VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 The roar of a chevy four?- oil pressure?

Yesterday I received a new exhaust system for my old car. The heat chamber was off by 90* so I took it to a local muffler shop and had them correct that.

Then, with the help of my son, I put it on. Wasn't near as bad as I've read it would be.

However, neither is it as quiet as I thought it should be, nor remember them being. There are no exhaust leaks, I've checked that.

The engine runs smooth and appears to be in fairly good shape.

Just how loud is that 4 banger supposed to be anyhow? It's not near as quiet as a new car. I'm not talking regular engine noises, the engine is fine.

My DIL said it sounded like a lawn mower.

Also, the oil pressure gauge reads 10 lbs at an idle. You know, I know, and dear ol ma knows that's not right.

On the old 6 cylinder Chrysler products there was a spring in the oil pump that would get weak and show low oil pressure. Also, if the engine was old and had low oil pressure it was nothing to get to that spring and stretch it so that it would show better oil pressure than what it really had. This helped sheisters sell a bad car as a good one.

Is there a similiar spring or adjustment in the old chevy four? That 10 lbs bothers me. Or am I worried about nothing?

In summation; how loud is that car supposed to be and what are your thoughts on the oil pressure.

I have a similar experience. My '25 is REALLY loud, way too loud. And I'm betting we got our aftermarket replacement exhaust systems at the same place, since there is only one out there.

An inferior muffler? If that's the case then a quick trip to the muffler shop should fix that.

A trip that shouldn't be necessary. Had I known in advance I would have gone to a local exhaust/muffler shop that specializes in making exhaust systems. He probaly would have done better for less.

Well, Well, Well, Where do you think the expression: Listen to the roar of the Chevy 4. came from? No, it is not going to be as quite as a new car, however, the engine needs the less restrictive exhaust. I assume you also received the tail pipe with the system?

Don't understand your statement that the heat stove was 90 degrees off. The stove is made to rotate a complete 360 so you can orient the heat pickup to the heat tube as required.

What does your oil gage read at engine speed? If it still reads 10 PSI I would suspect the gage is stuck on 10 PSI (which is the maximum reading on that gage). What does the gage read with engine off?

I may be talking out-of-school here as I don't have a four banger, but the repair manual on splash lubed early sixes indicates 12 pounds is an average oil pressure and that anything above zero is probably OK at warm idle. My 33 has a warm idle of around seven pounds.

Early Chrysler sixes were not splash lubricated, therefore required higher oil pressures.

The spring you talked about stretching is on the oil pressure relief valve. This valve would normally only operate during warm up, as most oil pumps wouldn't be capable of overpressuring a warm engine and increasing the bypass pressure would gain you nothing.

George

Yes, I also got a tail pipe.

The heat stove was welded in place. The heat tube faced the cowl, the air breather tube faced the engine.

With the engine shut off the oil pressure gauge sits at zero. Simply turning the engine over w/o starting it the gauge will read about 5-7 lbs. Once started it reads 10 lbs. at all times. It certainly isn't stuck but it may be weak.

There is 1/2 quart too much in the crankcase but I don't see how that would affect it.

Sounds to me you have a really strong oil pump! Also about that 1/2 quart over full, My dipstick on the 28 reads on the full mark at 4 quarts, I put in the 5th quart anyway.

I think maybe tomorrow I'll see if I can pick up an inexpensive oil gauge and see what it says.

My oil gauge always "pins the needle" also (10 lbs.) until the engine is warmed up real good, and idled down to a low rpm. Even then, it only drops off a little bit. But the engine is tight, everything is new.

I also thought my stove was located wrong. Eventually figured out it would rotate, and felt dumb. It was stuck, looked welded, but could actually be rotated.

rlb2 , When you go to town drive the old Chevy and give the folks a sight for sore eyes! I think your car is doing just what should be expected of it in regards to the oil pressure, on these cars high oil pressure is not an issue,,, just have some oil pressure that you can see, 10 Psi after warm up is great! oil level is more important just be sure to keep it above the FULL mark. ans don't forget to give those rockers a squirt at every junction of moving parts every 2 or 3 hundred miles and before driving after a couple of days shut down, it does run off you know. Also fill the grease cup on the waterpump with waterpump grease and turn it a 1/2 turn when you think about it. and give the generator and starter a couple of squirts once in a while. Check the tranny and see if the gear lube is migrating back to the differential, if it is, then drain it off at the Differential fill plug, to keep it off the brake bands. Someone told me to park going down hill and it will run back into the tranny, but I didn't try it, I don't have a hill.

Count on it. Just as soon as I get the ol thing street legal I'm goin for a ride

I grew up with those old cars. Lived with an uncle in the early to late 60's who made a fair living working on them. He taught me alot.

Then for quite awhile all I could afford were cars from the late 40's and early 50's. 95% were Chevy's

Granted that's been awhile back but I still remember a few things and more comes back all the time.

So far I have been keeping the rocker arms well oiled. I saturate the felt thingy as well. Oil is getting up there, I see small pools of oil laying on the head. But I don't see oil coming through the ports in the rocker arms.

I have also oiled the generator and starter. Filled the grease cups on the water pump and distributor. Showed that to my son. He commented that if you had a car like that it required alot of work. So I showed him the passage in the instruction manual where it says it's easier and cheaper to maintain a car than a horse. He had a good laugh.

I am a tad concerned about oil leaking to the rear. I see some small drops of oil at the rear of the transmission. There ain't no hills in South East Louisiana for sure. Ain't gonna park that one lookin down.

I haven't seen any signs of oil on the brakes yet though. I plan on taking them off and having them relined someday soon so I'll find out then for sure.

Geez, I sure hope I can get those brakes relined locally.

You said -"I saturate the felt thingy as well. Oil is getting up there, I see small pools of oil laying on the head. But I don't see oil coming through the ports in the rocker arms."

No! Oil is NOT getting up there! There is NO provision for oil to get up there (except the oil can mounted on the firewall). YOU have to put oil up there or it goes dry!

There's holes in the top centers of the rocker arms, just like the 6's in the late 40's and early 50's. I'll look again tomorrow just to be sure.

I'm tempted to remove them anyhow cause they've worn some rough spots where the push rods hit them. Kinda hard to adjust them like that.

I was just thinking, I may be off-base on the above comments. I remember from another string that your car has a '28 engine. I am not familiar with if the 28 took oil up top, or not.

No biggy. The later model Chevy 6's I mentioned weren't known for getting oil to their rockers either even though they were designed to.

The 28 has no provision for pumping oil to the rockers or shafts, there is a felt pad covering the valves, that needs to be saturated with engine oil and the valve cover also has holes to squirt oil into the area. As to oiling problems with the later sixes I feel that it is as much a maintenance problem as anything, the old non- detergent oils when dirty would sludge up and stop up the circuit, during overhauls it is imperiative that the pipe from the tappet area all the way to the rocker shafts and the shafts themselves must be cleaned and good flow of oil must be provided. Remember there is not any forced full 360 degree rotation af any parts in the area under the rocker cover unless rotators are used on the valves, and that area needs only a minimal amount of oil flow to keep everything well lubed.

So thats what those holes in the rocker arm cover are for. Neat.

MMM So if the ol car doesn't burn oil I run the risk of over filling the crankcase. And if it does burn oil, it'll never run low as long as I keep the rockers well oiled.

I really doubt if having the oil above the FULL on the dipstick is over filling it, We have had several discussions here about that, When I changed the oil the first time I was sure the book said it held 5 quarts, but it showed to be above the full with 4, so I added another quart, I doubt that the amount of oil used in the rocker oiling will do any damage by over filling the crankcase. Any of you Gurus want to comment on this? JYD? Ray? Chipper? any of you mates from down under?

UUmmm, I was trying to make a funny.

It'd take alot more oil than what one would use on the rockers to cause any damage. A full quart would do it. I remember being told that if the crankcase is over filled by a quart or more the oil will foam (bubble?). The bubbles have air in them. The end result being that the oil does not get tp all the parts needing it.

I don't know how true that is. That's what I was taught. I was told that 1 qt over was about the same as 1 qt under.

I believe in one of my books it said the 4 held 5 qts. I'll double check.

You jest keep on makin' them funnys! I think that 5 quarts is right, I don't know if the filter gets drained when the oil is changed or not, I will go by the book and always put in 5 quarts. also when my cars stop dripping oil I know they need some more added.

Bringin back memories of those ol chevy 6's. Perpetual oil changes. I use to buy oil in 2 gallon cans and threaten to put a 55 gal. drum on top of the car.

Yep, I remember pulling in the gas stations and tellin them to filler'up and check the gas....and that ain't no lie. As long as you kept oil in'm those ol 6's would run forever.

My engine is indeed a 28. No doubt about that. It still has the strap for the oil filter but the filter is gone. I've read that alot of people will put the canister there but have the oil tube run straight through the canister leaving the appearance of having a filter.

rbl2 Page 234 of the 1928 Chevrolet Repair Manual "Change the oil in the crankcase".states Four quarts are required. My '26 runs at 6-8 psi at idle and 10 psi at cruise speeds.

Like I said earlier, I'll get another gauge to double check. I'll post the results here for y'all.

Thanks for your many responses.

As a matter of review:

Oil capacity of the 4-cylinder engine is 4 quarts except for the 1927 and 1928. The 1927 and 1928 take 5 quarts IF YOU CHANGE THE OIL FILTER.

Oil is not pumped up to the valve train on any of the 4-cylinder engines. Likewise, any excess oil on the rocker arms will NOT go to the bottom of the engine.

It is necessary to manually oil the rocker arms and the "O" rings at the top of the pushrods. The 4 holes in the top of the 1928 cover allow you to place oil on the pad without removing the valve cover.

Oil pressure: If you have any, that's good. On the 1925 engine the center main is pressure lubricated. All other engines are splash lubricated. The oil pump just moves the oil from the pan/sump to the troughs under each rod. In fact no pressure and maximum flow is the ideal situation.

Those of you who kept up with my "School is in Session" observed the installation of a gear driven pump on the 1928 engine we built. Oil pressure on that engine is max 10 pounds when cold and 7-10 when wormed up. In fact it may be more but the gage only goes to 10 pounds.

A quick comment about overfilling the 4-cylinder engine. The lubrication system was designed to fill the troughs under each rod. When full the rods just barely scraped through this oil. Some was deflected through a hole in the rod to lubricate the rod bearing. Splash oil was sent up to the top of the engine and filled reservoirs above the three main bearings and those above the camshaft. From these reservoirs the oil drained through the bearings and back to the sump/pan. Some oil was diverted through a small trough to the timing gears. The excess drained back into the pan/sump. Splash oil lubricated the wrist pins and the cylinder walls. This is the designed system. Assuming you overfilled the crankcase (and the amount to overfill is not known to me) and the level was ABOVE the troughs under each rod. Now the rod would be striking a solid substance. For temporary operation, such as when an oil pump has failed, additional oil could be added to get you back home, however it is not a wise operation for the rod to strike solid oil.

To keep the record straight! the 1927 "Capitol" AA series and the 28 "National" AB series have 30 pound oil pressure indicating gauges. The average gauge reading is approxitmately eight pounds on AA: twelve pounds on AB. A zero or near zero reading at any time should be considered a warning and proper investigation made. "Its in the book!"
I agree with Ray, overfilling the oil sump does not make for a happy motor or engine!

Walt said: "To keep the record straight! the 1927 "Capitol" AA series and the 28 "National" AB series have 30 pound oil pressure indicating gauges."

How can I tell if I have one of those engines?

My push rods are covered and the engine at one time had an oil filter. This is why I believe it is a '28.

If it has a single exhaust outlet it is NOT 1928. If it has two exhaust outlets into a single pipe the HEAD is 1928, but the block may be earlier. If it has side covers it is most likely 1928 also. To be exact: read the dates on the block and the head.

Walt is correct on the maximum reading on the oil pressure gages for the 1927/28. Can't verify the average reading listed. Both the 1927 and 1928 engines use the same oil pump, and oil distribution valve assembly.

Yep! The manual says 8 lbs for the AA and 12 lbs for the AB. After warmed up, my 28 runs 13 to 14 lbs at road speed and 8 to 9 at idel. Maxie.