BBC oil pressure? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Slammed70 · 05-18-2007, 09:19 PM

Workin on a 97 1/2T, its got a transplanted mid '70s 454 in it.

When you first start it, oil pressure is good.....3/4 of the guage and damn near maxed with highway RPMs.

But after about 15 mins or however long it takes to warm up, the oil pressure dramitically drops. wont even register at idle, barely moves/flickers at RPM.

Any idea what would cause this.

I thinks its got 10-30 Mobil 1 in it, other than that I have no idea.

Thanks,
Mitch-

corn · 05-18-2007, 09:25 PM

The senders on the 88 & up trucks cause a lot of trouble. Does it have a mechanical gage or the factory electric?

Slammed70 · 05-18-2007, 09:33 PM

Its got a set of them Equiss mechanical guages....or how ever they're spelled.

corn · 05-19-2007, 12:49 AM

No idea then. I have Equus gages in my 89 & they work great. try the 88-98 board maybe...

http://67-72chevytrucks.com/vboard/f...splay.php?f=12

Slammed70 · 05-19-2007, 03:54 AM

Quote:

Originally Posted by corn

No idea then. I have Equus gages in my 89 & they work great. try the 88-98 board maybe...

Yeah, Equus....I thought it was some weird spelling like that.

Thanks for the link, sadly it doesnt help though. Where as its not using the computer...or any of its guages.

Lol, I think I forgot to mention that it was carbureted...I appologize for the lack of info there.

1968SWBBigBlock · 05-19-2007, 08:52 AM

I would go buy another gague- prefer mechanical and plumb it in as my 1st double check.
Actually - change you oil filter 1st - put on a napa gold or a wix filter - the bypass valve in the filter might be an issue.

**clay68c10** · 05-19-2007, 11:02 AM

Try another gauge and then I'd also change oil to 15-40 and see what that does. If it's still that low when it's warmed up your bearings are probably toast.

Slammed70 · 05-19-2007, 06:55 PM

Quote:

Originally Posted by clay68c10

If it's still that low when it's warmed up your bearings are probably toast.

Cam bearing?

KFreddy · 05-19-2007, 07:28 PM

Just for informations sake what should the oil pressre be at numericaly that is?

Slammed70 · 05-19-2007, 09:25 PM

Quote:

Originally Posted by KFreddy

Just for informations sake what should the oil pressre be at numericaly that is?

All the cars Ive worked on it has varied, SBCs usually run 15-25 at idle, 40-60 at RPMs....thats an average though, some (my camaro for instance) would have 6-7 at idle, and 65-70 at RPM.

Not to sure about BBCs though, Ive only only had one...the one in my truck. It runs about 15 at idle, and 30-35 at RPM.

Im probably wrong though.....thats just what I have noticed through out my years.

mnunn454 · 05-20-2007, 09:11 AM

I was experiencing a similar problem with a 396. At 1st I thought it was the gauge, but it turned out to be bad/worn out main bearings.

Sorry to be the bearer of bad news.

Slammed70 · 05-20-2007, 05:35 PM

Quote:

Originally Posted by mnunn454

I was experiencing a similar problem with a 396. At 1st I thought it was the gauge, but it turned out to be bad/worn out main bearings.

Sorry to be the bearer of bad news.

Meh...its not mine, that just means more money for me. But more work at the same time.

KFreddy · 05-21-2007, 12:03 PM

Quote:

Originally Posted by corn

The senders on the 88 & up trucks cause a lot of trouble. Does it have a mechanical gage or the factory electric?

I had the same problem with my '96 Impala SS with an autometer gauge, as corn stated it's most likely a sender issue. If it is an aftermarket gauge you can check the wire from the gauge to the sender and check that the sender is tight and that the wire/ connection is not burnt or frayed or partially disconected. Being a '97 assuming that it's a factory gauge I would check the 4 harnesses that connect to th PCM make sure they are tight and seated. Again check the sender and the harness wire if you can.

EAST SIDE LOW LIFE · 05-22-2007, 09:05 AM

I have a buddy with a factory BB 67 Vette 427/400hp. motor with only 40,000 miles. His readings are as follows ....

* Idle cold - 40 to 60 lbs pressure

* Idle warm - 40 lbs.

* Running @ RPM. - 60 lbs,

esll.

Oil gauge mech. ........................... I also run a mech. gauge on my 70'LWB.

eedgell · 05-22-2007, 07:11 PM

Oil pressure will vary depending on the type of oil and oil pump. If not the gauge then most likely bearings. Pressure starts to build in the cam bearings first then to the crank assembly. Dont sound good.

69RAT · 05-22-2007, 08:52 PM

my 396 runs 35-40 at warm idle and 55-60 at highway. My 455 did the same thing, it was mains, in a motorhome..... can you say expensive!!!!!!

Slammed70 · 05-22-2007, 09:06 PM

Main bearing look heavily worn (coppers showing), gonna pull the cam later and get a look at them bearings.

The front main bearing....it more worn than the others too. Almost like the belts were so tight that it lifted the crank up into the bearings.

05-18-2007, 09:25 PM	#2
corn Registered User Join Date: Dec 2003 Location: here Posts: 5,789	Re: BBC oil pressure? The senders on the 88 & up trucks cause a lot of trouble. Does it have a mechanical gage or the factory electric?

05-19-2007, 12:49 AM	#4
corn Registered User Join Date: Dec 2003 Location: here Posts: 5,789	Re: BBC oil pressure? No idea then. I have Equus gages in my 89 & they work great. try the 88-98 board maybe... http://67-72chevytrucks.com/vboard/f...splay.php?f=12

05-19-2007, 08:52 AM	#6
1968SWBBigBlock Active Member Join Date: Oct 2006 Location: Ohio Posts: 1,643	Re: BBC oil pressure? I would go buy another gague- prefer mechanical and plumb it in as my 1st double check. Actually - change you oil filter 1st - put on a napa gold or a wix filter - the bypass valve in the filter might be an issue. __________________ 1968 SWB 454 + .040, 490HP x 540 FT pounds of Torque 10-1 Kb Forged pistons, recon rods w/ ARP wave loc bolts 781 heads Ported with 2.19/1.88 SSTvalves Lunati 60204 cam, Micro Trol lifters, Ported Edelbrock Performer Rpm manifold armor coated, Pertronix Triple Strike Ignition Holley 770 Street Avenger carb,Headers armor coated Built by Watson Ruppel Performance in Sarahsville Ohio. Hardshift Tranny Built Turbo 350,TSI 10" 3000 stall 12 Bolt Eaton Posi 4.10 Richmond Gears moser axles 18.5" x 31" Hoosier Pro Street Radials ET Classic 5 Wheels - polished Power Steering, Power Brakes,Disc Brakes,Tach & Gauge Dash, Tilt,Factory Air (gone) Custom Paint & Body Work Special thanks to my wife, my son and my money tree

05-19-2007, 11:02 AM	#7
clay68c10 Senior Member Join Date: Aug 2004 Location: Centennial, CO Posts: 2,964	Re: BBC oil pressure? Try another gauge and then I'd also change oil to 15-40 and see what that does. If it's still that low when it's warmed up your bearings are probably toast. __________________ ClusterTruck: 68 C10 Bought in 89, wrecked in 03. Slow low $ rebuild started '17. 6.0 & TKO http://67-72chevytrucks.com/vboard/s...d.php?t=788602 93 K1500 Short Step, 350, NV4500, EBL flash ECU. Vortec heads & roller cam someday... 05 Jeep Wrangler Unlimited. 3” lift & 6-speed 02 E320 the insurance total “free car” 13 Tahoe LTZ

05-19-2007, 07:28 PM	#9
KFreddy Active Member Join Date: Apr 2005 Location: Miami, Florida Posts: 286	Re: BBC oil pressure? Just for informations sake what should the oil pressre be at numericaly that is? __________________ "The Great State of Florida"

05-20-2007, 09:11 AM	#11
mnunn454 Registered User Join Date: Dec 2006 Location: Rhode Island Posts: 602	Re: BBC oil pressure? I was experiencing a similar problem with a 396. At 1st I thought it was the gauge, but it turned out to be bad/worn out main bearings. Sorry to be the bearer of bad news. __________________ 69 C-10 SWB Fleetside 454/TH400 (For Sale) http://67-72chevytrucks.com/vboard/c...ct=1299&cat=12 70 El Camino 454 TH700 29 Model A 4-DR Sedan Deluxe

05-22-2007, 09:05 AM	#14
EAST SIDE LOW LIFE Senior Member Join Date: Mar 2007 Location: VANCOUVER ISLAND, B.C., Canada Posts: 1,602	Re: BBC oil pressure? I have a buddy with a factory BB 67 Vette 427/400hp. motor with only 40,000 miles. His readings are as follows .... * Idle cold - 40 to 60 lbs pressure * Idle warm - 40 lbs. * Running @ RPM. - 60 lbs, esll. Oil gauge mech. ........................... I also run a mech. gauge on my 70'LWB. __________________ Tomorrow is for doing today's stuff. ************************************* This truck has just the right amount of energy for me! Author: Warren Lake .... (member) Last edited by EAST SIDE LOW LIFE; 05-22-2007 at 09:10 AM.

05-22-2007, 07:11 PM	#15
eedgell It's the air up here Join Date: Mar 2007 Location: Western Colorado Posts: 710	Re: BBC oil pressure? Oil pressure will vary depending on the type of oil and oil pump. If not the gauge then most likely bearings. Pressure starts to build in the cam bearings first then to the crank assembly. Dont sound good. __________________ 1971 cheyenne k10 4 speed np 205 454 BB factory a/c Never drink down stream of the herd! Eric

05-22-2007, 08:52 PM	#16
69RAT Registered User Join Date: Apr 2006 Location: hopeless in Washington Posts: 105	Re: BBC oil pressure? my 396 runs 35-40 at warm idle and 55-60 at highway. My 455 did the same thing, it was mains, in a motorhome..... can you say expensive!!!!!! __________________ '69 Chevy CST#'s 396/TH400, A/C



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