Fan history is from a Service Bulletin issued back in '85. That Service Bulletin doesn't say why the Engineers selected whatever temp they selected, but when GM went to dual suckers in '90, they burned those parameters into the ECM (until the LT1 came along in '92). I do know that the 226 degree or so idle coolant temp is necessary for the CAT to do it's thing. Hooking up a scanner to any emissions controlled car, a/c off, is going to give you something around that number from the CTS (and it may be why the OEM's don't include anything more than a needle on most temp gages).

For what it's worth, I've owned mine since new and the only way I've been able to get the Aux Fan to come on (sans a weeping head gasket or with a lower temp switch - a big deal back then, but long since deleted) is to put the nose up against the garage wall and turn the a/c off (which except for smog tests, I seldom do). If it comes on at all - my Scanner shows 228 at the CTS which matches the Book. Prior to doing that, I often wondered what in the hell it was for (other than an extra 100 Bucks Chevy tacked onto the sticker). And since finding out that more Vettes left the Factory with the Heavy Duty Radiator and without the Aux Fan, I still do. I haven't checked for a difference between the CTS and dash sender in ages, but a 2 to 3 degree difference wouldn't be unusal - anything more would. Otherwise, I run 205 to 212 at idle, the thermostat (195) at cruise which is how it was when I drove it off the Dealer's lot. Keeping it that way has meant a new radiator, a completely rebuilt a/c system and a couple of head gaskets - all before 50,000 miles - but the cooling system on these cars wasn't ever their real problem.

BADDUCK

My aux fan came on a few times in traffic in summer at around 236*- 238* when I first bought it in 2005. I installed a new sensor that turns on the aux fan at 205* and a 180* stat. Now the main fan never turns on unless I run the AC. That's what I'm going by. Unless it's mid summer neither fan comes on now.

SunCr

You don't need the switch for it to work as designed, but if it helps you enjoy your Vette, have at it. My experience with running both is that it eventually overwhelmed alternator output (no more than 35 amps at idle) and when the voltage dropped, the fans slowed down. The temperatures then climbed (and of course vent temps went with it). Using the Main with ECM control of the Relay keeps it happy - and the vents in the 40's. If you want to check your gage for accuracy, buy a scanner and you might also want to throw in a Shop Manual, but get the Electrical Supplement and Bulletins since there are a couple mistakes.

BADDUCK

I don't think you read my post. Neither fan runs most of the time even in the summer. Both fans almost never run.

I still say the numbers you are quoting are wrong on the aux fan spec. In 1989 the aux fan comes on around 236*.

SlumdogVette89

Do any of you know if I am able to replace my broken 350 motor with a 454 in 1989 vette?

hcbph

Poor place to put this. Better to check at; http://forum.grumpysperformance.com/...90ff6937f5c3ad

aklim

Before I go there, how do you KNOW how hot it runs? I don't trust the gauge. I would see what the ECM sees with a scanner and then check the temp sensor itself with an infra red thermometer. The gauge could be wrong, the sensor could be wrong. Till you know, you really don't know.