Exhaust smoke, oil in one carburetor ?

[rmel]

I became a proponent of leak down testing a couple of years ago.

I began to notice a wee bit of loss in power on my 710 EFI, and
suspected it was time for a top end job. First thing I did was a
compression test as it's a quick way to tell you if there's a serious
issue. Yup, #3 have VERY low pressure, I think 90 psi if I remember
correctly. Checked the valves and the gap was fine. So out came
the leak down tester -- nailed it. On #3 I could literally hear
air escaping into the exhaust header with ear close to exhaust pipe.
Very little blow by though, so rings were OK.

So I proceeded with a top end job, and confirmed, #3 exhaust
valve was recessed into the seat with a poor seal. I was itching
to do this job for other reasons -- oil leaks.

On your rig, I'd suspect rings given the blow by you showed.

[Hugues]

So i received my leak-down tester today:
https://www.amazon.de/-/en/dp/B01AGLD4O ... ct_details

I performed a check on all cylinders, initially intended to run it first on hot engine, but by the time I figured out how to run the test, all cylinders were kind of cold.
I could re-do it tomorrow with warm engine, but here's my cold readings
#1 57% - noise from oil filler tube
#2 30% - a bit of noise from oil filler tube
#4 40% - noise from oil filler tube
#3 85% - noise from oil filler tube, repeated twice this measure, same, no noise in exhaust or air intake

I rechecked #1 right after #3 to be sure of #3 value, same value as initial measure.

I'm not sure what is the maximum % loss acceptable, on the gauge the green area stops at 40%, so #1 and #3 would be out.

Is it worth re-doing the test with a hot engine tomorrow ? I guess so.

[rmel]

Hmmm, sure looks like your rings are kaput. And you could hear the air escaping which is
confirmation. Given the extent of work for a top end rebuild, I'd give it a second test at
hot, but I suspect it won't make a big difference.

Between 3 Pinzies, and one particularly cranky one -- I've done 4 top end jobs and would
be happy to share with you some of the more subtle techniques for a successful overhaul,
IF that is new to you. Though you are in the "Land of Pinz'ies" expertise may be as common
as Starbucks coffee shops

ron

[Hugues]

So I repeated the leak-down test with a warm engine today

As a reference, the values with a COLD engine were:
#1 57%
#2 30%
#4 40%
#3 85%

And today with a WARM engine:
#1 42%
#2 25%
#4 32%
#3 82%

They all went down except cylinder #3 which is still showing 82% leakage.
They all made noise in the oil filler tube.

So yes, it would make sense that I open up the head and check these rings, especially #3.
I will start a separate thread about this, I would like to do the work myself, and I do have questions

thanks a lot guys,

[rmel]

#3 runs the hottest. Takes the most abuse.

Your #1 ain't great either. If all were in the
shape of even #4, it would be a case of getting
another season on it, worn but operable.

Now you know where the "El Fumar" is coming from

ron