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View Full Version : overheating - need some help finding out possible causes



Tomm
11-27-2010, 12:23 AM
I had a leak in one of my coolant hoses. Replaced the part and now the coolant maintains its level, but the car engine overheats!

after I had put the new hose in, filled up coolant and blead the system i took the car for a ride to try it out. at first it was fine. I turned on the heat and it worked, warm air was comming out. but driving a bit more, the hot air turned cold all of a sudden, and at the same time i noticed that the water temp gauge was going up rather fast. I turned around and just made it home, but i'm sure that if i had driven some more it would have overheated badly.

Checked coolant level and it was good. touched the in-line at the heater core and it was cold. there is no leaks.

Wondering what the causes could be. Water pump? Thermostat?

My car: 96 2.8 12v

Nateness
11-27-2010, 12:39 AM
Your symptoms point to water pump.

If the thermostat had failed, then the heater core would remain hot throughout the duration of your drive.

Tomm
11-27-2010, 10:18 AM
Replaced the water pump as part of a timingbelt kit 23k miles ago... Could it realy fail that fast?

walky_talky20
11-27-2010, 10:31 AM
Usually not. Was the replacement a plastic or metal impeller water pump?

Are you sure you got all of the air out? Try idling it with the coolant cap off to see if takes any more coolant. And I think the 12V has few places to bleed the air out (bleed screws).

FNK
11-27-2010, 11:13 AM
Did you add the same coolant in your reservoir?
Different coolant dont mix, they clog the rad+engine... What color is your anti-freeze?

Tomm
11-27-2010, 11:18 AM
It was plastic, part of the Blauparts t-belt kit... seemed like good quality.

I've blead it at the heater core and that's the only bleading point i have found, been looking at the cylinder head without finding any bleader screws. At other occations after having flushed or otherwise emptied out the coolant, bleading at the core has been enough, usually having to top of after the first drive.

But yes, I will definitely try to blead it some more, assuming that new air might have worked it's way up to the core. Makes sense in a way... since the heat was working at the start but then not.

Thanks Walky

Tomm
11-27-2010, 11:23 AM
Did you add the same coolant in your reservoir?
Different coolant dont mix, they clog the rad+engine... What color is your anti-freeze?

Pink, always been pink, I even did a flush with pink about a year ago so it should all be pink. G 012 A8FA4 and G 012 A8G1G, those two fluids should be the same right? and mixable as long as they start with G012?

FNK
11-27-2010, 12:12 PM
Yes they should the same product, but different production number.

Run you car until working temps is reach, then shutoff the car and open the G12 tank (with caution), air bubble should come out if Air is in the system. (Do it another time if air was in) Alternative bleed technique

Else your water pump is most likely in need of replacement.

J Ozzie
11-27-2010, 12:18 PM
Ew dude id never get the Plastic one put in my car.. you always hear about them failing.. When i had the Timing belt done i had them put in the metal Impeller water pump.

Sounds like that thing isnt doing its job. Whens the last time you completely flushed the system?

Tomm
11-27-2010, 12:26 PM
flushed it 23k ago when i did the kit.

J Ozzie
11-27-2010, 12:29 PM
throwing it out there, what about sensors? is your coolant sensor toast?

Tomm
11-27-2010, 12:53 PM
temp sensor would be working because the gauge is working fine.

The hose with the bleeder hole is acting wierd on me now. it's all slippery after the bleeding and slips way to easy. no matter how hard i tighten the hose clamp, you can still slide it easily and it still bleeds.

J Ozzie
11-27-2010, 03:42 PM
True, Any chance you get get someone to scan for you?

walky_talky20
11-27-2010, 09:30 PM
On the 12v, there should be a coolant bleed screw in the coolant hard pipe below the coolant reservoir. Filling procedure from bentley is as follows:

- open bleed screw and pull back heater core to expose bleeder hole
- fill coolant in reservoir until coolant flows out of bleed screw
- close bleed screw (11 ft lb.)
- continue to fill coolant until coolant flows out of bleeder hole (heater core hose)
- Push on the coolant hose and tighten
- Close cap and turn heat on full
- Start car and hold revs at 2,000 for 3 minutes
- Continue letting the engine idle until lower rad hose is hot
- Recheck coolant level and fill as needed.

Tomm
11-28-2010, 09:33 AM
http://s951.photobucket.com/albums/ad352/davli_photo/?action=view&current=DSC02961.jpg

Look at this. I was wondering yesterday why the hose was behaving so soft and wobly. The plastic pipe is broken of, must have happened yesterday as i was moving the hose back and forth and retightening. The hose clamp was only holding on to the loose bit. The plastic is so brittle, I was able to crush the part that was inside the hose by simply pressing on it. I broke in to pieces and i was trying to have it fall out of the hose rather than into it, but a little piece might actually have fallen into the hose, I was only able to reconstruct 3/4 of the pipe section with the pieces i recovered.

How about that heater core. I guess i could cut the hose abit or file down the stopper ring on the plastic pipe to be able to slide the hose on further, but the plastic is really so brittle that it seems likely that it will break again. Possibly a new heater core huh... I cant believe Audi made the pipe out of plastic...

Tomm
11-28-2010, 09:34 AM
Oh, if the pic above doesn't work (it seem it doesn't), try this link

http://i951.photobucket.com/albums/ad352/davli_photo/DSC02961.jpg

Audi0s
11-28-2010, 01:55 PM
Wow that sucks. You can still save that, put the hose on as far as you can.Spray some wd40 or something to lubricate it. Try bleeding again as mentioned. I think the piece that broke is the out pipe, so that piece if probably in the motor somewhere.