Oil Consumption Concern

Discussion in 'Small Block Tech' started by 71Custom455, Mar 24, 2002.

  1. 71Custom455

    71Custom455 Member

    I noticed on a 4 hour road trip awhile back, something that's got me scratching my head. About 3/4 of the way to my destination I start hearing what sounds like a valve tap from my otherwise reliable 350 engine. At the next exit I pop the hood and check the oil and low and behold what started out as an engine full of oil 10-40 if I remember correctly, was almost bone dry not quite but almost. I poured in 4 qts. and continued on my way. I haven't made a trip that long at that consistent high speed since but was curious about the unexplained oil consumption.

    Can anyone offer some thoughts?

  2. quick85

    quick85 wrench turner

    oil presure sensor leaking?
  3. 71Custom455

    71Custom455 Member

    Oil Consumption

    Shortly after this adventure and after overheating and darn near destroying my engine I installed all new and expensive Autometer gauges. No visible leaks, no blue smoke just unexplained oil consumption. Traveling at 50-60 mph with full oil, pressure hovers around 38-40 psi at idle maybe 10-12 psi

  4. 72skylark

    72skylark 4 Doors of Fury!

    you're lucky all you heard was the valves... I did a similar thing, I went for a 4 hout road trip, and didn't check the level before I left home. Well 3 1/2 hours into the trip I'm pulling up a steep VT hill going pretty quick and I hear a nasty engine knock, it went away when I slowed down. It was about 3quarts down... it's all good though... so I ignored the leak and just made sure I had oil in it for a while....

    but to the point I found my major source of oil leak. And it was the last place I'd EVER think OIL would be leaking from.... the fuel pump! It was coming out of the weep hole in the fuel pump everytime the pump was pumped. it must've been getting into the non fuel side of the piston and being pumped out... $15 and 15 minutes later it's all fixed.
  5. CyberBuick

    CyberBuick What she used to be....

    Indeed an interesting topic.. I have a '71 350 and Q3 '2001 I took a trip from LA to Big Sac, drove over 8hrs stoping only for gas, driving around 80mph (pertronix ignition). When I finally checked into a hotel that night (around 1am) I checked and was down around 1/2-3/4ths a quart.. In the manuals, it talks about driving highway speeds for a continuous time will use more oil. They never say tho whats 'excessive'...

    I have a question about Autometer gauges tho, how tough is the install of everything? Tach and Oil mainly.. Plus, do you use the tubing and everything in the kit or buy better? tia

  6. 71Custom455

    71Custom455 Member

    Oil Consumption

    The Autometer Gauges: Water Temp, Oil Pressure, Volt meter were a relatively easy install. I decided not to use the plastic tubing that came with the gauges but instead opted for a thicker copper tubing. It sure has saved my engine and me alot of dollars installing the gauges insteadof relyingon idiot lights. The problem with idiot light is, that by the time they come on thedamage is done and it is toooooooooooo late!!!!!!!

    What exactly did the 15 dollars buy and what could you possibly install in 15 minutes in a buick to fix that leak?????

  7. CyberBuick

    CyberBuick What she used to be....

    What exactly is 'relatively easy'? :/ If I may ask, what did the entire setup run cost wise? The gauges aren't 'that' cheap, and the new sending units to go with everything. I am thinking it's pricey..

    I have to agree on the idiot lights, with the exception of maybe the HOT light. Ever taken a trip with the AC on then pulled into a gas station? When ya start'er up again, that stupid light stays on until ya either let it cool off a bit, or get back on the road. The one thing I hate is the Oil light, I mean, whens it set to come on, when it's defunct of oil? shesh!

    thanks -n- sorry for the rant

  8. Darryl Roederer

    Darryl Roederer Life is good

    Tell me a little about the engine...
    What year? Mileage? rebuilt? Valve job?

    Are there any obvious leaks? And if so, where from?

    Just off the top of my head, I'd say, provided there's not an obvious leak, that your valve seals are worn.

    Here are a couple things you can try...

    Park the car up on some ramps, on a clean [non oil spill] part of your driveway. Remove the PCV tube from the air cleaner, and run the car for about 3 minutes at about 2500-3000 rpm.
    watch the temp guage when you do this
    Then shut the car off... Dont idle it down, kill it from 2500 r's.

    Look around under the car for leaks that may only be happening at higher rpm's/ higher oil pressures.

    No leaks? OK, then have someone else start the car up, [after it sits for about 5 minutes], stand behind it and watch for a puff of white smoke on the re-start.

    Next, imedeatly move to the engine compartment. Look for smoke comming out of the PCV tube.

    If you find oil under the car, your problem is obvious.
    If you get smoke from the tail-pipe, its [likely] valve seals.
    If there's smoke from the PCV tube, the rings are worn.

    Depending on what you find, you can move on to a compression test, a leak-down test, etc. to detirmine the general condition of the engine.

    The oil is either leaking out onto the ground, or burning in the cylinders.... It's not "magically" dis-appearing, so it should not be too hard to find.

    Dont forget to re connect your PCV when your done.
  9. 72skylark

    72skylark 4 Doors of Fury!

    I replaced the fuel pump that cost $15, and took 15 minutes.
    it wasn't a real visible leak, cause it only leaked when it was running, but what tipped me off was there was a little drip of oil on the bend in the metal fuel line... and there is nothing in that area that would get oil on there... actually now that I remember I replaced the fuel pump cause I thought it was going bad... ended up being a sticky float valve...

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