Volvo penta SX coupler or cone clutch went bad?

Status
Not open for further replies.
Joined
Mar 2, 2019
Messages
4
Hi everybody and thanks for a nice forum!

I have had a couple of boats and last year I bought a Glastron GX185 2005 with a VP 4,3 and Sx sterndrive. Engine runs fine and the whole shot is good but there is something slipping when reaching above 3500 rpm or when doing a sharp turn and then turning back to straight. No smell in engine room for what I've felt, and I've tried with different props - still there. The boat has run at least 30 hours with the symptoms, not getting worse. Splines on crank shaft is fine and Im quite sure the prop has no caviation. Should add that I'm using the right gear lube.

So far Im guessing on bad cone clutch or bad coupler, however, for what I've heard if coupler is bad, its reaaally bad, or does someone know if it can slip under circumstances presented above?

Grateful for help!

Greetings from Sweden :)

/Rickard
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,582
something slipping when reaching above 3500 rpm or when doing a sharp turn and then turning back to straight

Maybe the trim is to high up and prop is coming out of the water a bit
 
Joined
Mar 2, 2019
Messages
4
Thanks for your answer but I have tried both with trim fully down and up a bit. Still same issue. Reaches about 34 mph at 3500 rpm and then nothing more but the engine still goes up to almost 5000 rpm. When crusing at about 25 mph (near 3000 rpm) and doing a sharp turn the boat offc goes "under surface" and when turning up to straight at about 10 mph the engine still has same rpm but does not accelerate (feels like its slipping on the clutch somehow..). Works perfectly fine if you pull of the throttle and give some throttle again.. Haven't heard about this symptoms anywhere.
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
12,944
It it does sound like you are experiencing Ventilation, usually from being overtrimmed for a given speed. What props are you using? Any bent/twisted/damaged blades? Is the skeg on the lower unit staight, free from rough edges? Does it do it during turns both Port and Starboard. Is the area of the transom in front of the outdrive, undamaged, and free of items that may interfere with the water flowing to the drive?
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
12,944
Cone clutches tend to grip harder as power is applied. But if they are extremely worn... The coupler, located under the water, is either one piece or sheared/broken.
if you are referring to the coupler between flywheel and driveshaft, you would smell it if it was slipping
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
12,944
Can't edit with iPad, and current website... so A very sharp turn will very often induce ventilation, and a lot of props do not recover when straighten out, unless power is reduced. A prop with more Rake and/Cupping might hold better and regrip sooner
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,304
number one killer of cone clutches is lack of maintenance.

either the oil level is too low or the shift linkage is not adjusted right

however it sounds like ventilation
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,465
Ayuh,...... Welcome Aboard,....... What size, 'n pitch prop ya got on it,..??

How beat up is it,..??

Got any pictures,..??
 
Joined
Mar 2, 2019
Messages
4
It it does sound like you are experiencing Ventilation, usually from being overtrimmed for a given speed. What props are you using? Any bent/twisted/damaged blades? Is the skeg on the lower unit staight, free from rough edges? Does it do it during turns both Port and Starboard. Is the area of the transom in front of the outdrive, undamaged, and free of items that may interfere with the water flowing to the drive?

Thanks for all your answers. Appreciate!
Regarding props I've tried with the original 21" alu 3-blade, a plastic 20" 4-blade and a 23" steel 3-blade. The 23" steel prop I tried the other day and it worked better than the other ones but werent able to try above 4000 rpm due to high waves. Good grip when turning sharp (no slip or cavitation) but starts to slip when turning to straight again until I pull of the gas, the engine stays at 3000 rpm but the boat wont accelerate until I pull of the gas and then give throttle again. Does the same at both port and starbord.

The sterndrive is in good condition, no rough edges or bad skeg.

Im wondering if it has something to do with ventilation, as you say. Could there be any cause other than overtrimmed? Such as exhaust or uneven/bad hull creating strange interference behind the boat?

No good pictures at the moment but Im going to the garage early this week so i can take some.

thanks again!
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,582
Im wondering if it has something to do with ventilation, as you say. Could there be any cause other than overtrimmed? Such as exhaust or uneven/bad hull creating strange interference behind the boat?

Other things can creat issues, and pics would help maybe identify
 

DouglasW

Petty Officer 1st Class
Joined
Apr 20, 2018
Messages
269
This could be a dumb question, but does the boat stay in the water, and if so, is there any growth on the bottom that could cause this?
 

dypcdiver

Lieutenant Junior Grade
Joined
Nov 1, 2005
Messages
1,016
We need a picture of the stern that shows the cavitation plate relative to the bottom of the hull/keel. Both from the back and from the side. Have the trim set in the position that you normally run the boat at.
 

Lou C

Supreme Mariner
Joined
Nov 10, 2002
Messages
11,802
All good suggestions to which I'll add, take a look at the gear oil and compare to new gear oil of the same type. Is it the same color? If its a lot darker, then that might be a sign of a cone clutch slipping and burning the gear oil. If it looks like new gear oil then a slipping cone clutch seems unlikely (good thing!)
 
Joined
Mar 2, 2019
Messages
4
All good suggestions to which I'll add, take a look at the gear oil and compare to new gear oil of the same type. Is it the same color? If its a lot darker, then that might be a sign of a cone clutch slipping and burning the gear oil. If it looks like new gear oil then a slipping cone clutch seems unlikely (good thing!)

Thanks for all suggestions. Just came back from the garage and will try to answer.
1. Oil - checked and looks like new (to keep in mind is that the boat has run about 1 hour since change)
2. The boat dosent stay in water (at least not during my time) - no growth at the hull but some marks ofc. Will take care of that before the season starts.
3. Yes SX has rubber hub in the prop but since I tried with 3 different props I can exclude that.

I´ll attach some pictures of hull and sterndrive. However I´m wondering about the exhaust, for what I know when reving the engine both cooling water and exhaust should go through the sterndrive and not come out through the bellow. I tried today and most water definitly goes through the bellow at the beginning of the sterndrive and just a small portion comes through the prop - could it be that if the exhaust comes out through the bellow it creates some bad airstructure in the water behind the boat? Ever heard about that before?

Also i seems like the stern perhaps is a bit high according to the hull, however I cant see any traces of rebuilding since new..

Thanks again!
 

Attachments

  • photo308736.jpg
    photo308736.jpg
    1.1 MB · Views: 11
  • photo308738.jpg
    photo308738.jpg
    1.7 MB · Views: 9
  • photo308740.jpg
    photo308740.jpg
    1.4 MB · Views: 11
  • photo308741.jpg
    photo308741.jpg
    1.3 MB · Views: 10
  • photo308742.jpg
    photo308742.jpg
    1.4 MB · Views: 11
Last edited:

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,582
Being an 18 footer there isn't a lot of weight and it has a deep V hull. The vent plate once trimmed out to level is at the bottom of the V. If it had some more weight it may stay planted more. Any prop which gives more lift just makes things worst

vpsx.jpg
Don't see an issue with the exhaust, its working as designed
 

Jason Johns

Recruit
Joined
Aug 1, 2023
Messages
1
How often would a clone clutch go bad? I have about 250 hours on mine and when I put it in drive it takes a few seconds to engage. I have noticed this getting worse or longer to engage.

MODERATOR EDIT: Please review the forum rule about posting to old threads and feel free to start your own thread on the issue.
 
Last edited by a moderator:
Status
Not open for further replies.
Top