I totally agree it should not be doing that. But now I am grasping at straws. I can run 1/2 quart over and under and the propblem is the same.

Could a loose rocker/lifter preload cause bleed off? I have to start thinking about what can casue bleed off before blaming it on sucking the pan dry.

 

I suppose it could, but wouldn't a rocker start "clacking" if that was a problem?

 

One would think so. But in terms of something bleeding off. I cant think of anything else in the motor that could do that.

 

Sometimes it rebounded, sometimes it didn't. I didn't stay into it that long after the oil pressure drop, fearing that I would ruin the motor.

 

My oil pressure does exactly what yours did in the video. It dips from 60 to 40 psi at 5K rpm. I thought it was weird, but I have a brand new Golen 383 with 10K miles on it so I figured it was normal for that to happen. Maybe ol' Golen will have an explanation...

 

Please, please, please call them and ask. There is no way that can be called normal. They might say it is very low risk and mostly likely harmless but it aint normal.

Point them to my video and claim it as your if it is truly the same.

This way nobody has to waste more time and money than they really need to. My engine builder talked to a very experienced oil pump engineer and he thought it was a momentary cavitation issue that COULD possibly be resolved using a slightly higher volume oil pump.

I am not onboard with that yet because I dont want to trade one problem for another like maybe wearing out drive stub gears.

I am nearly ready to start pulling bearing caps and checking bearings for piece of mind and I really am not looking forward to.

 

OK. I have an idea. I had a similar problem, but, when I was cranking a 383ci LT1. Oil pressure went to zero. I thought... Hey that does not look normal, there must be a problem. I stopped the cranking, and, pulled the intake.

The oil pump drive was loose. The (single) bolt had backed off. This could happen under high loads as the drive gear would raise the drive (due to loose bolt, and high pump loading). The gear could disengage from the cam shaft. Result... Zero pressure, or, wide pressure values as you have reported. The gear could engage/ disengage and cause a cyclic pressure value as the load varied (from rpm).

I used lock_tite red on the single bolt. Yes, the really hard stuff. I do not like the gm design, and, it is made of a termoplastic material (easy to fail, especially under the bolt head - clamp load). If I get a chance (next time), I will eliminate and machine a piece from alum with a mechanical keeper or wire lock fastener.

Hope this helps.

B.

 

I will look into this next. It cant hurt to inspect the gear anyway. I know for fact that I red lock-tited it down the last ime I pulled the cam but I know how fragile that plastic is. Thanks.

 

I will try to help you guys as best I can.

So what brand oil filters are you all using?

We sell about 65 LT1 383ci engines a year with the stock oil pans and we use the Melling M-55HV high volume oil pump with he 55-S1 pick up tube welded onto the pump and 1/4" off the bottom of the pan. We do not see many of these problems but I had one of my customers direct me to this post and he is having the same problem that you guys are. After Adam called me today I thought about the last time I had a customer with this type of problem and he was using a Fram oil filter and once he changed the filter to a WIX brand the problem went away. We have had many problems with Fram oil filters over the years on our circle track race engines as well as street engines and they do exactly what I saw in that video that one of you posted. What we found inside the filters was the paper walls collapsing and causing the oil pressure to drop under higher RPM's. Cant say that this is going to solve your problem but it is something to look into. After that we run about a .0025" oil clearance on the mains and rods which works great and we use a 20/50 weight oil to give us about 30 psi idle oil pressure hot and about 60-70 psi at WOT 5000-6500 rpm.

Let me know and I will do my best to help out.

Thanks,
Chad Golen

 

Chad,
Thanks for the reply. I really appreciate your help in resolving this annoying issue. I hope you were able to see the video I attached.

I have used K&N oil filters for quite some time. After putting the Melling 10554 pump in and setting the pickup at 1/4", both of which did nothing to help the issue. I pulled the K&N and installed a AC Delco filter. That did nothing to help the problem as well. I also have the adpter bypass plugeed to force all oil through the filter but i dont see how that could cause the problem.

I am using 5/30 standard Penzoil and have 70# at cold idle and 20-22# at hot idle according tho the mechanical guage and have acceptable oil pressure under all NON WOT conditions. The pump spring is the GM white spring.

My engine builder believes it to be a pump cavitation issue of some type considering the oil pressures have relatively remained unchanged since the motor was new. He thinks maybe a high volume pump would resolve the issue but I want to avoid introducing potential new issues. Its my understanding that the Melling 10554 pump is a very popular pump and there seems to be no real history indicating that this pump is prone to this problem.

When I had the pan off the first time after ~8K miles. I did notice some gold flake bearing material sediment on the bottom of the pan. It was not a severe amount and could not be seen except in direct sunlight. The pickup recently fell off and there was a good deal of driving put on the motor in this condition but I only saw the low pressure light come on briefly a handful of times. That may have caused some bearing damage but to this day I have no knocking and pressures remain very good. It could also be some thrust bearing wear.

If I end up pulling the pan again, my engine builder is going to pull all the caps and check the bearings for damage.

It just seems like there is a very temporary bleed off condition causing the crazy pressure drop. It makes no sense to me that a bearing could cause this and I dont believe its the result of g-forces washing the oil away from the pickup. It does this in 3rd gear too which is not going to move the oil enough to cause the issue.

 

If and when I do buildup my motor, I'd use part#22101 with the white spring, FWIW.
http://www.moroso.com/catalog/catego...?catcode=14444

 

WRD:

Is it normal for the oil pressure to increase with increase with increase RPMs, though? Mine does this but it is directly proportional to the speed of the engine and doesn't fall at all at higher RPMs.

As far as your bleedoff problems go, that's really weird. Is it possible (I haven't dealt with oil issues very much), that a gasket or seal is building up pressure and then releasing it due to a defect? I would think it unlikely since you would notice other problems, but I'm stumped on this one, too.

 

While it may not be the problem, you should start using Napa Gold oil filters. They are made by wix, and are by far the best filter for our cars. In the past 5 years I have tried just about every filter, and the Napa Gold gets me on average 5psi more then any other I have ran, Including the $15 K&N. I had this problem about 4 years ago, and the Napa Gold almost knocked it out completely. Mine still drops off a little bit, but i'm not worried about a 2psi drop.

Wix>K&N

 

Mclovin is correct the Wix oil filter is the best and the Napa Gold is made by Wix. That is all that we use here at Golen Engine and never have a problem and we dyno about 4 engines a week on average.

If any of you guys would like to call me direct to discuss the problem that would be fine, I will do my best to help you.

Call me at 1-800-591-9171 ext 2

thanks
Chad

 

I will try a Wix filter next. They have them at Oreilly auto parts.

Let me ask this question about my pressure drop problem. Forget about why its happening. From looking at my vid, would you think its an indicator of something very bad to come or would you just overlook and not sweat bullets and just drive it and enjoy it?