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forged internals? are u sure ur not getting piston slap cause by cold forged pistons and goes away when they expand after engine heats up? sounds kinda like a diesel engine...but the best u can do is add an oil pressure gauge and make sure ur oil pressure isnt too low...

 

you probably have clearances that are to loose on the bearings. or if you use forged pistons they tend to do that if the clearnace on them is to big also. try using a thicker oil like 10-40 or if that doesnt work try 20-50. these motors need a tight/factory clearance to run 10-30 or 5-30.

 

Yea it has forged pistons and i guess that's would could be happening, b/c after the first startup it dosen't do it anymore. Is it normal for the piston slap on cold forged pistons? Why did it only start happening after i switched to fully synthetic oil? it didn't happen when i was using regular cheap oil.

 

Why did it only start to happen after i switched to fully synthetic oil? I'll try some thicker fully synthetic oil on my next oil change to see if it fixes the problem.

 

can u give us some oil pressure numbers?

 

Im goin to put the guage in when i get time and i'll post the #'s, I think it's just normal for forged pistons to do that on cold start ups or maybe im wrong

 

used a mechanical gauge it reads accurate.....

 

I know this is 7 years after the last post on the subject but my 2.3 CL does the same thing (it has 252,000 on it but I replaced the oil pump while doing the timing belt & water pump figuring it might be the culprit). After doing this to no avail, and until I have time to pull the oil pan and plastic-gauge the bearings, I decided to try something to nurse it. I bought a non-chip key and I crank the engine until the oil light goes out (usually about 15-20 seconds). Then I put my chip key in and start it. No knocking at all now at cold startup. And I still run it to 5,000 rpm sometimes and it's relatively quiet. Shame no-one has come up with a definitive solution to the problem but I really believe it's a rod bearing. After a month or so of doing this I decided to change from regular synthetic to Shell Rotella synthetic 5 w 40 (yes it's diesel oil). Now I only have to crank it for 10 seconds in the morning or after it sits for a couple hours. Hope the non-chip key idea helps someone. Cold oil pressure is 60 at idle and 80 above 1000 rpm. When hot, the oil pressure is 8 at idle, 11 at 1000, 20 at 1500, 28 at 2000, 38 at 2500, 42 at 2000 and 52 at 3500. Don't know what it's supposed to be but it seems normal across the board except just a little low at idle when it's hot. I have not been able to find a spec on the oil pressure.