496ho oil pressure dropped
 

Hi does anyone have any ideas why my 496 would suddenly drop its oil pressure after running at 50 mph.
Was running about 40psi few minutes previuosly then I just increased the speed a little from 40 to 50 ran a few mins then heard the lifters clattering. Looked at oil pressure (15 to 20 ish) as I backed throttle right off to idle pressure dropped to nothing. No alarms came on.
Got a tow back and had a brief look. Cranked engine on starter no loud knocks, then started at idle briefly, now with oil having cooled a little oil psi just below 20, top end clatter still there but less than when it first happened.
Oil levels all good and new oil.
Have recently had sump off to clean up and do some paint work due to extenal corrosion also replaced crank seals but not done anything that I'm aware of that could cause any internal probs with engine???

Any advice or ideas?

Thanks in advance
Simon

Did the water temp go up a lot? Lack of water flow would cause the oil temp to go up a lot, thinning the oil.

Oil pick up in the pan could have came loose or cracked when you had the pan off.

Thanks for responding guys all ideas appreciated.

Oil pickup intact
Water temp stayed at normal running temp.

Have progressed a little since posting. Pulled engine out and dropped off pan. Not torn down any further yet but have found metal debris in pan some of the larger bits are about 1/2 to 3/4" long very thin and hard silver metal. Not sure what a cam bearing would look like if it had spun and detroyed itself. Would like to try work out where this is from before diving in for the full strip down.

Sorry to hear it's not something simple. You'll have to check the rod and main bearings too.

Piston skirts? What ever it is doesnt sound like good news

What really seems awesome to me is that you actually caught it before it totally exploded.

I would not be so lucky..

And if it were mine with metal in the pan, there's no reason not to strip it now. You'd wanna make sure you got all of the meal out of everything. Just my 2 cents.

Best of luck!

Take it apart for sure

Started stripping out, found no. 5&6 big end bearing obliterated.
Scoring on all remaining ends and mains. Quite a lot of corrosion on all bearings in bottom end. Crankshaft quite grooved around 5&6.

Just about to start stripping out cam and top end.

Motor had loads of external corrosion low down and a waterline around it just above sump level. Spent loads of time a month or so ago doing a big clean up and respray. Wish I had looked a bit deeper now while sump was off.

Although I'm not really looking for a horse power up rate (don't have the budget for anything big) thinking of contacting Raylar to see it's worth doing anything crank and piston wise to strengthen the engine as I am looking at a new crank or crank repair at this stage as a minimum. Would be interested in anyone’s thoughts on this.

500 EFI and your done!!