[Smallblock454]

Hi,

OK - after some thinking. It may not restart directly after an AOS failure if the engine is hot and the engine has sucked in a huge amount of engine oil. But to get hydro locked, the amount of engine oil really has to be huge

Also if the AOS failed the engine would run rough at idle, because there is a leak in the negative pressure system of the engine case. And if cold it would start maybe badly.

So an easy test would be first to inspect the throttle body. If you find lots of oil in the throttle body that may lead to an failed AOS. Throttle body should be cleaned. Next would be to inspect the AOS (the AOS separates engine oil from intake air) and replace it.

You've said that the car has stand for some years. So maybe the diaphragm of the AOS decomposed while the car was not used for a long time (hope decomposed is the right english term).

Next would be to remove the coil packs and sparks. All sparks should look oily and burned and have a crust. If it's only one spark that looks oily or all sparks of one cylinder bank look oily and the rest looks OK, than it's not a simple AOS problem.

If all sparks look oily and crusted the engine should be turned over without sparks for 30-60 secs so the oil gets out of the cylinders. For a test you can try to clean the sparks with a copper brush – maybe it's better to replace them. Electrode distance should also be checked.

If you have the tools, i would do a compression test at this point (when spark plugs are out) - just to make shure every cylinder works properly.

Than i would drain the oil and check the oil filter. If you find fine metal debree or plastic parts in the oil filter (you have to cut it and roll it out), than there might be another problem.

If there is nothing conspicuous, put a new oil filter in fill up the oil and start the engine. It should run and i would say happy boxstering.

If you find a lot of fine metal debree or plastic parts in the oil filter (you have to cut it and roll it out), than there might be another problem.

In that case there is more than a failed AOS, so you should remove the oil pan and inspect for more debree. If there is more, you have to look where it's coming from. A failed IMS bearing can be the cause for it.

As you can see there are some steps to do to diagnose the reason for the failing. That can't be done in 10 or 15 minutes. So a mechanic will need some time to do it properly. And if it's a failed AOS the amount of money you have to throw into the car is much less than you have to throw in for a new engine. So i would recommend to diagnose everything very properly before doing any investment.

Hope that helps. Good luck!

Regards from Germany
Markus