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Help with oil pressure, rebuilt motor first start up
#1205194
03/28/12 02:52 PM
03/28/12 02:52 PM
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Joined: Apr 2003
Posts: 915 near New Haven, CT
fireeng
OP
super stock
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OP
super stock
Joined: Apr 2003
Posts: 915
near New Haven, CT
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The guys at the shop started my motor for the first time today. Initially they had 70 pounds of oil pressure. After running the motor for a couple of minutes the oil pressure at idle dropped down to around 10 pounds and when you rev it up they can hear a little rattle or knock. It sounded like it was running smooth before it warmed up. Any thoughts?? The engine is a 72 340 bored 40 over with basically a stock rebuild. I spoke to the guy who assembled the engine in 2004 and he thought it could possibly be the pressure relief on the oil pump not working properly. Everything in the engine was replaced with a new rebuild kit after it came back from the machine shop. I have zero knowledge when it comes to engines so I am acting as a go between trying to get information. I know that if there is help out there, I can start here for info. Thanks for any input Scott
2016 Diesel Ram 3500 Mason Dump 1971 Challenger 2013 Jeep Wrangler 1979 Dodge Ram Power Wagon 400 Mini Pumper My other car is a Fire Truck.
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Re: Help with oil pressure, rebuilt motor first start up
[Re: fireeng]
#1205195
03/28/12 03:11 PM
03/28/12 03:11 PM
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Joined: Mar 2007
Posts: 3,277 West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,277
West Coast, USA
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Maybe they used a thin break-in oil, and the timing is a little too advanced causing some slight detonation.
Check the valve adjustment/ lifter preload, change the oil and filter(cut open the oil filter and see what it's caught) and double check the timing. Let us know what the initial timing is set at and the what the total timing is too.
Last edited by jbc426; 03/28/12 03:17 PM.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's 1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: Help with oil pressure, rebuilt motor first start up
[Re: jamesc]
#1205199
03/28/12 03:43 PM
03/28/12 03:43 PM
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Joined: Feb 2005
Posts: 20,173 PA.
pittsburghracer
"Little"John
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"Little"John
Joined: Feb 2005
Posts: 20,173
PA.
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Are you saying this engine was built in 2004 and never started. Lots can happen in 7 plus years. A Friend of mine just started one that sat half that long and the same thing happened with his oil pressure. He removed the oil pan and a mouse hade built a nest in his oil pan and plugged up the oil pickup. MORE INFO WILL BE NEEDED.
1970 Duster Edelbrock headed 408 5.984@112.52 422 Indy headed small block 5.982@112.56 mph 9.42@138.27
Livin and lovin life one day at a time
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Re: Help with oil pressure, rebuilt motor first start up
[Re: pittsburghracer]
#1205200
03/28/12 04:30 PM
03/28/12 04:30 PM
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Joined: Apr 2003
Posts: 915 near New Haven, CT
fireeng
OP
super stock
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OP
super stock
Joined: Apr 2003
Posts: 915
near New Haven, CT
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Thanks for the replies. I just got a call from the shop, they dropped the oil pan and found the clearances on the crank off by more then 20 thousands, so back to the machine shop she goes......
I spoke to the guy who assembled the motor and he said he plastigauged it back then and found everything to be within the correct tolerances. Does that make sense??
It's only money right?
My bad on this last posted info, what they told me is that the crank was ground 20 thoundsand and the are finding clearences now between 5 and 6 thousands.
So we contacted a new machine shop (because the one I used won't take an assembled engine) who is going to tear down the motor check everything out, fix it up and reassemble it the right way.
How much I ask................that remains to be seen.
Last edited by fireeng; 03/28/12 05:19 PM.
2016 Diesel Ram 3500 Mason Dump 1971 Challenger 2013 Jeep Wrangler 1979 Dodge Ram Power Wagon 400 Mini Pumper My other car is a Fire Truck.
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Re: Help with oil pressure, rebuilt motor first start up
[Re: fireeng]
#1205201
03/28/12 06:26 PM
03/28/12 06:26 PM
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Joined: Jan 2003
Posts: 75,005 U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,005
U.S.S.A.
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Quote:
Thanks for the replies. I just got a call from the shop, they dropped the oil pan and found the clearances on the crank off by more then 20 thousands, so back to the machine shop she goes......
I spoke to the guy who assembled the motor and he said he plastigauged it back then and found everything to be within the correct tolerances. Does that make sense??
It's only money right?
My bad on this last posted info, what they told me is that the crank was ground 20 thoundsand and the are finding clearences now between 5 and 6 thousands.
So we contacted a new machine shop (because the one I used won't take an assembled engine) who is going to tear down the motor check everything out, fix it up and reassemble it the right way.
How much I ask................that remains to be seen.
Plastiguage ???
sounds like you are going to be on the hook to have it done CORRECTLY ...
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