Oil pressure drop??
 

Guys, Here is the deal, Fresh big block rebuilds, Dyno'ed, Sheets show oil pressuer 49.5 @ 3000 rpm, 51.8 @ 5500 rpm, only change from dyno pulls are dressed out motors , have stock remote oil coolers, and remote oil filter set up with 1/2" lines.. problem is on start up oil pressure is good on both . after warm up @ idle my port oil gauge reads close to 10 psi to 0 psi !! Full roller valve train. Engine is not ticking or knocking, not over heating, start fine.after running hard.. pressure on both motors read 40-50 crusing, tried mechanical gauge reads identical ? On my second oil change less than 20 hrs, cut filters they are clean?? talked to my builder he said not to worry ?..I plan on installing larger coolers this winter.. using Castrol 15 w 40 oil..:ernaehrung004:

Put a new sending unit on.

Mechanical guages are reading the same as his electric, so this won't change anything.

Run some straight 40 weight Valvoline Racing oil or M1 15-50 and retest.

You probably need a bigger oil cooler.

There could be an issue with the oil bypass as well.

I agree with Griff, mechanical gauge is correct!

How about an oil temp gauge?

If not, you can get an infrared temp gun and shoot several areas of the engine oil pan, cooler and lines.

Should be somewhere between 210 and 330 degrees after a real hard run.

Just a thought.

Dave

330? is this a typo? I would not run it higher than 280. Over 300 you are risking an oil related bearing failure. Oil temp gauges are just as important as water temp gauges on hi perf. engines. I'm still amazed at the number of people that don't have them.

anyone have the line drawing of oil path flow on a gen VI ?..where is the bypass ?

bypass is under the filter adapter pad.

It should be removed in my opinion

Dave,,,,you need to get an oil temp of whats in your pan.

Give me a call

Thanks Dennis..I'll call ya..Can you get me a decient price on some correct size coolers ?I'm doing a dash up grade adding temp oil temp gauges.. I hook some up temporally to check..Shoot me your number again..

Yep typo...Meant 300 TOPS. Only a spike to 300 though after a real long WOT run. Thanks for the catch!

Dave

What generation engine block are you running ?
If you are running a gen 5 or 6 there are two bypass valves installed in the engine block one for the filter bypass and the other one is for the gm factory remote oil cooler witch is up inside the block where the threads for the remote adapter would bolt up to the block remove the one in the middle. where the adapter is and the one offset needs to be changed to a 30 psi or plugged so all the oil will go throught the filter and cooler.
Do a search here on bypass valves
dont run until you get your problem sorted out with the right bypass valve or you will be removing the engines due to you buring them up like a lot of other guys have done. I spent a lot of research on my set up with the right bypass valve install I still have not fired up my engine but for right now I'm only running a filter on the block and will be motioring the oil temp then going from there I hope I can run just a larger filter and no cooler my set up is pretty light 24 foot boat, and make sure you run a good filter like napa wix do not run fram they are junk.


GM (General Motors) 25161284



Email this to a friend

25161284 - 1991-2000 & 454 - 502 GM Performance Crate Engines Big Block Chevy Oil Filter Bypass Valve - 30 LB Bypass Pressure Used With Sandwich Adapter For External Oil Cooler Only 25161284


Pace Price Qty
$7.95



Detailed Description
Used on Gen V & VI engines when running an external oil cooler with a sandwich adapter between the block & oil filter. The 30 Lb valve compensates for the restriction caused by running an external cooler. Used in the location adjacent to the oil filter nipple on the oil filter pad. For standard non-sanwich adapter applications use GM # 25013759

25013759 - 1991-2000 (And GM Performance Parts 454 & 502 Engines) Big Block Chevy Oil Cooler / Oil Filter Bypass Valve 25013759
Gen V & Gen VI Engines Use 2 Of These

Pace Price Qty
$6.95



Detailed Description
Gen V & Gen VI Big Block Chevy Engines & All GM Performance Parts 454 & 502 crate engines use two of these bypass valves. Location for oil filter bypass valve is adjacent to oil filter nipple on oil filter mounting pad, Location for second valve (For oil cooler bypass) is above oil filter nipple in block on filter mounting pad. If a cooler is not connected to the oil cooler ports on the oil pan rail, the second valve is not needed. Engines using a sandwich adapter between the block and oil filter to connect a remote oil cooler must use GM # 25161284 oil filter bypass valve (in the location adjacent to oil filter nipple) to compensate for higher system backpressure






http://www.offshoreonly.com/forums/s...ght=oil+bypass

I can tell you right now you are baking the oil and that is why your oil pressure is low you need some way to check the oil temp right before the oil go's back in to the motor right at the engine block filter pad is the best place

running 96 Gen VI..they are not merc motors, originally Kodiak marine crate motors that I had made to 540's then stroked to 565's

You need to check the bypass valve or valves I'm pretty sure you have a 11 lbs spring presure valve install and with that the bypass valve is open the whole time and the oil is not being filtered and cooled you need the 30 lbs bypass valve spring presure installed in the filter pad check the center where the oil fiter would spin on to the block and make sure there is not one there if there is remove the one in the middle it will be in the block where the filter adaptor screws to the block these valve work on differential pressure and with the 11lbs will think the filter is pluged and will then open and bypass or filter and cooler then would make your oil very hot and break down and then you see low oil pressure if you run it like that to long you will gernade the engine
http://paceperformance.com/index.asp...&ProdID=113140

http://paceperformance.com/index.asp...D&ProdID=22977

Put merc oil filters on them and they will run cooler oil temps.:ernaehrung004:

If you really had 0 to 10 lbs. of oil pressure, the low oil pressure warning buzzer would activate. Is that system working?

nope long gone.. anyone have instructions to remove and plug bypass ?

This thread has it covered with a pic. Great thread if you haven't read it all yet.

http://www.offshoreonly.com/forums/s...+bypass&page=2

Photo courtesy of PatriYacht

http://i43.photobucket.com/albums/e3...h_DSCF0498.jpg

A screw driver or long 3/8 bolt will tread right in to it did you look at the bypass valves at the pace performance you need the 30 psi valve call any gm dealer they might have one is stock or next day if you are going to plug it you will need a 3/8 npt pipe plug and a 3/8 ntp tap and be sure you remove all the metal from tapping when done

I'm pretty sure I can get to it..have to drain the oil pull off the block adapter . I'll cut the filter open.. THIS BLOCK was REPLACED when I rebuilt..said its prob a 11lb bypass valve, engine shop said he'd stand by his work . but he's cross state..so plan is to remove and plug the by pass, oil /filter change. reassemble. fire and check. Install temp gauges..time is running out have to be winterized or pull by OCT15. ..maybe I can get SKramer and Fullforce to help ?????

I helped a friend build a couple Cigarette smoking 502's this past winter and they had low oil pressure and high oil temp.
The problem was he had standard oil filters.
He replaced them with HP4's and changed to mobile one.
He picked up about 40 psi and lost 100 degrees on oil temp.

question with the block adapters do you leave the spin on filter nipple or remove ?..I think I removed mine ??

Just saw this thread here Dave... of course I will help!

Fullforce,

Fix him up!! Anything I can do to help...you got my number!

Dave

we will not leave dave hangin.....

No Kelleys this year?

we smoked a drive in Lake Effect last Friday, a week after getting it in... he was out all summer!!

tried for 3 digit MPH, broke at 90...

Nope not this year...Been pretty busy racing OSS/ OPA in our SVL 27' Activator canopy boat. Don't know if you knew that or not. Heading out to LOTO on Thursday for the race this weekend. BTW been running 90 all summer long in my 353! Still dialing in the set-up. MIght be a couple left in her!

Dave

Cool.. dial her in! you know theres more!

we went 97 last year, he made a few changes,mainly ditching mufflers.. hit 94 with ease the first week out with no trim, saw a lean condition, then found that the intercooler was leaking water into engine..got a new one and on the first good pass the Imco upper let loose!



Sorry Dave (SCARAB3DMC) I highjacked ya!!

GEN 6 blocks have 1/8 " pipe plugs in lifter gallery area,are you sure one didn't get left out? cold you would be ok but hot it would leak off enough,especially at idle to drop oil pressure to zero. Does it come up with rpm?,Smitty

You would not be OK without a galley plug at any rpm or hot/cold, that is alot of bleed off.

yes it increases with rpm

Good suggestion Smitty.That's a common mistake and it would cause what's happening.

How could you even get decent pressure with a galley plug missing? that is a big hole, the oil would just shoot out before building pressure!

I just realized that you were talking plugs in valley, I was thinking the ones at the front of the block...I forgot about the valley ones, I have old school 454's.....