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  1. merc850

    New wiring harness for 1979 70hp?

    Post a picture of the plug and the serial Nr. I think it uses a flat plug inside the cowling.
  2. merc850

    1981 Merc 115 i6 issues

    Some tanks have filter on the pickup which might be clogged.
  3. merc850

    Should I buy this Mercury 40 horse?

    Lots of exterior damage (missing clamp screws) who knows what has happened to the powerhead internals!
  4. merc850

    1973 Mercury 850 Won’t Idle

    Some of the pistons look like they have damaged or stuck rings
  5. merc850

    How to manually raise 1974 Mercury 85 with power trim

    No you turn it to the right to release.
  6. merc850

    1976 Mercury 1150 - Water Problems, Several of Them

    There is a jacket that is cooled to keep the exhaust from burning it up. Fig. 26. I noticed a white thing in one picture is water coming out of it?
  7. merc850

    1976 Mercury 1150 - Water Problems, Several of Them

    Looks like a leak in the exhaust water jacket cover.
  8. merc850

    70s merc 850 85 hp mercontroller

    You have the wiring harness take the box apart and check the wires if they're bad and you have extra just cut them and wire to the new control switch. Newer controls short the switchbox to ground to stop, yours puts + power to switchbox and removes it to stop so you have to figure that one out...
  9. merc850

    1976 Mercury 1150 - Water Problems, Several of Them

    The bolts on the water jacket cover go thru the 2 pieces and have a nut on them; even if they break you can replace them with stainless. Don't rev it past 2,500rpm in neutral!
  10. merc850

    How to manually raise 1974 Mercury 85 with power trim

    That's the way.
  11. merc850

    1976 Mercury Tilt/Trim Controls

    Once you set the "finger" to stop the trim before the motor starts overreving it's a handy feature. Trim in to take off then out for hi-speed running. Make sure the tilt pin is installed into at least the first hole.
  12. merc850

    1976 Mercury 1150 Yellow Fluid Leak (Steering?)

    Have you thought about fixing that under dash wiring with a terminal strip? you can run all the neg wires to a common terminal then run a fused pos. wire to the terminal strip and branch off of it. I see a gage but I don't know if it's a tach or speedo if it's not a tach get one (this site has...
  13. merc850

    1976 Mercury 1150 Yellow Fluid Leak (Steering?)

    It's also possible that it has hydraulic steering that is leaking.
  14. merc850

    1976 Mercury 1150 Yellow Fluid Leak (Steering?)

    Before you work on the motor study this diagram that "goo" might be coming from the LU - if the seals in the waterpump are shot gear lube can be pumped thru the cooling system.
  15. merc850

    Mercury 850 thunderbolt 1974 gearbox check

    If you can find another motor 74-75 that has a damaged powerhead buy it for spare parts starter etc or even power trim.
  16. merc850

    Mercury 850 thunderbolt 1974 gearbox check

    Make a mark on the hub and the flexplate on the flywheel that line up, remove the stator with a 3/16" Allen wrench; the wires go into a rubber grommet that you pull off. Use a Moto tool to carefully remove the plastic potting compound until you see the connections to the windings. Make your...
  17. merc850

    Mercury 850 thunderbolt 1974 gearbox check

    That's why they used nuts and bolts on the terminals and the ignition switch uses soldered connections; because any disconnection of the wiring while the motor is running can result in destruction of the rectifier or switchbox or both, make sure the battery connections are clean and tight.
  18. merc850

    Mercury 850 thunderbolt 1974 gearbox check

    That LU looks serviceable but apply lots of penetrating oil first. Another piece that needs to be looked at is the alternator stator under the flywheel, the wires might be corroded they are yellow and run down the stbd. side of the block.
  19. merc850

    Mercury 850 thunderbolt 1974 gearbox check

    Here's the LU diagram and the bearing carrier tool which might be still available from Merc this is used to undo/do the nut and tork it properly. Look fopr corrosion on the housing where the nut is - soak it for a while with penetrating oil. Usually a slide hammer is used to pull the carrier...
  20. merc850

    Froze up 25 hp 5842749 serial no.

    Replacing the flywheel is unusual has the new one caused a jamming problem?
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