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Total nightmare big oil usage


Bullitt455
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So I took my beloved Skylark for a small ride with my grandson on his birthday and with 15 miles I have had to put 10 litres of oil in to get her home she still sounds great when idling but man that's an incredible amount of oil out of the exhaust I can't seem to see any leaks I'm going to lift her up next weekend has anyone got any ideas on what it could be the engine is a 455ci big block and has been awesome thanks

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Something similar happened to dads 70 LeSabre. Turned out to be (?) on the automatic transmission allowing oil to be sucked into the engine.(sorry, the part name escapes me...)

That wasn't all that big a repair as it was on the outside of the transmission once diagnosed.

 

As to the diaphram, should it be that, replacing the fuel pump is not a huge effort either.

You didn't say what year Skylark but with ethanol in the gas those original fuel pumps are susceptible to breaking down due to the gas today. Mew replacement pumps have proper diaphram material that are not effected by the enthanol.

That happened to Dads 51 Nash only it had the effect of putting gas into the engine (not good) and found the problem when idling with oil leaking out the fill tube. Was lucky there was no spark under the hood with that gas/oil mixture.

 

Good luck and come back to let us know how you make out.

 

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I had a similar experience as dei's father.

And like dei I can't remember the name of the part but it is used to kick down the tranny into passing gear when you floor it.

Part was not expensive and is outside of the tranny, so was easy to replace.

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46 minutes ago, 91vert said:

And like dei I can't remember the name of the part but it is used to kick down the tranny into passing gear when you floor it.

That would be the transmission modulator, also with diaphragm, usually external and threads into the transmission case.  But in my experience when that fails it sucks ATF, rather than motor oil, into the combustion chamber.

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15 minutes ago, Grimy said:

That would be the transmission modulator, also with diaphragm, usually external and threads into the transmission case.  But in my experience when that fails it sucks ATF, rather than motor oil, into the combustion chamber.

 

Now that you mention it you are right.

It sure puts out the smoke for anyone following.

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12 hours ago, Bullitt455 said:

So I took my beloved Skylark for a small ride with my grandson on his birthday and with 15 miles I have had to put 10 litres of oil in to get her home she still sounds great when idling but man that's an incredible amount of oil out of the exhaust I can't seem to see any leaks I'm going to lift her up next weekend has anyone got any ideas on what it could be the engine is a 455ci big block and has been awesome thanks

 

Before you jump to any conclusions,  I had a 73 Estate Wagon with 455.  I was running down the highway at normal speeds.  I began to hear tap, tap, tap from under the hood.  I pulled off the highway and went to a gas station.  Pulled the stick for oil.  Nothing registered.  I dumped in a qt.  Nothing registered.  I dumped in another qt.  Nothing registered.   By the 4th qt the stick finally read full.  To this day I have no idea where the oil went. Never smoked from the tailpipe.  It never happened again. 

 

Oil can and does evaporate.  Was it very hot the last time you drove the Buick?  Was it very hot the day you discovered 10 litres gone?    

 

Another incident was a brand new Ford F150 that arrived to my shop without oil.   It was 4 qt low.   No idea where the oil went.  Truck has less than 1000 miles on it.        

 

If you see no leaks, fill it with good quality oil and drive.  Probably never happen again like my 455.  

Edited by avgwarhawk (see edit history)
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11 hours ago, Bullitt455 said:

15 miles I have had to put 10 litres of oil

Check the oil to be sure you are not waaaay over-full.  Even a big hole in a piston would not use that much oil (and it would not be idling well either)

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IF the fuel pump diaphram being broke can allow oil into the fuel, it CAN do just the opposite . . . fuel into the oil.  Which means the oil on the dipstick should smell of fuel, plus being far too full!

 

An un-baffled pcv valve can suck oil mist into the bottom of the carb, but NOT that much that soon.

 

How did you know to check the oil?  Just curious.

 

NTX5467

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  • 2 weeks later...

I once had the same problem on a non Buick engine.  Turned out the intake manifold gasket was gone and this allowed oil to be sucked from the engine internals into the carb induction space.  I ended up pulling the conrods and honing bores and replacing rings ( and replacing necessary gaskets   -- the intake being one of them )    Problem solved, thought it was just rings and blow pass.

It was a short time later when a friend said to me that when he was a garage mechanic, the intake gasket was the culprit  -- common problem.    If I had only known sooner, could of saved me a lot of work, $$, greasy hands and sore neck / back.

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Hey guys again thank you for all the input 
And so I had a little look around under the hood and came up I think with something rather strange now don't get me wrong I am not even close to being a mechanic but I'm pretty certain this isn't right can you possibly give me some thoughts on this I will post two photos but basically it appears my engine has two pcv valves which is puzzling me.
From photo one hopefully you can see a hose from back of inlet manifold which when I looked is without doubt a pcv valve and the hose goes to the front of the carbarrettor now I thought it was supposed to go to a valve cover anyhow moving I then find another pcv valve which is in said valve cover along with a hose just dangling down the side of the engine I'm really lost here guys and girls as you can probably tell I don't drive her too much just drool over her on my drive but when I have taken her out probably 1000 miles in seven years not a single problem so any thoughts would be appreciated thanks Steve

IMG_20200731_173826.jpg

IMG_20200731_174325.jpg

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That valve cover hose should not have a PCV valve, but it may have a short brass sleeve that allows the hose to be hooked up to the cover itself.  The other end would likely go into the factory air-cleaner.  That hose would provide fresh, filtered, air into the engine so that the PCV system can suck out the fumes.

 

As for engine oil loss I would check the connection for the oil pressure sender unit.  If you still have the electronic sender unit for the light I would replace it.  I have seen several of these begin to leak externally and you won't ever see a drip.  You may see some oil on the bottom of the car but I have seen cases where that did not happen.  

 

If your car has a gauge it may be worth trying to tighten that line at the same spot.  

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Maybe the PCV valve in the valve cover is plugged and caused the intake gasket to fail, pulling oil vapor from the valley area into the combustion chamber?  The PCV valve behind the carb pulls a vacuum on the crankcase.  Air needs to be allowed in somewhere.  As stated above, that spot on the valve cover would normally be open to atmosphere (through a mesh filter in the original air cleaner housing).  Install a breather cap in the valve cover.

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On 7/31/2020 at 1:14 PM, Bullitt455 said:

I just want to make it clear that I have never touched the hoses or anything this is how she was when I bought her and never a problem

Thanks steve

 

Status update?  Also where does the hose go from the valve cover in the second picture?

 

I would agree that 1 liter of oil gone / 1.5 miles, it is pouring out somewhere.  I do not believe it is the PVC system.  The car can not ingest that much oil through the intake and even run.  The plugs would be completely fouled out.   Just IMO

Edited by Larry Schramm (see edit history)
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That's the strange thing it just dangles down the side of the valve cover towards the floor I cannot see anywhere it would or should have been attached to and it definitely is a pcv valve in the valve cover the hose is connected to which I'm pretty certain isn't right

Thanks

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