How bad is it? Engine problems 996

[Ingenjören]

Hello.

I'm the happy but concerned owner of a 1999 C4.
I bought it this Winter from the previous owner who had just finished the repair and overhaul of the Engine due to a seized con rod.
According to previous owner the job was done by an authorized workshop and that two pistons and connecting rods was replaced together with all the bearings, seals and gaskets. All done by the book. They also made an upgrade with an improved oil pump. Intermediate shaft bearing was also replaced.

When I was out driving the oil pressure was suddenly gone. Stopped the car. I let it cool down a bit and started. Pressure was low but OK. Got it back to the garage.
Investigated and decided to replace the oil pressure sensor. Got a new one which was easily replaced(30 minutes including a coffee).
Engine started and the oil pressure was OK but not more. Got worse once the Engine got warm.
Decided to go for my first oil change and this is where the not so funny part start.
I found the oil filter cartridge to be rather contaminated with metal particles.
Found none on the oil plug but this is a bit worrying.
Anyway. I made sure that all the oil was drained out and filled up with 5W50. Started. Waited a second or two and then read a clear 5 bar on the dash.
Still I could hear a knocking noise from the Engine. Switched off and filled up to max and started again. Could not hear any noise.

Now(sorry for the long story) I don't know how to proceed.
I'm guessing that if I do an oil change again in a week or two and if I then find even more glitter/metal in the oil that the Engine is in a desperate need of yet Another overhaul. Still I fear that during this week or two I will damage the Engine even more.

What is interesting is the fact that the Engine runs just fine and without any metallic knocking noise or similar.

What is your experiences? Is there any easy way to check? Can you access the moving parts in the Engine witout completely dismantle it?
What would you do?


Best regards

/Fredrik

[BYprodriver]

Dear soon to be unhappy 996 owner, if the con rod seized on the crankshaft journal, it wears the crankshaft enough to cause excessive clearance between the crank & it's bearing insert. In order to restore proper oil pressure at operating temperature you need to replace that crankshaft & rebuild the engine. Before you start the engine again, remove the oil filter housing & filter, then stick your finger into the hole where the filter attaches. There is probably metallic particles there & in the filter.

[Sapientoni]

I just rebuilt a Cayman 3.4 with #1 rod bearing spun. I replaced one rod and two pistons. I also replaced one main bearing pair, as it had received a bunch of the flaking from the rod journal. I plastigaged everything else and miked what I could. Had to have that rod journal "metalized" back to stock as they don't make undersize/oversize bearings for these animals. It took months for the crank to get back. I learned a nearby tractor repair/machine shop is the reputed best place to take any crankshaft and has quick turn around. Mine is running sweet at present. I have a few used rods and pistons left over at a decent price if you need them.