Help no forward or reverse alpha one, gen.1 mercruiser, 4.3L

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Jul 14, 2012
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14 months ago I had the 4.3L engine pulled for a blown head gasket. (Done by good shop) Engine was repaired and the boat ran great all last summer. EXCEPT throttle handle seemed too tight against the side)

Extremely cold winter last year and my winterizing "not so good" I cracked two exhaust manifolds. No oil in the engine oil and no leaks from the case.
(ENGINE CASE was winterized just forgot to drain the exhaust manifolds.) Oil in lower unit was drained and clear last fall.
New skeg was welded on prior to winterizing. Local shop did it without disassembling lower unit, (he reportedly has done it multiple times in past without trouble. He runs a hose with towels above prop shaft and welds small areas at a time.) looks beautiful.

Problems: engine starts fine but will not go in gear forward or reverse.
Throttle lever is now 3/8 of an inch from wall, last year had been too tight against wall
"rubbing" clicking back of motor when idling if higher rpm goes away or cannot hear
engine dies if It , ? starts to go into gear

Oil in lower unit drained and looks beautiful (no steal, small amount of aluminum "aprox 1 BB" when oil strained through paper towel. (only aprox 1 quart obtained, but oil came out when top drain removed so was full ??/ I expected more)
Gears in upper unit looks perfect.
Upper gear appears to advance and engage correctly with shifting, obviously top off.
in neutral prop spins with a clicking both back and forth
with throttle forward prop rotates with clicks forward relatively easily, goes backward against much more resistance and I can watch the gears move in open upper unit, If it was solid I would be turning the engine over moving the prop.. (what's normal)
With throttle in reverse does the exact opposite

HELP, can anyone give me a "next step" or best suggestion. The shop that did the engine was busy and thought the killl switch on the throttle was possibly bad. They said ,they could not bypass it but that I could try that. ??
Suggestions?
 

dubs283

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Jul 27, 2005
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with the drive in gear and you can rotate propshaft and see the upper gears turning?? sounds like a spun coupler
 
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Jul 14, 2012
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Sounds like I spun the coupler. But, how can I be sure that it's not a cable? I can watch the "shoe" fully engage but how do I know the shaft is properly in to the shoe. My concern is that the shaft was only into the shoe 1/4 of the way since engine was pulled a year ago.
Is there a way to ADJUST it forward the rest of the way or at least make sure that it IS completely seated prior to pulling the engine to check the coupler..
Thanks
 

ktbarrentine

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Dec 12, 2011
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My concern is that the shaft was only into the shoe 1/4 of the way

What "shoe" are you referring to? Got photos?

You need to pull your outdrive and check the yoke shaft splines, check the coupler splines, check U-joints, etc.
 
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Sorry, not shoe I was referring to the "coupler" on the back of the engine. My guess is that I stripped the coupler splines and am looking for a way to diagnose without pulling the lower unit. I want to make sure it is not just a cable adjustment before I pull the unit and "make things worse."
 

dubs283

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My guess is that I stripped the coupler splines and am looking for a way to diagnose without pulling the lower unit.

run the engine and look at the splined shaft at the rear of the motor, if its not turning the coupler is definitely shot, if it is turning the coupler may be okay, but the only way to be absolutely sure is to pull the drive

pulling the drive is no big deal, it should be part of your routine maintenance anyways
 

ktbarrentine

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Understand.... So, you should be able to see the shaft between the transom and the coupler (with a flashlight, most likely). WHen you start the engine, you can see if the shaft is turning. If not, the coupler splines (or coupler rubber) is completely shot. Either way, the drive has to come off.... six nuts and the trim ram shaft. takes five minutes.

If (with engine off), you can put in fwd and turn the prop CCW (like you said, you can see the gears in the upper turning), and the shaft between the transom and the coupler is turning, that is another way to say the coupler is shot.

If (with engine off), you can put in fwd and turn the prop CCW (like you said, you can see the gears in the upper turning), but the shaft between the transom and the coupler is not turning, then it is between the drive and the gimbal bearing, maybe bad/broken U-joints?.... as I said, though, once you have the drive off, you will be able to tell right away...
 
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Jul 14, 2012
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YOU GUYS ARE "MARVELOUS." THANKS A MILLION. Not good news, but at least I know the problem. Hand turning the prop smoothly turns the shaft into the engine. Coupler has gone to heaven,
New question this means I ran the engine for at least 5 minutes with no water, ran engine another 5 with hose attached water ran out of hub, think 1/4 strength kitchen faucet. Never sounded hot or smelled hot.
Questions?
Best way to tell if I damaged engine running with NO water.
New heads from over heating engine 14 months ago. Cause never found. Boat ran great all last year 20x's. No way this could have been going bad all this time.(does not seem possible)
Used coupler on ebay, good idea or bad?
How much water would go through engine just with water pressure from hose" wide open"
Exhaust hoses not burn't I assume this a good sign.
Any thing else to check
Thanks a million
 

ktbarrentine

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You may have dodged a bullet on the engine..... But your exhaust shutters may be toast. You can run the engine with the drive removed by putting a water hose in the water inlet hole on the bell housing (taped or otherwise held in place to keep from falling out) and check your temps, but I would still take off the exhaust boots and check the shutters.
When you run on muffs, if the drive is not turning (impeller not turning), then the impeller actually blocks flow to the engine (unless the impeller is shot, allowing water to get by).
I would shy away from anything used (ebay or otherwise) that goes in the drive train. Bite the bullet (it is a B.O.A.T.). Good luck.
 
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Jul 14, 2012
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Another question, This engine was pulled and rebuilt 14 months ago, best I can tell that is the first time the engine has been out of the boat since new 1990. Another web sight says mercury "recommends" these be replaced every time engine is pulled. (if over 30hrs of run time). Is this true?
 
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Sorry, a different site said Mercury "recommends" couplers be replaced every time engine is pulled if over 30hrs on them.. Engine last out 1990
. If so I just want to ask for discount on repeat engine pull. (still under warranty) If not then I won't mention. I have decided repairing this is above my pay grade.
Thanks Brian
 

Fishermark

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Oct 19, 2003
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Sorry, a different site said Mercury "recommends" couplers be replaced every time engine is pulled if over 30hrs on them.. Engine last out 1990
. If so I just want to ask for discount on repeat engine pull. (still under warranty) If not then I won't mention. I have decided repairing this is above my pay grade.
Thanks Brian

Absolutely not - that would be silly. No need to replace a couple that is not bad.

By the way - I only just found this post... you apparently have a duplicate post out there that I replied to regarding the coupler issue.
 
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Jul 14, 2012
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Thanks, that's what I needed. I did not want to complain or ask about the warranty if couplers are not routinely replaced at time of engine changes. (as suggested on other site)
Yes, I have a duplicate post, I don't know how that happened or how to fix it.
Thanks again
 
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