Magnetoz

So I'm looking at buying a busted 96 A4 that recently got a timing belt change after a locked up water pump. Owner says the belt split but didn't come off. Now it cranks sputters but won't start. I've done the TB on the 30v a couple times. Could there be more serious damage to this engine or possibly a botched repair job. I figure improper timing could prevent the car from starting.... And i don't believe the repairs were done by an Audi mechanic.
I had a 12v before for about 4 years but did virtually zero work to it. How much different is it from the 30v in my avant?

DaveInSaltLake

the 12V has a single cam in each head and only a single cam position sensor. The 30V will run with one bad CPS....the 12V won't.

Most of your 30V troubleshooting skills will apply to the 12V

--OOOO--Audifox

Do a compression test on each cylinder. It' easy and it will tell you a lot. If you have equal compression on all cylinders, it's not the valves. could be timing belt on wrong or something else.

Magnetoz

I would guess not. I haven't checked codes. My laptop is down anyway. Is there any other way to check the sensor? Could i swap one out of my 30v that i know is good?

I'm wondering if from sitting the cylinder walls have been washed or flooded and just need some oil to build compression to get it to fire. I suppose if i check the compression, i'll also be able to ascertain the condition of the plugs as well.

I don't suppose the mechanic would appreciate me doing car repair in his parking lot... trying to determine if its worth $900 without having it towed. Maybe i could go by late and do a comp test after they're closed.

I've never had to do a compression test. Can i use the starter to turn the engine or should i crank it by hand? Pull the fuel pump fuse..?

Thanks for the suggestions so far.

DaveInSaltLake

I think the CPS would throw a code, even if it's not running....as long as it cranks over a half dozen times or so. I'd check for spark first. A 12V with a bad CPS won't spark. Look for a good blue spark...white or yellow is poor and would indicate a problem with the ignition system.

After checking for spark I'd check for fuel pressure by cracking a banjo on the upstream side of the fuel filter. If it sprays out then you're probably fine. If not, look at the fuel pump and fp relay.

Check the air filter...rarely are they truly clogged, but you never know.

Then, if you know you have the Big 3: air, spark, and fuel, there are only 2 things left.

Timing...the big 3 getting there at the right time and under compression.

Exhaust...somewhere for the byproducts to go. Make sure there's not a potato in the exhaust. Bang on the muffler and cats to see if they're plugged with broken catalyst or rusty baffles pieces.

Within about 10 minutes you should be able to narrow down the system that's giving you problems.