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Old 10-28-2004, 09:20 PM
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oil pressure drop on new engine break in...

okay, so everything went well for awhile until... i just got the timing right and started the newly built 383 and brought it up to 2000rpm. the engine ran fine, adjusted the timing and everything. i ran it for about 10 minutes before i noticed the water was out and it was getting hot so i shut it off. during this time the oil psi got no lower then 50 psi.(just to mention, i have a high volume oil pump.) then we started it up after it cooled this time with more water and a hose ready. what happened was the oil psi went up to about 50 on the intial start, then it began to slowly decline and i watched as it went to 20 psi at 2000rpm so i shut it. what i need is reasons why this would happen, i tried it twice and the same thing happened. it just kept going lower. there is a small oil leak in the front bottom of the timing cover but no other leaks at all.

i plan to do some trouble shooting but i wanted to see what everyone else thought.

also, when i had primed the engine it went up to 60 psi and stayed there for the good 5-10 minutes i did it. i did that like 3 times to make sure everything was lubed right.

all input would help.
thanks,
mike

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Old 10-29-2004, 05:56 AM
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My first thoughts would be that your sending unit isn't very good quality, something either wore out really fast, or there was a blockage somewhere. I'd be nervous about starting it back up before putting in a different sending unit, and pulling the pan and putting yet another pump on. The price of another high-volume pump is pretty cheap compared to going through that engine again, and any time you see a significant drop in oil pressure in a brand spanking new engine, you need to be extra careful how you proceed. And if the pump and sending unit don't bring the pressure back up to where it should be, you really need to (and I hate to say it) pull it out and tear it back down. A blockage is usually impossible to deal with in an intact engine.

A question I have for you is this: How well do you know the people in your machine shop, and how well do you trust that they did a good block prep before putting the plugs in? Since you're still getting some oil pressure, the odds of it being small, gritty crap (if it turns out to be a blockage, and not a pump or sending unit problem) that will get in between bearings and completely ruin them, not to mention the crank, cam, etc.

Yep, definitely want to be very, very careful.

Last edited by Stickman; 10-29-2004 at 06:03 AM.
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Old 10-29-2004, 06:21 AM
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oil pressure

Do you have the bypass blocked in the oil filter adapter??

What typ of filter are you running???

Keith
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Old 10-29-2004, 07:13 AM
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okay first, the machine shop i would hope did a good job, my friend has done ALOT of business with them and he was the one who took my block in and such. also i have the summit oil filter adapter that doesn't have the stock bypass, it supposedly makes it so all the oil goes through the filter first, the filter is a k&n preformance gold filter.

yeah my first thing was i am chaning the gauge to see it it went out, then next i am changing the oil and filter/mount. is is possible that too much assembly lube could cause blockage? i used sort of alot. is it possible that the high volume pump sucked my pan dry and just started sucking in air?

thanks, mike

oh also today i am going to take the distributor out and prime the engine again and see if the oil psi drops with that.
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Old 10-29-2004, 07:16 AM
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oil

I would not change that adapter. You want all the oil to go through the filter. The first thing i would do it try switching to a new filter. For the reason you stated it could be blocked by all the assembly lube. I have not seen the K&N filter do this but the frams are know for this problem....

You have a good idea to try the primer again and see of the pressure comes back up.

Keep us updated.

Keith
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Old 10-29-2004, 07:37 AM
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Assembly grease can cause pressure to drop sometimes, right after startup, but after you've run it for a few minutes and it's warmed up, that's unlikely a cause, or even a contributing factor.

Also, like K-star said, if you haven't changed the filter already, do that even before you try anything else, then use a primer and see what the pressure comes up to. It's possible your filter is blocked, though unless the filter is bad, it's unlikely that it was blocked by foreign substances, since you're obviously intelligent enough to have made sure the bottom end and pan were clean before you buttoned things up.

Unfortunately, if it was metal dust or other contaminants, they'd have made the trip (the rest of the way) through the journals before being deposited in the pan, and picked up again by the pump and caught in the filter, so if the pressure does come back up after changing the filter, you may have troubles anyway. Hopefully, though, this isn't the case. With a little luck, you just have a sending unit that isn't reading right. After you change the filter, be sure to try a new sending unit before you go through the trouble of pulling the pan and replacing the pump, and cross your fingers (hey, it can't hurt). As anyone who's messed around with high-performance engines at all knows, all sending units are NOT created equal, and I'd pick this for the likliest suspect.

P.S.
By the way, SMART MOVE, eliminating the stock bypass. I know of several engines that have been ruined because of this "handy" little feature. Factory engineers apparently figure that even dirty oil is better than nothing at all, but then they engineer engines for stupid people who don't bother to watch guages closely. For those of us who don't fall into that category, it causes far more problems than it would ever prevent.
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Old 10-29-2004, 07:40 AM
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Go with K-Stars advice, change the filter, try a Wix or Napa or K&N. I had the same symptoms with a Fram filter a couple of year ago.
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Old 10-29-2004, 03:30 PM
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well thanks to everyone for your advice, i am off to try all the above things and i shall post back when i see what happens.
mike

hey also, no one replied to what i said about the oil pump sucking in air. if possible could i get a straight answer if a high volume oil pump can suck a stock pan dry? please state some sorces such as websites or magazines, i have posted before about this and get so many different answers. is it possible to have an air pocket in the oil?
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Old 10-30-2004, 10:07 AM
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What are your rod side bearing clearances on the crank? Looser clearances can have an effect on your pressure, especially at low rpm. Mine are somewhat loose for a street motor(0.025) so at 1000rpm I'm only seeing 20psi as well and using a std volume pump.

The only time your pan is going to get sucked dry is if you start restricting oil flowback with screens and are turning something like +5000rpm for a signifcant period of time with a std volume oil pan. Or if yer seriously into road racing as well but then you should be looking at aftermarket baffled kicked out pans anyway that hold more oil to begin with.

Next time I rebuild my motor I will go with a high volume pump instead mind you.
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Old 10-30-2004, 11:59 AM
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You can suck air IF the pick up tube is pulling away from the pump.Did you spotweld the pick up tube in place?If it pulls away the oil may still be sucking up into the pump but with a gap you will also pull in air.
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Old 10-30-2004, 01:44 PM
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the pick up is already welded on there, it is a stock pickup/pump in a stock pan, just has high volume flow.
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Old 10-30-2004, 07:58 PM
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The stock pickup in the stock pan is just fine.Have you completly ruled out the gauge as the source of the problem?Is it mechanical or electrical?When you primed it did oil flow from all the rockers?It dosen't need to just gush out of each,but does need to flow from everything.Other than that I'm stumped.I would try another gauge,and hope that was it,you just shouldnt loose oil pressure on a fresh rebuild with all new components,unless it is faulty equipment or something internal.Good luck man-Rcastle-
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Old 10-30-2004, 09:16 PM
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okay...it's a mechanical gauge. i went today and did alot of that stuff above. i used the gray arp assembly lube when assemblying my engine, when i drained the oil it was about as gray as that lube. so i am hoping that this is the reason the psi went down, i changed the filter and have yet to cut it open and check it out, but i also changed the oil. i primed the engine and BAM! 60psi of pressure on my new gauge with some copper tubing instead of the plastic tubing. the pressure stayed there as i held the drill at full speed, the drill ended up dying and then the pressure went down. so with alittle luck it might have just been a clogged oil filter or bad gauge. i might possibly start it tomorrow and get back to you guys with the result.
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Old 10-30-2004, 09:30 PM
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I think you found your engine gremlin.
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Old 10-31-2004, 05:49 PM
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well everyone you want to hear the GREAT!!!! news!??!?

well everyone you want to hear the GREAT!!!! news!??!?

well everyone you want to hear the GREAT!!!! news!??!? i started the engine up after the oil/guage change and bam it runs fine at 85 psi. the psi then drops as it warms up to 60 and stays there. so i am happy until.....when there was only about 2 minutes left in the break in i hear a BAM! and so i shut the car fast. it was like a loud tin type metal to metal sound. so well i freak out of coarse. i change the oil and figure that i could let it idle now and see if maybe that noise was something else. i start it up and right away BANG BANG BANG so i shut it off. i hate this!!! i followed everything by the book and yet it still fails. i have no idea what it is but is probably not good. maybe i'll get a sound clip up if i dare start it again.
mike
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