Yamaha 150 Lower Unit Separation

[edgutgesell]

I have a 1985 Yamaha 150 (ETXK). I am finally getting around to replaceing my waterpump. This is a saltwater engine and the impellar was allegedly replaced 3 years ago. I removed the six bolts on the cavitation plate and the one under the trim tab. The lower unit drops down slightly (about 1/16th inch) on the rear of the lower unit but does not want to budge on the front of the lower unit. Have I missed something like another hidden bolt in the front of the lower unit? I do have the Yamaha shop manual and a Sealoc manual. Any assistance would be greatly appreciated!

 

[edgutgesell]

Re: Yamaha 150 Lower Unit Separation

Oh! One thing I forgot to mention! When removing the six bolts in the cavitation plate, I broke the head off of one. (Always at least one!) Looking at the engine from the stern of the boat, it was the front most bolt on the port side. As you may recall from my first question above, the front of the lower unit is the area where the unit seems to be bound. The head of the bolt came off cleanly alittle above the lower unit casting. Maybe that bolt didn't break off cleanly causing the remaining bolt shoulder to bind in the lower unit bolt hole? Just a thought. Are the holes in the lower unit casting that close to the bolt shoulder diameter to cause a bind? If that is a possibility, how do I pry the lower unit off without damaging the lower unit?

 

[Ray Neudecker]

Re: Yamaha 150 Lower Unit Separation

Major pain in your you know what. Very likely the broken off bolt is holding you up. Likely it broke because it was corroded to the housing. Heat may help to break it loose or you may have to drill it out.

 

[edgutgesell]

Re: Yamaha 150 Lower Unit Separation

Thanks for your reply Ray! The bolt broke off flush with the lower unit casting. Looks like the next step is to drill it out since I can't get hold of it. It would be nice to have the shoulder of the bolt to grab on to, but if I drill it out the shoulder of the bolt it will be gone. Can I get away with 5 main bolts and the one under the trim tab holding the lower unit?? Are the holes in the lower unit casting that close to the diameter of the broken bolt shoulder to bind the lower unit?? As near as I can tell with the two Yamaha service manuals I have, other things that could hold the lower unit from separating would be the front dowel pin (rear of lower unit has separated about 1/8", front of lower unit is not separated) or the driveshaft spline. Driveshaft spline corrosion would appear to be the death of my engine!! It appears that any prying would damage the mating surfaces of the lower unit and the intermediate aluminum castings. I also have a Rude 70 that I have been serviceing and have replaced the impeller solo numerous times. The Yamaha lower unit is quite a bit larger and looks heavier than the Evinrude so pulling the Yammie LU solo would be ill advised?? My plan was to leave the six bolts loosely in place to hold the loose lower unit until I could get muscle assistance from my two sons!! I guess I am looking for any possible solution to what may be a serious problem without further damage caused by me. I would still like to have a relatively intact engine that a professional can repair if necessary!! I have read the broken bolt horror stories on this site. Any other suggestions or tips would be hugely appreciated!!!

 

[cousinabe]

Re: Yamaha 150 Lower Unit Separation

is there a bolt underneath the trim tab zinc that needs to be removed?

 

[cousinabe]

Re: Yamaha 150 Lower Unit Separation

never mind... i saw you removed that one.
good luck.

 

[Ray Neudecker]

Re: Yamaha 150 Lower Unit Separation

Even though not reccomended, you could get by without one bolt. Putting a helicoil in after drilling out the bolt would be a better solution.

 

[rodbolt]

Re: Yamaha 150 Lower Unit Separation

heat heat and more heat.
propane just aint hot enough.
whats happened is the corrosion has grabbed the bolt, usually not the threads.
its also caused by a severe lack of maint.
so heat the case at the hole where the bolt pased through it.
I am half crippled and do them by myself almost daily.
its really not that much heavier then the 70 jonnyrude but a heckuva lot easier to reinstall.
make sure you check the steady bushing in the midsection just above the pump for deterioration. they go bad as the corrosion build underneath them and causes them to collapse on the drive shaft.

usually I can back the bolts out with heat. its rare I drill one.
if nothing else I make it hot enough to pull the threads with the fastener and helicoil it.

 

[edgutgesell]

Re: Yamaha 150 Lower Unit Separation

Thanks rodbolt & Ray,

As usual you have the answers. I think I will need to come up with an actylene torch. I have used oxy acetylene in the past, the long distant past. As you have mentioned, aluminum is an excellent heat sink and I hope it is. I don't want to melt the casting. I can't get the aluminum too hot?? Mapp is a waste of time?? If I understand you correctly, with bolts breaking, its not the threads that seize but the bolt shank corroding inside of the aluminum casting. Is that correct?? That would explain why heating the aluminum casting expands it and allows enough clearance, freeing the bolt. Rodbolt, I think I saw one of your answers to bolt problems where you said that chlorox bleach turns aluminum oxide to fish slime. Fish (fluke) slime seems slipperyer than WD40. Is bleach worth a preliminary shot??

 

[rodbolt]

Re: Yamaha 150 Lower Unit Separation

I doubt chlrox will help yours as it does not defy gravity well.
mapp may be hot enough and yes you cn overheat the Al. and makeit run a bit. however if you watch carefully you will see it wrinkle just before it runs nd it will quit as oon as the heat is removed or moved to another spot.
Its rare I break bolts any more but I have done it a year or so, and I have slept at a holiday inn.
it may be wise to use the long bolt from under the tb in one of the side holes as the cse may be hotter than you ish to carry when it drops. I have some oak wedges that I made that I drive between the mating surfaces to aid in removal,especially on mercrusier,merc and OMC/volvo drives. I have also had to resort to wood chisels and screwdrivers to wedge them apart.
saltwater i great stuff.
that why I found its so much easier to use heat before I snap the fastener than after.

 

[edgutgesell]

Re: Yamaha 150 Lower Unit Separation

Thanks rodbolt. I'll post my results!!

 

[edgutgesell]

Re: Yamaha 150 Lower Unit Separation

Hi Ray and Rodbolt. I drilled out the broken lower unit bolt and the lower unit separated fairly easily. With the MAPP gas torch, I was able to extract the the broken off threads from the leg. There was enough of a nub to grab with vice grips. Heat did it. Rodbolt, you were right as usual. The LU wasn't that much heavier than my Jonnyrude LU.

Why I was dropping the lower unit was to rebuild the water pump. I was not getting a tell-tale stream while on the muffs. The impeller was replaced by a professional 3 yrs ago. I expected to see an impeller with vanes missing! Not so. The impeller looked relatively undamaged and the cartridge that is inserted inside of the waterpump housing had some minor scuffs, but otherwise fairly undamaged. (IMO) The impeller vanes had taken a set, but otherwise showed minor wear. I put impellers with more wear showing back into service in my Jonnyrude! I backflushed through the pee hole and it doesn't seem clogged. Any thoughts?

Also, the insertable replacement cartridge in my waterpump housing seems to be non-insertable. Is there some trick to removing the old cartridge and inserting the new?? I have the complete OEM waterpump rebuild kit from Yamaha.

Also, one thing always leads to another. The shift shaft shows erosion and appears to be eroded by at least 25%. In a past thread, some guy claimed to have replaced the shift rod without removing the power head. He claimed to have done the job by removing the intake manifold with reeds and had sufficient clearance to do the job. Any conclusion to that repair procedure? I know you guys say pull the power head. I would like to avoid pulling the power head if possible. My powerhead shows good even compression on all six cylinders and seems to run well. I am seriously thinking of re-powering if pulling the powerhead is the only choice.

As always, your replies are greatly appreciated!!!

 

[edgutgesell]

Re: Yamaha 150 Lower Unit Separation

Could the waterpump housing with non-removable insert cartridge be an aftermarket waterpump kit???

 

[Ray Neudecker]

Re: Yamaha 150 Lower Unit Separation

I haven't personally tried pulling the manifold and carbs method myself. I fortunately don't have to deal with saltwater motors. He got a little vague about how he got it back in. On a fresh water motor. I would prefer to pull the powerhead. A salt water motor is a different animal, specially a twenty year old one. I suspect, I might try it first on a salt water motor. If you yanked the intake as one piece and pulled the flywheel if might be possible with a few curse words to get it back in.
Not sure about the insertable cartridge you are refering to. The rubber sealer tube for the pipe does not come in the aftermarket kits. The factory one has two rubber tits that have to be pushed in to remove.

 

[Ray Neudecker]

Re: Yamaha 150 Lower Unit Separation

Also, low water pressure on the hose side,poppit valve problems, a pump housing that is warped or not sealed properly and around here, dirt dobbers can cause the no peeing on the hose.

 

[rodbolt]

Re: Yamaha 150 Lower Unit Separation

I tried it once, wont come out without bending the shaft.
the insert,if glued in, has to be removed with a punch and hammer. look inside the area where the shaft passes and you will see where to place the punch.

 

[edgutgesell]

Re: Yamaha 150 Lower Unit Separation

Thanks guys! I am going to order the new SS shift shaft. I have a 25" leg engine so I think I need to order the correct length shaft. I am also going to order some 3/8" DeWalt pilot point drill bits in anticipation of pulling the powerhead.

I reviewed removal of the powerhead this morning in both of my manuals and with the anticipation of broken bolts the process looks doable. I first will try to install the shift shaft by removing the whole intake manifold assm. carbs and all and since I already have experience in replaceing stators, I will remove the flywheel.

I also ordered a new OEM waterpump housing yesterday so I can complete the waterpump rebuild. I am going to reinstall the LU and use the boat until either the shift shaft breaks or replace it at the end of this season. I sprayed the shift shaft with a liberal coating of "Fluid Film" to hopefully slow down the corrosion process. I don't think that I will venture far from shore and make sure my "Sea Tow" towing insurance is paid up. I am not sure that the MAPP gas setup I bought is hot enough to do the seized bolt heating, but I will try it first. I am going to give this shift shaft replacement a shot and if I run into too many problems I will re-power. Do you think I have a plan? Thanks again for all of your inputs!!!