I've had my 20B on a test stand all wired up and ready to run for
months. But even after endless troubleshooting I haven't been able to
achieve a successful start.
Today I hooked up a compression tester and I?ve probably found the
problem. Rotors one peaks out at 35 ? 40 psi and leaks down the instant
I stop cranking the engine, rotor two peaks around 50 psi and leaks
slowly down, rotor three peaks and will hold about 60 psi. I didn?t own
a compression tester when I did the rebuild and figured since I replaced
practically everything but the rotors and housings I should be OK.
Any thoughts, comments, or suggestions before I start tearing down the
engine?
TIA
Jay
Remove the schrader valve from the compression tester and watch it
while the starter turns the engine over. It should equal pulse 70 to 80
psi three times in a row on each rotor.
Sounds like you have one or more stuck
apex seals. Remove the exhaust manifold and use a small screw driver
to push on the apex seals through the exhaust port. If you cannot
feel them move in and out under the influence of the springs you
have a stuck seal. Spray WD40 in there and keep trying.
Remove the plugs and put some auto transmission oil in the engine.
Turn it over a few times and let it sit over night. Then check the
seals again. Once you get it running it will clean itself up.
Are you mixing oil with the fuel?
Paul Lamar
I have heard a few comments over the years of leftover carbon in the
apex slots sticking seals after a rebuild.
Do you recall any issues getting the apex seal springs inserted, that is
a hint.
As Paul says, pull the exhaust, check the apex springs for spring. Try
ATF in the plugs/exhaust, turn over the engine
and work the apex seals manually.
How bad was the edge flaking on the rotor housings you used?
vendor seals?
Cheers
Cary
I also meant to ask about the battery and starter.
A low battery/poor starter will result in low compression even if
everything else is in order.
Sound or video of a start attempt could tell us a lot.
~Cary
That is so true about the starter. Randy Lewis just went through
that exercise. You must really spin that engine.
Paul Lamar
It's been some time since the rebuild so I don't remember with any certainty
details of installing the apex seals. They are OEM parts and I don't recall
any slot flaking. The starter is a brand new as well as the battery.
If Paul's suggestion doesn't get me going I'll record the engine being
turned over.
Jay
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