Hello everyone!


I have another one issue linked or not with this https://camaroforums.com/forum/93-02...ump-lt1-81354/ one.
Need your advice and suggestions!


About month ago when my water pump started to leak, exactly that day I tried to reach home and in a half of my way I visited a shop where I parked my car and switched off the engine. When I returned to my car I noticed that tha fan is still tries to cool down the engine and some coolant leak form the pump detected. I thought was that some air passed to the water pump and there is no any coolant around the ECT sensor and it gives to the PCM a wrong data about the temperature. So I drove to home and all the way fan was working. Then at home I switched off the engine but the fan was working too. I don't know how the fans work on these cars from the factory, but mine often work some time after the engine is switched off - it is about 1-2 minutes in winter and up to 5-10 mintutes in summer. But this time it is already passed about 20 minutes and the fan is still working. So I went to my fuse box and tried to pull out all three relays and also a 10A fuse. But the fan still worked. Then I decided to disconnect the battery and it helped. I gave two hours to the engine to cool down and connected the battery again - fan didn't start again. That was the last day I used the car.
Two weeks ago I tried to start the car but the battery was discharged to 6 volts and it was surprise for me.
Today I brought well charged battery to my car, connected it. Turned a key to the 'on' position but didn't start the engine and then swithed off again and pull out a key. And in 20 seconds the fan is started again and yes - on a cold engine that didn't run about a month. Also tried to pull out all relays and fuses - didn't help. Also a fuse for PCM.


I know that my car is '95 and has a three relay configuration when two fans work at low speed and at high when it needed. But my car has a setup when the second fan is operated by the manual switch and only runs when I switch it. But what can be with my first fan??? How to check it?


Within a few days I will receive my own built cable to read the PCM about what temperature is from the ECT sensor and what fan relays it commands to run or not. But I think something is wrong with the fan.




Thank you very much!

 

i would look to the temp sensor as you are, also for a short in the switch that has been added. it has to be getting power from someplace.

 

Thank you very much!


I will look at ECT sensor with Scan9495 as soon as my cable will return to me.
That sacond manual fan looks like normal because it still off and runs only when I switched it on, so its behaviour is good. The problem is with the first fan only.


Also I know that to switch fans on PCM gives them a ground, but I can't understand where the first fan finds a graound for it self. That is the question for me too.


So is that a PCM/sensor issue or an electrical issue?

 

if its not the temp sencor,have someone put some dye in the engine an check for gasket leaks ,?is the water light on or does it come on ,with my 95 when my fans came on at the wrong times it turned out to be a slow gasket leak ,took over a year to become a problem ,also pressure test could be done too,hope it just the water temp sencor though,but if its not,then do the other things if it keeps doing it

 

Thank you for advice!
But can you give me some clue about this process, cause I don't understand a relationship between fan behaviour and leaking gaskets in the engine? Is it about that some coolant goes from the cooling jacket into the engine? Please explain me if I wrong.


All I have leaking now is a water pump, that leaks from the weep hole and needs to be replaced, so I finished to use a car and ordered some parts. But noticed this strange fan behaviour and try to understand is it goes from water pump problem or is independent issue just started in the same time. My first tought was that ECT sensor went worn because of the air in the coolant caused by leaking water pump. For now I do not know what to think.


Thank you for your advice!

 

you can test the temp sensors with ohm meter. lt1 has two one for guage in the area of the number 1 spark plug and one for computer on the water pump.

 

cooling system info here 4th Gen LT1 F-body Tech Articles

 

Thank you very much.
My plans for nearest few days:
1. Test ECT sensor with multimeter and also with Scan9495.
2. Pop up the car and try to collate fans wiring with the diagram provided, cause my setup isn't stock.
This may give the answer to questions:
1. Why my fan can operate even with ignition key off?
2. Why all three relays and also 10A fuse doesn't do anything at all?
3. How the second fan manual control is organized?
4. Possibility of returning to a stock setup, where fans operate with two speeds together.

 

,[QUOTE=Novo;720597]Thank you for advice!
But can you give me some clue about this process, cause I don't understand a relationship between fan behaviour and leaking gaskets in the engine? Is it about that some coolant goes from the cooling jacket into the engine? Please explought was that ECT sensor went worn because of the air in the coolant caused by leaking water pump. For now I do not know what to think.


are your fans hard wired to the battery an then the temp sencor it could be i would think that would drain the battery, stock i think mine ran one fan then the other depending on how hot the car was stock. but my thing was this.it was very slow ,an it can be so slow that i did not get water in the oil at all,for some time in my case the leak was so slow it was not leaking in the
engine ,it was leaking on the outside of the engine in the back of the heads ,the test craby mentions ,also try running the car with no cap on the rad an if 10 minutes later you got a gyser of water it could be a slow gasket leak, use plain water ,with mine the dye was not spotted, then that test confirmed along with visable leak in the back of the heads ,but if its the temp cencor ,with mine i had been pounding on the 20 year old engine or was doing a burnout an my water light came on one day,then the water light shut off then came on an off at different times ,did not think much about it,until about 9 months later the light stayed on ,an my fans were acting up comeing on when it was cold ,i had also gone through 2 water pumps at the end too,hope its not the case with you,any good shop can find a leak in no time ,but when its that slow,then that test works,in my case i should have a picture of the burn out about 100 feet long an 10 feet high,as it cost me alot,so no more burn outs now ,mine was just a stock lt1 engine ,sounds like yours is beefed up,then i moved onto the 406. long story,but it could have been fixed

 

Fans can run with the car off if the temps are high enough. Engine temps continue to climb after the motor is off. If the motor is near over heating the fans will attempt to cool the coolant in case you attempt to restart it in the next few minutes.

You need to get your coolant system sealed up and holding pressure before you spend to much effort in chasing a fan issue. If you system will not maintain pressure you will get air pockets from the coolant boiling. If these air pocket blocking coolant flow to a sensor your fans will not turn on. I am not saying you don't have a fan issue only that testing a any part of the coolant system in a system that will not hold pressure can be a waste of time. Getting the system to hold pressure is step one in any coolant system repair.

FYI: Coolant system needs pressure to stop boiling.