454 LOSES OIL PRESSURE - Team Camaro Tech
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post #1 of 12 (permalink) Old Mar 22nd, 01, 11:00 PM Thread Starter
 
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HELLO I HAVE A 1989 454 FROM A MOTOR HOME THAT LOSES OIL PRESSURE AS IT WARMS UP THAN KNOCKS.IT GOES FROM 40LBS AT IDLE TO 0.IT TAKES ABOUT 15 OR 20 MINUTES TO KNOCK.THE MOTOR HAS APPROXMITELY 32K AND IS STOCK EXCEPT FOR BEING CARBURATED.IVE CHANGED THE OIL PUMP AND ROD BEARINGS TRYING TO FIX THIS PROBLUM.THE OLD BEARINGS LOOKED NEW.
IT IS INSTALLED IN A 86 CHEVY 4X4.THIS STARTED AFTER A DAY OF "MUDDING" IN A LAKE.
THE TRUCK HAS SAT FOR 2.5 YEARS (STARTED RIGHT UP)AND IM READY TO START ON IT BUT I DONT KNOW WHERE .PLEASE HELP.
THANX EDD
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post #2 of 12 (permalink) Old Mar 23rd, 01, 05:02 AM
 
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is it on a mecanical gage or eletrict.the only other thing i can think of if you allready changed the crank bearing is the cam bearings.
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post #3 of 12 (permalink) Old Mar 23rd, 01, 05:59 PM
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Ever since you posted your problem I have been trying to figure out what could be happening. How much water did you get into the motor? Did it set for very long with water in it? Did you take a look at the mains? Does the motor get hot when you run it before the knock starts?You said it had 40psi of oil pressure at idle does it go higher if you rev the motor when you first start it? If you could please answer these questions I will try or ask some people if they have ever heard of a problem like yours

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post #4 of 12 (permalink) Old Mar 23rd, 01, 06:44 PM
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It seems I remember something about the diamiter of the distributor gear and/or the distributor lower housing.
Check around and see if you have the right distributor for that year engine, and that there is no leaking of oil from the lower dist lifter gallerey that goes around the grouve in the distributor housing.
The oil pump pickup should be welded on or it will fall off the pump and cause low, or no pressure.
David

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post #5 of 12 (permalink) Old Mar 23rd, 01, 10:12 PM Thread Starter
 
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THANK YOU for the responses.here is what i know.i wasnt in the truck when it sucked water but i saw it.the truck was submerged and my wife let the rpms drop.well i screamed for her to rev it and when she did it shot a cylnder of water out of the exhust(i just cringed) but the motor did not die and the knocking didnt start till the way home.the motor was proubly cool enough not to knock till i stoped runnng through 6 feet of water and went home.the oil pressure sits on 40 at idle and bumps to 60psi with increased rpms.for every little bit it heats up the pressure equaly drops till the motor is at operaing temperature,than when all oil pressure is gone the knock starts.if i could keep the motor 140 degrees it would not knock.the gauge is mechanical,i evan changed it.i did not look at the main bearings,the oil pump shaft is not welded and the distributor is out of a chevy 350 i had to go from computer ignition to hei.you guys suggest it and ill try it.THANK YOU EDD
post #6 of 12 (permalink) Old Mar 23rd, 01, 10:55 PM
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First off, I was trying to figure out what in the world you was doing driving in 6 feet of water??? Must have been quite an experience! Check those mains...you may have spun a bearing...sometimes they make noise and sometimes they dont. Also, check the oil pump pickup screen...I have seen engine (mostly fords though) that have excellent oil pressure at cold startup and then lose it down to nothing the longer the engine runs and it was caused by a load of crud stuck in the pickup. The first thing I would suspect for knocking after sucking a load of water thru a running engine would be 1 or more cracked pistons, but that has nothing to do with oil pressure (unless there are piston fragments stuck in the oil pump pickup). Hope this helps.

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[This message has been edited by travis (edited 03-24-2001).]
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post #7 of 12 (permalink) Old Mar 24th, 01, 12:00 AM Thread Starter
 
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the pick up screen is new.ive had cracked pistons in 350s before.this thing starts right up and idles like a champ.if i had a spun bearing wouldent it have no oil pressure?ive started this thing and run it 50 times in the last 2 years and it always does it the same way.i guess i dont understand how a bearing can let the oil through one minute and not the next.now i know clearances and all that but this seems realy weird.WHY WAS I IN 6 FT OF WATER?IT STARTED WITH A 74 TYPE LT Z28. .MY FIRST CAR A 74 CAMARO WITH A 350,4 BOLTMAIN, TRICK FLOW HEADS THE WHOLE KIT AND KABODDLE .THAN I STUCK THAT MOTOR IN A 88 TOYOTA 4X4.HOLE SHOT CONVERTER TCI RACE PREPED TRANNY I WAS HOOKED.TALK ABOUT TORQUE.(NOW SCREW UP A GOOD THING )SOLD THAT TRUCK BOUGHT A CHEVY FULL SIZE PUT 456 GEARS IN TO GIVE THE 305 (YES 305 )MOTOR MORE TORQUE.WELL THAT WASNT ENOUGH SO I BIG BLOCKED IT..NOW WE GO MUDDING. FIRST YOU TAKE A 4WD AND LIFT IT TO FIT BIG TIRES .THAN YOU KEEP DRIVING THROUGH STUFF UNTILL YOU CANT ANY MORE.THERES NOTHING LIKE WATER 4 INCHES BELOW YOURE WINDOW...MY POINT,IM A CAMARO GUY AT HEART AND I KNOW A LITTLE ABOUT A LITTLE.AND A LOT ABOUT NOTHING. THANX EDD


post #8 of 12 (permalink) Old Mar 24th, 01, 12:18 AM
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Check the mains I think you had an oil pan full of water and on the way back from your submarine duty it killed a main. The only thing is that usually won't cause a complete loss of oil pressure. One more idea I wonder if the water in the motor caused enough sludge in the upper end so that the oil return is restricted to the point that after you run it awile the pan is empty? I have never seen it happen but I have never been in 6ft of water either.

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post #9 of 12 (permalink) Old Mar 24th, 01, 04:29 PM Thread Starter
 
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OK THE WATER WENT IN AND OUT OF THE EXHUST PIPE NOT IN THE CARB.IF WATER MADE IT TO MY CYLINDERS THAT IS AS FAR AS IT GOT BEFORE IT GOT SHOT BACK OUT.IT NEVER STALLED OR DIED SO I DONT THINK IT MADE IT MY IT TO MY MOTOR .NO SLUDGE IN THE MOTOR.FLOW JUST SLOWS DOWN THAN STOPS.THE SAME EVERY TIME.PLEASE DONT GIVE UP I CANT. THANX EDD
post #10 of 12 (permalink) Old Mar 24th, 01, 04:47 PM
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OK, Like the others said, there is a good possibility that you have either spun a main bearing or the main bearing clearance is too large. I think the point you are missing is oil viscosity. When the oil is cold, it is thicker, once it warms up it thins out as it is designed to do. Also, just cant get rid of the thought that your cam bearings maybe have seen better days. Definitely the first thing to check is main bearing clearance and condition, after you have done that we may be able to help if that is not the problem. If you want you can contact me personally and I will try to elaborate.

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[This message has been edited by AUTODR (edited 03-24-2001).]
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post #11 of 12 (permalink) Old Mar 25th, 01, 01:49 PM
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OK - been thinking about this one and came up with a wild (but easy to test) idea. Aside from the bearing problem (which is likely) you could also have lost the oil pump pickup. When you first start the motor all the oil has drained back into the pan while the engine was off and not much oil is flowing because it is cold and thick. But as the oil warms and starts really circulating, the level drops below the pump inlet (since there's no pickup). What if you tried adding an extra quart of oil? just to test and then drain it back out - if oil pressure stays up there after the motor is warm then you probably lost the pickup, if the same thing happens, the pickup is probably fine. Just an idea . . .
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post #12 of 12 (permalink) Old Mar 25th, 01, 06:55 PM Thread Starter
 
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OKAY I GET IT .THE OIL HAS TO MUCH SPACE.I WAS THINKING A SPUN BEARING WOULD HAVE PLUGED SOMETHING UP.NOW WHERE DO I START,CAM OR MAINS ?IVE HAD THE PAN OFF 2 TIMES SO I CAN PULL THE PAN IN THE TRUCK AND PLASTIC GAUGE THE MAINS OR AM I PAST THE POINT OF IN VEHICLE REPAIR ? THE OIL GAUGE IS HOOKED UP TO A PORT ON THE DRIVERS FRONT OF THE BLOCK ,DOES THAT MATTER IN DIAGNOSTIC THINKING ???IM NOT TRYING TO AVOID REPLACEING ANYTHING I JUST WANT TO FIX THE RIGHT PART THIS TIME SO FAR MY DIAGNOSTIC SKILLS HAVE BEEN LACKING TO SAY THE LEAST ? I APRECIATE ALL OF YOU TAKING THE TIME TO HELP WITH THIS.IF I WERE TO SELL THE COMPLETE MOTOR ANY THOUGHTS ON WHAT ITS WORTH ? GOING BACK TO A SMALL BLOCK MIGHT BE AN EAZY ANSWER.REAMBER IVE GONE WITH OUT THIS TRUCK FOR OVER 2 YEARS.AND I JUST WANT TO PLAY.2 YEARS AGO ID HAVE LAUGHED AT THE IDEA OF A SMALL BLOCK AGAIN, BUT THINGS CHANGE.
THANK YOU
EDD
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