93 LT1 runs HOT ?
Thread Starter
Heel & Toe
Joined: Oct 2003
Posts: 15
Likes: 0
From: pinellas park fl.
93 LT1 runs HOT ?
Any ideas ? what would happen if i removed the thermostat? The car runs very hot. The coolant goes to 253 at times. The fan comes on at 235. I have replaced the waterpump, hoses,and thermostat and burped the bleeders.
Melting Slicks
Joined: Feb 2005
Posts: 2,135
Likes: 0
From: Sebastian Florida
St. Jude Donor '06
Instead of throwing parts at the problem, how about a littke research.
Are both fans coming on when the temp reaches 237?
Did you look at the fron of the radiator for debris blocking the radiator?
Have you tried undoing the hoses one at a time(not the hoses going to/from Rad.) to see if you might have a blockage?
Are both fans coming on when the temp reaches 237?
Did you look at the fron of the radiator for debris blocking the radiator?
Have you tried undoing the hoses one at a time(not the hoses going to/from Rad.) to see if you might have a blockage?
Pro
Joined: Oct 2005
Posts: 557
Likes: 1
From: Ottawa Ontario
Never run with an open Tstat. You will very much regret it. Your temps are getting a bit high but are still in the range. I would suggest you might need a new radiator. They do get old and plugged. Your fan is coming on at 235 and should at 230 but that could just be a guage calibration issue.
Turn on your AC fan also. If it doesn't help much and your cars still running a bit hot on the open road its not getting enough air through the rad.
Turn on your AC fan also. If it doesn't help much and your cars still running a bit hot on the open road its not getting enough air through the rad.
Thread Starter
Heel & Toe
Joined: Oct 2003
Posts: 15
Likes: 0
From: pinellas park fl.
Originally Posted by Randy93
Instead of throwing parts at the problem, how about a littke research.
Are both fans coming on when the temp reaches 237?
Did you look at the fron of the radiator for debris blocking the radiator?
Have you tried undoing the hoses one at a time(not the hoses going to/from Rad.) to see if you might have a blockage?
Are both fans coming on when the temp reaches 237?
Did you look at the fron of the radiator for debris blocking the radiator?
Have you tried undoing the hoses one at a time(not the hoses going to/from Rad.) to see if you might have a blockage?
Safety Car
Joined: Feb 1999
Posts: 3,504
Likes: 4
From: Mexico Beach FL
It is not a good idea to run any vehicle without a thermsostat.
But, with the LT1/LT4 "reverse flow" engine, it is COMPLETELY counter productive to run it without a thermostat.
The reason:
There is a special thermostat in a LT1.
That special thermostat is designed to close one coolant path when it opens the other, and you never want both coolant paths open at the same time -- without a thermostat, both coolant paths are open all the time.
One coolant path directs coolant through the radiator; the other coolant path directs coolant to recirculate through the heads/block without going through the radiator.
The idea is:
When the engine is cold, the coolant recirculates through the engine to prevent hot-spots without going through the radiator.
When the engine is warm, the coolant goes through the engine and then to the radiator for cooling.
Without a thermostat:
Some of the coolant circulates through the engine without going through the radiator.
Some of the coolant circulates through the engine and goes through the radator.
The coolant that doesn't go through the radiator, does nothing to cool the engine.
The reverse flow LT1/LT4 is NOT like a conventional cooling system.
Tom Piper
But, with the LT1/LT4 "reverse flow" engine, it is COMPLETELY counter productive to run it without a thermostat.
The reason:
There is a special thermostat in a LT1.
That special thermostat is designed to close one coolant path when it opens the other, and you never want both coolant paths open at the same time -- without a thermostat, both coolant paths are open all the time.
One coolant path directs coolant through the radiator; the other coolant path directs coolant to recirculate through the heads/block without going through the radiator.
The idea is:
When the engine is cold, the coolant recirculates through the engine to prevent hot-spots without going through the radiator.
When the engine is warm, the coolant goes through the engine and then to the radiator for cooling.
Without a thermostat:
Some of the coolant circulates through the engine without going through the radiator.
Some of the coolant circulates through the engine and goes through the radator.
The coolant that doesn't go through the radiator, does nothing to cool the engine.
The reverse flow LT1/LT4 is NOT like a conventional cooling system.
Tom Piper
Last edited by Tom Piper; Jul 11, 2006 at 01:51 PM.
Burning Brakes
Joined: Mar 2006
Posts: 808
Likes: 0
From: Metairie Louisiana
Originally Posted by fatboytm
I can hear a fan kick on at 235, I don't know if 1 or 2 fans are running.
Safety Car
Joined: Feb 1999
Posts: 3,504
Likes: 4
From: Mexico Beach FL
If a '93 is like a '92, the primary fan should come on at about 221*F rising and the seconday fan should come on at about 233*F rising.
And, since the heads get the coolant coming from the radiator first (unlike a conventional system), the heads run at least 15 degrees cooler than the digital temperature readout is reading, because the digital temperature sensor is located where the coolant is the hottest on its way back to the radiator from the engine.
Tom Piper
And, since the heads get the coolant coming from the radiator first (unlike a conventional system), the heads run at least 15 degrees cooler than the digital temperature readout is reading, because the digital temperature sensor is located where the coolant is the hottest on its way back to the radiator from the engine.
Tom Piper
Burning Brakes
Joined: Nov 2005
Posts: 848
Likes: 1
From: 1992 LT1 6 speed Cayman Islands
Originally Posted by Tom Piper
It is not a good idea to run any vehicle without a thermsostat.
But, with the LT1/LT4 "reverse flow" engine, it is COMPLETELY counter productive to run it without a thermostat.
The reason:
There is a special thermostat in a LT1.
That special thermostat is designed to close one coolant path when it opens the other, and you never want both coolant paths open at the same time -- without a thermostat, both coolant paths are open all the time.
One coolant path directs coolant through the radiator; the other coolant path directs coolant to recirculate through the heads/block without going through the radiator.
The idea is:
When the engine is cold, the coolant recirculates through the engine to prevent hot-spots without going through the radiator.
When the engine is warm, the coolant goes through the engine and then to the radiator for cooling.
Without a thermostat:
Some of the coolant circulates through the engine without going through the radiator.
Some of the coolant circulates through the engine and goes through the radator.
The coolant that doesn't go through the radiator, does nothing to cool the engine.
The reverse flow LT1/LT4 is NOT like a conventional cooling system.
Tom Piper
But, with the LT1/LT4 "reverse flow" engine, it is COMPLETELY counter productive to run it without a thermostat.
The reason:
There is a special thermostat in a LT1.
That special thermostat is designed to close one coolant path when it opens the other, and you never want both coolant paths open at the same time -- without a thermostat, both coolant paths are open all the time.
One coolant path directs coolant through the radiator; the other coolant path directs coolant to recirculate through the heads/block without going through the radiator.
The idea is:
When the engine is cold, the coolant recirculates through the engine to prevent hot-spots without going through the radiator.
When the engine is warm, the coolant goes through the engine and then to the radiator for cooling.
Without a thermostat:
Some of the coolant circulates through the engine without going through the radiator.
Some of the coolant circulates through the engine and goes through the radator.
The coolant that doesn't go through the radiator, does nothing to cool the engine.
The reverse flow LT1/LT4 is NOT like a conventional cooling system.
Tom Piper
And be sure to check the front of the radiator between the condenser and the radiator for debris that gets sucked into this area.
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Thread Starter
Heel & Toe
Joined: Oct 2003
Posts: 15
Likes: 0
From: pinellas park fl.
Originally Posted by Tom Piper
If a '93 is like a '92, the primary fan should come on at about 221*F rising and the seconday fan should come on at about 233*F rising.
And, since the heads get the coolant coming from the radiator first (unlike a conventional system), the heads run at least 15 degrees cooler than the digital temperature readout is reading, because the digital temperature sensor is located where the coolant is the hottest on its way back to the radiator from the engine.
Tom Piper
And, since the heads get the coolant coming from the radiator first (unlike a conventional system), the heads run at least 15 degrees cooler than the digital temperature readout is reading, because the digital temperature sensor is located where the coolant is the hottest on its way back to the radiator from the engine.
Tom Piper
I started the car and let it idle. the main fan NEVER turned on. the secondary fan came on at 235. so now i see the problem.So i'm still lost.
Safety Car
Joined: Feb 1999
Posts: 3,504
Likes: 4
From: Mexico Beach FL
Originally Posted by fatboytm
I started the car and let it idle. the main fan NEVER turned on. the secondary fan came on at 235. so now i see the problem.So i'm still lost.
The fan relays (there are two, in '95 I think three) are mounted on the left side of the fan shroud.
I think the relays are identical, so try switching them and see if the other fan works.
I think the fan relays are fed power from a fusible link behind the battery.
Tom Piper
Last edited by Tom Piper; Jul 11, 2006 at 02:37 PM.
Burning Brakes
Joined: Nov 2005
Posts: 848
Likes: 1
From: 1992 LT1 6 speed Cayman Islands
The first step is to test the wires that go to the main fan. Test the green one for current, if there is current then test the other one for continuety to ground.
1) If there is no continuety to ground, clean the chassis ground that is located on the drivers side of the frame next to the radiator.
2) If there is current and and ground on these wires your fan is burnt out and will need to be replaced.
3) If there is no current on the green wire, the problem is a bad current connection, a broken wire, a bad fuse, a bad fusable link, a bad coolant sensor, ECM , relay or bad A/C sensor.
Do the above tests at the fan wire and report back. If the problem is no current we will take you through the diognosis of the different supply circuits until you isolate the cause.
Good luck
Jerris
1) If there is no continuety to ground, clean the chassis ground that is located on the drivers side of the frame next to the radiator.
2) If there is current and and ground on these wires your fan is burnt out and will need to be replaced.
3) If there is no current on the green wire, the problem is a bad current connection, a broken wire, a bad fuse, a bad fusable link, a bad coolant sensor, ECM , relay or bad A/C sensor.
Do the above tests at the fan wire and report back. If the problem is no current we will take you through the diognosis of the different supply circuits until you isolate the cause.
Good luck
Jerris
Last edited by Jerris; Jul 11, 2006 at 02:38 PM.
Thread Starter
Heel & Toe
Joined: Oct 2003
Posts: 15
Likes: 0
From: pinellas park fl.
Originally Posted by Tom Piper
The ECM commands the fan relays to turn the fans on.
The fan relays (there are two, in '95 I think three) are mounted on the left side of the fan shroud.
I think the relays are identical, so try switching them and see if the other fan works.
I think the fan relays are fed power from a fusible link behind the battery.
Tom Piper
The fan relays (there are two, in '95 I think three) are mounted on the left side of the fan shroud.
I think the relays are identical, so try switching them and see if the other fan works.
I think the fan relays are fed power from a fusible link behind the battery.
Tom Piper
Burning Brakes
Joined: Nov 2005
Posts: 848
Likes: 1
From: 1992 LT1 6 speed Cayman Islands
Originally Posted by fatboytm
I just switch them and the main fan (Driver side) never came on. The 2nd.fan kicked on at 235.
Now we know that the relay is not the problem. Do the tests I suggested above so that we can decide is the problem is the ground (one step, easy to do) or the current supply (many potential sources of the problem) or the fan itself (just replace the fan ti fix)
Finding tghe problem is not that difficult, you just have to be methodical and do one step at a time.
Jerris
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
On my 93 there is a fuse panel between the master cyl. and battery. In it is a large 40 amp fuse (2 of them) that feeds the fan.
In my case the motor was bad. I simply switched the plug on the relay and verified it. ie the other motor did not run.
IMO 253 is way too hot. At I believe it was 241 it would turn the ac off.
In my case the motor was bad. I simply switched the plug on the relay and verified it. ie the other motor did not run.
IMO 253 is way too hot. At I believe it was 241 it would turn the ac off.
Burning Brakes
Joined: Nov 2005
Posts: 848
Likes: 1
From: 1992 LT1 6 speed Cayman Islands
Just a quick correction........ I just looked at my 92 FSM and I see that the green wire to the relay should have 12 volts whenever the key is on.
ALL of the switching for the fan is done through the ground circuit so keep this in mind when doing the tests I perscribed above.
Jerris
ALL of the switching for the fan is done through the ground circuit so keep this in mind when doing the tests I perscribed above.
Jerris
Thread Starter
Heel & Toe
Joined: Oct 2003
Posts: 15
Likes: 0
From: pinellas park fl.
Originally Posted by Jerris
Just a quick correction........ I just looked at my 92 FSM and I see that the green wire to the relay should have 12 volts whenever the key is on.
ALL of the switching for the fan is done through the ground circuit so keep this in mind when doing the tests I perscribed above.
Jerris
ALL of the switching for the fan is done through the ground circuit so keep this in mind when doing the tests I perscribed above.
Jerris
I just got done un-plugging the fan motor and putting my meter leads in the plug itself and i started the car, at at 225 i had voltage. so i have power to the motor leads, so the fan must be bad.
Safety Car
Joined: Feb 1999
Posts: 3,504
Likes: 4
From: Mexico Beach FL
Originally Posted by fatboytm
I did check the fuses.
I just got done un-plugging the fan motor and putting my meter leads in the plug itself and i started the car, at at 225 i had voltage. so i have power to the motor leads, so the fan must be bad.
I just got done un-plugging the fan motor and putting my meter leads in the plug itself and i started the car, at at 225 i had voltage. so i have power to the motor leads, so the fan must be bad.
However, in a case like this, I like to confirm the problem before taking a fan out.
It takes very little current to drive a voltmeter (microamps) and a lot of current to drive the fan (probably 5 amps or more).
So, to make sure, I would use some jumper wires (just momentarily) directly from the battery to the fan motor terminals and see if the fan runs.
If the fan doesn't run, you've confirmed the diagnosis.
If the fan runs, you're not done trouble-shooting.
Tom Piper
Drifting
Joined: Sep 2005
Posts: 1,867
Likes: 3
From: Pasadena Maryland
Whenever I do that, run wires from the battery to a device I always put a fuse in EACH wire. I made up a set just for troubleshooting. I also made a cigar lighter plug with fuses on the positive & negitive for probing around.
Safety Car
Joined: Oct 2002
Posts: 3,991
Likes: 0
From: Phoenix AZ
Originally Posted by Jerris
And be sure to check the front of the radiator between the condenser and the radiator for debris that gets sucked into this area.
Drifting
Joined: Sep 2005
Posts: 1,867
Likes: 3
From: Pasadena Maryland
Originally Posted by Tom Piper
It takes very little current to drive a voltmeter (microamps) and a lot of current to drive the fan (probably 5 amps or more).
Tom Piper
Tom Piper