Knocking on startup, time to scrap?

Mechanics are like a "box of chocolates"; you never know what's inside and inside some are a load of BS. IMHO; not worth messing with - if the problem was s-plugs, injectors, coils - Why does the engine smooth out after it warms up a bit. This could be indicative of an intermittent coil, but they usually stop firing when they get hot not cold.

Here's my internet diagnosis from what your describing above:
1. You do have a head gasket problem; keep an eye your engine coolant level
2. CEL usually pops up right away or a minute or two after a problem; but your head gasket problem may just be getting bad enough to turn on the CEL. An OBDII code reader will probably display P0300; misfires.
What tests did the mechanic perform to arrive at his conclusions?

This probably wasn't much help; but in today's used car market - I'm pretty sure you could find someone to take on this project car. As long as it's still running and you don't end up bending a rod before you pawn it off to someone else.

Good Luck

 

Tampa Hybrids does a head gasket job for like $2100 I think. That seems pretty reasonable and usually happens about 135K. I paid $1800 for a head gasket job on my truck and I felt it was a bargain considering it a V8. If you want to keep the car for another 10 years..I would research that. FOr sure a new EGR value, spark plugs and top end cleaning with sea foam.....or even a Piston soak might get you along for another year or two. But if you plan on keeping it long term. I would start saving for a Head Gasket job.

 

That would place the mechanic in the fairly honest category; but without diagnostic testing you can never be sure.

I would check the coolant level every morning before startup; to gauge size of head gasket leak. Use a marker, if you have to. DO NOT keep topping off the coolant level. If the coolant takes more than a couple of weeks to empty the bottle; and the car runs fine after 1-2 minutes warm-up - it's a fairly small seepage that opens up when the engine cools down. But your playing with fire, too much coolant in the combustion chamber will cause hydro-lock and will require an engine replacement. If I was going to keep the car; I'd lean more towards an overhauled/rebuilt engine, since it already has 225K on the clock. People had punched holes in the side of their engines; because of this. The car will be much more difficult to sell and you'll loose a lot of bargaining power; if it doesn't run.

Just my 2 cents.....

 

Probably the head gasket sealer (poured in by seller) starting to let go. Pretty much every 3rd gen for sale with over 150K is a can of worms.

 

That's a bargain in my opinion. I just got quoted $3200 (Lexington, KY).

 

Glad to hear it wasn't a total loss...

If your not making mistakes, your not living

Good luck in your future endeavors...