Ok so I over heated while in the drive through and so I pull into the lot and shut it down. Steam builds up and leaks from under the fill bottle or tank cap.
Check my fan it works but it’s not getting power.
My question is the air pressure build up. I have an air leak in the cooling system right or coolant wouldn’t boil and leak back into the tank… it’s over heated couple times and it didn’t shoot everything back out from the tank like this time.
There may be a leak causing the boil over but that should be the second thing to tackle as in this instance it sounds like the boiling over is either a symptom of another problem or a minor problem made worse by a bigger one.
Since you’ve confirmed that the fan is not working you should fix that first then see if you’re still overheating or boiling over. If you are then its time to look for leaks and check your thermostat.
listen to colin and once you get your fan working as it should, do a pressure test on your cooling system and any weak points will be exposed.
Two more thoughts would be:
- try a new radiator cap
- What’s the age of your radiator?
if your fan isn’t kicking on, you’re going to overheat and the cap is going to release pressure into the overflow tank. if that’s the case, everything’s doing what it’s supposed to…except the fan! haha. if you’ve tested the motor, it’s time to test the rest of the circuit. disconnect the fan switch. KOEO, loop the switch connector pins using a cotter pin or suitable supplement. if the fan kicks on, circuit is good and the switch needs replacing.
i hope it’s a 92 engine! haha.
it wouldn’t hurt to test the rest of the system as well tho, even if the switch turns out to be the problem. you can find cooling system pressure test kits for cheap. i picked mine up for 40$. mityvac i think. comes with all necessary adaptors for testing the system and caps. even for ld diesel trucks! haha. but yes. never just simply replace a cap and assume it’s gonna work proper. you’d be surprised at how many new caps you’ll have to go through, when actually testing them, that will not vent or hold pressure to the specification on the cap. basically, it never hurts to test. and a pressure tester will be vital in pinpointing any future leaks anyways
I tested the fan and it works fine its just not getting power.
How do I test the fan relay? And how can I verify getting power?
what year is the car? just loop the fan switch. if the fan operates, the rest of the circuit is good and the switch is at fault. use a cotter pin to jump the 2 fan switch pins together at the connector.
all the fan switch does is complete the circuit when it reaches its specified temp. by looping the pins you are completing the circuit, essentially doing what the switch does
It’s a 91, what other sensors or switch can I test replace
I’m still not following you how to test the relay. I need to follow the color spec wires.
91 eh? that sucks. the fan switch is at the back of the block. up near the oil filter. it will have a rubber boot (or should), covering 2 wires. all you have to do is loop those 2 wires with the key on. if the an engages, the switch is bad. you can test the relay. but this method tests the relay, and the entire circuit up to the switch and would confirm if the switch has failed. which is fairly common
Has it been your experience that the switch is a common failure point? My experience has been the opposite, I’ve never seen a failed ECT switch but have seen numerous faulty fan relays.
tbh, no. and the one i did was a b18b
i just prefer testing at that point because it involves the entire circuit. in this case the relay is much more accessible though. and judging by the failure rate you’re explaining, maybe a better place to hit. op, maybe a better idea to remove the relay, apply power and ground while checking continuity across it
So I finally swapped in a used good engine harness and even heat shrink most wires and reconditioned it.
No cel but the ecu read 6 blips pause.
The Engine Coolant Temp Switch. I’ve noticed it wet outside and inside the plug with a clear oily film.
I’m going to change it later today I’ll keep you posted.
Ok so I changed the coolant temperature switch under the distributor and the ecu still reads #6.
What’s the next step?
Fan still doesn’t turn on
Wait, wait, wait, lets back up just a second here. So your car is throwing a code 6? When did this start? You never mentioned this in your first post and this is a very important piece of information. Have you reset the ECU?
Regardless, the big thing that needs to be pointed out here is that the code 6 is NOT related to your ECT Switch, it is related to your ECT Sensor. Although they have similar names and many people often incorrectly interchange the names they are in fact very different devices doing very different things. The ECT Switch is only there to help tell the fan(s) to go on when the coolant temp is over a certain temp. The ECT Sensor is the device that tells your ECU the temperature of the coolant. There is also an ECT Sending Unit which is the device which sends coolant temp info to the gauge in your gauge cluster.
Your ECT switch is located on the back of your block since your engine is a 91. The ECT Sensor and Sending Units are located on the side of the head.
I would not have simply replaced the ECT sensor because of the code. The code doesn’t 100% mean that the problem is a faulty sensor, it just means there’s a problem with the system - it could be wiring or a faulty ECU. My suggestion would be to slow down and really think through this process more - this is best done by following the troubleshooting procedures in your Helms manual. There will be one procedure to test the cooling fan system and another to test the ECT sensor system. If you go through both procedures you should be able to find the root of your problem.
Yeah sorry I got caught up in to deep that I forgot to mention the code.
And I did realize I changed the wrong sensor also.
Don’t get since I just replaced it 2 years ago. I’ll do it tonight. Asap.
scrutinize the connector and wiring close to it. it’s location, under the distributor, makes it inherant to poor connection and broken wires/sheathing due to oil contamination. however, it shouldn’t be the cause of the fan not coming on, as the ecm does not control fan operation. but regardless, must be resolved
Ok so I p picked up the fan switch in the back of the block, I just changed it 2 years ago. After inspection I did notice it seemed burnt-out, the tips were charred. So I swapped it out, reset the ecu warmed up the car and boom.
Fan turns on.
It took me a new harness, new water temp and fan switch.
what about code 6?
and if the pins were charred on the switch, that can be a sign of high resistance. make sure the terminals for the switch connector are clean and tight. being that it is a coolant switch, they can be prone to electrolisis, so make sure the the connector pins aren’t turning a greenish color as well