Borg Warner 71cr gearbox problems

[davitosan]

I have a Borg Warner 71cr gearbox on a Ford diesel and it works O K but in forward there is a high pitched noise. Oil level is correct, no overheating evident, alignment has been checked .. Does anyone have a suggestion re a cause

[GordMay]

Greetings and welcome aboard the CF,davitosan.

➥ http://boatinfo.no/lib/gear/manuals/..._drive.html#/0

[NCboatrx]

Some more information is needed before anyone can help you.
Is the noise new?
How long has it been going on?
At what engine speed is it prevalent?
Has anything changed recently like a new propeller or a grounding?

[davitosan]

The gearbox is used but new to me, recently installed in the boat. The previous owner had not used it for a couple of years and cant recall if there was a noise or not.
It only happens in forward and is there immediately no matter what revs and increases as revs increased. I suspect a thrust bearing could be pitted or something but wonder if anyone has had similar experience.There is no sign of any malfunction other than the noise. It is high pitched and I dont think there is anything in the gears that revolves at such a high speed to cause it. Thanks for your response

[shakey doug]

Take look at side the filter also the fwd -rev flow valve possible rubbish under valve or weak spring. are you using ATF oil?

[davitosan]

The Borg Warner manual tells me to use engine oil if revs are below 3000 and that is what I have done. I am contemplating replacing with atf but am looking for all suggestions first. The filter and valve are difficult to get at ( what else in a boat ) and would need removal of the motor so I am hoping that is not the problem. Possibly wishfull thinking

[shakey doug]

I do not envy you with regards to access. To test gear box rear race disconnect the shaft coupling then run in gear unloaded, or use a length of timber if possible against the coupling face while in gear to load and unload bearing noting any noise change.Does the noise sound mechanical or hydraulic? can be checked by using a screw driver or wooden dow up to ear around valve filter and rear bearing.Is there any time lag between noise and the flow valve movement? If unit has high hrs using engine oil the filter is a prime suspect if you change to atf oil with a slight improvement its the filter..What part world are you in and what is the water temp.

[davitosan]

Thanks for some tests that I will try. Our part of the world is Encounter Bay South Australia and the Summer temp is about 69f
Re a filter , according to the BW manual that came with unit it doesnt show one in the parts diagram for this model only in previous versions. both in and out oil pipes from cooler are on top of housing. I am even wondering if the oil is not warmed enough and I will next change it for atf which is lighter than the sae 30. There is absolutely no sign of excess heat. Thanks again

[shakey doug]

Atf is now the preferred oil, level should be checked immediately after shut down check easiest and cheapest first. If its running the std cooler, temp should not be a problem the std cooler is run in Tassie. Forgot to mention the pressure relief as a possible noise source this set to bypass at 200psi.

[GILow]

Also suggest you double check shaft alignment. Dad had pretty much the same symptoms recently and it turned out the mechanic forgot to align the engine to the shaft after an engine rebuild.

FWIW I find it hard to believe to previous owner cannot remember if the gearbox made the sound before. I smell a bit of a rat there.

Matt


Sent from my iPhone using Cruisers Sailing Forum

[TeddyDiver]

If it's not the thrust bearing get a counter rotating propeller and you'll have the noise only on reverse

[sailersteve]

This just a thought for anyone interested in it ; After taking out a gearbox & having it pulled apart several times and checked , the last time rebuilt , ( still made noise ). We were told if your motor has even the slightest miss fire , can cause a gearbox to make noise. ours was a low rumble , not a high pitch. After a valve adjustment & motor running great our low rumble was gone . JUST SAYING !

[davitosan]

A bit more info. The noise is not there for the first minute or so at about 1500rpm after cold start. Then it begins and is present at all forward engaged speeds , increasing in volume as revs increased

[GILow]

Originally Posted by davitosan

A bit more info. The noise is not there for the first minute or so at about 1500rpm after cold start. Then it begins and is present at all forward engaged speeds , increasing in volume as revs increased

Exactly how Dad described his situation. The only difference, now I think about it, was that he said he felt his gearbox was getting hot too. But he had no reference point and that might have been normal warming. Either way, it turned out to be an alignment problem.

Just sayin.

Matt


Sent from my iPad using Cruisers Sailing Forum

[davitosan]

Thanks all with suggestions.. I have changed oil with no result but noticed that at the drain plug the manual shows a spring between the plug and a washer and it is not there. wonder if this could be the cause of high pitch noise