Twin DF140 Lower Units Keep Cracking

[TXFishin]

I have two 2003 DF140's, both engines have gone through two lower units each (4 lower units), they continue to crack near the prop where the bearing carrier meets the gear case housing, infamous " J " crack.

I have been told this is due to heat/expansion/corrosion, however, the last set of lower units have less than 50 hours on them and have been flushed religiously.

Initially I thought the first set of lower units that cracked were due to the previous owners neglect for proper care, but the second set of lower units completely under my watch and taken care of cracked in less than 50 hours.

I am reluctant to spend the money and replace the lower units again without knowing what is causing this to crack, specially with little to no usage.

I am at a point now where i have spent half as much as a new engine would cost just in lower units and considering a re-power with another brand (Mercury, Evinrude or Yamaha) and walking away from Suzuki

In my 30 years of boat ownership I have never seen anything like this

[Solarman]

I'd agree with you. That isn't right. Four gear case housings on each motor is not acceptable. I think you should send a letter stating how disappointed and unacceptable this is, directly to Suzuki. This sounds like a defect in the manufacturing, or engineering process / design. Less than 50 hours each, should be Suzuki's fault.

Wish you the best.

[TXFishin]

I'd agree with you. That isn't right. Four gear case housings on each motor is not acceptable. I think you should send a letter stating how disappointed and unacceptable this is, directly to Suzuki. This sounds like a defect in the manufacturing, or engineering process / design. Less than 50 hours each, should be Suzuki's fault.

Wish you the best.

Actually it was not 4 each, it is 4 total, 2 on each engine, and the current ones are bad as well, which is still way too many seeing as I've owned boats for 30 years and have never seen anything like this under my care.

I'm just trying to find a reason why I should stay with Suzuki and keep hitting myself in the forehead. Like I mentioned, I excused the first set of lower units thinking it was neglect in part I the previous owner and keeping the boat on slings that maybe they were getting dunked at high tide or something, but when the second two lower units, for all practical purposes cracked sitting in my driveway, well that's a little beyond my threshold

I wrote Suzuki a letter and sent pictures, but I seriously doubt I'll here back from them or they will do anything so I'm not holding my breath

Right now I'm looking at prices on Mercury and Yamaha

[TXFishin]

Personally I think it is a design flaw, and given the care I have done to the last lower units I don't know what else could be done to prevent it, remove the bearing carrier after every trip, clean and reseal?

They cracked with such low hours too, in fact early this year when I changed the water pumps getting ready for fishing season they looked fine, I went out once since then and they practically cracked sitting in the driveway

It's sad really, they start and run fine, but I can't live with the cost of replacing lower units more often than changing gear oil.

[noelm007]

Hands up anyone who has had more than one cracked gear case......

[nelbur]

Is there any chance that the engines have been left tilted up in harsh winter weather? If the drain hole is plugged rain water can fill the exhaust area at the base of the prop, and a hard freeze might break the lower unit. If you always store the boat with the engines vertical, this can not happen. Not sure where you live.

[TXFishin]

Is there any chance that the engines have been left tilted up in harsh winter weather? If the drain hole is plugged rain water can fill the exhaust area at the base of the prop, and a hard freeze might break the lower unit. If you always store the boat with the engines vertical, this can not happen. Not sure where you live.

No freezes here, mild winter in Houston this year and engines are always left tilted downward.

It really is the oddest thing I have ever seen in 30 years of owning boats.

I am leaning towards stray electrical issue, I am going to poke around with my voltmeter and see what happens.

[Moonlighter]

Yes, it is a seriously weird situation to have not one, but two, motors to have the same problem, and to have it then happen twice really is quite bizarre.

The odds that the root cause is the engines design or construction themselves seems remote, otherwise we would hear of many more doing the same thing - and the fact is, we don't.

And bear in mind that the DF90,100 and 115 share the same lower units. If they were cracking chronically, we would have heard about it loud and clear by now, the same as we all know about the infamous Engine holder corrosion on those same models.

But, no such pattern of reports seems to exist. I actually just rang a good mate who is a Suzuki master technician who has well over 20 years experience with these engines, and he said he's never seen this problem in a 4 stroke Suzuki. He did say is was not uncommon in the 2 stroke Suzuki and Yamahas in those old days, but he has never seen a 4 stroke have such a problem. In fact, he described the gearboxes on these models as "built like a truck".

So, this logically points to something to do with the specific installation, or the specific operating or maintenance conditions, that you have there. (please note I'm not in any way meaning to be critical or lay blame at all, am just trying to think this through logically to try to help find the root cause and thus a real solution)

If the assessment is that heat/expansion in the bearing carrier area is leading to internal corrosion/swelling and this is causing the cracking, then as you say, the question of what is really causing such an anomaly needs to be investigated.

So my problem solving approach might be to ask, Why would the bearing be getting excessively hot? Was there in fact any hard evidence of that bearing getting hot - discolouration, melting adjacent seals etc - some evidence that gives such a proposition credibility? If so, then....

What could cause excessive heat in that area? Some excessive load on the bearing somehow? Bearing itself out of tolerance? Previous owner put wrong spec bearings in there sometime? Excessive play in gear assembly due to poor maintenance by previous owner? Props of an unsuitable size or design, or out of balance?? Motors set too low, or Prop shafts both bent??

Many of these seem unlikely, but worth checking to at least try to rule such things out.

One thought - When the new lower units went on, did the original internals go into a new case, or were complete new gearboxes and housings installed as a total unit? If just the cases were replaced, then rather than looking at the cases as the problem, I'd be looking at the internals or something that they share in common as the potential root cause, such as gearbox oil. Or previous owner may have run them low on oil or without oil and damaged both of them and putting the old guts into new cases simply transferred the problem?

Hope you figure it out and get it sorted. Best of luck!