LT1Mike

Ok, my car is running way to hot at highway speeds...250 today and I need to solve it... I got 71k miles, coolant just flushed (it was doing it before then), water pump has 25k on it, just curious why its heating like this?? I was gonna change my tstat and rad cap since there 14 yrs old, It only heats up bad at constant speed. 97 z BTW. Air dam is on also.

Guest47904

Any mods to grill that could be restricting air flow?

Does the coolant circulate with the cap off and engine at operating temp?

What does the temp do sitting at idle?

Do the fans turn on without influence from things like the AC?

How fast does the temp rise from dead cold?

LT1Mike

I have a billet grill... not sure if that would effect.

Haven't checked yet personally but when my rad was flushed they said it did.

it will be around 210 or above which doesn't bother me its when I'm on the highway for longer then 15 mins that it gets CLOSE to 260.


Yes fans come on when they need to.

It actually take 10 mins of driving for the tstat to get there.210... weird thing is, if I city drive it will be 210 and under sometimes... if I jump on the highway its gonna go up on temp.

MaximumJavelin

Did the shop remove the air deflector and forget to put it back on?

LT1Mike

The air dam? It's still on there. It was doin this before I flushed coolant. I was gonna change the tstat since its the stock unit in 97 and rad cap is stock. That's the only OEM things besides the cam on my car. Would a stuck or broken thermostat do this? Or even a radiator cap that's broke?

moparman

If you haven't, check the radiator level when engine is cold. If low, add coolant and bleed. If full, try bleeding it again.

LT1Mike

Yea it was full. I blended it again and only a dribble came out.

LT1Mike

Ok took out tstat and yea its shot. Wouldn't work in boiling water... so I went to o reillys and they have the actual 180 replacement for 35 dollars which is ridiculous... should I just buy a 160 from slp?

Jlo

Autozone should have the 160 tstat it's a Motorad brand..no need to buy the slp one..If your car doesn't have a tune for the fans I would get the SLP fan switch. My car is stock with a 160 tstat and an slp fan switch and stays at 175-180 all day...GL

frankzlt1

if you change to a lower tstat you will need to get the pcm reprogrammed, i got a 160 in mine and love it remember cooler the car the better on the hardware. plus you will get a little more hp out of it.

LT1Mike

Yea I was gonna do a wideband tune on it in a month... would it be fine to drive till then? My fans come on 8 degrees ahead now.. the owner of the car before me did that.

frankzlt1

with the engine running cooler the car may run a bit richer until the tune because the car is use to running hotter. your gas mileage will go to ****.

Jlo

It's not absolutely necessary to get a tune when switching to the lower temp tstat but to gain the benefits of it you need to have the fans reprogrammed to come on at a early temp! get a manual fan switch if you don't want to get it tuned

Jlo

The thermostat only has control of opening temp to allow coolant flow, after that it does nothing but cause a predetermined amount of restriction in the flow. To make the most of the lower temperature thermostat, it should be accompanied by reprogramming of the fans, so that they will come on at a lower temperature. This will help to maintain a lower overall temperature in all driving conditions (especially when stopped in traffic). It is not mandatory that you do this and a 160%u00BA can be installed by itself with no other modification.


Something else to consider is that when the engine gets to ~220%u00BA (even before the stock fan ON temp of~226%u00BA) and you are at MAP loads of 70Kpa or more, the PCM begins to retard the timing. That is one reason why people feel their cars don't run well when they are hot. The GM folks built the retard into the spark tables because when the engine is hotter, there is more chance for spark knock. If you can keep the temperatures from getting up into that range, then you might feel more power when you need it.

Altering the fan ON temps can be done through reprogramming the computer or an aftermarket "fan switch" such as sold by SLP and JET . Manual fan switches can also be wired up to operate the fan relays so that the fans can be operated at any given time the driver wants (like in staging lanes). There are explanations on how to wire the manual switch up on the 'net and there are even a couple of wiring diagrams in the electrical section of my Tech Page. If you look at the fan schematics, you can probably see that there can be several solutions to operating the fans manually (my preference being to control the existing relays).

This is a copy & paste from the SHOBOX website...Great info..

frankzlt1

your right about the fans but the car will run a little richer because of the computer is programmed for a higher temp reading.