lower unit weldable or not

cforcht · Jun 29, 2012

Hi, new to the forum as well as a new boat owner. learning a lot after buying a "project" boat. unfortunately the learning part is the realization not everything wrong with the boat was disclosed. live and learn

heres a pic of the lower unit. pre alpha I believe. 1978 vintage on an Ebko Cobra with 228 I/O. I found it has a crack when trying to put oil in. is this weldable or not? if so what precautions if any, should I take before welding it. the majority of the crack is shown in the pic. it wraps around the nose about 1 inch or so thats not pictured. I assume I need to dis-assemble and clean the lower before welding. any insight is greatly appreciated. thanks.

Reel Poor · Jun 29, 2012

Re: lower unit weldable or not

You need a replacement gear case. It can be welded but would likely distort the case enough to cause gear and bearing fitment problems. I don't feel it would ever be a "reliable" fix.

cforcht · Jun 29, 2012

Re: lower unit weldable or not

thanks for the input. I think I may take it apart just for giggles to see what it looks like inside. I have located and entire outdrive for 250.00 and am considering it heavily. simply for the sake of having spare parts from the unit I have removed.

Reel Poor · Jun 29, 2012

Re: lower unit weldable or not

If you replace the drive be sure it is a compatible drive for your engine. Mercruiser made different gear ratios for different engines. Also check the gear oil for contaminants. Don't want to make a 250 dollar mistake.

wellcraft-classic210 · Jun 29, 2012

Re: lower unit weldable or not

Given all the parts that can wear and labor, cost & complexity of internal repairs-- You may want too at least consider a new SEI replacement unit.

If you do go used -- its might be best to make sure it passes a pressure test & has a good skeg along with any other checks.

spdracr39 · Jun 29, 2012

Re: lower unit weldable or not

New SEI lower is what I would do but if that isn't an option you could swap the lower from the replacement unit and sell the old upper to get some of your money back.

cforcht · Jun 29, 2012

Re: lower unit weldable or not

as much as I would like to go new I cannot. the drive in question is an 888 where mine appears to be an 898. base don looking at the diagrams from service manuals and comparing to my drive. so if I am right the ratio should be fine. since the 888 is ford 302 where mine is GM 305. Im learning more every day. thanks for the input guys.

haulnazz15 · Jun 29, 2012

Re: lower unit weldable or not

The 888 and 898 should both be 1.5 ratios I believe.

scf8169 · Jul 4, 2012

Re: lower unit weldable or not

As a welder by trade, I will say that there are welders out there good enough to weld that lower casing- but you will spend a heck of a lot more to do it and get it right than you will to just replace it. And yes, the ratio is the same. From what I've read, all V8's are 1.47:1 uppers, the lowers on a mercruiser alpha 1 are all interchangeable, no matter the engine.

cforcht · Jul 4, 2012

Re: lower unit weldable or not

I myself am a machinist by trade. within that trade I have spent many years welding, both MIG and TIG in fact spent about 10 years as foreman where I worked taking TIG welding jobs home almost on a daily basis. the problem is where the crack is located. its thru the bearing areas in the lower. as much as I felt it was fixable I just opted to buy the complete used outdrive for 250. even got the engine coupler. I have it apart and it looks great. but the upper drive shaft seal leaked enough that it wouldnt pass a pressure check. I have parts coming to replace all the seals and gaskets. as well as the water pump while im in there. I would have the parts today if it weren't a holiday. it does have a chunk missing from the skeg but I can fix that aside from that its a nice outdrive. at least it crack free. and the 888 and 898 are 1.5 ratio from the factory. thanks to all for the replies.

haulnazz15 · Jul 4, 2012

Re: lower unit weldable or not

scf8169 said:
all V8's are 1.47:1 uppers, the lowers on a mercruiser alpha 1 are all interchangeable, no matter the engine.

The Ford 351w and the Chevy 454 paired with an alpha are both 1.32 gear ratios. It was a bit of an odd pairing having the 351w using a 1.32, while the nearly identical Chevy 350 used the 1.50. I still don't know what the reasoning was behind it.

cforcht · Jul 4, 2012

Re: lower unit weldable or not

just a guess but I would say the lower 1.32 ratio was for a higher torque engine. using the lower ratio would tend to turn the prop faster so the same prop from the 1.5 ratio drive would require more torque from the engine to drive it. thereby keeping the rpm of the engine lower because of the added load of the lower ratio. someone chime in if Im wrong.

haulnazz15 · Jul 4, 2012

Re: lower unit weldable or not

The theory behind it is fine, because that's why the 1.32 ratio was used, to prevent lots of torque from a 454 from chewing up the drive gears. However, the torque from a 350 and 351W is going to be pretty much the same, yet they used two different ratios.

cforcht · Jul 4, 2012

Re: lower unit weldable or not

who knows. Im sure there was some reason behind it. only the engineer who made that decision would be able to answer the question.

TilliamWe · Jul 4, 2012

Re: lower unit weldable or not

cforcht said:
the drive in question is an 888 where mine appears to be an 898...so if I am right the ratio should be fine. since the 888 is ford 302 where mine is GM 305...

Not sure where all this 351 talk is coming from. An 888 was a 302. But even the 888 used the 1.32 ratio. I am not sure that the ratios will match up well for you.

cforcht · Jul 4, 2012

Re: lower unit weldable or not

According to the service manual and serial number the ratio is 1.5. I actually have the 898 and 888 both are 1.5 ratio. I physically checked to make sure.

TilliamWe · Jul 5, 2012

Re: lower unit weldable or not

Then you're on the right track.

lower unit weldable or not

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