Drove while 2 quarts low on oil

[IcePatch]

Posting this to document my enormous stupidity:

Driving back home on the interstate, I started hearing a VERY low "thud" intermittently. I first attributed it to road noise/someone with subs next to me at first but it became more persistent and suspiciously tied to engine RPM.
I glanced down at my oil pressure to see it falling from 60 to 30. This is the stock gauge and normally it's pegged just past 60 when driving because high pressure oil pump. Just as any smart and well developed individual would do, I immediately panicked, assumed the worst (toasted rod bearing), and drove it the remaining 3 miles home while babying the throttle and ignoring the pressure gauge. It didn't overheat, it didn't stall at stop signs, in fact at idle and low throttle it sounded fine. I had attributed the low pressure to the assumed "rod bearing", but after calming down and thinking about it I checked the oil level and sure enough it was just a tiny drip at the bottom of the dipstick, about 2 quarts low from full.

I know it leaks, I know I should have checked it.

I've never messed with a rotating assembly but if I find gold in the filter this weekend it looks like I'll be doing bearings and gaskets this summer.
Wish me luck lads.

 

[Rickf]

I had to explain to an engineer friend of mine the relation to pressure and volume when he launched his SBC. Your engine probably sucked up a bit of air when most of the oil went up the pushrods and hung around the lifter valley & valve cover. Make sure you don't have the nylon type timing gear with parts floating around the pan and pump screen.

 

[Vbb199]

I've completely ran a 350 out of oil and drove it, it'll be OK

It does hurt it, and it does shorten its lifespan, but a good 350 can take starvation a couple times

 

[Bextreme04]

I agree with Vince, it takes more than that to break it. Top her off and she will likely be just fine.

 

[fast 99]

Took a 700 mile trip a few years ago in a K20 350 with 4.11 gears 75mph. Truck never used oil in town. This was the first road trip. About 3/4 the way back I checked the oil at a rest stop. Off the stick. Had 1 quart with me. Added it, still off the stick. There wasn't any place to buy more until I got back into the city. No choice but to go on. Made it back ok. Drained the pan next day, 1 quart. Used that motor for another year and took it out. Did a quick re-ring on it for a friend. Some bearing wear but not too bad. It's still going in another truck.

 

[Vbb199]

Yea, my old burb got completely ran dry. Like 0 oil pressure on the gauge, nothing registering on the stick.

Drove it like that for the day, finally added oil, it was fine, still a running truck to this day with its current owner.

 

[Bextreme04]

Yea, my old burb got completely ran dry. Like 0 oil pressure on the gauge, nothing registering on the stick.

Drove it like that for the day, finally added oil, it was fine, still a running truck to this day with its current owner.

Why am I not surprised?!?!

 

[SirRobyn0]

I agree with all the other guys that say it's probably fine. I use to have a customer with a Suburban 350 in it and she'd run it out of oil regularly. It's amazing what an otherwise healthy engine will take. No matter how many times I told her she could swing by the shop every few weeks, and that I'd not only check it, but top it off for free she'd never do it. When the oil got low enough for the light to flicker on and the lifters to clatter she'd come by, I'd fill it and idle it till it quieted down. This went on for a few years before she sold the truck.

My 1996 Grand Cherokee. When I bought it, it was a private party sale and the price was right to move quickly. When I went to look at it I pulled the stick and there was no oil on it. On a short test drive the pressure gauge would drop every time I hit the brakes. So what did I do I went and bought 5 quarts or oil, put 3 in the crankcase to bring it up to full, the oil pressure was good, the engine was quiet. So I made an offer, bought the Jeep, and have put about 75K on it since then. Still going strong, and valve gaskets fixed the oil usage.

 

[shiftpro]

Remember the 460 Ford? Not a bad engine really, smooth power. I had a 74 Thunderbird with one and it was really really hard to keep it under 80 mph. The slightest pressure on the go pedal and it was hitting 100. So run a 460 low on oil and clack clack clack goes a rod. I was doing engine machining back i the late 70's and the cure to keeping a 460 alive was to match the oil holes on the cranks mains and rods to a certain extent. The oil holes on the mains needed a generous chamfer so the bearing holes would line up. I think the rods journals were ok but most definitely the mains were off. Sometime as far as half a hole. Stupid Fords..

 

[AuroraGirl]

Remember the 460 Ford? Not a bad engine really, smooth power. I had a 74 Thunderbird with one and it was really really hard to keep it under 80 mph. The slightest pressure on the go pedal and it was hitting 100. So run a 460 low on oil and clack clack clack goes a rod. I was doing engine machining back i the late 70's and the cure to keeping a 460 alive was to match the oil holes on the cranks mains and rods to a certain extent. The oil holes on the mains needed a generous chamfer so the bearing holes would line up. I think the rods journals were ok but most definitely the mains were off. Sometime as far as half a hole. Stupid Fords..

my 400m I had in my 77 LTD surprisingly burned the amount of oil the owners manual said it would, and thats 40 years later. I was impressed.

but it wasnt going anywhere on its own or quickly. ooooooooooof.

 

[Vbb199]

Why am I not surprised?!?!

Hey now. I take care of stuff I love.

When my bbc read 0 psi on a cold start up, I IMMEDIATELY turned it off.

All it was, a half quart low, and for some reason, the sender takes a moment to send a signal.

Turned it back on, read 0, even tho my mechanic hand held gauge said 60.


The truck gauge finally registered 60.

 

[waterpirate]

When my 87 5.7 took a crap 2 years ago, the esc shut the motor down. I waited and it started and i drove it for 3 days knocking like a sum bit. When I tore the motor down, I swear to this day had I just been smart enough to change the oil pump and do the heads, she would still be driving. lol Low on oil, no biggie, fill and monitor.
Eric

 

[Bextreme04]

I agree with all the other guys that say it's probably fine. I use to have a customer with a Suburban 350 in it and she'd run it out of oil regularly. It's amazing what an otherwise healthy engine will take. No matter how many times I told her she could swing by the shop every few weeks, and that I'd not only check it, but top it off for free she'd never do it. When the oil got low enough for the light to flicker on and the lifters to clatter she'd come by, I'd fill it and idle it till it quieted down. This went on for a few years before she sold the truck.

My 1996 Grand Cherokee. When I bought it, it was a private party sale and the price was right to move quickly. When I went to look at it I pulled the stick and there was no oil on it. On a short test drive the pressure gauge would drop every time I hit the brakes. So what did I do I went and bought 5 quarts or oil, put 3 in the crankcase to bring it up to full, the oil pressure was good, the engine was quiet. So I made an offer, bought the Jeep, and have put about 75K on it since then. Still going strong, and valve gaskets fixed the oil usage.

My commuter 93 Honda civic is the same way. I just kind of don't care about it, so it gets run until the oil light flickers and then I top it off. It pushes oil into the cooling system because it has a blown head gasket. Its been blown since AT LEAST last summer, but still runs and drives like a champ, so I'll get around to fixing it eventually.

Remember the 460 Ford? Not a bad engine really, smooth power. I had a 74 Thunderbird with one and it was really really hard to keep it under 80 mph. The slightest pressure on the go pedal and it was hitting 100. So run a 460 low on oil and clack clack clack goes a rod. I was doing engine machining back i the late 70's and the cure to keeping a 460 alive was to match the oil holes on the cranks mains and rods to a certain extent. The oil holes on the mains needed a generous chamfer so the bearing holes would line up. I think the rods journals were ok but most definitely the mains were off. Sometime as far as half a hole. Stupid Fords..

The Buick 455's are the same way. The oil feed holes in the block are not very precise, so the bearing itself can cover half the hole. There are a lot of improvements to be made to keep a Buick 455 from starving important parts of the motor of oil at high RPM.

 

[Soundmound]

It's probably fine. I drove an '89 Isuzu pup on 33" off-road tires delivering pizza as a kid. Burned oil like crazy, had a burnt valve and was running on three cylinders best case and the manual gear box leaked like a sieve too. I knew to add gear oil when you could smell the heat in the cab through the busted shift boot. Engine oil "consumption" (it leaked a bit too) was pretty much a 1/3 quart a day +/-. I beat that truck to doggone death on a daily basis and all it did was put money in my pocket. Hell I MADE $250 when I sold it and I don't feel bad about it either. Kid bought it and gave it a third life with the full custom mini-truck treatment. I'm going to have to go and scare up one of these for the wife to learn the five speed shuffle. I bet there's at least one decent one out there still and if not I bet she's still a "runner and a driver".

 

[IcePatch]

Update: Added 2 quarts, oil level is happy and the pressure gauge is back to pegged, but she's now got a dead miss on at least 2 holes. Gonna borrow a compression tester and figure out which ones. Gonna also check under the valve covers while cranking for possible wiped cam lobes.