How to Flush Hydraulic Gearbox ? BW72

[Shanaly]

hello i've just tapped a thread on top near the shaft output boss, so a bit of swarf must have dropped into the hydraulic fluid.
how to flush it all through? engine/box not currently running?
thanks in advance

Capn John

[sdowney717]

did you drill into the gear box?
where does this tapped hole lead?

If it goes into the gears, likely try draining then perhaps flush with kerosene and drain again.

If it went into the hydraulic pressure circuit, who knows, perhaps suck it out with a vacuum pump.

What you did I dont understand why you did what you did.

[delmarrey]

Originally Posted by sdowney717

did you drill into the gear box?
where does this tapped hole lead?

If it goes into the gears, likely try draining then perhaps flush with kerosene and drain again.

If it went into the hydraulic pressure circuit, who knows, perhaps suck it out with a vacuum pump. Or a vacuum with a small tube taped to the hose.

What you did I dont understand why you did what you did.

Could be for a temp gauge.

But the next time drilling into a seal case put heavy grease on your drill and on the tap too. The chips will stick to the heavy grease and come out with the tools.

The other option is to run a strong vacuum next to the tools to collect the chips as they come off.

If the case is iron you could use a magnet to get the chips. If aluminum they won't hurt the gears but could damage the bearings by causing them to slide rather then roll.

As above, you could drain the oil and use a vacuum.

[Seahunter]

Remove lower cooling line to drain oil. Flush trany with required oil 3 times (and hand turn) pumping out with hand or electric oil pump at dipstick and cooler line connector. Replace cooler line/plug. Fill to required level (dipstick).

[Lancerbye]

The last BW72 that I overhauled had a magnetic drain plug, check there first. I usually put beeswax on a tap or drill when I want to catch the majority of the filings, also makes a great aluminum tapping lube.

[Redcoat]

Or you can disconect the lower cooling line from your exchanger.Then buy a gallon of ATF.If you have enough Hydralic hose just stick it in the ATF. Then disconect the upper line and get a gallon jug to catch the swag.Pull the choke on your engine and crank. It will cycle the ATF pretty fast so be ready. Flush your whole system in about 3 minutes.Unless you have no room to access your tranny.

[Shanaly]

hello all and many thanks for such great ideas. fyi the problem arose because i simply retapped the 5/8 thread for the hot ATF out valve (i.e. to cooler on engine). th reason was that the previous hose fitting had partly stripped the thread through wear and apparently being slightly too large for the hole - because it was too long, or did not taper enough. odd, i grant. thanks again i'll let you know what happens!