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AJ97
12-22-2018, 07:35 AM
I have a 97 A4 2.8 v6 (12 valve) thatís been having more coolant problems again. when I bought the car 2 years ago the previous owner didnít take care of it, used universal coolant, slugged the system, heater core busted, radiator, thermostat, a lot of hoses, overflow tank, oil cooler and gasket. I managed to get all that done (and thatís just the cooling system!) and it was running okay until it was just leaking so much I had to constantly top off with water after every drive. Took it to a shop where they said it was a blown head gasket. I parked it in my garage all upset, taking it there I thought it was just going to be the water pump and timing belt items, 6 months later I decided I would try just that and replaced the timing belt and water pump and other various items while I was in there, cleaned it up really good too, there was about an inch and a half of sludge all around the engine, I spent about 3 days just cleaning it. I also changed out the temp sensor on the top passenger side hardline. It was running great with no leaks, but would occasionally overheat (to the middle of normal operating temp and 3/4) when the engine is idling after coming up to a red light or stop sign, Iíve noticed this only happens when the heater is off. The hot air from the core doesnít seem affected when it starts to overheat and will stay just as warm as it was before. Iíve tried bleeding the system many times from both spots, on the rubber hose and on the hard coolant line by the expansion tank. So Iíve just left it alone and always drive with the heat on, itís winter anyways so it works out. But lately itís started loosing coolant more frequently, and needs topped off a little every 1-2 weeks. I canít find the leak. the overheating seems to be getting more frequent and happens with the heat on now too.

Bull0914dog
12-22-2018, 08:19 AM
When my temp was rising at idle I found that the clutch for the fan was going bad replaced it and it's fine now.

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vrmm
12-22-2018, 09:41 AM
I can't see it being the hg no matter how gunked up it was. ^ that's a good place to start. Obviously finding a leak... Or is it burning it? You could put a switch in for your aux fan to run all the time. I'd personally keep it simple and cut the wires by the power steering resevoir and then to 12v powered by shoving a wire into something in the fuse box that's key forward only and ground the other side. I would've suggested burping in the first place but it sounds beyond that.

Blazius
12-22-2018, 10:31 AM
Overheating at stops ? You got air in system.

AJ97
12-22-2018, 10:44 AM
I can't see it being the hg no matter how gunked up it was. ^ that's a good place to start. Obviously finding a leak... Or is it burning it? You could put a switch in for your aux fan to run all the time. I'd personally keep it simple and cut the wires by the power steering resevoir and then to 12v powered by shoving a wire into something in the fuse box that's key forward only and ground the other side. I would've suggested burping in the first place but it sounds beyond that.


I checked the radiator fan, it comes on immediately after starting the engine and stays running. Even if I turn on the ¬ďAuto¬Ē mode on hot on the AC (the AC compressor is off the car, bypassed with a shorter accessory belt) it still overheats. The aux fan works fine, if I don¬ít put it in ¬ďauto¬Ē it¬íll automatically kick on from a cold start idling after about 10 minutes or so. From a cold start just idling it could run forever and never overheat at all. It¬ís only when driving and then coming to a stop on occasion that it does it. Checked for bubbling in the expansion tank, and there¬ís no bubbling at all. There is an oil leak on the passenger rear side of the engine, thinking it¬ís the cam plug and seal. So I ordered that. But that¬ís been leaking slowly ever since I got the car, I just top the oil off when it¬ís low. No foam in the oil. Doesn¬ít look like anything is mixing. I did order that one sensor in the radiator on the driver side, believe it¬ís the fan switch. But can¬ít get to it with the tools I have without removing the carrier. So I haven¬ít gotten around to that one yet. Should I try to bypass the heater core (had it bypassed for 6 months when I first got it due to the core failure, had no heat all winter in CO!!) and see if it still does it?

- - - Updated - - -


I checked the radiator fan, it comes on immediately after starting the engine and stays running. Even if I turn on the ¬ďAuto¬Ē mode on hot on the AC (the AC compressor is off the car, bypassed with a shorter accessory belt) it still overheats. The aux fan works fine, if I don¬ít put it in ¬ďauto¬Ē it¬íll automatically kick on from a cold start idling after about 10 minutes or so. From a cold start just idling it could run forever and never overheat at all. It¬ís only when driving and then coming to a stop on occasion that it does it. Checked for bubbling in the expansion tank, and there¬ís no bubbling at all. There is an oil leak on the passenger rear side of the engine, thinking it¬ís the cam plug and seal. So I ordered that. But that¬ís been leaking slowly ever since I got the car, I just top the oil off when it¬ís low. No foam in the oil. Doesn¬ít look like anything is mixing. I did order that one sensor in the radiator on the driver side, believe it¬ís the fan switch. But can¬ít get to it with the tools I have without removing the carrier. So I haven¬ít gotten around to that one yet. Should I try to bypass the heater core (had it bypassed for 6 months when I first got it due to the core failure, had no heat all winter in CO!!) and see if it still does it?

Not sure why the formatting did that!

walky_talky20
12-22-2018, 07:00 PM
Overheating and eating coolant? I think you might need a headgasket.



I'd suggest you do some easy checks to see if you have a headgasket failure:
- Does it smoke more than normal or does the exhaust smell funny?
- Pull your spark plugs out and compare them. Do they all match or are any of them super clean?
- Look inside the plug holes with a flashlight. Do all the pistons tops match or any of them super clean?
- Remove the coolant cap and put your nose there and take a big sniff. Does it smell like sweet coolant or does it smell like a tailpipe / actual death.
- Is the car magically making more oil as you drive it? Any weirdness coming back on the dipstick?
- Check the compression. Whatcha get?

Blazius
12-23-2018, 02:47 AM
tailpipe / actual death.



Lmao. I dont think its a headgasket failure. If there is one thing that doesnt break its the headgasket. But good points check them anyway.
If hes overheating at stops either his thermo doesnt open properly , but it opens enough to let some coolant go thru radiator and it cools somewhat while driving cause of pressure, or he is got a leak and air went inside the system. I had both of those.

AJ97
12-23-2018, 03:44 PM
Lmao. I dont think its a headgasket failure. If there is one thing that doesnt break its the headgasket. But good points check them anyway.
If hes overheating at stops either his thermo doesnt open properly , but it opens enough to let some coolant go thru radiator and it cools somewhat while driving cause of pressure, or he is got a leak and air went inside the system. I had both of those.
I donít think itís the HG either. When I took it to that shop about a year ago for the diagnostic, I had told them that it overheated quite a few times since Iíve had it (from all the various problems) from a busted hose, or part spraying coolant while driving or whatever the problem may be that time. So I think thatís mostly what they used to diagnose it. I donít think itís the thermostat because I replaced it 2 years ago when I first got the car (slide the timing belt forward a bit without removing it) and then also did the t-stat again when I did the timing belt about 6 months ago. Unless itís faulty part and isnít performing correctly. But I did get a failsafe thermo so if it ever does fail itíll lock in the open position. Iím thinking I still have air in the core somewhere. It just sucks trying to bleed it, because I loose so much coolant in the process and hate having to buy that stuff at $15 a half gal.

AJ97
12-23-2018, 03:56 PM
Overheating and eating coolant? I think you might need a headgasket.



I'd suggest you do some easy checks to see if you have a headgasket failure:
- Does it smoke more than normal or does the exhaust smell funny?
- Pull your spark plugs out and compare them. Do they all match or are any of them super clean?
- Look inside the plug holes with a flashlight. Do all the pistons tops match or any of them super clean?
- Remove the coolant cap and put your nose there and take a big sniff. Does it smell like sweet coolant or does it smell like a tailpipe / actual death.
- Is the car magically making more oil as you drive it? Any weirdness coming back on the dipstick?
- Check the compression. Whatcha get?

- Yes, I think itís smoking from the tail pipe more than normal. Itís pretty cold here (20-40F) when Iím driving, Iíll look out the mirror and see a huge cloud of smoke, looking at other peoples tail pipes they arenít smoking nearly as much as mine, I chalked this up to just being an older car and it being cold temperatures.

- Iíll have to do that with the plugs and check them when I have time, along with the cylinder heads and smell of the coolant tank. When I did the Tbelt I also replaced all the plugs with new NKG iridium ones.

-nothing weird looking on the dip stick, it also doesnít seem to gain any oil. Only looses it from that small leak I have. Constantly smells like burning oil, again most likely from that oil leak on the passenger side.


- Iíll also have to do this when I go to check the plugs on a day off, but I donít have a compression tester so Iím gonna have to pick one up somewhere or makeshift my own to check it, but Iíll check the compression of each cylinder once I can. To check it would I turn the engine over by hand at the crank, or should I turn it over with the key? (Honestly have never checked compression on my own, so Iíll have to do some research!)

Blazius
12-23-2018, 04:42 PM
Yes, its possible you got air in heater,and its a pain to get out, cause its the highest point of the car and you will loose a lot of coolant, exact same issue I had thankfully its more like 5 bucks/ liter here. Cheap thermos can fail at any point

Try bleeding the outlet port of the heater ( where the valve is ) slowly , giving it some gas, heater fan turned to max obviously, you will loose coolant but do it until its spraying out, then turn the fans down then do it more. Also the car will overheat while you are doing this so watch out and obviously try doing it while the engine is warming up.

vrmm
12-23-2018, 07:16 PM
Comp check is by key turning over like 6 times. I'd check the thermostat regardless. Mine only lasted about 6 months and somehow it was able to pop out of it's guide. I'd have heat but the car never fully warmed up. So I may not have had fun heat either. Burping is not really that difficult on our cars. Doing it on a Subaru is a pain in the ass. I've spent days... A4 I just dump coolant in and hardly do anything to burp it.