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1990 4HP Lower Unit not Releasing

M

Mr. Dave

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Removed two bolts holding lower unit of Johnson (Model J4RESR) to midsection for impeller change. Lower unit swivels back and forth about an inch but it remains flush to the midsection. Tried gently pulling on lower unit while slowly turning flywheel, in neutral and drive, with no change. There doesn't seem to be a way to disconnect the shift mechanism from either end so I'm hoping someone has an answer. Thanks
 
Sounds like the drive shaft splines are stuck in the crank shaft. Give the lower unit a few wraps with a rubber mallet.
 
Thanks Boobie, for reply. Tried several mallet hits but no change. As far as I Know the lower unit has never been off so I'm sure it is well stuck. Was just reading "1984 Evinrude 4HP"post and I think this guy had the same problem. New water pump repair kit came with tube of grease for upper shaft splines so that should have been a big clue.
 
Has anyone heard of changing the impeller coming from the gearbox side? I think I remember reading about a guy doing that. May save me the hassle of trying to get he drive shaft out of the crankshaft, at least, for now.
 
Thanks Racerone. The 2008 thread I referred to "1984 Evenrude 4HP" said the only way to get the stuck lower unit off was to force it down with a #40 screwdriver and some rags. He said the pump housing would be destroyed by the pin but it was the only way. Does this sound right? The advice seemed to work for the guy but I'd like your opinion before I try. Thanks
 
Take it apart that way and then turn it upside down and put penetrating oil down the drive shaft to bust it loose. May want to hang it by the drive shaft at the same time. When you get the drive shaft out you can put it back together correctly.
 
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OK Boobie, I agree. The impeller kit comes with all the parts I'll destroy by forcing the sections apart so unless someone has a better idea, I'll try my luck. It seems to me that I don't really have a choice if I ever want to use the motor again. I'm assuming that it is rust holding the shaft in the crank since both are steel, I wonder if CLR might work to dissolve the rust, it does a great job getting rust off my tools. Thanks for your help, I'll keep you posted.
 
So far, no luck. I've forced the lower section as much as I can without busting the housing and still nothing. My guess is that the old impeller is corroded on the shaft and trying to force that off by prying the housing won't work. My next plan is to use a chisel, thru the one inch opening, and break apart the black plastic impeller housing until
the impeller is free.
 
On the forward neutral only units you need to remove the powwerhead anyways to put it back together. Remove the bolts holding the powerhead on and turn it upside down and spray some WD on the driveshaft and let it drip down to the crank then hang it off the ground a couple inches and let gravity do the work. You need to disconnect the shift shaft to pull the gearbox.
 
Kimcrwbr1, I think racerone might be on to something. I pulled the gearbox apart and the shift rod seems to be a straight up/down rod that should pull right out if the lower unit came off. I tried pulling the powerhead to see if I could inject some WD-40 but with the shaft stuck in the crank and stuck on the impeller there just is no gap. All I can do is wiggle the lower unit back and forth about an inch. A similar thread can be found in SEARCH FORUMS under topic "stuck lower unit" from 2008 called "1984
Evenrude 4 HP" (yeah, he spelled it wrong).) The shift rod issue came up then, too. Thank to both for replies.
 
If it does not have reverse it is difficult if not impossible to stick it back into the gearbox while the shift rod is still in the exhaust housing you will see once apart and try to put it together
 
Got it, I definitely don't have reverse, just neutral/forward. My idea to break apart the black plastic impeller housing with a chisel thru the small gap is still on the table, unless you feel the shift rod is the real problem and have a suggestion to correct it. With the gearbox apart I can see how much a pain it will be to re-install the shift rod. I'll leave it apart, just in case.
 
Racerone,
Is the "wrapspring" neutral the same as the clutchspring in the lower unit gearbox? Seems the semi-circle end of the simple up/down shiftrod impacts it during operation.
Thanks
 
Correct---The shift rod moves to contact the wrap spring and then there is no drive.-----Nothing to connect or disconnect on this simple set-up !
 
Racerone,
Thanks. You've followed this thread and know what I'm up against so unless I hear anything different I'll try to break up the old plastic impeller housing in order to move this project forward.
 
Yes i just converted a 1984 to a long shaft last year. I still say time and weight does wonders possibly spray some WD in the exhaust port as you hang acinderblock from the powerhead an tie it a couple inches off the ground by the gearbox. Just get creative but never hit the gearbox with a hammer period. Use a 2X4 and a hammer!
 
I also found out you can fine tune them to a crawl ifyou set the points with a timing light. It takesmore time but you will have a one pull start motor from the effort. There are two marks on the points plate andtwo on the flywheel 180 degrees out. The mark on the flywheel must be between the two marks on the plate then it will idle down to a crawl.
 
Kim, I removed much of the old impeller housing and found the impeller stuck on the shaft. I took your advice and poured a cup of WD-40 down the inside of the upside down midsection and plan to leave it there for at least a week. The cinder block is a great idea and I'll set it up tomorrow. I haven't hammered on any housings except for a few rubber mallet whacks at Boobie's earlier suggestion. I hope to have better luck getting this thing apart after letting it soak. Thanks
 
Im confused you say you removed some of the impeller housing? There is only the top cover and plate the metal plate is probably holding the shaft in the housing with the pin in the shaft once again you will see once you can unbolt the impeller cover the shaft will slide right out of the pinion.
 
Kim, Sorry for the confusion. The lower unit, midsection and powerhead are all held tight together by the shaft stuck in the crank and on the impeller. The only access I have is thru a one inch opening when I slide the gearbox and midsection to the side. Since the impeller housing is right there I've been able, with a hammer and chisel, to break some up in order to remove the lower unit via the pinion. I've removed some but not enough. I decided to take your advice and soak everything for a week in WD-40 before continuing.
 
Guys, Thanks for the info. (I've been installing a new fuel tank in my truck so I've not been checking in.) The motor is hanging upside down by the lower unit in my shed for a few days now soaking in WD-40. I'll pick up some acetone tomorrow and be ready for another week of soaking if the shaft doesn't come out this weekend. If, after a
week of soaking in WD-40 and then a week of atf/acetone, it is still stuck, I'll try P/S fluid. Let me know if you think a week of soaking n P/S or the atf/acetone is too long.
Thanks
 
Kim, I had the same concern, but I think I can still get a seal. I always thought that ATF and P/S fluid were the same, only ATF had a red stain included. I never thought of either of these as rust removers or as any kind of penetrating oil. I'm willing to try anything so it is another few days of WD-40, or another penetrating oil, and then acetone/ATF and then P/S fluid. I'll keep you posted.
 
Bought a product called "Blaster" made by a company in Ohio. It is supposed to break up all rust and corrosion fast. I sprayed about 1/2 of the 11 oz. can down the midsection, waited an hour per instructions, and gave the powerhead a few hits with a rubber mallet, and the unit dropped almost a 1/4 inch! It won't budge anymore but I think there is some hope. The motor is still hanging upside down by the lower unit so I'll leave the "Blaster" soaking until success.
 
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