4 blade prop

CIVANO

Well-Known Member
i was talking to the outfit that services my 4 stroke 250 yamaha and he said they have found that people running 4 blade props can have some bearing problems if they don't change the lower unit oil more often than usual. he said check the color of the oil and if black, change the oil. He said they have found it gets black much quicker. Just FYI
 
i was talking to the outfit that services my 4 stroke 250 yamaha and he said they have found that people running 4 blade props can have some bearing problems if they don't change the lower unit oil more often than usual. he said check the color of the oil and if black, change the oil. He said they have found it gets black much quicker. Just FYI
As long as the prop was in good shape why would the bearing load change - or the oil deteriorate quicker?
 
Interesting to read this. I have ran a 4 blade for 8-9 years now on my F-150. ( love how it has helped the performance of my trophy. I have never had oil discoloration or lower end problems.

I am no mechanic but sounds to me that if one just switches a 3 to a 4 matching size and pitch without testing their W.O.T rpm range it could create an issue ? Maybe? Usually starting with a drop of 2 inches in pitch gets it close for most rigs. Spot on for me. lost 2-3 mph top end but more than made up for it everywhere else. I will have to ask my local shop if this leg oil thing is something that should be a concern to me.
 
And that's why I do all my own servicing. Too many pimple faced 19 year old "mechanics" out there that spew BS and can't count their balls and come up with the right number. But what do I know, I'm just a dumb 66 year old mechanical engineer.
 
And that's why I do all my own servicing. Too many pimple faced 19 year old "mechanics" out there that spew BS and can't count their balls and come up with the right number. But what do I know, I'm just a dumb 66 year old mechanical engineer.[/QUOTE lol, i do my service myself too, been running a 4 blade for 4 season now, no black gear oil, only get in about 50-70 hrs a year and change gear oil every year, oil is like new when I flush it. News to me never heard such a thing
 
i was talking to the outfit that services my 4 stroke 250 yamaha and he said they have found that people running 4 blade props can have some bearing problems if they don't change the lower unit oil more often than usual. he said check the color of the oil and if black, change the oil. He said they have found it gets black much quicker. Just FYI

Well he did say "check the colour of the oil and if black, change the oil"
Can't call that bad advice can you?
 
Good advise for sure, if oil is black it needs a change
Oil in a crankcase can become dark because of carbon waste from combustion. Why would oil in a drive unit become black? We change drive oil because of wear and tear or water intrusion (where it turns milky). In 50 years of boating I have not seen black gear oil with 3 or 4 blade props. The suggestion that a 4 blade prop can cause gear lube to prematurely "wear out" and turn black is ridiculous.
 
Oil in a crankcase can become dark because of carbon waste from combustion. Why would oil in a drive unit become black? We change drive oil because of wear and tear or water intrusion (where it turns milky). In 50 years of boating I have not seen black gear oil with 3 or 4 blade props. The suggestion that a 4 blade prop can cause gear lube to prematurely "wear out" and turn black is ridiculous.
Agreed, my experience with 4/5 blade props is they are smaller diameter than 3 blade and so engines actually smooth out with less vibration with the smaller diameter wheels.
 
Ne
Oil in a crankcase can become dark because of carbon waste from combustion. Why would oil in a drive unit become black? We change drive oil because of wear and tear or water intrusion (where it turns milky). In 50 years of boating I have not seen black gear oil with 3 or 4 blade props. The suggestion that a 4 blade prop can cause gear lube to prematurely "wear out" and turn black is ridiculous.[/QUOTE. Never seen black oil come out of my lower gear, so I guess no need to change it lol
 
Properly fit 4 blade will be more efficient and create less stress on the motor. I love 4 blades for the improved mileage and lower RPM for cruise speed. Add to that motor longevity if you actually run cruise speed majority of time.
 
Interesting to read this. I have ran a 4 blade for 8-9 years now on my F-150. ( love how it has helped the performance of my trophy. I have never had oil discoloration or lower end problems.

I am no mechanic but sounds to me that if one just switches a 3 to a 4 matching size and pitch without testing their W.O.T rpm range it could create an issue ? Maybe? Usually starting with a drop of 2 inches in pitch gets it close for most rigs. Spot on for me. lost 2-3 mph top end but more than made up for it everywhere else. I will have to ask my local shop if this leg oil thing is something that should be a concern to me.


I have been wanting to put a 4 blade on my F150... Now I have to
 
Sounds to me like guys are pitching wrong. 4 k rpm cruising. No matter how many blades. If you cant turn a 4 blade at 4k rpm. Then you need mo powa

Or it's a combo of that and guys going fast and burning fuel.

Could also be engine height. Improper hub cooling


Many variables to that
 
Oil in a crankcase can become dark because of carbon waste from combustion. Why would oil in a drive unit become black? We change drive oil because of wear and tear or water intrusion (where it turns milky). In 50 years of boating I have not seen black gear oil with 3 or 4 blade props. The suggestion that a 4 blade prop can cause gear lube to prematurely "wear out" and turn black is ridiculous.
I always thought black is the detergents doing their job. Oxidation. My gear oil was black the other day little bit of water in it.
 
Back
Top