looooooooow oil pressure/spun bearing


SG007
12-28-2005, 10:00 AM
Oil pressure is like non-existant...on idle I'm in the red, during acceleration at 15-20...scary. It's going to seize on me one of these days. I was told I also spun a bearing and that's what the knocking business was...

Turns out the a-hole that had the car before me used gear oil to bump up the pressure. All I need is a chainsaw and an alibi, I swear.

Time for a new 350? :grinyes:

wrightz28
12-28-2005, 10:15 AM
you could try an oil pump first, becasue if it is indeed a spun bearing you'll know when the pan comes down,

SG007
12-28-2005, 10:29 AM
That's true..
Damn I was getting all excited about a 350. lol

wrightz28
12-28-2005, 10:40 AM
No one's stopping you from the 350. There could be an unfortunate accident while removing the pan that would require a new motor :D

SG007
12-28-2005, 10:48 AM
Haha LIFE.

FormulaLT1
12-28-2005, 11:39 AM
Well be very careful while driving her. A spun bearing is no joke and can cause the rods to bust right threw your oil pan. A 350 sounds like a excellent plan though. Go for the TPI induction system though if you go that right. I am and always was a fan of the L98.

92zcamaroperson
12-28-2005, 03:27 PM
Are there any other signs of low pressure? Could be your oil pressure sending unit going bad.......or...... uh......Sounds bad I think the only solution would be a big block.......

SG007
12-28-2005, 03:39 PM
uh......Sounds bad I think the only solution would be a big block.......

Just what the doctor ordered. :naughty: No way, for a daily driver I think a 350 is just fine.

RahX
12-28-2005, 05:54 PM
have you actually put a gauge on it? going by the pic and you mentioning putting a 350 in it im guessing its got a 305. as far as i know those early 90s 305s were pretty low pressure engines from the factory think the spec was like 8psi(minimum) at 1000rpm and 24psi(minimum) at 4000rpm.

SG007
12-28-2005, 08:14 PM
Howbout I changed the oil again just for shits and giggles and I found metal shards in the old oil. Proof enough?

RahX
12-29-2005, 01:58 AM
no but still enough to put a 350 in it ;)

silicon212
12-29-2005, 02:33 AM
Oil pressure spec on the 305 (or any other factory small block) is 45PSI @ 2000 RPM.

I'd say it's new engine time. A spun bearing will result in the need for a crank kit, a new connecting rod (or rods) and new piston (or pistons) and possibly new cylinder head(s) as well. The knock you hear isn't just from the bearing - the sharp rap is the sound created by the piston crashing into the cylinder head due to the severely increased clearance on the rod bearing.

It's not good news. That engine should idle at no worse than 25-30PSI given a good oil (avoid 10w40).

SG007
12-29-2005, 11:20 AM
I'm looking to drop this in...350 (http://www.jegs.com/webapp/wcs/stores/servlet/CategoryDisplay?lang=-1&catalogId=10002&storeId=10001&categoryId=19687&searchItemId=59287)...but how difficult is switching my tbi over to carb? I'm buying headers, but is there anything else I should be looking at that I missed? Thanks guys....I'm so flippin excited, I got my loan and everything....I can't wait!

FormulaLT1
12-29-2005, 11:25 AM
What size engine is in there now? Should be a easy switch to a carb.

SG007
12-29-2005, 12:03 PM
305 TBI....and what about the fuel pump? My friend who's helping me with the swap thinks I should keep the EFI setup, but I don't know how that would work with the motor I plan on getting...I don't know, I'm confused. lol

wrightz28
12-30-2005, 10:16 AM
You might get away with the tbi pump with a carb. Tbi system pressure isn't all taht high. It will depend on whatever carburater you decide to use (street avenger is my recomendation if you're not up to speed with carbs).

If you decide to go with a multiport system (tpi) you sill need to swap the pump.

SG007
12-30-2005, 12:44 PM
I need to keep the TBI setup to pass inspection though, don't I? No way I'm getting through with a carb...

wrightz28
12-30-2005, 12:57 PM
That all depends, on the local sniffers anyway.

Last time I looked up ours, IL-Chicago metro area, if the vehicle fails the IM240 standard test 3 times, it will then be subjected to idle testing as prescribed to test proceudres at the time of manufacturing. If it still fails then the hood gets opened, and would then be a good time to mention the car has been modified.

But, people have gotten through the sniff test with carbed 400 ci. motors around here and they are pretty strict. Just so long as it meets the required emission levels.

If you do keep the TBI setup, i'm not sure if it bolts right up to the 350, I know the TPI plenums require some finese to bolt up, but do work.

SG007
12-30-2005, 03:42 PM
Well all I need to convert over to carb is the fuel pressure regulator, right? I could always go to some small garage and wink to get a sticker, haha.

wrightz28
12-30-2005, 04:16 PM
I could always go to some small garage and wink to get a sticker, haha.

Why not, that's how I got mine through inspection, send it with the wife and her 'charm' :D

SG007
12-30-2005, 04:51 PM
Haha sounds like a plan.

92zcamaroperson
12-31-2005, 09:10 PM
yeah all you need is the adjustable fpr and some fuel line. You will also have to get a vacuum activated switch for your converter lock up. Or wire up a switch and kick it yourself for highway use. Or go with out anything and hope your trans doesnt overheat. Youll have to either try to tune the carb yourself or take it to a speed shop. If everything is in good tune and efficient you could easily pass a sniffer test. But you gotta get a good tune.

AcIdBuRn83355
01-03-2006, 01:35 PM
here is a suggestion... the 305 and 350 blocks are pretty well the same (mounting locations and what not) drop in the 350... put your headers on it... go to the local junkyard and pick up a throttle body for an 87-93 350 w/ tbi.... take all the sensors off of the 305 and install them on the 350... hook up the 350 throttle body and you should be good...

only difference from the 305 - the 350 throttle body is the injector sizes... so just run the 350 tb and dont worry about a carb...

anyways... and that knocking sound you hear isnt the piston hitting the head... otherwise you would be bending valves and all kinds of nice stuff like that... its the rod knocking against the crank due to the bearing clearence being greater then the maximum tolerance... aka... spun bearing.... for the time being... if your needing to drive the vehicle... change the oil and substitued 1 or 2 quarts of the oil with Lucas HD Oil stabalizer.... can be a life saver in positions like this...

thats my 2 cents..
-AcId-

-EDIT- tbi pressure is around 12-13psi... most carbs are around 2-6psi... depending on the company... and for driveablity reasons... and performance reasons... stick w/ tbi... you can have it dyno tuned to make more power then a carb... get better fuel economy.... and a lot better driveability.... without the hastle of haveing to remove a bunch of crap

SG007
01-03-2006, 02:00 PM
Thanks hun.

silicon212
01-03-2006, 11:39 PM
anyways... and that knocking sound you hear isnt the piston hitting the head... otherwise you would be bending valves and all kinds of nice stuff like that... its the rod knocking against the crank due to the bearing clearence being greater then the maximum tolerance... aka... spun bearing.... for the time being... if your needing to drive the vehicle... change the oil and substitued 1 or 2 quarts of the oil with Lucas HD Oil stabalizer.... can be a life saver in positions like this...

Wrong.

Have you ever seen the piston crowns for the cylinders with spun bearings? Notice that combustion-chamber shape? I've built many engines in my day, and this is one of the things that happens to an engine that spins a bearing. You're right about bent valves in SOME cases - there's definite cylinder head damage in these cases, I've seen valve seats get knocked loose and all other sorts of things like that. Valve bending doesn't occur too much though because the valves still are operating in synch with the cylinder (when the piston travels to the top, and beyond, the valves are closed).

While you're at it, why don't you tell him to put sawdust in the crankcase "if he needs to drive it"? You don't tell someone to drive an engine with a spun bearing. Oil pressure is going to be low to non-existent. When the engine starts knocking, you park it, then you fix it. There is no driving it, unless you actually want to be stranded somewhere.

666_speed
01-04-2006, 12:02 AM
with the car my mom just bought it had a spun bearing and we didnt know it and it was loaded down with lucas oil to keep us from hearing the knock....had it about 60 miles total til it completley locked....not a good idea at all like silicon stated

Add your comment to this topic!