Lower Unit Thoughts: Set ME Straight

[buckstop108]

I have a 1992 85 HP V4 Rude in a tiller model. I bought it used and the first thing that I did was had the impeller, seals and gaskets replaced. This seems to be a annual thing now since I find water in the oil all the time. I have had the seals around the prop shaft changed, the seals around the drive shaft were moved a bit, because the Mechanic said a groove sometimes gets worn in. It finally got to the point where I run her for a few hours and just drop the oil and replace it. This lower unit has kept me off the water too many times and almost cost me my spring smallmouth trip. Now to my thinking. The water is starting to get hard and I will fishing thru a hole soon (I hope). I was thinking of buying a new or rebuilt lower unit in hopes of solving the water issue. Since I like to take every opportunity to get every thing out of the motor as it pertains to speed and hole shot . Are there hot-rod versions of lower units that will give me more speed and if so what else would I have to change and how much would I expect to pay.

 

[tashasdaddy]

Re: Lower Unit Thoughts: Set ME Straight

have the one you have rebuilt, are you changing, the seal/washer on the drain and vent screw everytime? that could be your leak #1 reason.

 

[buckstop108]

Re: Lower Unit Thoughts: Set ME Straight

Yes I am. After the first time, I looked for any possible explaination. That was the first suggestion I got so I went out and purchased a bunch of them.

 

[larky]

Re: Lower Unit Thoughts: Set ME Straight

try a pressure test. It should narrow it down to which seal is leaking. I think you are only supposed to put like 5-10 psi in them, in a barrel and under water of course.

 

[Dhadley]

Re: Lower Unit Thoughts: Set ME Straight

Do a vacuume test also. The pressure & vacuume test will tell which seal is leaking. You can spray soapy water around each seal if you don't want to submerge the unit. You'll be able to tell which one it is easily.

If you've been using aftermarket seals, use OE seals. Especially the propshaft seals. If you've been using OE propshaft seals, go back a few years on the V4's until you get a different number seal on the same propshaft.

 

[mikesea]

Re: Lower Unit Thoughts: Set ME Straight

As you may know,there are many possibilities for leaks,which is why a pressure test,and/or vacuum test is really the only whay to locate the problem,has the mechanic?pulled the carrier out of the lower ,to replace the prop shaft seals?at that poing changing the o-ring which is located about 8 inches from the end of the exhust end of the lower ,that o-ring can be troublesome,as well as the little orings that are located on the bolts that screw the carrier in,then there are the shift shaft orings,and more,you should buy a KIT and replace every part in it,only after doing the checks that will locate the problem,you should then re ccheck after the reseal job,its true that prop shafts as well as drive shafts can end up with grooves,but I have found its usually the seal,is your prop shaft strait"?

 

[HighTrim]

Re: Lower Unit Thoughts: Set ME Straight

To pressure/vacuum test a lower unit:

a) drain the gear oil
b) use an appropriate adapter with a gauge tee'd in to apply pressure or vacuum. No more than 15 psig for pressure. You can use a bicycle pump or any other compressed air source for pressure. For vacuum, you need a vacuum pump.
c) LU should retain some pressure or vacuum for 45 minutes minimum.
d) If pressure doesn't hold, submerge LU in water to find leak source, or spray soapy water as Mr Hadley stated. [possibilities: drive shaft seal, prop shaft seal(s) (usually two), shift shaft seal and the fill/drain screw washers.]
e) replace offending seal(s) as required.

 

[BillP]

Re: Lower Unit Thoughts: Set ME Straight

I don't know if this applys to a 92 but...earlier omc drive shafts had chrome plating for their seal surface under the wp. Water stands on this seal and leaves mineral deposits (salt in my case) which eventually corrode or wear the chrome. The rough surface eats seals (in a few hrs) and lets the amount of water in like you are experiencing. I had it happen and the best fix was a new drive shaft...I couldn't find a new shaft and every used shaft had the same problem, so had a shop turn the drive shaft and polish the seal surface. That worked and gave no problems for several hundred hrs that I owned it. You may want to check it.

bp

 

[buckstop108]

Re: Lower Unit Thoughts: Set ME Straight

The mechanic that did the last three jobs told me that he did do both the vacuum and pressure check. He stated that he left the pressure hook-up over night and the norm would be 45 minutes and it held tight. He of course can not understand why it would still be leaking. He did mention that when he replaced the seals around the drive shaft he moved it a little just in case there was a groove. I can't remember if he said anything about the gear shift shaft. I asked about the prop shaft being bent and he stated that it was fine and I would feel it in the tiller handle if it was bent. With all these variables in where and why it would still be leaking, is why I was wondering about a new lower unit. The money that I have spent on this unit already I think I might have had a new one. Although I have no idea what they cost. I think a rebuilt one is coming in at around $1500. I did have fishing line once on the prop shaft. But it has leaked since then. Would heavy weeds cause a problem like this. Several Lakes I fish in are choked with weeds. I wasn't sure if they could get wrapped around the prop for a short time and cause a problem. I don't see that happening, but what do I know. Thanks for all the help and input I really do appreciate it. Maybe a new mechanic is what the doctor is ordering.