low 408 oil pressure
07-23-2006, 04:22 PM
#1
low 408 oil pressure i just recently completed builing an iron block 408 and it came time to fire it up and the oil pressure is extremely low. at first start up it was a little over 20 psi and once it got up to temp it dropped down below 20 and seamed to keep dropping. brought engine up to 3000 rpm to break cam in and it raised to about 30 psi. i was wondering if anyone could tell me where to start looking for problems? or is this just one of the aspects of the new clearances in the motor?
07-23-2006, 04:31 PM
#2
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I would not start it anymore. Take the front timing cover off and drop the oil pan a bit and check the O ring for the oil pickup tube. Also do you have a double roller chain? Because the spacers throw everything off. I had to bend mine on my 347 to fit perfect too. And you can easily install the spacers wrong.
Last edited by JMBLOWNWS6; 07-23-2006 at 04:37 PM.
07-23-2006, 05:20 PM
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as said check the oil pump o-ring, also the rear and front oil galley plugs.
what are your bearing clearances? these will/can affect oil pressure; if the bearings are setup loose your oil pressure will be lower, not necessarily a bad thing. for a street engine the rod bearings should be in the .0015-.0018 range and on the mains about .002-.0022 IIRC
what are your bearing clearances? these will/can affect oil pressure; if the bearings are setup loose your oil pressure will be lower, not necessarily a bad thing. for a street engine the rod bearings should be in the .0015-.0018 range and on the mains about .002-.0022 IIRC
07-24-2006, 12:00 AM
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My 408 according to tech2 was making 33-36psi at operating temp idle and 55psi at 3000rpm.
If you find nothing wrong with the oil pump etc, you can blow compressed air through the oil galleries and hear for any leakage. Probley best with the oil pan off.
If you find nothing wrong with the oil pump etc, you can blow compressed air through the oil galleries and hear for any leakage. Probley best with the oil pan off.
07-24-2006, 12:53 AM
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Too low man. Pull that thing out and have it looked at before you have the same problem I did. A big clunk and a hole in your pocket. Low oil pressure will cause all kinds of unwanted problems.
Check the simple stuff first. Mechanical guage on the oil pressure sender, pick up O ring. Maybe drop the pan and check the picup tube to bottom of pan clearance. If it all check out, internal issues are present.
Check the simple stuff first. Mechanical guage on the oil pressure sender, pick up O ring. Maybe drop the pan and check the picup tube to bottom of pan clearance. If it all check out, internal issues are present.
