Mercruiser Lower Unit Gear Casing Wear with Excessive Fwd/Aft Play in Prop

[jasonabbott]

I have used this site for a lot of great reference information and really appreciate the wealth of knowledge available here. I searched around on here this evening and couldn?t find anything on my current dilemma. My boat was in for service and a water pump job recently. I?d say the boat was run for a total of no more than 6 hours since I got it back.

Standing at the stern of the boat this evening I nudged the prop with my leg and noticed a distinct gritty sound as the prop turned ? like the casing was packed with sand and as the prop turned that sand was being ground between metal surfaces. Naturally I grabbed the prop and turned it in both directions and the gritty sound was very severe. On closer inspection I discovered the prop was no longer fairly snug inside the gear casing and it actually moved aft at least a half inch. As the prop was moved forward and aft along the shaft, I noticed the shaft sleeve would fall away from the locking tab washer almost to the point the tabs would not rest in the grooves of the sleeve. I know, an obvious problem here, right?

Needless to say, I removed the prop. What I found was considerable wear around the inner area of the gear casing as seen in the pics. Can anyone tell me what might have caused this excessive forward and aft play in the prop and what might be done to correct it? Also, I?m concerned about the wear on the inner edges of the gear casing hub. It does not appear to be something that can be ?fixed? without replacing the entire lower unit, but it?s possible I could be wrong here. Any input on this is greatly appreciated. If it matters, the prop is a 3 blade SS Stiletto, and I have had it on the drive for over 2 years with absolutely no issues until now.

The drive serial number is OC747676 if it matters.

Thanks for any input on this!!!

Jason R. Abbott

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[Bt Doctur]

Re: Mercruiser Lower Unit Gear Casing Wear with Excessive Fwd/Aft Play in Prop

somebody forgot the thrust washer that goes on first.

 

[jasonabbott]

Re: Mercruiser Lower Unit Gear Casing Wear with Excessive Fwd/Aft Play in Prop

Thanks for the reply, and yes, that's correct....I went out there after posting that last night and realized it was missing. I was too pissed off to update this and got on here now to do it. Any advice on the condition of my casing now? I left a message at the shop that did the work, but doubt they will own responsibility for the thrust washer being missing.

 

[ENSIGN]

Re: Mercruiser Lower Unit Gear Casing Wear with Excessive Fwd/Aft Play in Prop

The case might be ok but you will need a new locking ring and tab washer.

 

[dubs283]

Re: Mercruiser Lower Unit Gear Casing Wear with Excessive Fwd/Aft Play in Prop

by the looks of the retainer there is a high possibility threads in the case have been damaged

doubt you'll be able to remove the retainer with the tool - probably have to drill and use a chisel/punch to break it out

then re-thread the case, probably not worth buying the tool but any local reputable repair shop will have one

 

[Hoosmatroos]

Re: Mercruiser Lower Unit Gear Casing Wear with Excessive Fwd/Aft Play in Prop

Indeed, new ring and the thrust washer and you're oke. But the shop should take care of that!!

 

[jasonabbott]

Re: Mercruiser Lower Unit Gear Casing Wear with Excessive Fwd/Aft Play in Prop

Thanks for all the input above! I talked with the Service Director this morning and all he could say was "I don't know how the prop would have been installed without the thrust washer in place". I said "I don't know WHY it was". In addition to that he said he's not sure what to do given the amount of time (2 months to the day) that has passed since I got my boat back from them and this issue was just now noticed. I told him I did check the prop when I got the boat back and it felt snug like it should at that time and since then I honestly had not given it a check by touch. Am I off my rocker here for not physically touching the prop after the 4 times I've used the boat since the repairs? He said bring it to their shop and they should be able to find a thrust washer laying around that will fit my drive. I said that's all fine and good, but my problem is a little bigger than just the thrust washer being missing. When I told him there was considerable wear to the hub of the gear casing he said bring it by and they will look at it. I think they own a ring and retainer replacement job if that's all that needs to happen but I'm not sure how to determine the extent of the damage to the inner hub.

 

[Don S]

Re: Mercruiser Lower Unit Gear Casing Wear with Excessive Fwd/Aft Play in Prop

The damage to the case is going to be determined by how many threads are left in the housing. That will have to be determined after the rest of the retainer is removed. Can't tell that from the pictures.

Had the prop installer tightened down the prop as it should have been (50 ft lbs) the prop would not have turned, so they obviously had to back off the nut and pulled back on the prop so it didn't drag to make it feel right.

 

[jasonabbott]

Re: Mercruiser Lower Unit Gear Casing Wear with Excessive Fwd/Aft Play in Prop

The damage to the case is going to be determined by how many threads are left in the housing. That will have to be determined after the rest of the retainer is removed. Can't tell that from the pictures.

Had the prop installer tightened down the prop as it should have been (50 ft lbs) the prop would not have turned, so they obviously had to back off the nut and pulled back on the prop so it didn't drag to make it feel right.

From the looks of it the nut would have tightened snug due to the thickness of the tab washer locking spacer and the prop would have been tight against the casing. Upon test run if they engaged the drive the snug would have gone away immediately but seems to me there would have been a distinct sound back there to indicate something wasn't right. Of course that's a lot of speculation on my part but it makes sense in my head anyway.....lol

I'm taking the boat by their shop around noon time so I'm hoping to have a solution from that meeting! Any doubt I might have on the sustainability of any repairs at this point makes me think the lower unit should be replaced, but I do realize that's a hefty price for a repair shop to absorb!

 

[adamjr]

Re: Mercruiser Lower Unit Gear Casing Wear with Excessive Fwd/Aft Play in Prop

Hi Jason. Wondering how your meeting went. Any satisfaction from the marina?

 

[jasonabbott]

Re: Mercruiser Lower Unit Gear Casing Wear with Excessive Fwd/Aft Play in Prop

Thanks for the inquiry on my status on this issue. I met with the Service Manager and he took a look at the lower unit. He insised he didn't know how they would have installed the prop without the thrust washer in place and he didn't know how it went so long without being noticed. I assured him the prop had not been removed since they did their work because I had no need to do so, and I also told him I didn't care to figure out how it was missed and it was beyond obvious the mistake had done damage to my lower unit. He agreed to extract the retainer nut and replace it, and also drain the gear oil and check it to see if there are any signs of internal issues. I guess he felt like throwing something extra in there to make me feel better on the gear oil. Can anyone identify with a need to check the gear oil after the thrust washer was not in place for about 6 hours of running? I suppose the amount of material missing from the retainer nut was minimal considering the original thickness of it and my estimate of about a 1/8 inch grove in the face of it. I will update when I get my boat back. Of course this time I will remove the prop to make sure all is in order before hitting the water.

 

[Don S]

Re: Mercruiser Lower Unit Gear Casing Wear with Excessive Fwd/Aft Play in Prop

You don't have to remove it to check, just push the prop toward the drive and turn it, if it hits the drive, you have a problem.

 

[adamjr]

Re: Mercruiser Lower Unit Gear Casing Wear with Excessive Fwd/Aft Play in Prop

Jason, I'm glad they're standing behind their work. I'm in a service business myself and I work as a tech. Sometimes you just have to take responsibility for something like that because it's the right thing to do. What happened in their shop was definitely a mistake regardless of an explanation or lack thereof so I'm glad to say they're going to remedy it. Hopefully you'll be on the water soon.