Loss of rpms in gear

[mike king]

I have a 81 catalina with atomic-4. She runs great ,but for one problem! When in gear 2500rpms it will run for about 5 mins. then it will drop down to 1000rpms with a slite squel and smoke out of the oil cap. I can take it out of gear rev up and put it back in gear with same result.My brother thinks it's the reversing gear, what do you think?
Thanks Mike

[Don Moyer]

Mike,

I'd be very surprised if your problem turns out to be the reversing gear. It sounds more to me like something is grabbing around the prop shaft. The smoke coming from the oil fill tube is most likely blowby induced by the great load being imposed on the engine

I'm wondering if the stuffing box or cutlass bearing is breaking down (especially the cutlass bearing) and bunching up around the prop shaft. We used to own a 1981 Catalina 30, and I remember that particular boat had a lot of problems with the bronze strut corroding away. While we never did have the cutlass bearing fail, we did have to replace the strut.

In terms of the reversing gear, you could remove the cover plate and examine the gear cage assembly and connecting linkage while someone turns the reversing gear around a couple times to see if anything looks grossly out of place. However, I can't come up with any likely candidates that would easily explain the amount of drag that you seem to be describing.

Please stay in touch. It's always important to the rest of us to learn of the final outcome of these episodes.

Don

[mike king]

loss of rpms

Hi Don,
Thanks for the input. How do I check the cutlass bearing ? Do I haul out to check the strut? Or is there another way to find the problem? I'm thinking about disconnecting the shaft and running in gear. Would this isolate the problem?
Thanks Mike

[Don Moyer]

Mike,

I don't know of any way to evaluate the cutlass bearing except to do a short haul. You could, as an alternative, remove the prop shaft as you suggest and then run the engine in gear for five or six minutes. You could also grab the engine output coupling with the prop shaft disconnected and pull hard in a sideways direction. If the rear thrust bearing is bad you should be able to feel some sideways clearance.

Don

[mike king]

Cutlass bearing

Hi Don,
Just got around to disconnecting the shaft coupling. Ran her in gear and all symptoms are gone! Looks like you were right. Planning haulout.since it is going to be out of the water, what parts should I replace? Where can I get: Strut and cutlass b.;what about shaft and prop. Do you know the dimensions of shaft? Should I replace the stuff box with dripless?
Thanks Mike

[Don Moyer]

Mike,

You'll have to measure the prop shaft to know the size. The Atomic 4 used 3/4", 7/8" and 1" shafts. West Marine sells cutlass bearings, and your local marina should be able to point you in the direction for the services you'll need to replace the cutlass bearing.

Don

[mike king]

Loss of rpms under load

Hi Don,
I just talked to two different prop shops and explained symptoms and both shops don't think it has anything to do with the drive-train. But I still plan pulling her out for inspection. If it is the reversing gear how quik can I get one from you? My brother is flying up from San Diego to help and don't have alot of time.
THanks Mike

[jhwelch]

Does your loss of RPMs also happen when you are in reverse for
5 minutes?

I recently replaced my reversing gear, so now know more about it
than I would like.

When it is in forwards 3 clutch plates are engaged, so the only problem
you should run across, if it really is the gear, is slippage, which
would speed the motor up, not slow it down.

Have you checked your oil level and / or changed the oil recently?
The revesing gear is lubricated with engine oil. Good luck.

[Don Moyer]

Mike,

You'll find rebuilt reversing gears in our online catalog ready for immediate shipment for $240 plus a refundable $100 core charge (product number OREV_01_226).

If you place your order before 2:00 Eastern Standard Time on any given day and select next day UPS, the reversing gear should be at your place the day after you order it. If you place your order on Friday, you'll have to place it through our telephone sales representative (Ken) at 610-421-4436 since our automated online process cannot accept orders for Saturday delivery.

I've also attached a pdf file containing the instructions for removing and replacing the reversing gear. You may want to study them so you'll have a leg up on the process, should you have to actually replace your reversing gear.

Don