Seems like a tension issue, just purchased car in last 30 days. The prior provided proof of replacement within 25K miles and 2 years. Ideas?

 

Need more information.
Model year? USA or Euro?

 

1990 S4

 

OK, searched your history, 90 S4, do not start the car.
Define immediate overheat, please, more info.

Probably Immediate tear down ( not hard ). I did one last night.
Might have cheap waterpump / impellor broken and lodged in place. Must inspect before restart.

Should have taken a while, 10 + minutes, to overheat, though.

 

I was driving at the time the light came on, with in 120 seconds went to pinned temp and steam coming out of engine compartment.

 

Did you get any dash warning when it happened?
(Don't try to recreate, if you did)
What exactly happened?

 

Ok, am rushing to work, out of synch with your posts, sorry.

Car has a circulation mode whereby water circulates in the block a while before t-stat opens. When t-stat opens, it closes-off the bypass mode and goes through block and rad.

Usually will take time to heat up unless virtually no water to begin with, else, real failure like waterpump breakdown. I don't want to alarm you, but if pump is bad, belt is next within seconds / minutes. You don't want valves to crash, hence my seemingly overreacting warning. Methodically tear down and inspect.

 

The red light came on in the CPU display, indicating toothed belt warning then within 2 minutes complete overheat and pinned temp gauge with red light. How do you know when the belt fails?

 

On your car, with motor running, motor will stop / valves will have hit pistons and bent slightly, most all of 32 of them. Not happened to me, others will chime in with exacts.

If lucky, belt is still intact and timing is intact. You've got to pull the covers.

Here's a picture of an 86, very similar to yours, so you can see the routing.

Gold colored pulley is tensioner.
Smooth silver pulley just to right and just above it is water pump, driven with backside of belt.

 

If the belt failed, your car would not run. Count yourself lucky here. I think your water pump has siezed and since the timing belt drives it, it has affected the timing belt tension and given you the warning.

DO NOT DRIVE THE CAR!

If you drive the car, you may do one of several things:
1.Break the timimng belt - this is bad because the valves and pistons will colide and this will be very expensive.
2. You may over heat the engine and warp the heads and this will be very expensive.
3. If the water pump impellar has come off, you may grind it into the block and this will be very expensive.

If you have never done a timing belt and water pump job, and you take it to a mechanic, this will be very expensive. You can do it yourself and it will not be very expensive; around $600 - maybe more, maybe less depending on what you decide to replace.

Here's a good write up on the timing belt job. http://members.rennlist.com/pirtle/tbelt.html

 

Also possible for belt to slip some cogs, partial valve crash, that would cause overheat and might run a while.
Location?

Good, am glad Andrew has posted, felt like a lone emergency room doctor here with a line of patients in pain.

 

Delaware, my shop opens in 30 minutes. I am a new owner and just wanted to get an idea of issue before he gets a look. Just dug through paperwork at office belt replaced within 12K miles and 24 months. However no mention of water pump.

 

New and rebuilt, there have been issues w/ WPs. Call and talk to Rog100.

 

Similar symptoms happened to me when my waterpump siezed (except no warning light because I have none). I assume it could overheat so quickly because the pump was not running efficiently for some minutes prior?

Marton

 

If the car was already hot and running it could easily overheat that fast if the waterpump totally failed.