Audi 100 overheats... - AudiWorld Forums

Notices

Audi 100 overheats...

Reply

 
 
Old 12-03-2017, 11:47 AM
  #1
Audiworld Junior Member
Thread Starter
 
Join Date: Apr 2016
Posts: 25
Default Audi 100 overheats...

Hi! Must try this forum for help. My 1992 100 2.8 q is making trouble. It overheats. I have change all that can be changed but it still gets hot. I have also bleed it in all possible ways. The fans dont kick in but they work when i hot wire them.
My last tought is the head gasket but it have no signs og such i can see. It sems like the water flow, sirculation is bad.
Any ideas?
Runehang is offline  
Reply With Quote
Old 12-04-2017, 03:38 AM
  #2
AudiWorld Senior Member
 
Join Date: Jul 2013
Posts: 849
Default

Could be that thermo switch in the radiator is defective..could be a blocked radiator..could be several issues including a thermostat. If the radiator is blocked..the upper radiator hose will be hot and the lower hose cold..that could be a defective thermostat too. How old is the radiator? Is the thermostat new? OEM? There is a lot of junk parts out there. Hard to do a diagnosis over the net with little information.
Rusty Spokes is offline  
Reply With Quote
Old 12-04-2017, 03:53 AM
  #3
Audiworld Junior Member
Thread Starter
 
Join Date: Apr 2016
Posts: 25
Default

Hi! Thank you for answering Rusty! The radiator, termoswitch, thermostat, waterpump and the multiswitch was new i july this year. I also took out the waterpump and thermostat to inspect it last week.
I suspect this problem came when i replaced the G62 and air got in the system. The engine runs great, no smoke, no oil in water and no water in oil. Strange.
I took it for a test drive friday and tought i solved it. All was fine for 15 mins but down a steep hill the temp climb to about 110 degrees. The fan works when hot wiring but did not came on
Runehang is offline  
Reply With Quote
Old 12-04-2017, 07:33 AM
  #4
AudiWorld Senior Member
 
Join Date: Jul 2013
Posts: 849
Default

The fansnot coming on when hot sounds like your problem. When you say "hot wired" the fan switch..did you bridge the connector when the thermo switch plugs into? If so..do you have two speeds? Will the fans come on with the A/C on?

Here is a link that talks about checking the fan switch. It is in the most part applicable to your car. You may not have some S6 parts like the after-run relay..or maybe you do.

SJM Autotechnik, Audi Technical Service Repair Information

And some information on bleeding the cooling system..the pictures are gone though.

http://forums.quattroworld.com/a6100/msgs/339.phtml

Last edited by Rusty Spokes; 12-04-2017 at 07:36 AM.
Rusty Spokes is offline  
Reply With Quote
Old 12-04-2017, 07:58 AM
  #5
Audiworld Junior Member
Thread Starter
 
Join Date: Apr 2016
Posts: 25
Default

Hi! I am greatfull for your help.
Yes the fan works at both speeds when i bridge the connectors. And no it wont come on when i turn on the ac.
I must find out where that power comes from. Is it the multiswitch?
And they should kick in about 90-95 degrees?
Runehang is offline  
Reply With Quote
Old 12-04-2017, 12:37 PM
  #6
AudiWorld Senior Member
 
Join Date: Jul 2013
Posts: 849
Default

If the fan works when you bridge the thermo switch..then the 12v power, grounds, resistor plate and relays are working. Sounds like a bad thermo switch or the radiator (plugged up) is not allowing hot coolant to run over the switch. Could be air in the block too. That keeps the coolant from flowing. If you confident the radiator is good..get a new thermo switch. Get a Wahler 251959481K which is a slightly cooler 87/76- 93/82 switch. The original switch is part number 191959481A 95/85-102/92 and is NLA.

The fans should come on with the A/C on..you need to investigate that problem..probably just a relay.

Here is a wiring diagram that might help with that.http://12v.org/urs/audi_c4_wiring_diagram.pdf
Rusty Spokes is offline  
Reply With Quote
Old 12-04-2017, 12:55 PM
  #7
Audiworld Junior Member
Thread Starter
 
Join Date: Apr 2016
Posts: 25
Default

Thanks a lot! Been out now. Its snow and on summer tires i did not drive far but the car ran for about 30 min at idle. I also res it up for a long time. The temp was steady at 90gC. I did bridge the fans in second speed. The termoswitch is new so that is strange. I will buy i new one like the one you recomend.
Runehang is offline  
Reply With Quote
Old 12-06-2017, 02:01 PM
  #8
Audiworld Junior Member
Thread Starter
 
Join Date: Apr 2016
Posts: 25
Default

After another test drive today, iím pretty convinced that the head gasket must be blown. The car act normal for a while, but it seems like the pressure is building up in the cooling system after a while.
So then i just have to do the jobb. But is it a change that the engine block also can have a crack or it that not so common? Its a AAH engine.
I thought about machining the heads and do all the gaskets.
Runehang is offline  
Reply With Quote
Old 12-06-2017, 02:30 PM
  #9
AudiWorld Senior Member
 
Join Date: Jul 2013
Posts: 849
Default

You can buy a test kit that will tell you if you have combustion gases in the coolant via the reservoir. I would try that first.
Amazon Amazon
Rusty Spokes is offline  
Reply With Quote
Old 12-07-2017, 05:36 AM
  #10
Audiworld Junior Member
Thread Starter
 
Join Date: Apr 2016
Posts: 25
Default

Originally Posted by Rusty Spokes View Post
You can buy a test kit that will tell you if you have combustion gases in the coolant via the reservoir. I would try that first. https://www.amazon.com/Lisle-75500-C.../dp/B0007ZDRUI

I will try that Thanks. This problem is driving me crazy. After bleeding the car yesterday, it worked all right for about 20 min exept from, ill think, the hot air in the cabin disapered driving Down hill. It came back drivin up hill.
Runehang is offline  
Reply With Quote
 
 
 


Thread Tools
Search this Thread
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -8. The time now is 02:33 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: