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Oil pressure issues Chrysler small block

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pismo10

Contributing Member
After a fresh oil/filter change I have about 45lbs of pressure using about 5.5-6 qts to fill a 1969 Chrysler small block with 4 bbl. Runs well some valve ticking/noise, not too bad, easy start, no real issues. After about every 3-4 hours of run time the valve train starts to sound louder, the pressure drops to about 25-30 lbs and I need to add about 1/2 a qt and all is fine again. Back to 45-50lbs, valve quiet right down, back in business for another 3-4 hours.

Valvoline 20W-50 is what is in there. Does it with every oil I have used, makes no difference.

So I am fine with this, it is a very old, very high hour engine that I will replace some day. I just need to keep the oil level up and it works fine. The is no oil leaking anywhere, it is just burning off.

The question I have is why such a dramatic difference with just down 1/2 a qt? If it was down 2-3 qts I could understand but just 1/2 qt, I am surprised it starts to act up so much.

It is like night and day, pressure cut in half, lots of noise, so out in the middle of the lake, I idle it down, put her in neutral, add the 1/2 qt while it is running and you can watch to oil pressure rise and hear the ticking subside immediately. Nice but why such a change over 1/2 a qt?

Any thoughts appreciated.

Thanks
 
pismo10 said:
After a fresh oil/filter change I have about 45lbs of pressure using about 5.5-6 qts to fill a 1969 Chrysler small block with 4 bbl. Runs well some valve ticking/noise, not too bad, easy start, no real issues. After about every 3-4 hours of run time the valve train starts to sound louder, the pressure drops to about 25-30 lbs and I need to add about 1/2 a qt and all is fine again. Back to 45-50lbs, valve quiet right down, back in business for another 3-4 hours.

Valvoline 20W-50 is what is in there. Does it with every oil I have used, makes no difference.

So I am fine with this, it is a very old, very high hour engine that I will replace some day. I just need to keep the oil level up and it works fine. The is no oil leaking anywhere, it is just burning off.

The question I have is why such a dramatic difference with just down 1/2 a qt? If it was down 2-3 qts I could understand but just 1/2 qt, I am surprised it starts to act up so much.

It is like night and day, pressure cut in half, lots of noise, so out in the middle of the lake, I idle it down, put her in neutral, add the 1/2 qt while it is running and you can watch to oil pressure rise and hear the ticking subside immediately. Nice but why such a change over 1/2 a qt?

Any thoughts appreciated.

Thanks
Click to expand...

It's probably not only a function of the oil level, but also the oil temperature. As the oil heats up the viscosity drops and so does the oil pressure. When you add the 1/2 quart of fresh oil, you're increasing the oil level but also instantly droping the oil temperature.

What do your engine temps look like?

-JJ
 
JJDebeers said:
It's probably not only a function of the oil level, but also the oil temperature. As the oil heats up the viscosity drops and so does the oil pressure. When you add the 1/2 quart of fresh oil, you're increasing the oil level but also instantly droping the oil temperature.

What do your engine temps look like?

-JJ
Click to expand...
I would tend to agree.

The average V-8 engine at cruise RPM can suspend up to 1 - 1.5 quarts of oil.
Even with this oil in suspension, your oil pump pick-up should be submerged.

Also, your hydraulic cam follows are probably getting tired. More specifically, the cam follower plunger/piston check discs.
Warmer oil offers less viscosity that perhaps may be sneaking past the check discs.
When the follower returns to the base circle, ZERO lash is not being held......... hence the valve clatter that you are hearing.

Hayden, and a few others, offer a thermostatically controlled remote oil filter base that works in harmony with an engine oil cooler.
The oil cooler is used on a By-Pass basis.... but all oil is still filtered.
If you suspect that this older and tired engine needs cooler oil, you may want to install an oil cooler system.


Not sure why, but this kit is showing two SAE male fittings, yet no SAE counter part.
An Air/Oil hose supplier will have these fittings that you need.
Also not shown is the oil cooler.

555-51715.jpg







.
 
also check your oil return passages to make sure they arent full of crud. I will also vouch for lucas its awesome stuff. at caterpillar school the instructor used it as assembly lube!!

will
 
Thanks for the replies.
I will certainly look into it more closely but I don't think it is temp related. The engine runs 130-140, very steady, I can touch everything all the time. Also, the oil issue is totally uniform. It will occur the moment I start up or any time. Down a 1/2 qt, = noise and low pressure, full oil = good pressure and quieter regardless of any other factors I can see.

Time for a new 350 EFi 300hp 71C combo. That would be nice..
 
"Down a 1/2 qt, = noise and low pressure, full oil = good pressure and quieter regardless of any other factors I can see."
Far reach here.........breached pickup tube possible or too many parts of hardened umbrella seals pulling into the pickup screen?
 
daves69 said:
"Down a 1/2 qt, = noise and low pressure, full oil = good pressure and quieter regardless of any other factors I can see."
Far reach here.........breached pickup tube possible or too many parts of hardened umbrella seals pulling into the pickup screen?
Click to expand...

What oil should be used on a 318?
 
i agree with daves69.....if the oil pick assy was was compromised somehow, it would do exactll what you are describing.
 
Since his issue is systemic, I would tend to disagree: happens every 3-4 hours, very predictable, blah blah blah...

If the pressure issues were random, then I would suspect an issue with the compromised pickup.

-JJ
 
Update on using Lucas oil stabilizer: My old, worn starboard engine, that clacked like crazy (lifters) at every cold start, has not made a single noise since adding the Lucas product. Great stuff!

Jeff
 
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