# oil pump failure imminate?



## ride400 (Jun 16, 2009)

The Story
I bought an engine for my car last summer. 1975 400 out of a Firebird! I installed it the day after I bought it and since has been giving me oil pressure issues. 10-w30 oil is what I am running as of now. I have tried 15w40 with the same issues. On a cold start the oil pressure indication is very good between 40-50 psi. ALTHOUGH after the engine warms up and the oil becomes a bit more viscous the oil pressure literally drops to to 0 psi. I do not hear any strange noises as of yet but I fear i will soon if I drive it the way it sits. I have changed the gauge and the capillary line as well with no change in indication. 

I am running long tube headers. Could they be heating the oil to the point where it causes an adverse indication? 

Is there another port I can take a true pressure reading other than the oil filter stand off?

Any recommendations?


----------



## jetstang (Nov 5, 2008)

I run 20W-50 in all my old cars.. 10W-40 in the winter, thicker is better, gives up a couple HP, but oil cools the motor also.
I had a 68 Firebird back in the day with the oil light on, I changed to a gauge, still at 0 hot at idle. I sold the car cheaper than I should based on that. The guy I sold it to drove it for years like that. I think the oil passage to the hook up point is just clogged. Mine didn't have any noise at idle, valvetrain or bottom end, telling me it did indeed have oil pressure. I too was confused..


----------



## ride400 (Jun 16, 2009)

I will have to try a thicker oil then. I wont be driving during the winter since I am from New England. Thoughts on strait 30 weight? I will have to try priming the supply line to the gauge as well which i haven't done yet. Im still a little suspicious there might be something a little more serous going on here since I did buy a used engine.


----------



## jetstang (Nov 5, 2008)

Is the engine noisy?
30W is winter oil. 
Get a motor flush to run through it. Then see what you have. If the motor is a little tired, 20W-50 will quiet up some woes.


----------



## BearGFR (Aug 25, 2008)

ride400 said:


> I have changed the gauge and the capillary line as well with no change in indication.


Capillary line? My pressure gauge uses an electrical sending unit. Are we talking 0 psi at idle? How about when running at cruising RPM? It's not cause for alarm if pressure drops to 10psi or so at idle, as long as it 'comes back' quickly off-idle. My brand new 2010 CTS has pretty low pressure at idle too, but it's "right there" as soon as I touch the throttle.

Bear


----------



## jetstang (Nov 5, 2008)

BearGFR said:


> Capillary line? My pressure gauge uses an electrical sending unit.
> 
> 
> > Most oil pressure gauges have 1/8" clear line that routes the oil to the gauge, capillary line, or whatever you want to call it..


----------



## ride400 (Jun 16, 2009)

I have all mechanical gauges. I tried the plastic tygon tubing line first and have since changed over to the copper hard line. 



jetstang said:


> Is the engine noisy?
> 30W is winter oil.
> Get a motor flush to run through it. Then see what you have. If the motor is a little tired, 20W-50 will quiet up some woes.


I hear no signs of oil starvation or bad lower end bearings throughout the oil pressure range. My valves need to be adjusted that's about it. What are your recommendations for an engine flush product? I have used sea foam before but lets not turn this into a product support thread. Just curious.


----------



## geeteeohguy (Feb 2, 2008)

Verify that you actually have an oil pressure problem. It may be the gauge, as stated above. IS there oil to your rocker arms? Are the lifters bleeding down? I have run into oiling issues in Pontiacs in the past...not really common, though. I had one with a blodked oil gallery due to a big glob of blue RTV coming loose (not my build!), and I had another where the oil gallery plugs were left out during the build. Other causes for actual low oil pressure are big clearances: cam bearings, main bearings, oil pump, etc. Verify you really DO have low oil pressure before you do a bunch of jumping through hoops. IMO, running thicker oil is a stopgap measure at best.


----------



## ride400 (Jun 16, 2009)

The chance the issue is actually a bad gauge is not likely. I have changed it out once with a brand new one, with the same reading on both gauges. 
I can answer truthfully about oil getting to the rockers. I haven't run the engine with out the covers on them. 
Is there another port that I can tap into with another guage somewhere on the block? besides the oil filter stand off?


----------



## 68greengoat (Sep 15, 2005)

I'm tapping into a port on the top of the motor by the firewall. Difficult to get to tho. Thick oil, thin oil you still should register pressure.... I have a plastic tube to a mechanical gauge. I run a high volume pump that registers just under 60psi when on the pedal....


----------



## ride400 (Jun 16, 2009)

Any chance you can get a picture o that port? Where is it relative to the distributor l/h or r/h?


----------



## dimitri (Feb 13, 2009)

Check your distributer gear and shaft for excess wear/play. This drives your oil pump off the cam.


----------



## 68greengoat (Sep 15, 2005)

Did I mention it leaks???? That or the valley pan... This is on a '73 455, but I assume it's the same....


----------



## BearGFR (Aug 25, 2008)

jetstang said:


> BearGFR said:
> 
> 
> > Capillary line? My pressure gauge uses an electrical sending unit.
> ...


----------



## ride400 (Jun 16, 2009)

Bear 
The oil pressure does indeed follow the throttle as it should and at operating rpm comes back to 40-60 psi. 

I had a tough time with that very issue. When I first went to hook up my oil lines I found my filter housing stripped. I ended up taping it out to 1/2 pipe thread and adding a reducer. 

68greengoat 
thanks for the pics. a big help. Im going to go look right now to see if i have that plug. The engine bay would look much cleaner if i cold take pressure form there. then I wouldn't have a copper line hooked to my firewall like it is now. UGLY!!


----------



## ride400 (Jun 16, 2009)

Found it 
the plug is there right where your picture stated, thanks 68greengoat

I will need to attach a different a gauge to that port and see what it reads. Im very interested. If it is the same indication with the current oil im running 10w30 then I will check the distributor gear and the oil pump. I just hope I dont have to pull then engine again for a bad pump!!!


----------



## jetstang (Nov 5, 2008)

The oil pressure should be great at the oil pump adapter, worse on the top of the motor. I would pull the oil pump adapter off of the motor and really clean it out, it may be a restricted port, and giving you a false reading. It's only 3 bolts and a gasket. 
As engines wear, there is more clearance between the bearings, so to take up this space, I run thicker oil. It is also extra protection for your motor as the engine heats up and the oil thins. Thicker oil also gives higher oil pressure. I don't run 10W30 in any old engine, 10w40 in the winter, 20w50 in the summer. Heavy oil will make the engine hard crank when it's cold.


----------



## 66tempestGT (Nov 28, 2009)

you have worn bearings. it doesnt take much oil pressure to live at an idle and it doesnt spend much of its life idling. your pump isnt going out but the engine is worn out. you have the pressure it needs when you are driving. unhook the guage and smile.


----------



## ride400 (Jun 16, 2009)

66tempestGT said:


> you have worn bearings. it doesnt take much oil pressure to live at an idle and it doesnt spend much of its life idling. your pump isnt going out but the engine is worn out. you have the pressure it needs when you are driving. unhook the guage and smile.



not what I want to hear but is the most likely cause :lol: I think I will leave the gauge hooked up for now though. hahahh


----------



## ride400 (Jun 16, 2009)

on a side note what is this for? Just forward of the aft spark plug. Its blocking a coolent cavity. I have no idea whats its for. Thanks for all your help by the way. this forum is great!!!!:cool


----------



## BearGFR (Aug 25, 2008)

ride400 said:


> I had a tough time with that very issue. When I first went to hook up my oil lines I found my filter housing stripped. I ended up taping it out to 1/2 pipe thread and adding a reducer.


Please don't be offended but I have to ask ---- did you remove the housing from the block to re-tap the hole?

Not sure what that "plug" is, but from the look of it, it looks like some sort of thermostatic vacuum control. My 69 has a similar beast plumbed into the water crossover on the front of the intake manifold. It's an "emission control" whose purpose is to sense engine coolant temp and use it to regulate things like distributor vacuum advance, air flaps on the air cleaner, etc.

Bear


----------



## ride400 (Jun 16, 2009)

oh yeah I did tap it on the bench. Wouldn't want to risk getting metal shavings in the engine at this point. 

Thats a pretty good theory on the plug. They do look like vacuum ports!!!


----------

