'76 Johnson 85hp V4 lower unit

[jasonnb]

Ok, finally got around to pressure testing my LU. It help 10lbs pressure for more than 30 minutes and showed no bubbles in the water, Pumped it up to 15 and it (have taken water pump off) blew bubbles from a very small spot on the very top driveshaft seal. I rotated the driveshaft a few times and the bubbles stayed in the same spot. I tried shifting the unit in/out of gear by pulling up/down on the shift rod and while it seemed that a bubble eventually formed, it took numerous shifts to see any air bubbles. I have no way to vacum test. <br /><br />Ok, what I want to do is bounce my assumptions off those on this board.<br /><br />I resealed this case 2 years ago for water intrusion and since I had never done this before, I assume I goofed as the water intrusion got better, but never fully stopped. It looks like I need to re-seal the driveshaft area. I'm wondering about the shift rod area. Should I completely reseal and riska goof ona seal that is good now or just replace the one that is bad?<br /><br />Also, when looking at the drain/vent plugs, there is a plastic washer on the plugs and another in the holes. Is this normal, or did the previous owner add one? I had never questioned it until now.

 

[ob]

Re: '76 Johnson 85hp V4 lower unit

If your lower unit held 10 lbs for the time mentioned I personally don't feel it necessary to change driveshaft or shiftrod seals.The drain and fill screws should just have one seal apiece.This may very well be the place where water is entering unit.However, if you have the unit removed and are familiar with the seal changeout procedure then you could just opt to change them anyway.

 

[sloopy]

Re: '76 Johnson 85hp V4 lower unit

your preasure is fine! but there should be a plastic washer on the oil plugs and you should also keep those plugs greased

 

[jasonnb]

Re: '76 Johnson 85hp V4 lower unit

Thanks guys. I don't mind the seal change if it is just the one seal, but it seeems to be on the border. I had thought there should only be lu/seal/plug and not lu/plastic/seal/plug. Looking at the extra seal embedded in the lu, it has a lip as if it had been overtightened. I will repeat the 10lb test to be sure. The first go round, I waited for 20-30 minutes then dipped it in water for another 20-30 while shifting it and spinning the drive shaft.

 

[jasonnb]

Re: '76 Johnson 85hp V4 lower unit

OK, double checked the LU. Left 12-14lbs in it last night. Checked tonight and there was still 12-14lbs in it 22 hours later. rechecked using the old seals and it blew air at 5lbs. Looks like I found my leak. <br /><br />Now for the next question. As I get this lu back together, is there any way to get a general idea of what kind of shape the bearings are in? In turning the drive shaft (water pump out), you can hear the gears turning, but there doesn't seem to be any play in the shaft. The prop shaft turns very silently and has little resistance. It won't free spin, but it seems to be good to me. Any rume of thumb? I have seen small fetal flecks, but no major chunks. some like large dust particles, but no big pieces.

 

[alcan]

Re: '76 Johnson 85hp V4 lower unit

Hi jasonnb<br /><br />The only way I know of to check bearing wear is to pull them out and look at them. It dosn't sound like you have a problem though. I agree that two plastic seal washers is no good. When I reseal a lower unit do to age,(normal wear and tear) I replace all the seals and any bearings that show wear. If they need a seal do to damage, (bent prop or drive shaft, fishing line,etc) then I'll replace just the affected seal.

 

[jasonnb]

Re: '76 Johnson 85hp V4 lower unit

Thanks alcan. As old as this motor is and the fact I suspect the previous owner didn't do normal maintenance, makes me question everything. The gears/bearings on the driveshaft make a bit more noise that I would like, but I'm not sure what would be considered normal. I do know that they have been subjected to water in the oil for a good while.

 

[alcan]

Re: '76 Johnson 85hp V4 lower unit

Hi jasonnb<br />Allthough water in the lower unit is never a good thing. While a lot of folks assume that water intrusion (especially salt)equals a total loss. It has been my expirence that most of the time very little if any real damage has been done. Most of the time, if there is a problem worth being concerned about you will be able to feel it by turning the unit by hand. There should be little doubt that something is not right.The gear oil used in the lower unit seems to be some pretty knarly stuff. It dosn't like to come off of stuff. Try washing it out of your clothes. My theory is that a good mix of sea water and gear oil isn't a death sentence until you get air envolved (oxygen). Peace of mind is worth alot in used outboards and there is no way I can sit here and tell you that yours is or is not in good condition. As I said earlier you'll just have to have a look see.

 

[jasonnb]

Re: '76 Johnson 85hp V4 lower unit

alcan, thanks for posting again. I don't sense any major damage (all water was fresh and the fluid was partly changed before each outing. The turning of teh driveshaft is smooth and the shaft won't move side/side when shaken pulled/pushed. I've run this unit for nearly 3 years and have always tried to maintain as well as possible. It gets used for fishing duty every other week with runs of no more than 2-3 miles and has never let me down, plus my trolling motor could probably get me home if necessary. Your comments about water intrusion makes sense as hard as the gear lube is to get/wash off anything. I feel the unit is ok, but guess I just wanted another, more experienced opinion, to give me piece of mind.