AFM Oil Pump Pressure
05-07-2009, 08:03 AM
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AFM Oil Pump Pressure Upon searching, I found that if you were removing the AFM/DOD and everything to do with it, that the oil pump would be too much pressure without it. How much is too much? Would I be better off replacing it with a ported or standard pump instead? I am just swapping in a cam with bolt ons in a truck 5.3 engine. Is there any value for this high pressure pump? Would it be just a matter of the spring pressure in the pump would need to be replaced with one for an LS1/6 pump? Thanks for any info
05-08-2009, 10:58 AM
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The only reason I am asking, is because I ordered a new OE LS2 oil pump from gmpartsdirect, but they said GM is back ordered and they dont know when they will have them in stock. If I can change the pressure in my pump, I would rather do that instaed since it is low mileage anyway. I just want to see if it's even possible.
05-08-2009, 01:36 PM
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The only reason I am asking, is because I ordered a new OE LS2 oil pump from gmpartsdirect, but they said GM is back ordered and they dont know when they will have them in stock. If I can change the pressure in my pump, I would rather do that instaed since it is low mileage anyway. I just want to see if it's even possible.
05-08-2009, 03:32 PM
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I use the same high volume pump in my silverado that you're referring to. It's a non-afm engine. 50PSI hot idle. Just use the stock WHITE colored bypass spring to bring your idle pressure down from 60 to 50PSI. I repeatidly shift at 6200RPM's+ and have no oil starvation issues. Run what you have. Just find a stock bypass spring
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05-09-2009, 10:07 PM
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OK, now I am a little confused. I pulled my pump yesterday and the part number is 12556436. From searching, this pump comes up as a 2001 year pump. Thats fine, but is the spring the only thing that makes these AFM engines high volume? Just seems odd to me. If this is the case, I wont buy a new pump, instead just replace the the spring as hirdlej mentioned. Where can I get the correct spring? Thanks.
05-10-2009, 04:10 PM
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OK, now I am a little confused. I pulled my pump yesterday and the part number is 12556436. From searching, this pump comes up as a 2001 year pump. Thats fine, but is the spring the only thing that makes these AFM engines high volume? Just seems odd to me. If this is the case, I wont buy a new pump, instead just replace the the spring as hirdlej mentioned. Where can I get the correct spring? Thanks.
The spring has nothing to do with the "high volume". The spring holds the relief valve closed: light spring, low pressure; heavy spring high pressure. By using the light spring, you reduce the pressure of your pump from whatever it may be for the VVT/AFM setup. I have a L92 without AFM, but with VVT. I plan to remove the VVT and will run the same pump.
