Replacing impeller on 1977 merc. 1500

[ventureman]

Is the shift linkage connected by any screws?
Besides the bolt under the trim tab, any other hidden bolts?
Gear in forward or neutral, or doesn't matter?
Or any helpful tips???

Thanks

 

[Laddies]

Re: Replacing impeller on 1977 merc. 1500

No screws it's spined shift into rev before removing and thats the only hidden screw

 

[Chris1956]

Re: Replacing impeller on 1977 merc. 1500

I put the shifter into neutral before removing the lower unit. It makes it easier to reassemble. Put grease on the driveshaft splines and shift shaft splines. I boat isn saltwater, so I ued to coat the entire driveshaft with grease to hold down the corrosion.

Replace the Oring seal on the waterpump base, as well as the gasket. Save the 3/4" oring in the water pump repair kit, in case the seal in your PTT cylinder fails.

 

[OldMercsRule]

Re: Replacing impeller on 1977 merc. 1500

Both Laddies and Chris1956 know far more then I do (or prolly ever will) about Mercs, (and I learn from them as two of the resident "BIG GUNS" all the time here on iboats). That said: it is problematic to "dry" shift the old inlines into reverse as forward is OK to dry shift into, (maybe Laddies has some sort of technique to avoid messing up a corntrol box which can happen 1 out of 3 to 5 times or so on a "dry" shift into reverse with out spinning the engine). I also always leave the engines in neutral when I change an impeller, not that I know what I'm doin' so I am glad to hear Chris1956 does it like I do. My overpriced $.02 JR

 

[ventureman]

Re: Replacing impeller on 1977 merc. 1500

I replaced the impeller today, and getting water thru' the pee hole now. Old impeller was beyond bad, no flabbers at all. Motor is good, easy start every time. Don't know how she will do on the water, as nothing is hooked up yet.
I am going to rewire the internal harness wire so that I can use the existing external wiring harness on the boat(from existing control box). New to me
power tilt and trim will need to be installed as well. The 175(refer to my other post) has 2 hoses, and the 150 has 4. Planning on removing the powerhead on the 175 after that since I found out that all my spark plugs were in good shape with no metal shavings or deposits. Might have thrown a rod or bearing, don't know! Was able to turn flywheel 1.5 turns before it stops. How do you know what the problem is???? Plan on rebuilding if possible. Cylinder 5 has been bored out on last rebuild. Where or how do I start on this project???

 

[Laddies]

Re: Replacing impeller on 1977 merc. 1500

First drop the gearcase so you know that the trouble is in the powerhead, then remove the heads and see what is not going up and down a broken rod will not move a piston and a bad bearing will show as the piston is being pulled down the bore with the crank, push on the piston to see if there is slop if there is that the bad bearing

 

[ventureman]

Re: Replacing impeller on 1977 merc. 1500

Thanks Laddies, I might remove the heads tomorrow and go from there. I love that motor before it locked up. Had it rebuilt several years ago at more than $2500.00. My gut feeling is power head problems since I was running it wide open and could hear things breaking apart and smoke from the upper body. I did not try to rebuilt again because I know it is very expensive. I found some pistion kits on ebay at reasonable price, so maybe I can do the rebuilt myself. Done a complete teardown on a 40 before(bearing problem), but a 175 Black Max seems too big a job and $$$$. If I can find cheap parts on ebay, it's worth a try.