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TOPIC: 59 mark 78a parts

Re:59 mark 78a parts 9 years 5 months ago #110448

For some reason I cave seen to get it past a certain point. The vertical water tube is about a half inch from the hole it slides into.I wiggle it to try and find the hole on the crank but no luck. Tomorrow I'm going to lay it on its side and try.

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Re:59 mark 78a parts 9 years 5 months ago #110454

Someone may have already suggested this, but when i was doing my Mark 75 i found it much easier to put the water-tube into the bottom of the powerhead first, and the as you raise the lower unit you will be able to see where it lines up with the waterpump on the LU.

Not sure if you are aready trying it that way, but i was having the same trouble until you are until i put the tube in the powerhead first.

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Re:59 mark 78a parts 9 years 5 months ago #110458

I'd rather work with a shift shaft than that water tube.it must be in the lower unit when assembling it and the top of the water tube must be held in a measured position from the drive shaft. did many back in the day I was young. if you need the measurement I will have to look it up. I used to tape it in place with masking tape.

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Re:59 mark 78a parts 9 years 5 months ago #110465

When I pulled it the vertical water tube stayed in the mid section. Or are you talking about the curved one from the pickup to the pump housing?

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Re:59 mark 78a parts 9 years 5 months ago #110469

No the one that stayed up in there is the one. on those DR's you can't get in to get the tube in the pump.

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Re:59 mark 78a parts 9 years 5 months ago #110495

Got it in. Made myself a special prying tool that I can easily push it back in place with. I'm kinda concerned about the bent copper tube though. Can it possibly wiggle out of place in the l/u? Oh here's what I've got going on inside my controls


What cable does this take?

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Re:59 mark 78a parts 9 years 5 months ago #110514

contact Joe Poole at fergusonpoolemarine.com/
he just found me a new cobra head and harness. Tell him the serial number and he will fix you up. A brand new harness (minus control box) cost me 2 bills, well worth it.

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Re:59 mark 78a parts 9 years 5 months ago #110522

I already extended my wiring harness. Just trying to get the cable. I think I found the one I need teleflex cc1700 but I'm not 100% sure yet. I did find a bracket on eBay for my pulley steering setup but I may try making one first.

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Re:59 mark 78a parts 9 years 5 months ago #110529

Are the vanes on the impeller supposed to flex the opposite way when changing direction or do they keep the same orientation but just rotate backwards?

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Re:59 mark 78a parts 9 years 5 months ago #110543

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craveman85 wrote:

Are the vanes on the impeller supposed to flex the opposite way when changing direction or do they keep the same orientation but just rotate backwards?


Nope, when the engine reverses rotation the impeller vanes should shift and go the other way as well. Otherwise it won't pump properly.

So, you can see that Reverse with an old, inflexible impeller wouldn't work out so well!!

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Re:59 mark 78a parts 9 years 5 months ago #110544

Maybe I had too much grease on it. The new one wasn't bending the other way. Looks like the lu is coming back off

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Re:59 mark 78a parts 9 years 5 months ago #110547

craveman85 wrote:

Maybe I had too much grease on it. The new one wasn't bending the other way. Looks like the lu is coming back off


Before you pull the lower again, i would fire it up and check to see if it is pumping in both directions. New impellers are very stiff, especially on the "squeeze side", and chances are that it wouldnt reverse direction by simply turning it by hand. I dont think too much grease is the problem. The water will wash away most of the grease after a bit of running anyway.

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Re:59 mark 78a parts 9 years 5 months ago #110558

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I'll second that, no need to take it back apart. When the pump is pumping in the lake, water resistance will be enough to force the pump vanes to orient in the proper direction.

I would only worry if an op-check in the water shows lack of pumping in one direction or the other......ed

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Re:59 mark 78a parts 9 years 3 months ago #113260

I have the boat ready and mounted the motor (replaced transom) and had it running quite well. Pumps water well both ways. Now I have an issue. The harness I got from Poole marine has the positive and negative posts on the opposite side as my original harness plug. It also has one extra wire which I believe is a ground. I believe it's the right part # but I'm wondering why the positive and negative are flipped. I think my next course of action here is to replace the engine harness or maybe just flip the ground/positive wires around on the engine harness side. I thought about just using the negative cable on the positive battery terminal and positive on the negative but the positive side has the heavier gauge wire going to the controls.

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Re:59 mark 78a parts 9 years 3 months ago #113271

Can you post a picture?
doc

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Re:59 mark 78a parts 9 years 3 months ago #113330

I fixed my problem. I realized I cut the cable to length before hand and couldn't return it so I lopped the plug off with a machete and wired it to myplug. All but the red wire was a smaller gauge also. I believe the red needed to be heavier because of the rectifier right?

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Re:59 mark 78a parts 9 years 3 months ago #113341

We had the same issue with the harness we got from Joe. We reversed the wires internally and ignored the extra wire. It works great.

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Re:59 mark 78a parts 9 years 3 months ago #113367

I've got it all hooked up and running. Seems like I May still have my Linkages and cable a bit off though. Also seems like when I start it in forward and then try and go to reverse it starts harder and I need more throttle

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Re:59 mark 78a parts 9 years 3 months ago #113368

call me 1 914 310 7086 Dave.

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Re:59 mark 78a parts 9 years 3 months ago #113369

I will if I get a chance. I work evenings and live in an area with poor reception if any at all.

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Re:59 mark 78a parts 9 years 3 months ago #113372

10-4 anytime till 11:00 pm eastern time.

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Re:59 mark 78a parts 9 years 3 months ago #113698

Got my wiring figured out. Everything is hooked up and I got my first test run in today. Seemed to stutter at low rpm and when I hit the throttle harder. I'm going to sit down with my manual and check all the linkages and clean out the carbs real good. I had it out for about 1.5 hours today. Seems like it used a lot of gas. I think I used about 5 gallons. I also had a little water around the fins under the spark plugs. I didn't really see anything milky in the cylinders. I ordered new gaskets for the whole powerhead.

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Re:59 mark 78a parts 9 years 3 months ago #113699

Just went out to go check my plugs again and make sure there was nothing milky. #4 hasn't fired at all. G brand new plugs) and had some water in the cylinder. Not going to run it again until my gaskets come in. Is it pretty much just the 2 gaskets then the little transfer port gaskets on the side? Is there anywhere else to get water in the cylinder? When I checked my plugs earlier on the lake I didn't see any water in it. Maybe the load on the engine broke up some gasket material.

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Re:59 mark 78a parts 9 years 3 months ago #113707

Is a 1959 58a the same as the 78a for impeller install?

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Re:59 mark 78a parts 9 years 3 months ago #113708

Not sure. Isn't the 4 cylinder a full gear shift lower unit?

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Re:59 mark 78a parts 9 years 3 months ago #113716

"Is a 1959 58a the same as the 78a for impeller install?"
No.
The 78A water pump housing does not require a spanner wrench to open the water pump housing to access & change the impeller like the 58A.
The 78A water pump housing is set on top of the gear case - like the '60s-'80s inline-6 and most every other size Merc of that era.
Exceptions include the 400 4 cyl and first edition 500 4 cyl.
Doc F

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Re:59 mark 78a parts 9 years 3 months ago #113721

Compression is still good so I'm assuming the exhaust gasket gave out. Are there any other ways water could get inside that cylinder?

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Re:59 mark 78a parts 9 years 3 months ago #113726

"so I'm assuming the exhaust gasket gave out. Are there any other ways water could get inside that cylinder?"

Look also for cracks or corrosion holes in the baffle plate - if it is a cast aluminum plate. If it has a stainless steel baffle plate, it probably doesn't have any leaks other than perhaps a dried out old gasket that is allowing water in.
While you have these parts removed, be sure and look for cracks in the block running horizontally between the exhaust ports and the front edge of the exhaust chamber.
There are thin casting lines that run the same way in the same basic area, so don't panic.
If you heat the area in question and dark ooze wicks out of the suspected 'crack' you have a crack and the source of your water intrusion.
doc

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Re:59 mark 78a parts 9 years 3 months ago #113805

No cracks anywhere. A lot of carbon build up in the exhaust chamber. My plate is stainless. No cracks in the plate either. Both the exhaust gaskets and the cover gasket were falling apart when I removed the parts. I only broke half of the bolts for each and luckily they are all protruding to weld a nut on them. I did notice some light scoring I on the pistons but it didn't seem too bad. Rings aren't stuck. I'm wondering since it sat for years if the previous owner might have tried cranking it over with everything dried out and maybe scratched it. Walls looked ok though. They don't look bad enough to require immediate attention but I'm going to try and source some .015 pistons and rings and hopefully get it rebuilt this winter. Unless the walls measure out good enough and I don't need a bore and a bigger piston. Maybe some stock size and some new rings will work.

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Re:59 mark 78a parts 9 years 3 months ago #113809

I also discovered today that if I cut the wire to the choke solenoid and put in a spade connector then I wouldn't need to fight with the screws holding the choke solenoid to the cover. That little mod saved me about 20 minutes fumbling with screws and the choke wire every time the cover comes off

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Re:59 mark 78a parts 9 years 3 months ago #113815

Anyone know of anyplace to get these old pistons and rings .015 over? And the other rebuild parts like bearings ect.

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Re:59 mark 78a parts 9 years 3 months ago #113881

"Anyone know of anyplace to get these old pistons and rings .015 over?"

What you are probably going to need to do is watch EBAY for '70s-'80's 500, 45hp 'classic fifty, and 40 4 cyl pistons (not 50 3 cyl)and rods with the later larger wrist-pins to snag the rods. Then 'cowboy up' for the related .015 pistons and rings, and bore your block respectively.
If you find 'WISCO' brand forged .020 pistons for this application, just be sure your bore guy knows the wiseco specifics before he bores.

I am 'on the hunt' for the exact same parts, so if I find more than I need,...I will post and share the wealth.
Currently I just need (2) STD pistons with the large wrist pins for my build, but will probably receive posts, etc related to the OS ones you need and will certainly share the wealth.
The related bearings and seals are readily available. If you have trouble locating them - just post and we'll fix you up.
doc

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Re:59 mark 78a parts 9 years 3 months ago #113941

Someone at one point in time thought it would be ok using stainless bolts for the exhaust plate. NOT OK!! I thought maybe I coils use my flux core welder to weld some nuts on the broken bolts but no luck there. Seized so bad I broke both of my broken screw extractors even with heat and pb for 2 days. Looks like I'm drilling.

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Re:59 mark 78a parts 9 years 3 months ago #113945

I have pretty good luck getting those evil little stainless cap-screws out by striking their heads with a punch and 3 pound hammer.
Hit straight down on the head, then hit the sides of the head from various angles. The idea is to try and compress the corrosion and consequently create a wee bit of space around the shank and threads.
If you get the cap-screw to move, but then it gets real tight again, repeat the process.
When that fails, I drill off the heads of the cap-screws so the cover and baffle plate can be removed, and then apply heat to the 'studs' (remains of the cap-screws). Striking the aluminum around the remaining 'studs' can also help while heating the surrounding aluminum.
doc

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Re:59 mark 78a parts 9 years 3 months ago #114246

A week of heating, hammering, cooling and a can of pb blaster had no effect. However a 5/16" drill and tap and some studs did the trick

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