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Pops out of gear @ 3400 rpms and overheats

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Bobbyh68

New member
Cant figure out whats going on, my volvo 4.3 GL with a SX-M 1.79 outdrive comes out of gear and revs up like its in Neutral. Than 10 seconds later, it overheats on me. I removed the prop and it does'nt look spun. Then I removed the outdrive and the splines on the shaft are fine. I looked at coupler with a flashlight and coupler splines look great. I cant tell if the rubber on coupler is fine.... Is there a better way to inspect coupler without removing the engine? Please help summers here..
 
Vovlo Penta's cone clutch arrangement is such that once engaged, them seldom let loose. IOW, the sliding sleeve should remain locked into the selected gear cup once a load is against the two. In fact... more load = more engagement force!
This is the nature of the cone clutch.
Unless you have metalic debris lodged in the oiling grooves, or if the gear oil has become hydrogenated, I doubt that this is your problem.

The rubber hubbed drive couplers may let go. Did you smell hot and/or burning rubber during this?
The propeller hub may be bad. Scribe a line through your outer hub and center prop hub. Re-create the scenario.... look to see if the line has shifted.
Try a known-to-be-good "like" propeller.

As for over-heating.... your seawater pump is engine driven. Even if the drive was to act as though it went into neutral, the seawater pump is still being driven. You may want to look elsewhere.


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sandkicker said:
How often does it do this?
Click to expand...

It happened about three times back to back, We were in the water about 25 mins. Drive kept slipping @ about 3400 rpms. After slipping started I would put in neutral and then try to drive and get boat on plain again. Boat overheated and we had to get towed in.
 
RicardoMarine said:
Vovlo Penta's cone clutch arrangement is such that once engaged, them seldom let loose. IOW, the sliding sleeve should remain locked into the selected gear cup once a load is against the two. In fact... more load = more engagement force!
This is the nature of the cone clutch.
Unless you have metalic debris lodged in the oiling grooves, or if the gear oil has become hydrogenated, I doubt that this is your problem.

The rubber hubbed drive couplers may let go. Did you smell hot and/or burning rubber during this?
The propeller hub may be bad. Scribe a line through your outer hub and center prop hub. Re-create the scenario.... look to see if the line has shifted.
Try a known-to-be-good "like" propeller.

As for over-heating.... your seawater pump is engine driven. Even if the drive was to act as though it went into neutral, the seawater pump is still being driven. You may want to look elsewhere.


.
Click to expand...

I did'nt smell any rubber burning. Im now going to focus on the prop. I will scribe a line accross prop and reinstall. Then I need to look at the sea pump, I think I have two different problems here. Thanks for your great suggestions.
 
FWIW..... picking up a large mass of seaweed and/or a plastic bag can sometimes cause the prop to "loose it's grip" resulting in an engine rev up (and not popping out of gear) and an overheat condition... (blocked inlet)
 
Let me give you guys an update: Boat is fixed and running great! I took my prop to a prop shop and its blades where slightly bent from being repaired over the years. I couldnt tell, The shop owner took one look and sold me a new one ($118 aluminum 14x23P). 2nd I replaced my impeller and t-stat and it fixed the overheating ploblem. Thanks for all the help guys, My wife is happy we get to use boat again.
 
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