Dancing oil pressure, Need ideas.......

[396_WAYS_TO_SPIT]

I had this same problem 2 weeks ago so I pulled the bottom end and changed the main bearrings. All the bearrings were fine except #3 but it was only showing slight copper in color. Had a very very small nick in the crank that played a factor to the copper to show.I polished the nick out of the crank, so thats ok now. Before my oil pressure was good untill 4k rpms then it would fall to 20lbs at wot. i just changed the main bearrings last weekend and took it out yesterday and the oil pressure was 70lbs @ hot idle and running. I keep the 70lbs until 5000 rpms then it falls to 20lbs. When I drop the r's to 4500 it goes back up to 75lbs! It ran great all day long with no problems. Where should I look now? I am going to install a mechanical guage and compare the numbers. Also, I have heard that running the sending unit dorectly over the oil filter ISNT the best place for a good reading. WHatcha guys think?
396

[Squirtin Thunder]

Michael Talk to DragBoats he had that problem and I am not sure what we came up with as the problem.

[diggler]

It could be a problem of windage. As the oils is whipped up and foams, it starts to pass air to the connecting rod journals. Air will compress, and oil won't.
Does this sound possible, or am I an idiot? :idea:

[Squirtin Thunder]

Does this sound possible, or am I an idiot? :idea:
Yes !!!
No !!!

[GofastRacer]

The pickup is to close to the pan!..

[Turbojack]

Could you be running out of oil in the pan?

[Fiat48]

I pick any of the above.

[steelcomp]

sounds like pick-up clearance.

[GofastRacer]

Could you be running out of oil in the pan?
Nope it's sucking the pan up!

[GofastRacer]

I pick any of the above.
I'll lay odds on clearance!.. ;)

[396_WAYS_TO_SPIT]

I am 3/8 to 1/2 from the bottom. I cant remember exactly but its one of those two. Like I said, Its only under hard acceleration and thats it. I can cruise at 4000,4200,4400,4600 and even 4800r's with no issues then 4900 and up it falls. I know for a fact that the pan has the correct ammount of oil in it because I just had the pan off and I refilled the pan. I get 9qts and its touching the windage tray and thats without the oil filter. I put 9qts including filter this weekend. I had 10qts in 2 weeks ago and the same thing so I know I am not running out of oil. The pan is a milodon full tray with trap doors. The oil pump is brand new"blueprinted" and the #5 maincap is massaged.
396

[396_WAYS_TO_SPIT]

I'll lay odds on clearance!.. ;)
What is ideal clearance? How do you check your clearance art? Just curious to see if I checked wrong.You may be right in this situation.
Michael

[GofastRacer]

Check it again, make sure the pickup is square to to bottom of the pan, lay a straight edge across the pan and measure, now lay the straight edge across the pickup and measure to the pan rail, add the thickness of the gasket, should have 3/8" min. I've seen this over and over and unless you have a leak by the pump it's a clearance problem!.. BTW, you should have saved the $$$$$$$$$$ and use a stock pump!.. :wink:

[steelcomp]

That just might be a POS pan.

[GofastRacer]

Could be but Milidons are a pretty good pan though??.. :confused:

[396_WAYS_TO_SPIT]

Come to think of it art. I have the extreme duty oil pickup on my pump. It has a brace comming off the pickup and connects to the pump. Then it has a bar that is welded to the bottom of the pickup so that it cant be too close to the pan. I will look for a pic of the pickup.

[396_WAYS_TO_SPIT]

That just might be a POS pan.
I have heard good and bad anout milodons..... :confused:

[Oldsquirt]

Since all the basic ideas have been covered......Did you use the correct Milodon pickup with that pan? If not, did you check to make sure the pickup you used did not interfere with the operation of the trap doors? Probably a long shot, but......

[MandDPerformance]

Did you put more oil in the engine after your bearing change than you took out to change your bearings? I strongly feel that your bearing change had little if no effect on your oil pressure. It could be a volume issue, an airation issue, or a cavitation issue. What kind of drainage do you have from the top of the engine to the pan? Any restrictions could slow oil flow back to the pickup and starve it at higher RPM. Could the pickup be too far from the pan?

[396_WAYS_TO_SPIT]

Here is what that little bar looks like. My pickup is different but it has the same little bar that goes around the pickup opening...
http://static.summitracing.com/global/images/prod/large/mil-18481_w.jpg

[396_WAYS_TO_SPIT]

Did you put more oil in the engine after your bearing change than you took out to change your bearings? I strongly feel that your bearing change had little if no effect on your oil pressure. It could be a volume issue, an airation issue, or a cavitation issue. What kind of drainage do you have from the top of the engine to the pan? Any restrictions could slow oil flow back to the pickup and starve it at higher RPM. Could the pickup be too far from the pan?
Good ideas. I put 9qts in. I might add another qt this week and take it out for a quick spin. I can dran 1 qt if needed but I'll be damned if I run out of oil. I dont have any restrictors in the block at all. I wonder if something got stuck in the sending unit??? Hmmmmm, keep the ideas comming fellas.....

[GofastRacer]

Ok, is the pickup square to the pan?, that little bar prevents it from being to close to the pan but if the other end is touching you'll be too close!. And yes another problem could be pump cavitation!..

[steelcomp]

Pick up interfearing with the trap door isn't a bad thing to check.
Not saying Milodon pans aren't any good, just that for some reason this particular pan might not be working that well. Sticking baffles, just not quite configured right. Who knows. There's a reason that a gooooood pan will cost you $600.00.

[GofastRacer]

But if it were a trap door issue, it would run out of oil long before 5000 rpm and the pressure wouldn't come up right away when the rpm drops because there still wouldn't be any oil in the sump!.. :confused:

[MandDPerformance]

But if it were a trap door issue, it would run out of oil long before 5000 rpm and the pressure wouldn't come up right away when the rpm drops because there still wouldn't be any oil in the sump!.. :confused:
Right you are.

[GofastRacer]

Good ideas. I put 9qts in. I might add another qt this week and take it out for a quick spin. I can dran 1 qt if needed but I'll be damned if I run out of oil. I dont have any restrictors in the block at all. I wonder if something got stuck in the sending unit??? Hmmmmm, keep the ideas comming fellas.....
Don't over fill the pan, all you'll do is airate the shit out of the oil. And no it's not the sending unit plugged or you wouldn't get any reading on the guage!

[Oldsquirt]

Art, I was thinking just enough interference to keep it from opening enough, not necessarily keeping it totally shut. But again, like I said, a long shot.

[83Dana454]

I had the same exact problem as you are having, it wasn't it a boat though. I built a 383 for my 72 Nova, oiling system consisted of a Milodon pan with matching pickup and a high volume oil pump. Engine has good oil pressure until I started to get into the 5000 RPM range and it would drop like a rock to 20 and lower, let up on the RPM alittle bit and the oil pressure would return to normal. I installed a full length windage tray and a rear pan baffle (fits between the oil pump and maincap) and problem was solved. I'm usure if it was the oil climbing up the back of the pan and into the crank during hard accel or if it was just the crank and rods foaming the oil all together but I decided to put both in, I didn't want to have to pull the pan back off again. Good luck man.

[MandDPerformance]

I've got possibly stupid question. What kind of boat are we talking about? I noticed on your personal profile 396 that you have jet boats. Is that still true? Or are we talking about a V-Drive?

[steelcomp]

But if it were a trap door issue, it would run out of oil long before 5000 rpm and the pressure wouldn't come up right away when the rpm drops because there still wouldn't be any oil in the sump!.. :confused:
I disagree. If the trap door wasn't opening at all, possibly, but not if the oil flow back to the sump is just restricted, not blocked. Even if the doors were stuck, this wouldn't stop oil from coming into the sump, nor would it mean the sump was empty... just not filling at the rate the pump was emptying it. Lower rpms, there's enough flow into the sump to feed the pump. Higher rpm's, the pump gets ahead of the return flow. Oil is still flowing into the sump, and the second the pump slows down to meet the flow, presure picks back up. Oil gets into the sump from other areas besides through the trap doors. I also doubt very much that it's a drain back issue. Never heard of that with a BB Chev. I'd be checking baffling and operation of trap doors or interfearance. Actually, I'd have tried another pan by now, just to see. Michael, I have a 10 qt. dooley I'd send you (you pay freight) to try. I never had any oil pressure issues...ran 6000-6200 rpm, 9 qts. in the pan, 675 hp. If you like it, you can buy it. If it solves your problem, and you get another pan, you can just send it back. No big.

[GofastRacer]

I disagree. If the trap door wasn't opening at all, possibly, but not if the oil flow back to the sump is just restricted, not blocked. Even if the doors were stuck, this wouldn't stop oil from coming into the sump, nor would it mean the sump was empty... just not filling at the rate the pump was emptying it. Lower rpms, there's enough flow into the sump to feed the pump. Higher rpm's, the pump gets ahead of the return flow. Oil is still flowing into the sump, and the second the pump slows down to meet the flow, presure picks back up. Oil gets into the sump from other areas besides through the trap doors. I also doubt very much that it's a drain back issue. Never heard of that with a BB Chev. I'd be checking baffling and operation of trap doors or interfearance. Actually, I'd have tried another pan by now, just to see. Michael, I have a 10 qt. dooley I'd send you (you pay freight) to try. I never had any oil pressure issues...ran 6000-6200 rpm, 9 qts. in the pan, 675 hp. If you like it, you can buy it. If it solves your problem, and you get another pan, you can just send it back. No big.
You're right to a point oil would still flow, there are slots all over to let oil in the sump but with a super pump it could overcome the amount of flow thru the slots and enpty the sump. But what are the odds of all the doors sticking shut at one time, LOL.. I don't believe this is the problem!. :smile:

[MandDPerformance]

It all boils down to emptying the pan or uncovering the pickup. I agree with you Steel on your trap door issue the way you are describing it providing this is a jet boat or circle boat, "Pickup in the front of the boat". However, if this is a traditional V-Drive, "I don't know what it is", I disagree. Can you please tell me what kind of boat this is.

[Oldsquirt]

It is a jetboat.
Where did 396 go anyway? Hope he's out pulling the engine and dropping the pan .....

[396_WAYS_TO_SPIT]

ok lets say the pump is cavatating.......how would we address it?

[MandDPerformance]

The pickup on the opposite page is traditional V-Drive pickup. This is a V-Drive boat correct? Right pan for the application. I'm sure so, but I can't help but ask.

[MandDPerformance]

ok lets say the pump is cavatating.......how would we address it?
Take the cap off and look for chatter marks or wear marks. Check gear to cap clearance. Does the pump have anti-cavitation grooves in it.

[396_WAYS_TO_SPIT]

Im here fellas, It is in a 1987 kachina jetboat with a 454 bbc. The picture is a v-drive pickup. I have the right pickup on the oil pump"for a jet" I just posted the pic to show the little bar design.

[GofastRacer]

Whoa wtf, it is a ditch pump duhhhh, hey why the long pickup?????????????, you have the wrong pan dude!..

[GofastRacer]

The sump is at the rear then????

[MandDPerformance]

Im here fellas, It is in a 1987 kachina jetboat with a 454 bbc. The picture is a v-drive pickup. I have the right pickup on the oil pump"for a jet" I just posted the pic to show the little bar design.
Not such a stupid question after all. :D :D :D :D
Wish I was right.

[396_WAYS_TO_SPIT]

Take the cap off and look for chatter marks or wear marks. Check gear to cap clearance. Does the pump have anti-cavitation grooves in it.
I had bergeron engeneering go through the oil pump for me. I will ask them tomorrow, what exactly they do when they go through the oil pump. ITs a melling hv pump before it was gone through.

[396_WAYS_TO_SPIT]

Whoa wtf, it is a ditch pump duhhhh, hey why the long pickup?????????????, you have the wrong pan dude!..
What do you mean art??????

[GofastRacer]

Not such a stupid question after all. :D :D :D :D
Wish I was right.
:D :D :D

[steelcomp]

Whoa wtf, it is a ditch pump duhhhh, hey why the long pickup?????????????, you have the wrong pan dude!..
You need to go sit in the corner...you're not paying attention. He only showed that pic as an example of the bar across the bottom of the pick up that's supposed to keep it from coming in contact with the bottom of the pan.
He said he has the right pick up.
Pay-attention, or you'll have de-tention! :argue:

[396_WAYS_TO_SPIT]

The sump is at the rear then????
Yes, the sump is in the rear. The oil pan will only go on one way. The windage tray coveres everything else. Also, the way the windage try look, it appears that is restricts the oil flow on its way down for some odd reason......

[GofastRacer]

What do you mean art??????
Well I thought you had a v-drive pan with the long pickup, but you explained it afterwards!..

[396_WAYS_TO_SPIT]

Pay-attention, or you'll have de-tention! :argue:
you guys are silly;);)

[Oldsquirt]

What do you mean art??????
I think he thinks the pickup you posted a pic of is what you are using and not just posted to illustrate the little stand-off bar below the screen.

[396_WAYS_TO_SPIT]

I have a jetboat oil pan with a jetboat pickup= rear sump oil pan;)

[GofastRacer]

You need to go sit in the corner...you're not paying attention. He only showed that pic as an example of the bar across the bottom of the pick up that's supposed to keep it from coming in contact with the bottom of the pan.
He said he has the right pick up.
Pay-attention, or you'll have de-tention! :argue:
Yeah yeah I know, I saw it late ok!.. :hammerhea :D

[steelcomp]

Yeah yeah I know, I saw it late ok!.. :hammerhea :D:D

[MandDPerformance]

Yeah yeah I know, I saw it late ok!.. :hammerhea :D
Glad you said it and not me. Stupid curiosity killed the stupid cat. :D :D

[396_WAYS_TO_SPIT]

you guys are cracking me up;) :D :D Scott I might just take you up on the offer. Pm me with the price of the pan and we can go from there. I might just want to buy it;)

[Moneypitt]

Before you do anything put a mechanical gauge on the motor. If it recovers as fast as you say it does that sorta eliminates the majority of the above ideas. Foamed oil remains foamed for a while, empty sumps do not recover that quickly, low clearance pick ups don't suddenly have enough at 100 rpms slower. I would sure suspect the sending unit/gauge. Electrical readings could change that fast, the sender looses contact to ground at a certain pressure, but regains it 2 lbs less, same could be said for the gauge, all an electrical set up is, is an OHM meter, measuring continuity to ground. More pressure, more ground, higher reading. BUT, if the grounding factor changes, the gauge changes. Enough, just put a good mechanical gauge on it and see if it does the same thing............MP

[steelcomp]

Before you do anything put a mechanical gauge on the motor. If it recovers as fast as you say it does that sorta eliminates the majority of the above ideas. Foamed oil remains foamed for a while, empty sumps do not recover that quickly, low clearance pick ups don't suddenly have enough at 100 rpms slower. I would sure suspect the sending unit/gauge. Electrical readings could change that fast, the sender looses contact to ground at a certain pressure, but regains it 2 lbs less, same could be said for the gauge, all an electrical set up is, is an OHM meter, measuring continuity to ground. More pressure, more ground, higher reading. BUT, if the grounding factor changes, the gauge changes. Enough, just put a good mechanical gauge on it and see if it does the same thing............MP
That's a good suggestion...at least that's eliminated as a possibility, and is easy enough.
Michael, I'm not trying to sell you a pan, I just know that guys have fought pan problems before, and would like to help. Check your pm's.

[cstraub]

I would suggest running the pan a quart to 2 quarts low. Warm her up and then do a hard accelleration test and and see what it does.
Chris

[franky]

Had the exact problem on a 468 on the dyno. Milodon "meatloaf pan", same pickup. We had installed a high volume "racing pump". Oil pressure dropped at 4,500-5,000 rpm. Though it was foaming, lowered the oil level, got worse.
The problem was that the pump was pumping the oil up in the motor faster than it could drain back to the pan. Put a lightly massaged STOCK pump with the modified relief plate and problem went away. The alternative would to have put a bigger volume pan, like a 14 qt.

[blowngas]

the guys at titan pumps maintain that oil drain back is a problem in BBC when high volume pumps are used and vapor travel going up thru the oil drain holes limit the oil returning to the pan-----and a lot of guys epoxy screens in the lifter valley which compounds the problem----they suggest running a pan vent from the fuel pump block off plate (if you are not running a mechanical pump) to the top of the valve cover on the fuel pump side----this allows a lot of the vapors to travel up thru the vent instead of the oil return holes which then allow the oil to return to the pan faster

[Hallett19]

I had a similar problem. I was running a high volume oil pump with a low volume oil pan and was sucking the pan dry at high rpm's. Ended up smoking the cam bearings and lifters.

[steelcomp]

the guys at titan pumps maintain that oil drain back is a problem in BBC when high volume pumps are used and vapor travel going up thru the oil drain holes limit the oil returning to the pan-----and a lot of guys epoxy screens in the lifter valley which compounds the problem----they suggest running a pan vent from the fuel pump block off plate (if you are not running a mechanical pump) to the top of the valve cover on the fuel pump side----this allows a lot of the vapors to travel up thru the vent instead of the oil return holes which then allow the oil to return to the pan fasterThat's all very true. Stef's makes an oil pan/crankcase breather that has a fitting that you weld in the pan in an inactive place, and it goes through a check valve into a breather, venting the oil pan directly to atmosphere. It's worth HP for a wet sump system.

[396_WAYS_TO_SPIT]

I am going to pull the pan and have bergeron inspect the trap doors for me. That may be the problem. It might be running out of oil due to the trap doors not working properly.

[GofastRacer]

I am going to pull the pan and have bergeron inspect the trap doors for me. That may be the problem. It might be running out of oil due to the trap doors not working properly.
Why don't you just look at the trap doors yourself and see if thyr'e working or not, and that ain't your problem anyways, it's either a clearance problem or the pump, as I said before you should have used a stock pump!..BTW, did you check for a loose ground wire on the guage??? :confused:

[GofastRacer]

Glad you said it and not me. Stupid curiosity killed the stupid cat. :D :D
LMAO!.. :D :D

[396_WAYS_TO_SPIT]

Why don't you just look at the trap doors yourself and see if thyr'e working or not, and that ain't your problem anyways, it's either a clearance problem or the pump, as I said before you should have used a stock pump!..BTW, did you check for a loose ground wire on the guage??? :confused:
Come to think of it, I did check the doors last week when the pan was off. They all functioned properly. I havent checked the guage yet but tomorrow I will for sure! I know its gotta be something simple! I just started this 2 weeks ago :confused: :confused: I didnt do it when I first put her in the water....... wait a minute, let me think...........When i first put her in the water I had 2 extra qts of oil because fiat48 told me to put them in to get hot oil splashed on the crank. I didnt change the oil at all. I just cut the filter and hit the lake! My oil pressure was perfect for 3 weeks! Now I have 9 qts in there and its acting up. Somthing looks funny there :confused:

[396_WAYS_TO_SPIT]

the guys at titan pumps maintain that oil drain back is a problem in BBC when high volume pumps are used and vapor travel going up thru the oil drain holes limit the oil returning to the pan-----and a lot of guys epoxy screens in the lifter valley which compounds the problem----they suggest running a pan vent from the fuel pump block off plate (if you are not running a mechanical pump) to the top of the valve cover on the fuel pump side----this allows a lot of the vapors to travel up thru the vent instead of the oil return holes which then allow the oil to return to the pan faster
That sounds like a good idea but I am running a mechanical pump :frown:

[hondajoey]

Mike what you need is a bigger impeller and turn that monster a little slower
J/k

[396_WAYS_TO_SPIT]

Mike what you need is a bigger impeller and turn that monster a little slower
J/k
:D :D :D :D :D

[GofastRacer]

So, what did you find out???

[396_WAYS_TO_SPIT]

i havent touched it yet, i got tied up. i am going to install a mechanical guage tomorrow and add a qt of oil and check it. i will start with the quick and easy stuff first. i want to back up my electrical guage before i rip my motor apart.

[GofastRacer]

Don't add no oil if it's up to capacity, that ain't going to help!..

[Mighty Thor]

Years ago I remember discussions in our Chevy Group about adding drain back holes in the lifter gallery cause oil was poolin under the intake and not draining back as fast as it could or should under hard accelertaion. Just out of curiosity what is the attitude of the engine in the boat, I assume that it tips slightly to the back even when the boat is on plane. Ie, maybe you are storeing an extra quart or so in the valve covers and lifter gallery at 4900 rpm you may be at a different plane angle than at 4800 and if the oil level in the pan is marginal at those speeds it may still be a cavitation issue even though some have suggested that the engine would not recover PSI so quickly. Then again I could be goofy.

[396_WAYS_TO_SPIT]

Don't add no oil if it's up to capacity, that ain't going to help!..
ok, I wont add any oil but I am going to do a small run and back up my guages readings before I tear into it. If I tear into it I will be adding a new pan,pump,pickup,and sending unit!