Oil "blow out" = Engine "Mis-Fire" ???

J

Jimbo75

Member
1975 Scout 2, Stock 345.

Saturday morning started out good...
Was heading up to Grass Valley for IH Sierra Fall Rallye, only made it to Sacramento (about 80 miles) before this happened (see pic).

Crossing over from I-5 to I-80, speeds averaging between 60-70mph. Truck seemed like it was "mis-firing" or my initial thought was not getting fuel. With steady pressure on gas pedal, was not getting consistent response from engine "cutting out". Thought it was fuel related because I could "pedal it" and keep it moving. Made it off the freeway to parking lot before I couldn't keep it going anymore. Would start OK but wouldn't idle or run even with pedaling.

Thats when I saw the oil...
Can kind of see the pattern sprayed down the passenger side in the pic. Could not tell where the oil leak/ spray came from or was coming from. Had evidence of oil from bottom of radiator all the way back to droplets on rear hard top glass.

Would think these HAVE to be connected but not yet sure how?

Trying to get short video posted of what the engine sounds like to help me get your feedback on steps to take moving forward. Will post if I can. Going to cross post between here and BP.

Thank you in advance.
 

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It is possible you have a bad fuel pump. Many times when they fail they dump fuel into the engine. If enough fuel gets in the oil, it will boil off and blow oil out. Smell the oil for fuel. See if it’s over full. Verify fuel pressure. The bad running symptoms sound a lot like fuel starvation. Do see the connection I’m making? If the engine had some new mechanical damage, you should hear it or see smoke when trying to run it. Excessive blow by should dump oil in to the air filter if you have the factory pcv plumbing.
 
Thanks Robert.
How do I verify fuel pressure?
Is it possible for fuel pump to be bad and still get fuel squirting @ carb. w/ manual manipulation of throttle?
Under normal operating conditions, should I be able to actually see fuel entering/spraying into carb. @ idle?
If fuel pump is bad and fuel has gotten into oil, will it require full oil change?
 
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Jimbo75 said:
Thanks Robert.
How do I verify fuel pressure?
Is it possible for fuel pump to be bad and still get fuel squirting @ carb. w/ manual manipulation of throttle?
Under normal operating conditions, should I be able to actually see fuel entering/spraying into carb. @ idle?
If fuel pump is bad and fuel has gotten into oil, will it require full oil change?
Click to expand...

To check fuel pressure, you would need to plumb a pressure gauge into the fuel line before the carb.

A little fuel in the oil is not an issue as it will simply cook off. if it was a bunch you would smell it and possibly a rise in oil level.
 
Thanks again Robert.
Got a vac./ pressure gauge on the way home yesterday.
-Plumbed in with "T" fitting just before carb and am getting steady 5.5 PSI (Pic Attached). Is this low, high or standard, will do some thread searching to see if I can answer.
-Also pulled same fuel line and routed to container to check fuel delivery. Got my daughter to run ignition while I monitored container, maybe 10 seconds of cranking. Fuel "pulsed" into container, NOT a steady stream. Seems this should be normal with a mechanical type fuel pump, correct? Each pulse seemed strong and consistent. Results of the 10 seconds in attached pic.
-I did also check the dipstick when I got home last night (before performing steps above), would say it does smell like fuel.

I have a new pump on order. Would like some additional feedback based on results of last night's testing before swapping in new.

Tried some vacuum testing also, will report that on BP thread.
 

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Jimbo75 said:
Thanks again Robert.
Got a vac./ pressure gauge on the way home yesterday.
-Plumbed in with "T" fitting just before carb and am getting steady 5.5 PSI (Pic Attached). Is this low, high or standard, will do some thread searching to see if I can answer.
-Also pulled same fuel line and routed to container to check fuel delivery. Got my daughter to run ignition while I monitored container, maybe 10 seconds of cranking. Fuel "pulsed" into container, NOT a steady stream. Seems this should be normal with a mechanical type fuel pump, correct? Each pulse seemed strong and consistent. Results of the 10 seconds in attached pic.
-I did also check the dipstick when I got home last night (before performing steps above), would say it does smell like fuel.

I have a new pump on order. Would like some additional feedback based on results of last night's testing before swapping in new.

Tried some vacuum testing also, will report that on BP thread.
Click to expand...

good pressure. FP it making the necessary pressure to fill your carb fine. We can ignore that for now.

I If you do not have a filter on the carburetor side of the fuel pump you are probably good with the pump you have. When you stop the engine, the gauge should hold the pressure a while.

From your video, I think you have an ignition problem and the oil is another issue.

Re adjust your point gap, replace the condenser, verify the plug wires are still OK and not high resistance. All of these can cause a slow degradation in running quality. A chronic miss can cause oil dilution with fuel.

It is odd that with all of the oil you don't have significant oil from the breather tube in the air cleaner. I do think your rings are sound and that there is not a hole in a piston or anything similar.
 
Thanks Robert.
I am hoping you are correct regarding ignition problem, also wondering if something could have gone internally wrong within carburetor? I was on a mission to get this thing sold but "unknown engine trouble" doesn't always look so great on a CL ad.

Hadn't considered plug wires as possible area of concern. Will test and/or replace accordingly.
What is appropriate point gap or range (345, Holley Distributor, Holley 2 barrel)?
 
When the plug wires get bad, the coil usually is what ultimately dies. Since the wire resistance gets high, the plug is no longer the easiest path to ground, the windings in the coil are end the spark energy jumps to ground in the coil destroying the insulation.
 
Anybody know what this little thing is? I have mounted on top of the coil. Following Roberts train of thought regarding coil, wondering if this could have something to do with something? Not sure if this is standard or PO syndrome?
Thanks
 

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SHE'S ALIIIIIIIIIIVE !!!!!
Big thanks to Robert for working me through potential problems.
Not able to truly pinpoint and/or diagnose the issue(s).
Replaced ALL things on the engine signed of ignition system and we have a nice running vehicle again.
Parts included:
condenser
points
rotor
cap
wires
coil
ballast resistor
spark plugs
 
Only the mystery of the oil slick remains. I guess now you can run her and possibly track it down. 👍
Good job on getting her running well again.
 
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