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Edge904
05-14-2007, 10:39 AM
I installed a 401 last year (someone else's rebuild). I started out with high oil pressure (http://www.bulltear.com/forums/viewtopic.php?t=5292&highlight=), but took care of that problem.

But now, almost all of the sudden, I have very low pressure. Cold pressure is good (~50 psi), but when the engine warms up, pressure drops to around 10psi and I have lifter noise.

I've changed filters, checked the plunger and spring (they appear to function), and pulled the Bulltear oil relocation adapter to check out the oil pump.. pump looks good.. although I haven't taken clearance measurements. There was some minor wear on the relocation adapter.

I had the distributor out recently for a different reason, and noticed while the gears did not appear worn, the black oxide coating was a bit worn from the surface.

I'm wondering what the next step is. Replace the spring and plunger? Pull the distributor and check out the cam gear? Yank the oil pan and make sure I don't have bearing bits stuck to the pickup? Something else?

tufcj
05-14-2007, 12:38 PM
I'd try the easy things first. Swap the spring/plunger. I've seen the springs weaken from age and heat.

If that doesn't solve it, and since it came on suddenly, next thing I'd do is pull the pan and look for bearing pieces, and check rod/main clearances. A bad cam bearing, or bad rod/main bearings would cause a sudden loss of oil pressure.

Bob
tufcj

jeepsr4ever
05-14-2007, 01:04 PM
Did you say you had a new sending unit? It may have poor readings.

Edge904
05-14-2007, 01:47 PM
Did you say you had a new sending unit? It may have poor readings.

It's a new mechanical gauge. Plus, I do hear tapping when the pressure drops.

I'll try a new spring, plunger, and fresh oil, and report back.

jeepsr4ever
05-21-2007, 04:00 PM
Yes the aluminum that the 626 is made of offers no more resistance to scratches than the stock oil filter adaptor unless its Ni plated or has a midplate on top. If you cant fidn the source of the issue I would try a midplate to see if the small scratches could be causing the lower oil pressure. That is if you cannot find any other issues.

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