Leak down test results. :(

[e30_vt]

I recently purchased my first E30 and prior to freshening up the 27+ year old engine I decided to perform a leak down test. Well, things don't look great.



Cylinder 1: ~ 20% loss

Cylinder 2: under 10%

Cylinder 3: under 10%

Cylinder 4: over 60% loss!!!!!

Cylinder 5: under 10%

Cylinder 6: under 10%



I re-tested cylinder 4 several times because this is my first time performing a leak down test. There was no air coming out of the throttle body or exhaust. No air/bubbling from the coolant reservoir. Very audible air hissing out of the dipstick tube and oil cap hole.



Based on the research that I have been doing this leads me to think that there is a problem with the either the piston, rings, or cylinder wall. Is this correct?



What should my next steps be? Swap the bottom end? Engine swap?



Can I drive it until the engine blows?



Any help and insights are appreciated.

[TobyB]

Generally, this means rings.

Dump a bunch (1/8 quart) of oil down there, roll the engine over once,
and recheck.

But don't panic- rings can stick, and sometimes recover.
Especially if it's been sitting for a long time with that cylinder open
If it runs well, drive it a while, and retest. And repeat. And repeat.

With the racey cars, we leak and compress every weekend, and look at the trends...

Yeah, you might have a real problem there, eventually...

...but don't freak just yet.

t

[whodwho]

Looking at your pic, are you setting the air pressure to 100 psi and then reading the other gauge?

[e30_vt]

Looking at your pic, are you setting the air pressure to 100 psi and then reading the other gauge?

No, I set it to 60. I calculated percentage based on the difference between the first gauge and second gauge.

[ak-]

You can still drive the car safely if you did in fact lose a ring - it's just going to consume more oil than normal, no need to freak out.
Cheapest option is probably to swap the motor with another good M20 since they are cheap as a whole, or rebuild the bottom end yourself if you're handy with a wrench.

[e30_vt]

You can still drive the car safely if you did in fact lose a ring - it's just going to consume more oil than normal, no need to freak out.
Cheapest option is probably to swap the motor with another good M20 since they are cheap as a whole, or rebuild the bottom end yourself if you're handy with a wrench.

Thank you for your response. Is there anything else that it could be beyond the rings? Such as cylinder wall, seals, etc...

[digger]

do a compression test that will tell you more about how well the thing will seal up when its actually running as there could be reasons why it leaks down like you measured ref Toby's post

[e30_vt]

Generally, this means rings.

Dump a bunch (1/8 quart) of oil down there, roll the engine over once,
and recheck.

But don't panic- rings can stick, and sometimes recover.
Especially if it's been sitting for a long time with that cylinder open
If it runs well, drive it a while, and retest. And repeat. And repeat.

With the racey cars, we leak and compress every weekend, and look at the trends...

Yeah, you might have a real problem there, eventually...

...but don't freak just yet.

t

do a compression test that will tell you more about how well the thing will seal up when its actually running as there could be reasons why it leaks down like you measured ref Toby's post

Awesome! Thank you both. I have a friend who is able to give me a bottom end next to nothing so I may go down that route. In the meantime I will drive it like it is and see how far it goes.

[packratbimmer]

Was the engine good and warm when you tested it? How much had it been driven? It might get progressively better if you drive it a while, especially if it just a gummed up oil ring or something forgiving like that.

Run non-synthetic oil like Castrol GTX and do a lot of hard de-cellerating after you have driven it a bit. Sometimes just "cleaning" up the rings and grooves will breath some life into an engine.