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Quoted From dreamer2355:
Do the radiator fans work?
Thats seems most logical step to tackle next if you only overheat at idle.
Yes, they work, but they start at 95-96 celcius, the water never gets that hot. (boils at 100, or even more due to pressure and coolant)
I tried the fans this morning, i put a small cable between ground a speed 1, fan starts, same on ground to speed 2, fan starts.
(the sensor have 3 cables, ground, speed 1 and speed 2, the fans come on to speed 2 at 98-100c)
Sensor is changed 2-3 times to a new one.I think the relay is blown, going to check that today.
Byt, this issue with the fans cannot be the problem, its not the temperature that is my problem, but the pressure.Edit: The fans work if i force them, i have checked the relay now but its working.
Are you using the correct rated radiator/reservoir pressure cap?_x000D_
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Did you check for combustion leaks in your coolant?_x000D_
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Keep us posted.If the fans aren’t working correctly then it will overheat in traffic but not while driving down the highway. This video may also point out some other things to check that might help you.
Quoted From EricTheCarGuy:
If the fans aren’t working correctly then it will overheat in traffic but not while driving down the highway. This video may also point out some other things to check that might help you.Yup, i´m on my 3rd round on that video now 🙂
Great tips in that, i´m trying them one by one.Its not overheating, its just too much pressure, the water is below 92c/197f. Thermostat opens when it should. But all hoses are rock hard and plenty plenty pressure.
If you check my video, you can hear the air in the hose, almost sound like you empty a bottle water and the air gets in.I have soldered a special cable now so i can run the fans with a button, going to take a trip now with fans on, but cool air inside the car on the heater.
Can i use the compression tester to see pressure inside the cooling system? i have a old cap i can drill a hole into and epoxy a quick-connector to it?
I also found a screw on a hose under the wipers, some sort of bleed screw, but when i look at pictures on the web, my sits the other way around.
Also going to check this one, can it be a solution inside this so the water only can go one way maybe…I didn’t see you mention that you had done a pressure test on the cooling system, or performed a block test. The pressure is coming from somewhere, and it may unfortunately be from a bad head gasket. Although I admit I didn’t watch the video you made.
Some more testing
Let the car idle on the parking lot for almost 2 hrs, no problem.
Fan inside the car off, radiator fans never came on.
Checked water-temp, inside gauge said 93-94c , my IR said 91c, radiator was 90-96c depending on where i measured.Took it for a hour ride, highway.
Radiator fans forced ON
After about 10min i stopped and checked hoses, all was stone hard. So i had to put heat in the car to max,
When i stopped, i let the fans run for about 2 more minutes, but i could feel on the hoses that the pressure was climbing so i had to open the cap and release pressure.
Water temp around 92-93c
(relay for radiator fans kick in a 96c, so thats why they never start)Can it be a big air pocket that heats water around it to boling and that creates steam/pressure ?
I have turned the bleeder screw around now, didnt se any valve or anything stopping coolant from one or another way.
Made a complete bleede now trough this screw, it was farting for a half hour before it was just plain water coming out 🙂
Letting it cool down now and going out to see how the water level is later, i hope it just were the air trapped causing it.
I checked the compression on all cylinders again too, dry test, all very consistant.Did you pressure test your radiator cap or check for combustion gases in your coolant yet?_x000D_
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Did you do a cooling system pressure test with the appropriate equipment?_x000D_
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Compression tests do not always show cooling system failures.I have tested compression on all cylinders 4-5 times now, all numbers add up and no cylinder is down/up on pressure. Biggest difference is 0.4 bar
Head gasket was my first thought too, but no evidence of it except for the pressure 🙂I have NO white smoke, and do NOT loose any water (until i let water out due to the pressure release when i remove the cap)
No fault codes stored (just a error about my gearbox).
I bought a test-kit now to see if there is combustion gases in the cooling system, going to test this later when the kids are in bed.
Oil is good, and had been on the same level last 7 months. Nothing to say that is water in the oil, or oil in the water.
I have not tested the pressure inside the coolant system yet, i do not havethe right tools.
Going to a friends garage tomorrow and he have stuff to check it properly.Coolant system checked for CO, no gases in the water or the steam/system at all. 0.00 on the tool.
(its a tool for heavy duty machines, but he said it read even the smallest particle on regular cars too)
Didnt use my kit i bought when my friend had a real tester in his service truck 🙂Took a run again to the store, aprox. 20min drive, when i got home it was pressure again, let it out and went in again.
I just need to open the cap for 1 second and close it to release the pressure, sometimes i need to repeat it.I´m getting crazy about this 🙂
Tomorrow we are going to pressure-check the system to see what pressure we are talking about, and pressurize the system to see if it leaks somewhere.One more video, this is whats happen when i open the cap to the coolant system.
The water dont go up to the cap, but trough a sensor in the bottom. I think its the level-sensor.It seems that you’ve ruled out a combustion leak as well as some other things, perhaps it’s as simple as a problem with the radiator cap. It is after all responsible for the pressure in the system. I’d recommend an OE cap for that vehicle as German cars can be picky like that.
Cap is changed, no difference.
But, i tried now to force the fans to start, connection positive and negative cables to each other on the back of the thermo switch, and the fans started!
I know that the thermo switch is good, i have measured it in boiling water.This tells me that the radiator is glogged and warm water doesnt reach the switch, so the fans starts.
I think to change to my new radiator is a first start 🙂I don’t know if you have a problem if I’m honest. When you say you have too much pressure in the system what do you mean? How did you measure it? You don’t have an overheat, the only symptom seems to be a bubbling sound inside the dash and some of the hoses. Firm hoses are actually normal, it means the system is functioning properly.
There are really only 2 things I can think of that could cause ‘too much pressure’. Air in the system, a faulty cap, or a combustion leak into the cooling system. I know you say you’ve done compression tests but I’ve seen plenty of head gasket failures that didn’t show up on a compression test, therefore I like to use the method in the video I posted earlier. That said if you don’t have an overheat I don’t think a head gasket failure is likely. If it were me I’d be bleeding the cooling system and if all was good there I’d move on. Don’t look for a problem where there isn’t one.
If i dont let the pressure out after stopping the car, i blow a hose or water starts pressing out in the bottom of the overflow tank (connection to the hoses).
But not any more, i have blowed a hole in the radiator now so i dont need to let pressure out any more 🙂
So i need to change the radiator anyway.Thats enough for me that pressure is really high. On my other Audi S4 from 94 (same body, turbo engine) and that hoses are not so hard.
I will check your video once more and do the other test to see for sure what it is 🙂
Going back to my buddys work again to see that gas sensor once more and run it a little longer this time.
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