Hi everyone,
I performed a leakdown test on a 6G75 3.8 Mitsubishi V6.
Engine has 140,000 miles. It is very clean inside though with no sludge or varnish, and crosshatching still on the bores.
The engine is on a stand, so I have easy access to everything.
The leakdown numbers are OK (10% or less per cylinder).
However, some of this is escaping from the exhaust valves.
On one of the exhaust valves I can hear the leak.
The rest I cannot, however when I spray brake cleaner into the port, it bubbles up on all exhaust valves so obviously some air is escaping.
My questions:
1. Is this normal, or should exhaust valves normally seal 100%
2. If this is normal, would it be worth lapping the valves?
3. Can this exhaust valve leak correct itself? In the sense, when the engine is warm, and/or combustion pressures are pushing the valves to seat more, could this essentially be a non-issue?
I performed a leakdown test on a 6G75 3.8 Mitsubishi V6.
Engine has 140,000 miles. It is very clean inside though with no sludge or varnish, and crosshatching still on the bores.
The engine is on a stand, so I have easy access to everything.
The leakdown numbers are OK (10% or less per cylinder).
However, some of this is escaping from the exhaust valves.
On one of the exhaust valves I can hear the leak.
The rest I cannot, however when I spray brake cleaner into the port, it bubbles up on all exhaust valves so obviously some air is escaping.
My questions:
1. Is this normal, or should exhaust valves normally seal 100%
2. If this is normal, would it be worth lapping the valves?
3. Can this exhaust valve leak correct itself? In the sense, when the engine is warm, and/or combustion pressures are pushing the valves to seat more, could this essentially be a non-issue?