The Stovebolt Site Forums The Shop Area Engine Shop 54 235 oil pressure

Just bought 54 chevy 3/4 ton with 235 engine, oil pressure starts off at 30 psi when first started. Had to drive it to the tag office, the pressure droped to near zero, however no engine knocking or unusal noises. Have changed the oil and added a new oil pressure gauge same results. I'm thinking if the pump was bad I'd have shelled out the motor by now. I have an add on filter,I believe the oil pressure gauge hookup is on the out going side from the filter, do you think something is plugged in the filter line or is it the pump. Hate to drop the pan this old truck has zero oil leaks. Thanks for any advice

Welcome to the 'bolt. Sounds like your guage is connected to the wrong side of the filter. The outflow side just drips back into the pan, not likely to see any pressure there.

Thanks for the advice I'll switch the gauge to the other side to see if it makes any difference, Guess I could ck my 55 to see which side it hooks to. I have considered bypassing the filter to see if that helps. I may be wrong in my assumption on which is the in side of the filter and which is the out flow. I am thinking the oil flows in the bottom , thru the filter, and out the top on the side. or is it the other way around. Been trying to find a sort of diagram that would show how the oil is suppose to flow thru the engine so as to try to figure out if I may have a blockage somewhere. Thanks again for the come back

Checked the oil pressure gauge is connected to the correct side of the oil filter any other ideas out there as to why my oil pressure maybe flucuating?

Maybe "loose" main bearings...not enough clearance to make noise, but enough to bleed the system once the oil warms up...just a thought.

Stuart

I got a question to add. Does it matter where the tee is located, either right at the inlet to the oilfilter or down at by the engine at the outlet going to the filter?

I've got a picture of the factory setup on page 11 of My Webshots "Tips and Tricks" album. Click on "full size" on that page to see it better.

With that said, it's the general consensus that it will work even if plumbed in reverse. My suggestion would be to pop off the valve cover and see if it's oiling up on top. If not, get a couple 1/8NPT plugs and plug the pressure and return ports (where the rubber lines enter the block) and see if you don't pick up 5-7 psi oil pressure. I like to use a gauge other than the stock dash mount to verify pressures. If you don't pick up the 5-7 psi it might be time for a leak-down test to determine where you're loosing your pressure. Might be something as simple as a clogged up oil pump screen, a loose or worn pump. You might get lucky!

As for Apachefiends question....the rear port on the block is the pressure side....I like to tee it there and add my gauge down at the block. Don't think it will make much difference as pressure is pressure. Somebody else might be able to add from their personal experiences.

Dave

You also might try removing oil line to pressure gauge and cleaning it out, I have had these lines pluged with old oil sluge as the oil never flows through the line only into it. just a thought.

My first thought is excessive bearing wear. I pulled my 235 apart with the same symptoms and found the rod bearings just worn out. No knocking, no smoking, no problems, just a lot of wear.

Make sure it's a 54 and not an earlier engine. Someone could have put an old engine in it just to put it back to work. A 53 and earlier engine would have lower oil pressure, it may be alright for that engine. Got an engine number?
Scott

Pretty sure its a 54 motor, 54 is the last numbers on the motor s/n. Thanks for all the advice, have to wait till this ice storm passes and warms up a bit to dig into it. The advise you all gave pretty much what I was thinking just wanted to make sure I hadn't overlooked anything, Didn't think about the main bearings being loose so will difinitely ck that if I have to pull the pan. Was really trying to avoid that as I said before the old truck has no oil leaks engine has so much of the original paint I have suspected it may have been rebuilt. My parts store says each year of these engines calls for a different oil pump, so kind of wondered if someone installed the incorrect one. Course since it has low oil pressure that could be why there are no oil leaks its all in the pan. Thanks again to all who replied

If it is bearing wear, you might get a lot of mileage out of your engine still by changing to a "heavier" oil. Prolly improve your pressure reading too.

I'm really thinking the screen on the oil pump may be clogged, the person I bought it from had just put in a new battery and water pump. When I checked the oil after I got it it looked clean like it had just been changed. I drove it some not much because of the pressure problem, decided to put in 30w oil as I didn't know what was in it. When I drained the oil it was real dirty looking. I don't think the truck has been ran much in the last few years, it had been in one family pretty much for ever, when the granpa died the family had an auction, the grandaughter bought it but never drove it much, proably less then 30miles in 2 yrs. So thinking if she did change the oil, maybe it has a lot of sludge in the pan. If its not getting oil on the top side think I'll dump in a can of auto trans fluid run it a while before I pull the pan. Was going to try 20w50 but tend to think straight weight may be better.According to my shop manual for the 54 it mentions there may be shims on the mains that can be removed to tighted the bearings up. Wish it wasn't so cold out so I could work on it, hard to buy a new toy and not be able to play with it. Guess I'll have to get a garage built this spring.

Trans fluid is not a good idea as an engine cleaner; there's too many friction enhancers and other additives that have no business being in an engine lubricating system. There are several "motor flush" concoctions out there if you want to do an internal cleanup, but what I've found to be most effective is simply a pint of kerosene added to the crankcase of a warmed-up engine, and about 15 minutes of fast idle with no load on the engine. Drain the crankcase while the engine is still hot, and refill with a good grade of 20W-50, or 15W-40. If the pressure is still low, it's time for some internal engine work.
Jerry

Well guys I pulled the valve cover today, I'm getting oil up there. the oil flows about as much as it could thru the pipe that dumps in the center of the rocker arm shaft. Eack rocker arm is weeping oil is that about normal? Oil pressure started out at 25-30 Psi dropped to about 5-7 psi after about 20-30 minutes. Did not notice any difference in the amount of oil flow on the top end. So now what should I do? Maybe flush with the kerosene see what happens? Did not disconnect the oil filter as it is connected with a T at the pressure exit from the block with the oil gauge. I'm running a new aftermarket guage. What you think?

Dually,
At what engine speed are the pressure readings you mention? It really sounds pretty good to me, for sure if these are slow idle readings & it picks up at a faster RPM. The fact that you're oiling on the top end is great. The lower end should have plenty of oil then. IMO a lot of pressure isn't too important, all you need is to keep a film of oil in the bearings. Seen a lot of motors including Detroit Diesels that idled in the range you have.
Doug

Low oil pressure could also be caused by bad/worn cam bearings. That's what was wrong with my 55-1st I had years ago. Very similar condition except my pressure would drop to near zero when hot. Silly me kept driving it until it started knocking and ruined the crank. I did rebuild it and mixed and matched parts from about 5 motors and ended up with a good one. Good luck with yours.

I have a 55 1st series with the same problem. It has good oil pressure when it starts and as it warms up, it goes to 0. I don't drive it too far or too often but have driven it as much as 40 miles and it never makes any unusual noise. I originally did the things you were talking about. I checked a different gauge, and even put a new oil pump in but it did the same thing. I have finally figured out that there is too much clearance somewhere. It does have new mainbearings with the right clearance. I hear that it is probably rod bearings or even cam bushings. I just hate to pull it out when it is running so good but I also hate to ruin everything internally.

I have the same problem with one of my "high-pressure" 1954 235 truck engines. My assumptions are the same as 55hays - bearings are simply worn out. I have removed the canister oil filter and plugged the oil-return hole in the block and plugged the outlet on the oil-gauge-line T-fitting (with brass pipe plugs).

The oil gauge still works and the oil pressure has increased by about 5 psi (to 5 psi at idle and a little higher at higher speeds). This is only a temporary fix because the oil pressure still decreases to almost zero at low idle when traveling long distances. I drove it over 1,000 last year but it needs to be rebuilt (I'll be temporarily swapping-in a rebuilt 261 by summer 2008).

Tim

Yes, it should pick up some pressure when the RPM is raised. Up to 20 or 30 PSI anyway when at cruising speed. Doug

Do you really have a 1954 3/4-ton Dually? 54 was the first year Chevy offered that. The book says the GVW rating goes up to 6500# with 6.50-16 tires (8-ply duals, rear). The "stock" 3600 GVW is 5800. That is cool. I would like to put duals on the back of my 50 3600 and widen the fenders, but haven't figured it all out yet. Modern dual wheels are too deep dished to fit (11" center-center vs. 9" centers on the old ones). Let's see some pictures!! Welcome to the 'bolt!

Thanks for all the advice, we have a snow storm coming in tonight so guess I'll plug off the filter, see what happens next week sometime. The oil pressure really doesn't pickup much with a increase in engine speed. I have a 55 1st series it idles at about 40 psi course never gave it any thought maybe the 55's gauge isn't reading right. Proably just the 54 on short missions till I get a garage built. Then start checking the inside of the motor. Wouldn't take much to jerk it out do a quick rebuild, forgot how easy these things are to work on. I debated on whether I had time to pull the valve cover and ck the oiling longer than it took to just do it. Love these old trucks

Quick note to Frank50, Yell its a 3/4 ton dually way cool, it has an excellant old grain bed on it with the removable sides, Has the bolts and wing nuts that holds the sides on and holds the sides and end boards together, has the little opening in the back to let the grain drain out. The only thing it didn't have was a hoist on the bed. The folks I bought it from used it for wheat harvest till the seventy's when they took the hoist out at the coop to lift the non hoist trucks up to dump the grain. Its like having a 1 1/2 or 2 ton grain truck in minature size. I'll put pictures up soon as I figure out how to do it. It is definitely a time machine, the glove box had extra points, coop related items, under the seat were the tire irons for breaking down split rims, a old tire pump with a wooden handle, couple different home made lug wrenches, extra key under the floor mat, couple more in the glove box, When I picked it up it was setting on main street( small town Kansas) with the keys in the ignition.

Well don't know what to think fired her up after sitting for couple of weeks ran for about 30 minutes oil pressure never dropped below about 25 psi. Guess I need to take her out for a spin see if it holds. I like problems that fix themselves but not banking on it just yet. Little lady says she is moving on to greener pastures but hey now I got room to put the dually in the garage. Everything has its good sides and bad.

These engines never did have a lot of pressure even though they are known as full-pressure engines. Not unusual to have little or no pressure at the gauge, especially at hot idle. As long as you are getting oil to the top of the engine as you say, you are good to go. The big thing is if oil is coming out of the rocker weep holes. If that is okay, then it's gravy. If you're worried about a dirty engine or clogged pickup, switch to full synthetic oil. It is incredibly detergent and will clean out the galleries in no time flat. Don't worry about putting such high-tech oil in a 'bolt engine. synthetic is great and will stop any wear dead in it's tracks and the engine will not wear at all any more after you switch to it. Just remember, the lowest oil pressure is at the rockers, so if you have oil coming out of the weep holes, you're good. When I was first going to start my '58 235 after it sat in the PO's garage for 5 years, I cranked and cranked the engine to try to get oil out of the rocker weep holes before giving it spark and firing it up. No oil to the rockers. My old mechanic friend said, "Fire it up. Those engines can run for a month with no oil to the top of the engine". So, I fired it up. Within 15 seconds, the rockers started to weep. I currently run 10W-40 Amsoil full synthetic and don't have any pressure problems at all, getting about 30 PSI at all times at speed and about 20 at hot idle. However, it is really not unusual to just have the needle barely above the peg. rocker oil is the key here. If the engine runs fine and you have oil to the rockers, don't sweat it.

Andy