4Driver4

Not possible. Tensioner adjusts tension on the fly.

Just Me

I would guess its a low-flow condition. Is that T-stat, blockage, or worn water pump? Dunno - but the t-stat is by far the most likely. As noted below, do some ,measurements, and look for coolant flow.

As to the idle condition - it will idle ok after years of sitting. It will idle OK with a O2 sensor gone - when cold its open loop, based on the spark and mixture maps. So you have a different problem - sticky throttle body, gummed injectors, etc. Who knows. Check injector flow.

G

Prospeeder

Seriously? Have you ever even fixed up cars youself? I have brought dozens cars 80s-90s that have sat for 5-8 years back with minmal effort. Sitting a year and a half is NOTHING. you read way to many horror stories that are not true.

Just Me

I will admit that if kept in a fairly dry environment, they can be fine.

I pulled a C4 out of a garage a couple years back, popped in a new battery, removed the plugs, sprayed in some mystery magic, turned the crank, and presto, it fired right up happily. The big issue is suspect is corrosion. And that's a BIG issue - but very, very dependent on environment. In or out? wet or dry floor? Heck, floor or dirt?

Fuel likely varnish. Oil completely off metal surfaces, but suck it up.

Lots of dangers - but well stored they can be remarkably easy to ressurect.

Like the VW is sleeper :-)

G

4Driver4

This isn't a priceless antique. It's a garden variety Audi...and Audi that mysteriously overheats and has sat around with the same fuel and oil in it for a year. I'm not saying it can't be repaired, just that it isn't worth it.

And yes, I can do a few basic repairs.

GTA_Driver

Indeed you can.