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Thread: Blows oil out tailpipe

  1. #1

    Blows oil out tailpipe

    Help! My 1977"S" is blowing oil out the exhaust and emptying the tank into the crankcase. I cleaned the screen and replaced the filter. This occurred suddenly and catastrophically. Glad I was not standing directly behind the tail pipe. Any thoughts?

  2. #2
    Only a couple: 1. This does NOT sound good. 2. Man, I'm glad it's not my car doing this.

  3. #3
    I agree. This does not sound good. Had to wipe the oil off the garage door after I had the brains to shut the door. Got oil all over the '55 Chrysler I am in the process of painting. I have looked at the "sump" circuit on this devil hoping to find a blockage. Is it possible to lose the suction side of the pump and still maintain the pressure side? Sorry if this sounds silly to the imformed as I have little experience with this engine.

  4. #4
    Sorry I came off so flippant. Really, if it was me? I'd have the car flatbed towed to the nearest mechanic I trusted...(an oxymoron?), get a diagnosis, make decisions from there.

  5. #5
    Your analysis was taken at face value. Quite similar to my take on the situation. Appointment made at "trusted" mechanic. My uneducated guess is pump(drawing side) related. Gawdamighty! Engine rebuild time? Hope not as I JUST purchased this thing! Ran fine at try out time. Motor Meister? Hope to hear from the folks here that there is something I am missing that is "typical" to this situation. My understanding is that crankcase(ideally) holds about 1 qt. of oil. Rest of oil is circulating, or in tank. It appears that my crankcase is drowning in oil, which probably bathes cylinders in oil which finds its way out! Any other path to the exhaust?(in liquid form by the quart!) Many thanks for your help, pwd. By the way, I believe it was you who sent me the photocopy of MFI info for my 69S. Great help

  6. #6
    My mistake, it was pzaviglia? who helped with the MFI. Thanks for the help anyway. Happy motoring!

  7. #7
    Roland Kunz

    How high is your oillevel in the oiltank ?

    How high your oilpressure ?

    Is the oil coming after the engine was driven several miles or say after one minute cold idle ?

    Your 77 must have the CIS and isnīt a MFI except you have a carrera engine.

    The engine and the oiltank have the same level. However if the engine is runing the oillevel in the tank goes up depending on the pumped oil volume ( revs ) and the heat expansion. The engine under full rev will fill the oiltank up and leaves some 0,5 L in the case. The restoil, some 1 L, in the case is splashed around and the oilsquirters pump some 15 L ( at 6 bar ) per minute on the backside from the pistons. They must get bathed to avoid overheating failures. The piston rings are designed for a controled oiling and pump some oil upside to oil the cylinderwalls.

    The pump is inside the case driven by the intermediade shaft and you cant split it. Suction is going from the inside sump out to the pipe on the driver side, The pressure pump is siting on the hose coming from the oiltank into the pipe under the oilcooler passenger side.

    If you short this ways you still need something to have secure oildelivery. A very long tube or hose might work but the oil will heat up very fast and the volume is not enough to run the system on the safe side.

    I canīt see how the oilsystem can have a such failure except someone did overfill it and/or the oiltankventing presses the oil into the manifold.

    If the oilpump wears out the both pumps have the same wear. The only thing that can wear the dry sump faster is little debris pumped trough scratching the aluminiumhousing wider. Those particles will then pumped trough the complete outside system including frontoilcooler and go into the Oilfilter siting on the oiltank.

    This is a very unlike failure as hard debris inside the enginecase come from things that will stop it before.

    They most plausible thing is a piston ring failure or bad valve guides with bad sealings. Filling up the exhaust while the car is standing. This is the indication from a to high level in the system or say overfilling as the maximal hot level is around the middle of the lower rocker arm pivot. The cooled down level is a thad under it and on minimum level cold you can drain 0,5 L by openeing the lower valve covers if you are fast you can see the cold oilevel inside the housing. Also following the brownish resueds you can see the normal levels.


    1.) Check your Ollevel, if to high the drain the complete system and refill 5 - 6 L to test out. 5 L is enough to run safe as long you donīt run it hot. Invest a new filter and cut the old open to check for particles.

    2.) If you still have the problem then it is the best to renew both oil pressure control valves and have the combustion chamber flow messured. Also check your exhaust valve guides while you are on it.

    Ring up Motormeister for sugestions from his side. Roy seems very capable from following his threads from the rennlist board.
    If you search for Motormeister on the boards you will have enough information to make your own opinion while you have a visit at his place.

    Sorry for the delay but this time I tried to find some links for the first mail.

    To answer your seperate quest you can shift to


  8. #8
    Roland, thanks for your response. To answer some of your questions, the oil level in the tank drops dramatically as oil (liquid and smoke) is blown/drips out exhaust. Oil pressure at idle is about 35psi indicated. When I removed the sump plug, approx. 3 quarts oil came out. Seems as if oil is not being pumped from crankcase to tank. Maybe plug in the return line or ??? I ran it with tank fill cover off to see if buildup of pressure in tank. No change. Your second suggestion sounds like good advise. I wish you happy motoring

  9. #9
    Roland Kunz

    Draining some 3-5 Liter from the engine case is normal exept you droped the oil with the runing engine.

    Sure does the oillevel in the tank drops.

    The pump will pull up to 60 L minute from the oiltank. The sump pump will move some 120 L but it doesnīt have enough oil to do that so it will pull more air then oil.
    If the engine is runing the oil will be mostly in the engine, cooler and in the oillines.
    The oiltank level will drop to half or even under it as there is allways a slight timedelay when you rev up the engine.

    The runing oilsystem has complete other rules then the static oilsystem.
    If you turn the engine off the hot oil will flush back trough the sumppump into the engine case and after a while the levels between the enginecase and the oiltank will be leveled ( physics; behaviour from luiquids in two connectet open cans )

    It is also normal that the vent flows air to compensate the levelchange and the overpressure on the filler is low except the engine is worn and the piston blows by.

    If your oilines would have been blocked your engine will not get enough oil and the pressure will drop and the bearings will turn to blue. It doesnīt matter where in the sytem the blockage will be. Now if you have a slight blockage the oil will not return fast enough to the oiltank and the pressure pump will see fresh air and your pressure will drop. Depending on the percentage this will not show up on idle.

    Now if we follow that idear the oilevel will rise in the engine and the crank will squisch the oil in the case then there is no big difference to the squirting coming from the valves. If the level gets even higher to the piston level then there will be more oil pumped into the combustion chamber and this will make foul the spark plugs after a while and the engine will stall except you rev it up to burn the plugs free. So if you look at a sparkplug you will see what is burned up inside.

    But the oil will sooner be runing into the exhaust runners as the ventury effect forces a slight underpressure and this will suck the oil up to the steems and the gases will blow them trough the exhaust.

    Just put a can under the exhaust tip and messure how much oil comes out.

    Not to forget is that if to much oil is in the case the oil will wander back to the oiltank via the venting connection.

    Following things are in my head:

    The suction tube from the sump pump has a crack and will lower the underpressure and therfore the delivered level.

    The engine was rebuilt and the newer 3,0 oilpump used. The newer pump has other oil capacitys and will pump more fluid on the pressure side while the sump pump has a lowered capacity.
    This was made to have more flow on low reves. The enginecase get a redesign at the oil relief valve and flushed the overpressure back into sump. If you didnīt adopt the case said problem could ocure under higher revs. Later pumps have the fixed strainercase and need a bowled strainer plate witch has no drain plug.

    Your oil pressure regulation valve is sticking in the open position.

    Your Oilfilter is blocked and both overpressure valves failed ( Cheap filters will burst, good filters will not fail, UFI oh wrong board )

    A rubber nose is internal bubled and blocks the passage under low pressure. Having a bend hose isnīt possible on the late engines.

    Your oilfilter or any one before was blocked and a cheap made unit witch shuts out the pressure relief valve ball. You will find it a front off your pressure pump mostly partially eaten up by the theets ( This was on a 2,4 S and the engine didnīt had any problems it was just found by lets say instinct ? better luck )

    Someone pluged the oillines with a paper or a rag and forgot to remove it.

    Maybe it is a mix from several small things abouve or none from them at all.

    Maybe others have some good guesses to.

    35 Psi are some 2 bar ? that sounds good. ( Sorry but Iīm metric


  10. #10
    Thanks for the reply, Roland. I have a few things to check, including my own sanity. I believe that I threw too much oil in on my last oil change. My pressure gauge is acting up; the next thing on my list is the relief valves. Seems that the engine liberates oil on its own schedule. Your insights are most appreciated...

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