1998 Johnson 150 Faststrike Lower Unit has extreme pressure in it

[KevinDaniel]

Guys, the other night I went to replace the gear oil in my lower unit and boy I had a surprise waiting on me. Ran the boat earlier that day so let it fully cool off for about 6 hours. Well when I loosened the top fill plug it was under so much pressure it sprayed gear oil everywhere for about 5 seconds while I was trying to tighten the fill plug back. I then barely loosed the lower drain plug and it hissed for several minutes. No water in the oil, but do I have a blown exhaust gasket or something letting the lower unit fill up with exhaust pressure???? Forget the mess i have to clean up and the terrible odor, I am trying to figure out my next parts/gaskets to order before I remove the lower unit.

Thoughts?

Kevin

[KevinDaniel]

I am an idiot... From what I have investigated, the pressure is not abnormal. I should have cracked the plug and let it vent before just unscrewing it. No water and the fact the pressure was there is actually a good sign of my seals working. Of course, I will fill from the bottom and let it drain from the top plug to ensure no air is trapped.

Nothing to see here!!! LOL

[gearcaseman]

Something unusual going on inside your case for pressure to build that way. Was your oil black and very bad smelling by any chance ? Hope you weren't wearing your best clothes !!

[gearcaseman]

Pressure like that indicates a problem. Was your oil burnt black with bad odor ?

[KevinDaniel]

Yes, the oil was real black and smelled terrible. I took it out today for a test run after changing the oil and it destroyed the lower unit. It ran fine for about 10 minutes and then RPM's shot up fast as it went into a free spin. Troller motor back to the boat ramp. What ever happened inside it cranked the lower unit open. Time for a new lower unit on this one if I decide to invest in it.

[KevinDaniel]

Pressure like that indicates a problem. Was your oil burnt black with bad odor ?

Gearcaseman, any recommendations on where I can get a new lower unit?

[KevinDaniel]

It is a 1998 Johnson 150 Fast Strike J150GLECD. Looks like this one is the one I need: https://www.sterndrive.cc/product/90...on_search=true but curious if anyone has any recommendations. I will get the old lower unit removed in the morning.

[ChampioNman]

The SEI case is a good case with a 3 year warranty. Here is what you get. A gearcase in the box. You'll have to move your driveshaft and shift rod over to the new case, also need to install a new water pump (doesn't come with one) and the sacrificial anode. You'll need to set your shift rod to spec. Follow the breakin process to a T.

[KevinDaniel]

The SEI case is a good case with a 3 year warranty. Here is what you get. A gearcase in the box. You'll have to move your driveshaft and shift rod over to the new case, also need to install a new water pump (doesn't come with one) and the sacrificial anode. You'll need to set your shift rod to spec. Follow the breakin process to a T.

Thank-you sir! I guess moving the driveshaft and shift rod to the SEI is possible to do without opening up the SEI unit? I wish I understood why my OEM gearcase had so much extreme pressure on it. I did notice when I put the new fluid in it each magnet had a good bit of shavings on them but no chunks. I honestly thought exhaust pressure must have been getting in there but a local mechanic told me that wasn't possible with my lower unit so I just put new gear oil in it and took it out. The oil that came out with all the pressure was pitch black and had a horrible odor to it so something was wrong obviously... LOL.

Thanks!!

[KevinDaniel]

Here are some pics of the carnage.

Foot split:

IMG_3310.JPG

Looking down the lower unit where pinion gear goes:

IMG_3313.JPG

Pinion gear sheared off:
IMG_3316.JPG

Driveshaft seems ok:
IMG_3317.JPG

Side view no lower unit:
IMG_3309.JPG

Took me forever to get the water pump impeller off of the driveshaft. The original driveshaft had a split pin through the pinion gear with the splines so I assume on the SEI unit I just put the splines down in the pinion gear and not worry about the split pin. I left the shift rod in the original foot so I can take some measurements and make a mark.

Thanks guys!

Kevin

[ChampioNman]

21 14" in neutral from the deck of the LU to the center of the shift rod eye.

[gearcaseman]

something went wrong in the pinion bearing area that caused extreme heat, breaking your lower driveshaft. This is the reason for the burnt oil smell. As Championman has stated, An S.E.I. unit is probably your best choice. I doubt that your housing will be rebuildable due to what happened.

[KevinDaniel]

Thanks guys! I am calling SEI and US Boatworks tomorrow. Here are the two I am looking at:

https://www.boatengine.com/lower-units/remanufacture/evinrude-johnson/evinrude-johnson-lower-unit-v6-1991-2002/

https://www.sterndrive.cc/product/90...on_search=true

[gearcaseman]

Just give S.E.I. your model number and they will help you. Very nice people.

[KevinDaniel]

I sent my info over to SEI via email and within 5 minutes Justin responded with everything I need. Wow! These guys are responsive for sure. Will have it ordered today. Thanks so much gearcaseman and ChampioNman!! This is my own fault. When I experienced that much pressure in the case and that extremely burnt oil I should have stopped and pulled it down. I was/am nervous about putting this much money in a 1998 outboard, but this thing runs so good.

[ChampioNman]

Remember no need for the upper driveshaft from them or shift rod you can use yours.

[PJ-Rohlf]

I blew the lower unit in a 97 130 johnson. I can't remember where I got mine off the top of my head but I know I had to pull the old one apart to remove the upper drive shaft to reuse. There is a metal clip that holds it to the lower, on the new one you just drop that into the lower shaft, make sure the splines are aligned, and tap it into that metal clip.

[Rick Lilly]

I have a good used one for sale. Rick

[KevinDaniel]

I got the rebuilt lower unit installed and cranked with muffs in the driveway and it shifted great. I did not go with SEI, but I went with US Boatworks rebuilt lower unit with all OMC parts. It was more money than the SEI unit, but after talking with them on the phone I was willing to pay more money to get OMC genuine parts vs chinese parts. With the new water pump it has much stronger water pressure and a better stream. The most water pressure I had before at 5200 RPM's was around 26 - 27 PSI. Just in the driveway with muffs it had 24 PSI around 2200 RPM's. It ran good in the driveway and I don't think the powerhead is hurt, but until I can get it back in the water and breakin the lower unit I just don't know for sure. With this lower unit I am only using HPF Pro Gearcase Lube Gear Oil. After this work and investment, I will spend $20 more dollars to run the Pro Gear Oil as this thing sees 62 MPH a good bit.

Special shoutout to ChampioNman on the shift rod length in neutral. The shift rod in the destroyed unit measured 21 1/4" in neutral from the mounting surface to center of the upper shift rod hole, so that I where I put it in the new unit. I removed the clip on the bottom of the upper drive shaft, cleaned and greased the splines and went with it. I did use a bunch of Dawn dish detergent on the water pump impeller to lubricate it on startup. Getting the cover over the impeller was certainly fun... dear goodness.

Once I can get it on the water one day this week I will post back with some video.

Kevin

[joebone1]

If you get the SEI, do the break in the way they ask and it won't give you any problems.