oil pressure question
 

what is a normal oil pressure for a big block....540 na 700 hoarse

Re: oil pressure question
 

I am guessing but would think anything in the 40's is fine with 15W-50 M-1 once warmed up at cruise.

Re: oil pressure question
 

what is your oil pressure? are you running an electric or mechanical gauge?

Re: oil pressure question
 

im in the 50"s but when i run it hard for a few minutes it drops to 40 im putting a oil temp gauge in today and trying it again, i have ran mechanical and electric they both stay the same.......



sorry phil i could not wait i bought a 540......awsome boat ran 79 on gps first time out in heavy chop

Re: oil pressure question
 

On my 540 since it was built (5 seasons ago) it has never had more than 35-36lbs running, and around 25 idleing. I've freshened it a couple of times and the bearings always looked like new. This is on a mechanical guage with 20/50 Amsoil racing oil.
I know the oil pump is fine, and on a test rig the oil pump is putting out 65lbs. I know the problem is in the crank. It is an Eagle and when we first assembled it the Radii on the rod journals were to large causing the rods to be way to tight. Now after having it fixed I have the opposite problem, low oil pressure. So other than replacing the crank or having it welded and reground I just deal with it.

Re: oil pressure question
 

my 509 with v-twin oil runs 75-80 psi cold and about 55-60 at warmed up cruise. Idle is about 40-45 warm. Oil temp runs 220-270 after a hard run. (oil pan temp)

Re: oil pressure question
 

Take 1 qt out of the pan. If this cures the problems then you have a windage issue. The crank is whipping up the oil causing the oil to be hotter and become aerated.

Re: oil pressure question
 

I shoot for 80 psi cold, 70-80 psi at WOT. Idle hot should be 30-40 psi with 25W50 Pennzoil Racing. Oil clearences need to be set up correctly.

Re: oil pressure question
 

With my 540s, the oil pressure usually runs about 60 when cruising. Drops backs to around 40 at idle. The oil temps will run up to 190 after a hard run.

Re: oil pressure question
 

Ok Mines Not A 540 :( Just A Modified 454 And My Oil Pressure At Idle Is 35 To 38 And Never Goes Over 42 Even After A Run. Is This A Problem? I Have Always Figured 10 Psi Per 1000 Rpm

Re: oil pressure question
 

I have a 540 CI 686 HP NA GM Bowtie Block, Callies Crank, Oliver Billet rods and Dan Olsen oil pan. All of the bearing clearances have been painstakingly set up and are on the tight side of the spectrum. The oil pump has been rubbed on to tighten clearances as well.

My oil pressures? 60psi cold, 50-55psi hot at WOT, and 18-20psi at idle after a hard run. The idle oil pressure will come back to 30psi after a little cool down time. I run dual oil temp sending units to an electric Gaffrig Livorsi gauge through a DPDT switch. One sees oil coming out of the block into the oil thermostat (hottest oil) and the other sees oil coming back into the block from the oil cooler (coolest oil.) I routinely see 250-270 during a hard run on the "hot" sender while seeing only around 180-190 on the cool sender. So I know the oil cooler is taking out anywhere from 60-80 degrees of oil temp. I also run dual oil pressure gauges, one Gaffrig Livorsi electric with the sending unit located in the top rear main galley plug (behind the distributor) and an Auto Meter Pro Comp mechanical gauge with a SS braided -3 line located off a T in the same location as the electrical sender (so they see the same pressure.) The gauge readings are typically within 3-5 psi with the mechanical gauge showing the higher readings.

70-80psi at WOT would be ideal and idle pressure shouldn't be below 30psi. I feel mine is too low. This is my second rebuild on this block but this time we did the new rotating assembly. This rebuild was primarily due to my concern with low oil pressure. Well, it didn't change things any. When I disassembled it the last time, the calico coated bearings (both mains and connecting rods) were in pretty decent shape so I'm convinced that the lower oil pressures in my setup aren't really hurting anything. I actually think that I may have an internal oil passage leak in the block itself.

I will guarantee that windage is NOT an issue in this engine with the Dan Olsen pan which is a 10qt in which I run 8qt.

I am very interested to see what others have to say here.

Dr. N

Re: oil pressure question
 

Those were about my numbers when I was running M-1 15-50. The switch to M-1 20-50 will pick up your hot idle and wot pressures noticeably, about 10+ pounds across the board for me.

What oil and filter do you run? I have seen a difference in oil pressure between brands of filters also.

The oil temp cooling efficiency numbers came off a major heat exchanger manufactures web site. I also have two senders, with the Teague Offshore cooler I see about 50* drop which is right in-line with the manufacturers specs.

Re: oil pressure question
 

Patrick,

That does not sound right, I assume you have verified these numbers with a mechanical gauge.

What generation block is it now and what generation is your oil filter pad adapter?

Read this thread by Articfriends and you should be able to pinpoint the bottle neck in your system http://www.offshoreonly.com/forums/s...ssure+problems.

Re: oil pressure question
 

10 psi per 1000rpms is what I alway's heard also. Unfortunatly in my motors case I don't have anywhere near that. I have a max of 35-36lbs hot at 5800rpms on a mech. gauge. The bearings have always looked fine.
Maybe pressure is a little over rated, volume and keeping the temps down seem more important. I certainly don't like the fact that my pressure is so low but I don't think I can really do anything about it other that replace the crank.

Kind of a different thing but a friends Comp Eliminator car has some crazy really small CI SBC that goes thru the traps at 10,500 rpms with a total of 20lbs of oil pressure with 0 wieght oil . Now I know that is completly different than holding a motor WOT for miles but it does show that pressure isn't everything.
I'm not an engine builder so I could be completly wrong , they are just opinions/observations. That is what is good about this board learing differen't opinions and things like that.

Re: oil pressure question
 

IT IS A MARK IV BLOCK RETRO FIT TO A ROLLER. THE ONLY THING I LEFT STOCK WAS THE CRANK. BEFORE THE REBUILD I WAS GETTING 60PSI AT IDLE AND 70 AT WOT. I REPLACED THE OIL PUMP WITH THE EXACT SAME MODEL AND DID NOT CHANGE ANY LINES. THE ENGINE IS STILL GETTING BROKEN IN SO I HAVE NOT MADE ANY LONG HARD RUNS AND HAVE ONLY GONE TO 4500RPM FOR A MIN OR TWO. WAITING ON A PROP FROM BBLADES SO I CAN GET TO 5000RPMS. I HAVE CHECKED OIL PRESSURE WITH A MECH GAUGE AND IS THE SAME. MY BUILDER DOES NOT THINK THIS IS A PROBLEM AND SAYS I AM GOOD TO GO.

Re: oil pressure question
 

Gen 4 mercruiser motors had the bypass built into the filter pad adapter. If this part was baked during the rebuild process, the spring is no good. This could result in lower oil pressure.

I had mine plugged as it is bltch to get at with the motor in. That way all the oil goes to the filter and no worries about it bypassing.

Re: oil pressure question
 

I DID NOT KNOW THAT I WILL TRY TO CHECK THAT IF I CAN GET TO IT. DO YOU HAVE ANY PICS OF WHAT YOU DID? I AM ALSO RUNNING A 8QT PAN WITH 9QT IN IT AND AM NOT GETTING ANY FOAM. I HAVE PUT 10 HRS ON IT SO FAR WITH NO PROBLEMS OR NOISES THAT I CAN HEAR AND OIL STILL LOOKS LIKE I HAVE NOT RUN THE ENGINE AT ALL. IF I HAVE TO PULL THE ENGINE AGAIN I AM GOING TO SET THE BOAT ON FIRE :rolleyes:

Re: oil pressure question
 

I agree with mrhorsepower,my 540 runs 80 psi cold at anything other than a idle,70 psi at wot fully warmed up,idles at 60 psi cold at 700 rpm's and drops to 40 at idle after a long, hard run but comes back up to 45 or so after a few minutes of idling. If you have a good high volume pump and your only seeing 40 or 50 psi at wot either oil is bleeding off thru a excessive clearence somewhere or there is a restriction in the oil plumbing causing oil pressure to bottle neck somewhere or a combination of both.Look at my oil pressure from stock hardware thread for in depth pictures and examples of restrictions.For anyone running any part of a stock 502 merc oiling system with a motor with a high volume oil pump or looser than factory clearences keep in mind every single factory fitting will cause a restriction as they are tiny. I experienced this on my first 502 blower motor,it would run 55-60 psi at wot cold and drop to 40-45 psi. I changed every bit of plumbing from the block out to the return fitting in and GAINED 10-15 psi. Bigger fittings can't create oil pressure but too small of ones can sure restrict it. Another tell talle sign is if you see excessive wear on your cam gear or distributer gear,the teeth will scallop because oil pump is deadheading against the plumbing,literally lifting the bypass valve in the pump constantly because pump is putting out more than fittings can flow,Smitty

Re: oil pressure question
 

Smitty,
After reading and rereading this post and your other post about oil systems it hit me. Maybe it isn't the rod side clearance that is the issue like I've thought maybe it's in the oil cooling system.
I know my bearing clearance is .0025" and I'm running a System 1 adjustable oil pump ( 234-900773-2) so if the rod side clearance is okay then there should be no reason for low oil pressure. But what got me thinking it was in the rigging of the new oil cooler cause several of my friends have had motors built buy the same guy and the ones that just used our old 502 accy's and just added oil coolers have the same low oil pressure issues, some are a little higher than other but knowwhere near the 50 and 80 numbers you guys have been seeing. We all can't have screwed up rod side clearances.
I do know when I rigged my new oil lines up I used 1/2" but I know for a fact I used a straight fitting into 90 degree adapters, and I've got the stock 502 filter adapter and stuff. Maybe this is the reason for the low oil pressure.

Re: oil pressure question
 

If you were to remove the remote filter housing and screw the filter directly to the engine, wouldn't that give an indication of how restrictive the cooler, etc. is? I wouldn't run the engine hard this way.

Re: oil pressure question
 

It is definitly making sense, I go thru a distributor gear a season and I don't have bypasses , it is blocked off. So that pump at 5800 is working it's ass off.
It looks like I will be rerigging the oil cooling system before I put the boat up for the season.
I'd try the filter / remote filter swap just to test but don't have any room.

Re: oil pressure question
 

My stock 502 filter adapter off my 2000 mpi had .380 " dia inlet/outlet holes,not nearly enough for a high volume oil pump,definately a big restriction. Your oil can only flow as good as the smallest restriction on your oiling system,this comes up over and over again on this board. The stock stuff is at 100% of what it can flow with a std volume oil pump and factory tight rod and main clearences.I hope you are able to solve your problem,here is a pic-,Smitty

Re: oil pressure question
 

It doesn't hurt to run as big a filter as possible with full flow fittings too and billet adapters,as you can see,a 3/8 bolt fits tight in the inlet in one pic,its head could almost fit in the part that replaced it,Smitty

Re: oil pressure question
 

It definitely looks like I need to redo the oil cooling system.

Re: oil pressure question
 

The reason I could not get mine off is the cast aluminium lightning oil pan that I run, the center bolt couldn't drop far enough to get it out. You should be able to get it off there with most metal pans. You could try just screwing a filter in it's place as DORaymond suggested above to see if that makes any difference to your oil pressure.

If it does then you know where to look. I drilled and deburred all the passages in the filter pad and the remote filter housing, used #10 lines with swept an fittings. You can either remove the spring from the filter pad housing, tap and plug it, or buy a good aftermarket one that doesn't have a bypass.

Make sure you keep the in and out right both there and at the remote filter mount as some filters have check valves in them.

Whenever I refresh the motor again I will not use braided lines again, instead I will use push-fit, as the braid deteriorates over time and gets painful to work around.

Re: oil pressure question
 

ILL GIVE IT A SHOT AND SEE WHAT HAPPENS. THANKS MARK

Re: oil pressure question
 

Wobble,

I run a Canton billet filter housing with a replacable cartridge element and also run M1 15/50. My oil cooler is a 3" diameter w/power steering cooler from Eddie Marine. My oil thermostat is a Merc part. The filter adapter has been internally rubbed to open up the passages for greater flow. All external plumbing is -10AN braided lines with Aeroquip fittings. Most of my my 90's, etc. are radiused but I do have a couple of 90* Aeroquip adapters into the oil cooler.

Re: oil pressure question
 

Believe it or not but about 15 years ago I heard that merc allowed as low as 10 psi on a big block after a hard run. This is where the Idiot light comes on in a car as well. Nothing is to be compared with a mechanical gauge. Prime a new motor with the mech. gauge before install, and you will know of any oiling issues/problems before a fireup or test run...BBB

Re: oil pressure question
 

It looks like you did a beautiful job of rigging your boat but you have a ton of 120 and what looks to be a 180 degree bend in your fittings. I went with -12 instead of -10 in case the fittings were a restriction. If I were you I would put a tee temporaily in the 1 st discharge fitting coming off your adapter and run a gauge off the tee just to see if there was a large pressure differential between what is very first leaving your block compared to what your seeing at the block after everything. If your seeing 70 psi leaving but only getting 35 or 40 at the block its time to replumb your oil system,Smitty

Re: oil pressure question
 

Well just made some changes on my oil system.

Removed two cast 90 adapters , and changed them to straights and made a new line block adapter to the cooler. It was actually kinked. Since the boat is going to be put up in a couple of weekends I didn't completley redo the system. I just wanted to see if my changes made a difference.
Well I started it up and saw no difference at first. Then as the motor was running and warming up I could see the guage climbing, I picked up around 8lbs at an idle.
Now I still think there is some sort of problem. When a motor and oil is cold shouldn't the pressure be higher ? Then as it warms up the pressure comes down. Why would it do the opposite in mine ? It's been really cold at night (low 40's) , and the oil is 20/50 , could that do something ? Oil is like goo cold trying to push thru some of those small orfices that are on the stock block adapter and cooler (I run the stock 502 and an HP500 one) ?
I did notice that just after I started it and the pressure was at 25 lbs , I slowly bumped the idle up to 1500-1800 and saw the pressure drop slightly. After the motor had warmed up for a while I would do the same thing and could then watch the oil pressure go up slightly.
I'm picking up my pressure just above where the oil filter goes on the side of the block. I think it's a -6 line going to the gauge.
This is something I've delt with for the last 5 years thinking it was the crank, now if it's in the oil system I hopefully can make it right.