JonJ1998

Hi All,

I have a 98 A4 Quattro 1.8L with a BIG overheating problem. Yesterday I was driving and all of a sudden the car started to overheat. I immediately turned on the heat and the cars temp didn't increase as fast. I pulled over, checked coolant level(good), checked oil(no coolant mixture or anything suspicious with the oil), no coolant smell out of the exhaust, no leaks. Well I continue to limp the car home and I lose ALL heat inside the cabin. So the car is overheating very rapidly, and no heat in the cabin. After I lost all heat I rechecked everything I mentioned above including the passenger side floor for coolant and there was nothing(oil, coolant, exhaust, etc) and all was the same. Any thoughts on this overheating situation? I was told it may be a thermostat. ?? I should also mention that I checked the waterpump pulley for play and there was none. And again, no leaks under car.

Any insight as to what this could be will be extremelllyyy appreciated.

Thanks so much.

Jon

AudiMick

Sounds like a a circulation problem. Maybe a plastic water pump impeller broke or your thermostat stuck closed.


Usually the Audi OEM thermostats fail open though so this would have to be an aftermarket one.

600whpA4

My guess would be the water pump failed or you have a huge air pocket in the system.

CH46-E

I just had a similar issue with my 97 1.8 A4tq. After replacing the entire cooling system, much hair pulling and wall punching I found the system, especially after a short drive the temp would max out, the coolant would disapear. Yep, Disapear. It seems the cooling system was over pressurizing due to a leaking head gasket. The number 2 and 3 cylinder "once hot" was pumping hot gas out and sucking coolant into the cylinders. I found this by pulling the plugs imeadiately after a drive.

This was especially perplexing since performing a leakdown check of each cylinder lead to nothing irregular.

Bizzare issue, but definateley worth checking out. I was able to replace the head gasket in just a few hours. Luckily the head didint warp or crack.

Problem sloved the car now runs great!

If you need any assistance please feel free to hit me up.

JonJ1998

Well Hi all,

Bad nes. I replaced the thermostat and the problem still exists. Again, the cabins 'heat' is cold, and the temp of the engine increases as normal(upon startup) and just never stops at half like it used to. It just keeps going untill overheat!

Any help is much appreciated.


Jon

JonJ1998

Well Hi all,

Bad news. I replaced the thermostat and the problem still exists. Again, the cabins 'heat' is cold, and the temp of the engine increases as normal(upon startup) and just never stops at half like it used to. It just keeps going untill overheat!

Any help is much appreciated.


Jon

AudiMick

Like CH46-E said above, if you are losing coolant it's possibly the head gasket. Blown head gaskets are not common on our cars although it does happen.

If not you have a circulation problem as the coolant is not moving thru the system.

That's typically something like a broken water pump impeller or a blockage somewhere like the radiator. If someone put the wrong type of coolant in there it will sludge up.

JonJ1998

It's interesting you say that. I had an oil change done about a week and a half ago at a Meineke and they 'topped off all fluids'. Is it possible that they put in the wrong coolant? If so, how can I tell and what do I do in that situation? if I take it to a shop and have them do a coolant flush, will that potentially solve the problem?

Thanks again for your help!!

AudiMick

If they mixed G12 with green coolant it takes 5-6 flushes to get it out. Find out what coolant was used.

Unless they added a lot I can't see this happening that quickly.