Bad knock, no oil pressure, help

[hatch]

Vehicle Info:

1990 Eclipse GSX
157,000 miles
Supposedly rebuilt 12-15k ago, head looks new/cleaned up really well compared to the block
Big 16G running 16psi
Stock fuel system
Stock SMIC
Turbo timer



Background info:

I bought the car for $1250, it ran fine except for a little blip of hesitation at idle every few seconds. Previous owner said the engine had been rebuilt with a new head about 12k miles ago. After owning it for a month or so I noticed a sound of like water trickling, couldn't really tell where it was coming from and didn't really think much about it.



How it happened:

On the cold days the car had started to want to boost spike up to close to 20psi and would hit fuel cut rather quickly. On one particular day I left work and proceeded to my usual interstate on ramp romp fest. I took it up to 80-90 and slowed back down, merged with traffic and was happy because the car seemed to have run its best ever, it pulled hard, and didn't spike boost and hit fuel cut. I leisurely drove up the interstate for probably 10 miles to my exit, car was fine at this point no odd noises, definitely no knocking, however I wasn't paying attention to the oil pressure at this point so I don't know what it was doing. I exited off and came to a stop at the red light, as soon as the light turned green and I gave it some gas...KNOCK KNOCK KNOCK. I limped it home (1-2 miles) and on the way noticed the oil pressure. When I got home I turned it off, but due to the turbo timer it ran for a little while, at this point I noticed that at idle it didn't knock at all, but if I blipped the throttle a tiny bit it knocked.



Where I'm at now:

The car is sitting in my garage, I'm transporting it up to my dad's house (he has a nice shop) this weekend. I haven't done any kind of tests on it or anything at this point. What are some things that could have happened? What should I look for? We are pretty much planning on pulling the engine at this point and performing a rebuild. But could it just be the oil pump or oil pump seals or something along those lines? With the knocking though I feel like I have probably bent a rod, but the 6-bolt rods are supposed to be pretty stout. I guess I could have floated a valve and smacked a piston, but whats throwing me off is the fact that it doesn't knock at idle.

Thanks, any input is appreciated, I just want some ideas of what to look for once we start working on it. I have already gotten the Chilton manual and done some reading, but this will be the first time I've done any major kind of engine work.

 

[BISHILVR]

I would look for a spun rod or main bearing, also if you have balance shafts there is a chance at a spun balance shaft bearing. If the balance shafts have been removed then the balance shaft bearing may not have been installed correctly to block off the oil supply to the balance shaft, or may have come loose and fallen into the oil pan. First off pull the pan and look into the bottom of it to see if you can find anything laying in there.

 

[Defiant]

My nickle's on a lost rear balance shaft bearing.

 

[hatch]

Ok, so if it is a bearing (rod, main, or balance shaft) and I ran it without any oil pressure for up to 10 mins at the most, what else could have been damaged?

 

[FORMONTOYA]

No oil pressure for 10 minutes? It would be hard to believe that you allowed the engine to run that long with all the noise it would have created, even at idle.

Oh well, you'll at least have the motor out fixing the first issue, time to look at ALL the bearings, rings, cam lobes, etc.......basically time for a "bare block" rebuild if that's the case. Which would really be the case (for me anyway) with a bearing failure.

 

[BISHILVR]

My nickle's on a lost rear balance shaft bearing.

Good call,

 

[hatch]

I don't really know when I lost oil pressure...if it was after the WOT romp then it was about 10 mins...but there was no noise on the interstate...so if it was no oil pressure after I exited the interstate then it was only no oil pressure for 2-3 mins. I kept the RPM under like 1500 after I exited the interstate.

 

[Defiant]

It's scrapped. Takes about fifteen seconds of oil starvation to kill a plain bearing.

 

[BISHILVR]

^^^ I love Defiants optimism .

 

[Karma]

It's scrapped. Takes about fifteen seconds of oil starvation to kill a plain bearing.

Not 100% true. An engine had the main bearings installed backwards. So the oil feed holes were blocked, the engine ran for 20 minutes with no hesitation. (diesel) But thats very rare. They usually last for a few minutes. No oil pressure sounds like a bearing somewhere. drain your oil through a cloth and if there are any filings it was a bearing. If you did spin a main its possible to get away with an over size bearing. Cross your fingers. And don't turn the engine over till you know what happened.

 

[BISHILVR]

^^^ Correction, that would be an UNDERSIZED bearing.