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Why would prop turn only at idle - 231 interceptor engine and a Model C Eaton outer drive

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copelandg

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I have a 1968 20' Thompson runabout with a 231 interceptor engine and a Model C Eaton outer drive.

I have not been able to identify anyone in my area (Lansing - Muskegon) who will work on this outer drive.

I have a problem that is perplexing that began on Monday.

The boat is shifting into gear and working fine at low speed in forward and in reverse, but goes nowhere upon exceleration, ....basically anything over 1000 rpm or so.....

It does not appear to be the the cable adjustments and does not appear to be popping out of gear based on the position of the shifter but otherwise is acting like it is going out of gear.....forward and reverse.

I have removed the yoke, front and rear joint housing and see nothing abnormal.

Before I tear into this any further, I have some questions I am hoping you can help with...

Can this problem originate within the outer drive?

If yes, what would that be and what am I looking for if I were to disassemble this further?

Thanking in advance for any advice.
 
copelandg said:
I have a 1968 20' Thompson runabout with a 231 interceptor engine and a Model C Eaton outer drive.

I have not been able to identify anyone in my area (Lansing - Muskegon) who will work on this outer drive.

I have a problem that is perplexing that began on Monday.

The boat is shifting into gear and working fine at low speed in forward and in reverse, but goes nowhere upon exceleration, ....basically anything over 1000 rpm or so.....

It does not appear to be the the cable adjustments and does not appear to be popping out of gear based on the position of the shifter but otherwise is acting like it is going out of gear.....forward and reverse.

I have removed the yoke, front and rear joint housing and see nothing abnormal.

Before I tear into this any further, I have some questions I am hoping you can help with...

Can this problem originate within the outer drive?

If yes, what would that be and what am I looking for if I were to disassemble this further?

Thanking in advance for any advice.
Click to expand...

Ayuh,.... Call Marysville Marine, in Marysville,...

They're the 1, 'n only supplier of Dana/ Eaton parts I know of, they also might work on 'em....

I'd think possibly the prop Hub is stripped... Try a different prop to see...
 
I agree re; the prop hub may be bad. Try another propeller.

If the Eaton is actually a Volvo Penta (w/ Eaton's name on it), it will be a cone clutch drive, and may be a 100 or an early 200 drive in 1968.
If this is an Eaton, I'm not familiar with which type of gear engagement Eaton used that many years ago.

Can you post a few photos of the drive?

Take a look here. One of these may be your drive. If so, capture the image and post it.

.
 
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Not cavitation...I wish...but that is exactly how it behaved.

OD oil was full.

Problem is there forward and reverse with nothing to obstruct the water flow.

Ran great the evening before...then throttling up as we pulled ou of th channel, something gave and there were were. Idles fine, no bangs or clangs or grinds but won't speed up...drop throttle to idle and things are fine.

Pretty sure this is an Eaton but always learning. Attached is the parts list with blow ups and serial #.

If the prop hub was the problem, what am I looking for?
 

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Look thoroughly through your PDF file and see what type of engine drive coupler this uses. I seem to recall that these were a rubber hub affair.
If you lost a hub, it may perhaps explain the slippage issue.

Question: do you place a high value on keeping this boat OEM with this Eaton drive?
If so, expect to spend some money on what may be rather hard to find parts, if not obsolete.

If not, consider replacing the entire drive with a mid to late 70's Volvo Penta drive.
With Borg Warner parts, you should be able to make the 231 work with the Volvo drive.

.
 
If you mean the engine drive plate.....nothing rubber there. All metal with metal springs. All looks sound and nothing slips with moderate pressure when I slip the drive shaft in there and twist by hand.

I can not make the propeller slip either but do see considerable and fresh scoring on rear of the propeller hub metal cylinder between the blades. So, the internal parts of the propeller could be slipping? Is that the idea? How can I check a prop to confirm this.
 
copelandg said:
How can I check a prop to confirm this.
Click to expand...
Mark the inner prop hub and the outer blade hub. Run the drive, and see if the marks are still aligned. If they've shifted, then your prop hub is slipping.

copelandg said:
To you question...I would like to keep OEM but most important to keep the boat on the water....
Click to expand...
Then I'd consider cutting my losses, and find a donor boat with a Volvo Penta drive.

The 250 or 270 would be inexpensive, yet these are pretty much bullet proof.
The 250 uses a smaller maine drive gear male yoke splines, and the lower unit gears are bevel cut.
The 270 uses the larger main drive gear male yoke splines, and the lower unit gears are hypoid cut (all are hypoid after the 250).
The 280 or 275 would also be a good choice.

You'll need a Borg Warner flywheel cover for the 231, a Borg Warner -slash- Volvo Penta PDS adapter housing (or Holman Moody, Eaton, Donzi), the transom shield, the Y-pipe, and a 1.61:1 ratio lower drive unit.

Any of these drives will connect to the 250, 270, 280 or 275 transom shield.
The 280 or 275 collar steering fork shaft diameter is larger than the 250 and 270.

Your prop selection will increase with these drives.

This is doable only if the Eaton transom cut-out is not larger than the Volvo Penta transom shield cut-out.


.
 
copelandg said:
If you mean the engine drive plate.....nothing rubber there. All metal with metal springs. All looks sound and nothing slips with moderate pressure when I slip the drive shaft in there and twist by hand.

I can not make the propeller slip either but do see considerable and fresh scoring on rear of the propeller hub metal cylinder between the blades. So, the internal parts of the propeller could be slipping? Is that the idea? How can I check a prop to confirm this.
Click to expand...

Ayuh,.... You either need Another prop, or take that 1 to a prop shop, 'n have it rehubbed....
 
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