The Stovebolt Site Forums The Shop Area Engine Shop Oil pressure concerns

Hello,

I have noticed that as the weather has gotten hotter here in SC that after warming up my oil pressure goes to almost 0.

On a cold start up the pressure is at 30 psi and then after a driver or idling in the drive for about 25 minutes or so the pressure slowly drops to what I can only guess 2 or 3 psi.

I am running Valvoline VR1 Racing SAE 10W-30 High Performance High Zinc Motor Oil based on a recommendation I got since it has high Zinc levels.

I can see the needle drop some when I shut it off and this is why I think it does have some oil pressure.

Image 1 is with the truck running after warm up and image 0 is after I turn it off, you can see the needle does move. Image 2 is while drive after the needle is almost on 0 and image 3 is cold start up.

Any advice would be greatly appreciated.

This is the original 235 engine and it runs strong and does not smoke at all. I don't know any more then that about the engine, as in rebuilt or not or millage. I have had it about a year with no issue and roughly 500 miles

Following᠁
I’m having same exact issue in my 52-53 216.
First image is after cold start.
Second image is after 20 min drive.

First thing I would do is plumb in a temporary gauge under the hood to verify the actual oil pressure.

Second thing I'd do is drain the 10w-30 and put in 15w-40 or 20w-50.

All of my cars use one or the other. The Cadillac has been using it for 23 years.

I've put nearly 3000 miles on my '50 216 (non rebuilt) in the last year and a half and it's had 20w-50 in it the whole time.

I should note that the oil pressure goes to 30psi at startup but drops to 15psi when driving and idles at about 7 or 8 psi.

That is normal for these Stovebolt engines with the splash oil system. Just do what Otto suggested & use 15W-40 weight oil.

George

Thanks Otto!
How would we go about plumbing a temporary guage? I’ll be honest idk even know for sure where mine is.

Disregard. I had it right. It’s where I tightened that wire previously.

I had to do that on another vehicle of mine that I was unsure about the true oil pressure.

I bought a Sun gauge that you would normally install under the dash. I disconnected the sending unit to the dash gauge and installed it in the same fitting. I just left the gauge under the hood while I tested the pressure at different rpms and temperatures until I was satisfied that my oil pressure was adequate at all ranges.

You could do the same thing with your truck. follow the oil tube from the dash gauge back to the engine. It should be on the driver side of the block.

Now that I'm thinking about this, reverse my two suggestions. You should be using heavier weight oil anyway, so change that first and see if the gauge on the dash shows higher psi. Is your engine newly rebuilt or is it 70 years old?

My engine is original from 52. Never been rebuilt. I’m using 15w-40.

Take it in steps. First thing first. Before you change the oil , do what Otto suggested. Plumb in a real mechanical oil pressure gauge. Not an electric pressure gauge, a mechanical gauge. Lets first see if your gauge is accurate. If you do have low oil pressure, do you have an oil filter? If you do, you might consider removing it as it has an effect on pressure. then, if you still have low pressure, then the higher viscosity oil.

So I have replace the oil with 20w50 and now this is where my gauge is at. Any thoughts?

I started the thread have OEM gauges not new gauges like the other person on the thread asking as well with electronic gauges.

Whet year is the "original 235"? If it's a 54 or newer, inspect the connecting rod bearings. Loose rod and/or main bearings cause low oil pressure if a 235 engine has a pressurized crankshaft. (54-63). Any other approach is wishful thinking. "Wish in one hand- - - - -etc."!

Yes it is a 54 235. Sound like a rebuild is in my future. Any thoughts on driving it at all until I can get the work done? Or is it a possible ticking time bomb. I am assuming I will need to pull the engine to check or can I just drop the pan?

I don't mean to be a nag here but you need an after market mechanical gauge to confirm one way or the other as to whether your current gauge is working correctly or not. $20, maybe less, at local auto parts place. Plumbs in where the current one plumbs in.

I will grab a gauge tomorrow from AutoZone and give that a try first. Not being a nag at all maybe saving me from a rebuild.

Right now, you have a "rebuildable" engine. Once one of those worn out rod bearings seizes up and puts the rod out the side of the block, you've got a boat anchor. Your choice whether or not to drive it. Do you like to play high stakes poker? Yes, you can check most, if not all of the bearing clearances by dropping the oil pan. The #1 main bearing is a little difficult to check, but it's doable. If any of the bearings are showing the copper middle layer, it's time to replace them. The ideal oil clearance is .0015" (1 1/2 thousandths). Also measure the crankshaft journals with a micrometer (not a dial caliper) for taper and out of round.
Jerry

@Dragsix
Any issue will removing the electronic oil guage? I do t need to drain the oil or anything right?

No need to drain the oil. There might be a little trickle when the sensor is removed, but nothing serious. You could install a "Street Tee" in the block and run both gauges.

www.ebay.com/itm/122354314082?

Jerry

Like Jerry said, put a T into the block and hook up both your fancy gauge and a mechanical gauge at the same time. Makes for a much better comparison. I used a 4" diameter, oil damped, 270 degree sweep, +-1psi mechanical gauge when I checked mine. I'll loan it to you if you'll pay the freight.

I put a 2” gauge I bought on Amazon and plumbed it into a tee. A picture tells a thousand words!

Thank you all for the help! I picked up a mechanical guage this evening at Oreilly’s. I’ll need to order a Tee and I’ll be in business! THANK YOU!!!

Update: Got the Tee on order from the eBay link provided. I’ll keep you guys posted.

I'd still put in a heavier weight oil.

So I put on another mechanical gauge with 20w50 oil and start up pressure was at 40psi and as soon as the temp gauge hit operating temp the gauge drops to 0-4psi and bounces between the two.

I think this is a rebuild. What do you guys think?

Phak - do you have 2 guages connected in that photo?

Well it is rebuild time for sure. The pan has so much sludge and I had another bearing all the copper was showing.

Any suggestions on rebuild kits?

Good on you for listening to Everyone. You saved yourself from creating a boat anchor.

A "kit" is just a way for the parts vendors to put the vacuum cleaner into your pocket. The parts you need are virtually all available on Ebay, or possibly by special order at a local parts store such as O'Reilly, Auto Zone, or maybe NAPA. While you've got the oil pan off, you should pull a couple of main bearing caps and inspect those bearings, also. The #2 and #3 mains are easy to inspect. #1 has a couple of small bolts that thread into the timing cover, and the #4 bearing cap also carries the rear oil seal for the crankshaft, so don't disturb those unless you find worn or scored bearings on 2 and 3. Engines made after mid-year 1955 have main bearings that can be changed pretty easily by rolling the upper bearing shells out of the block. 54 and early 55 mains have a locator dowel on the upper bearing shells that require the crankshaft to be lowered almost a full inch. That's a real PITA that usually makes it easier to pull the engine and work with it on a stand. Drop me a private message if you like, and I'll send you some specifications from my shop manual to use when measuring the crankshaft to be sure you buy the right size bearings. The standard size of the connecting rod journals is 2.3125", and the normal undersizes are .010", .020", and .030". "Undersize" bearings usually have a number stamped on the back of the bearing shell indicating the size. Have fun!
Jerry

Glad you figured it out Scott! Saved you quite a bit of money!

Thank you everyone.

Not to sound stupid but are you saying I can replace the rod bearing with out removing the engine or crank? I will add the crank where I removed the bearing feels like it has a small groove, is that by design or wear?

I am pretty mechanically inclined but have never rebuilt an engine or messed with internals. Just bolt on stuff.

Yes, the rod bearings can be changed with the engine in the truck. Since you've probably got the early model 235, a main bearing change will be difficult. Check the stamped number on the machined pad behind the distributor to see if the engine is actually the same year as the truck- - - -a lot of things can happen in 70-something years, including swapping in a later model engine.

Small score marks and other blemishes can be polished out using a strip of fine grit emery cloth and a "shoeshine" motion on the journal- - - -just do a VERY good cleanup to get rid of the gritty residue. Measure the crankshaft for out of round and taper wear first- - - -a little is OK, but serious wear will require a full overhaul- - - -pull the engine and strip things down to bare bones. Have the EMT's standing by to give your checkbook a little CPR in that case! Back in "days of old when knights were bold", an "in the frame ring and valve job" and rod bearing change was a routine "minor overhaul".
Jerry

I can do that. Us micrometer or dial calipers to check of out around? I assume based on the measurement it will tell me if I need an undersized bearing or not.

Also from what could tell the engine has a manufacture date of 55 and the truck is a 54.


When I pull the main to inspect if they look good just torque done to speck or should I do something else first?

Sent you a pm like you said in the previous post.

Scott,

The Engine serial number you displayed above, ending in "F54U" indicates this is a 1954 Thriftmaster 235 installed in a 3100 1/2T truck at the Flint manufacturing plant according to the info found 1954 Chevrolet Truck Info Kit available at the GM Heritage web site.

What engine date info did you see to indicate this may have been manufactured in '55?

Dan

The google and help from the wife. Lol

Thank for that information. So I would say then this is the original engine for the truck.

That's good to know. It sort of makes it more fun to repair it knowing that it will stay with the truck since new.

100%

Yes, I still have the dash gauge connected (small line to the right) and the second large line on the left, is the supply line to the bypass filter.

Phak- What engine do you have?
I’m the picture you posted, is that your throttle spring?

I have a ‘59 235 in my ‘52 3100 and yes, that is the accelerator return spring.

Micrometers are the measuring device used to get most accurate readings, dial calipers have too many ways that can be cocked, thus getting a poor reading.

Ed

I ordered a micrometer and we shall see what the crank measure. I did notice that one of the mains seam to be rubbing on the crank. Is this normal wear over 70 years?

The mains did not look work like the connecting rod bearings.

With the exception of the thrust surface, those two bearings look pretty good.