Small Block Normalcy (what should it be doing?)

[60short]

Lets start with the basics ..

= makes noise, smells bad, gets hot, leaks oil=

makes noises - check! sounds great

smells bad - check! smells like old truck should

gets hot - check! yep- stays cool since the shroud was installed

leaks oil - check! shes absolutely a leaker - we will deal with that in a bit

I have a small block in my recently resurrected truck thats starting to give me some worries (oil pressure)

So, this is an unknown year / make / model of small block - its got a smog era intake on it, and a rebuild / re manufactured tag on it.


I am trying to get an answer as to what normal oil pressure for a well worn small block is ( i have been told lots of different answers )

So I have been checking the oil level before I start it, and here is what I am seeing

Ive got a 80 psi gauge - probably a bit of a wide swing, but thats what ive got for now... im checking to see if I can borrow something that may show some better numbers

Cold Start : 40 PSI @ Idle
Freeway : 30 PSI @ 55 mph / 2900 rpm
Off Freeway (after freeway driving) : 20 PSI @ 30 mph / 1900 rpm
Hot idle : 5ish?

Is this acceptable?
If not, what are the odds that I can just pop an oil pump in there?

It looks like the pan can come out with having to pull the engine - I am working on the street, so I want to try and plan what I can do and get it done in one go.

Thank you!

[YoungPup1977]

10 lbs of pressure for every thousand RPM is the rule of thumb, If you pull the the oil pump it may not just be the pump.....once you pull the pan, oil pump, pull off the bottom half of the rod bearings and CHECK the bearings, you may find the bearings have a bit of clearance....just my 2 cents. Have fun on the street and good luck !!

[geezer#99]

First thing you do is put a good mechanical gauge on it.
If you get the same numbers and you hear no rattling at idle, keep driving it.

[mattfranklin]

What viscosity oil are you using? I have used heavier oil (DELO 15W-40 or even tried different brands of 20W-50) to slow down leaks in my older vehicles. You're in So-Cal, so you can probably get away with using heavier if you need it.
If you were in the northern US or Canada, I'd say only do that in the summer.

Next oil change put in the heavier stuff. See if it makes a difference with the oil pressure and leaks and noise.

[Dead Parrot]

Normal oil for a stock 350 is 10w-30. The only number that is a little bit worrisome is the 5psi at hot idle. But you are probably in a part of the gauge scale that makes that a bit of a guess. If you don't have lifter rattle/clatter at hot idle, don't worry too much.

Changing to a thicker oil to 'fix' low oil pressure just masks a problem, it doesn't fix it.

Valve cover gaskets are the leading suspects for SBC oil leaks.

As for bad smells, a small fuel leak can create a lot of bad engine smell.

[GASoline71]

If straight 30wt wasn't so hard to find... I'd still be running that. LOL.

Main rule of thumb I've always gone by... If a SBC ain't leaking oil... it's out!

Gary

[60short]

Originally Posted by YoungPup1977

10 lbs of pressure for every thousand RPM is the rule of thumb, If you pull the the oil pump it may not just be the pump.....once you pull the pan, oil pump, pull off the bottom half of the rod bearings and CHECK the bearings, you may find the bearings have a bit of clearance....just my 2 cents. Have fun on the street and good luck !!

ill have to do some digging into what replacing the bearings entails - Ive seen pictures of scoring, on bearings, but im an engine newbie

Originally Posted by geezer#99

First thing you do is put a good mechanical gauge on it.
If you get the same numbers and you hear no rattling at idle, keep driving it.

its a bit loud, but i haven't been hearing anything abnormal - a buddy is supposed to let me borrow a mechanical gauge - if he falls through,Im gonna try to buy one just to have

Originally Posted by mattfranklin

What viscosity oil are you using? I have used heavier oil (DELO 15W-40 or even tried different brands of 20W-50) to slow down leaks in my older vehicles. You're in So-Cal, so you can probably get away with using heavier if you need it.
If you were in the northern US or Canada, I'd say only do that in the summer.

Next oil change put in the heavier stuff. See if it makes a difference with the oil pressure and leaks and noise.

currently running 10-30 - I run 15-40 in my Volvo for the zinc, but that is getting driven very little at the moment.

I am thinking about doing an oil-change, and sticking a camera up the drainplug to see if I can see anything worrysome

Originally Posted by Dead Parrot

Normal oil for a stock 350 is 10w-30. The only number that is a little bit worrisome is the 5psi at hot idle. But you are probably in a part of the gauge scale that makes that a bit of a guess. If you don't have lifter rattle/clatter at hot idle, don't worry too much.

Changing to a thicker oil to 'fix' low oil pressure just masks a problem, it doesn't fix it.

Valve cover gaskets are the leading suspects for SBC oil leaks.

As for bad smells, a small fuel leak can create a lot of bad engine smell.

yea, its hard to tell - gauge is graduated in 20 PSI, so its all a rough estimate at this point..

It doesnt' sound any different engine wise hot vs cold, so I guess thats a good thing ?

I have no problem putting different oil in, but as you said, if I am just manipulating the gauge, won't we still have the same problem of not building enough pressure?

Ive got a set of rubber gaskets to go on

Originally Posted by GASoline71

If straight 30wt wasn't so hard to find... I'd still be running that. LOL.

Main rule of thumb I've always gone by... If a SBC ain't leaking oil... it's out!

Gary

right - thats what Ive always been told, but Id like to get it to the point where I am changing the oil and filter, not just topping off and changing the filter every 3


Thanks All - I will report back shortly...

[mattfranklin]

Originally Posted by Dead Parrot

...Changing to a thicker oil to 'fix' low oil pressure just masks a problem, it doesn't fix it...

Yes, that and it helps with the diagnostics. Or maybe buy a little time before getting the rebuild it really needs. It's bought me at least 4-5 extra years with my daily driver Accord.

[cadillac_al]

Originally Posted by mattfranklin

Yes, that and it helps with the diagnostics. Or maybe buy a little time before getting the rebuild it really needs. It's bought me at least 4-5 extra years with my daily driver Accord.

I'd say it is better to mask the problem than tear into an engine that still runs ok. They like 10w30 when they are new and tight. When they get older they start liking some 15w40. When the bearings get loose that nice 10w30 has a hard time filling the extra clearance.

[60short]

Originally Posted by mattfranklin

Yes, that and it helps with the diagnostics. Or maybe buy a little time before getting the rebuild it really needs. It's bought me at least 4-5 extra years with my daily driver Accord.

Originally Posted by cadillac_al

I'd say it is better to mask the problem than tear into an engine that still runs ok. They like 10w30 when they are new and tight. When they get older they start liking some 15w40. When the bearings get loose that nice 10w30 has a hard time filling the extra clearance.

I did an oil change last night, dang I love that truck, no floor jack, just a drainpain and a wrench - 15 minutes in and out.

Put in 5.5 quarts of Del0 15w40 - oil pressure was definitely better last night (both cold and warm), but this morning after the drive in to work, it still feels like its sitting a bit low on the gauge (buddy is looking for correct adapters for his gauge)

I will try and attach some photos to help illustrate what Im seeing.

this first picture is warm idle the night of the oil change
Warm idle night of oil change by Keith, on Flickr


this second picture is warm idle the morning after the oil change

Warm Idle day after oil change by Keith, on Flickr

I am wondering if there may be something in the pan that is getting stuck towards / infront of the pickup, but if I am dropping the pan, I will probably change the pump anyways.

Thanks all!

[Alex V.]

That pressure is low, but the engine is still lubricated so as long as it's not something going downhill fast it could last a good while. I don't default to thick oils, but I second the suggestions to put some 15w40 in it and see what it does for it. Especially in the warmer climate it certainly won't hurt it, and if it brings your oil pressure up a bit I'd run it and not worry. BTW, in your stock engine high ZDDP content isn't necessary so any 15w40 is fine - Rotella T4 is cheap and has a good reputation.