Knock and Low Oil Pressure

[TheDirtyBen]

I just replaced my lower intake gaskets on my 94 achieva 3100. prior to this, there was no knock and oil pressure stayed around 40 PSI, regardless of RPMs. afterwards, i now have a top end knock and oil pressure @ idle is around 10-15 PSI and sometimes drops into the low warning area. pressure also now rises and falls with RPM. i ripped it all apart, looking for screw ups on my part, and everthing looks as it should. thinking maybe the oil filter was restricting flow, i changed the oil and filter for a second time. still have the same problems. any ideas what the hell happened or how to fix my problems? btw, it just turned 176k miles and she's running strong otherwise.

[geoffinbc]

Why did you replace the gaskets? Was there coolant leaking into the oil? If so I would have to suspect that the damage was already done to the motor.

[TheDirtyBen]

engine has 117k on it. i know it's a problem area on the 3x00s and thought it was causing a performance problem that i miss-diagnosed. turns out the IAC and it's port needed cleaned. anyways, i've noticed that i have almost normal oil pressure upon cold start up. but it goes down as the engine heats up. also, i lose performance as the engine heats up.
finally, oil pressure does increase as i accelerate, but can get dangerously low sittin at a stop light.

[geoffinbc]

Sounds like there may have been some prior damage. If bearing clearances are too high then it would cause both your knocking and low pressure.

[RednBlack]

117 thou, or 176 thou? Low oil pressure and knock ain't good. Even if it has 10 miles on it. Either way,...Knock is bad. Damage is done.

[TheDirtyBen]

oops, 177k on the engine.

[RednBlack]

Sounds like there may have been some prior damage. If bearing clearances are too high then it would cause both your knocking and low pressure.

I agree. Time for teardown. Find out what damage is there. I suspect rods first, since it is a high RPM. Mains knock all the time. I suspect you rolled a rod bearing.

[TheDirtyBen]

well, if that's the case....i'm gonna have to just beat the piss out of it. i don't have ANY money to do repairs on it. and if i were to dig in that deeply, i would just assume to rebuild or replace it.

[RednBlack]

Crank kits are cheaper than a rebuild. Doesn't mean a lot of money. Time maybe...

[TheDirtyBen]

still, i don't have the money for that. i need to sell my mustang before i can do anything. and if it sells for enough, i'd rather just buy a complete 3400 and do the swap, or find someone whom will trade....mustang for a complete 3400!

[patgizz]

i'll give ya a complete 30k miles 2001 3100 for a mustang

actually not, mustang2's are fugly.

[TheDirtyBen]

well this one is fuglier. the car itself is in bad shape. however, it has a fresh 302 stroker w/ roller cam conversion and 760 Holley double pumper, and fresh AOD tranny.