The Stovebolt Site Forums The Shop Area Engine Shop 235 Oil Pressure Troubles

Hi Everyone,

This seems to be the best forum to put this. I have a 57 Chevy pickup with a 62 235/3speed drive-train. The engine was professionally rebuilt a year ago. I bet I don't have 500 miles on it. The rear-end is 3.55.

My trouble is that I was driving this morning about 55mph on the highway. I had gone about 15 miles and I noticed my oil pressure dropped from 31lbs to 15lbs. Over the next 5 miles, it dropped gradually to about 5lbs. I pulled over and it dropped to zero. The engine never got hot and I never heard any hammering. The oil was full on the dipstick. The truck would not re-start but tried. I called a wrecker and by the time he got there (an hour later) the truck would start and I drove it up on the flatbed. When we got it home, it started and I pulled into the garage. The oil pressure was just a little over zero. I have done nothing to it.

What do you suggest is the problem? What should I check first? Thanks.

It's interesting that a couple of people have seriously thought that the mechanical guage on the dash was bad and has suggested switching to an aftermarket guage set. Is this really something to consider? As you probably know, there's a mechanical guage on the 57 Chevy truck.

Jerry

You might want to pull the distributor and make sure the bottom of it isn't all chewed up. It drives the oil pump.

Otherwise, pull the oil pan and look to see if the pickup tube is all clogged with debris. It sounds like you have an oil pumping problem rather than a bearing problem.

Jerry,

You have stated the truck wouldn't restart after the disaster, but it tried. It did start later after sitting for some time.

When it wouldn't start the first time, what was it doing! With the oil pressure question comes the thought that some bearing or clearance might have partially seized.

A quick look at the oil for dilution and fuel smell would be a starter. Although your rig might have a mechanical gauge, I would still tap into the system with a known good pressure gauge just for a pre-surgery benchmark.

As noted above, pulling the pan will allow you to inspect the suction side of the pump, and the discharge pipe that leads into the engine.

Hopefully the pan is a easy drop on the '57 pickup. Scratch your head for a plausible explanation before you rip into it. Contrary to popular belief, "sh&t doesn't usually just happen".

Stuart

Could of just boiled the gas out of the carb and flooded the motor, this can wash the cylinders plus the too rich condition makes for a hard start. What kind of oil did you add after the rebuild?

Valvoline 10w40.

It turned over fine and seemed to want to fire but just wouldn't. The symptoms were like when a balast resistor goes bad. After about an hour and a half (waiting for a flatbed) if started right up. I attribute this problem to it being just a little out of time. Could be wrong though.

Jerry, I have the same problem with my 54 that has a 62 motor in it. It too has been rebuilt but I don't know when. Checked the pickup tube etc and all was clean. I have good pressure at startup but run around 10 on the highway after warmup and zilch, nada, at idle. However, I do not have any problems restarting like you mentioned. Hope you find your problem and will share.

Jerry,

Your engine was running when you pulled over and shut it down. My guess on your hard re-start would be fuel, but certainly not timing. Keep us posted and good luck.

Stuart

I'd pull the valve cover and check for oil flow to the rockers. If it is low or nonexistent then you know the gauge isn't lying.

Then pull the pan and check the screen/pickup tube,pressure tube, and pump in that order. If no problem is noted, pull the main caps down and check bearings.

If there is no noise it is not likely to be a rod, but mains can bleed off a lot of pressure before making audible noises.

On an old car I had, once I had good pressure one minute, then rapidly dropping pressure until it hit 0, never to return. A little piece of debris was able to fit through the filter screen at the pickup. The debris lodged into the lobe of the pump, causing the pump to seize up. This torqued the drive shaft so that it broke into two pieces. While I had the pan off, I replaced the pickup.

I'm betting that the difficult starting is separate from the oil pressure issue. My recommendation is to see if you can find a root cause of the oil pressure loss, then tackle the starting problem separately.

Bill

Well; I just came in from the garage. It's knocking now. I've had enough of that mess. I have a strong 283 powerpack that will drop right in there.

As you may know, I have a 57 Chevy truck and a 59 Impala Sport Coupe. The 59 is undergoing a frame-off restoration. The truck is a 20,000 mile retro hotrod with 235, 2x2bbl, headers, dual exhaust with Flowmaster 40's, lowered 2.5", etc. (I need to update the pictures on cardomain.com).

The challenge. I had a 235 built last summer and installed it later in the year. I had some fuel issues and didn't get to drive it much before winter. This spring I drove it some but have had some clutch issues. This weekend I finally decided to take it on a road-trip. After only about 10 miles of highway speed (no; really it was 55) the engine is now knocking. Of course it's been 15 months on a 12 month warranty. The shop will not honor their work (at least on our first discussion). I've had nothing but trouble trying to hotrod this engine. Getting the carbs setup was a pain too. Ok; so I have a bad engine and I'm looking at options. One option is to rebuild the 235 (been there and done that). Even with the 2 carbs, it just doesn't have the 'zip' that I'd like to see. I'm thinking of converting to V8 with automatic. Let's table this discussion for a moment.

I have bought a 350RamJet crate motor and 'built' 700R4 transmission for the 59. The goal has been a stock looking car with upgraded drive-line, brakes and cold AC. The 'numbers' 283 Powerpack was rock solid when I removed it and I have the original Powerglide and another 700R4.

Here's where your opinion comes in. Should I return the 59 to stock and put the RamJet and 700R4 in the truck, keeping the truck as a hotrod and returning the 59 to a 'numbers' car? Or, should I continue my 59 project as planned and put the 283 in the truck? I assume I could get a V8 bellhousing and stay with the 3-speed on the column or I could put the Powerglide or 700R4 in the truck and make it an 'easy' driver. I know it's my decision but I value your opinions.

Being personally familiar with your cars I know they are very nice and expertly cared for. I really hate it that you've had so much trouble with the inline engines. Just don't want to see you go the V8 route out of frustration Jerry but I certainly can understand how you must feel about 6 bangers at this point. Can't say I blame you a bit. Since it is opinions you've asked for then I'll offer mine for what it's worth. Since you bought the RamJet for the Greensfork Impala it obviously must be what you wanted before all this trouble occured so that is my recommendation; stay with the plan my friend. You've had enough disappointment.

Next...rebuild the 235 and sell the 283 to me. I can have my son-in-law from Hagerstown there to pick it in 24 hours. Don't you love it when a plan comes together...

Dave; that sounds like a great plan but since that's a 'numbers' motor, it's not going far from my garage.

If you knew that car came from Greensfork, you DO know my cars. Did you know the previous owner? He was a great guy.

Somehow I knew you wouldn't buy off on that part of my comment, HA. I'd keep it too along with the original tranny.

Yes, I knew the original owner in a round about way when I lived over there. I also came to see your truck once at your house if you recall. It was still in AF blue and original setup.

Yes; after I make that post I realized you were probably the guy who stopped by one day on your way back to Colorado.

I've got this same question posted in the 58-60 forum in Chevytalk (where I hang out most of the time) and it's about 50:50 on their opinions.