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Results 1 to 19 of 19
  1. #1

    Default No Reverse on 1970 Mercury 500 Thunderbolt - Help Please!

    Hello All!

    Yesterday I bought a 1970 Glastron Skiflite V-142 (Mercury 500 Firebolt) from a friend of mine for $500. He told me something was up with the ignition so I replaced the ignition switch on it and it fired right up which is great. Buuuuttt.... I put it in the water and now I'm running into this problem: neutral works fine, idles great, sounds great, forward works great, but I need to push the throttle REALLYYYY far forward to reach a good speed (25-30 mph or so) and I have no reverse. It almost feels like it engages and the engine revs really high when I push it the whole way into reverse, but I get no backwards thrust.. Is it possible that when I took apart the controls to put in the new ignition, I put it back together in the wrong way and now it's not engaging into reverse? Could it be as simple as opening the control box and adjusting something in there to make it right or will I have to take the lower unit off and make adjustments in there too? This is all assuming that something else isn't wrong which I don't really think is the case because it was my buddy who sold me the boat and I think he would have told me if the reverse wasn't working at all..

    Any help would be greatly appreciated.

    Thanks so much,

    Sam

  2. #2
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    16,836

    Default Re: No Reverse on 1970 Mercury 500 Thunderbolt - Help Please!

    Common problem after an impeller change. Assuming the remote cable is properly adjusted, then the top and bottom shifting is simply misaligned.

    Jeff

  3. #3

    Default Re: No Reverse on 1970 Mercury 500 Thunderbolt - Help Please!

    Quote Originally Posted by kimcrwbr1 View Post
    It may just need adjusting. With the engine off make sure the control handle is straight up neutral and the fast idle lever is all the way down. Can you spin the prop in both directions? Disconnect both the shift and throttle cable at the motor and check the adjustment after assuring it is in neutral and the throttle is all the way to its stop in slow. Those older motors will get some slop in the linkage you need to check the cables move smooth when disconnected. If there is alot of slop in the controls you can still get the bushings to tighten it up and new cables wouldnt hurt either the motor linkages seems to stay pretty tight. Is that the mercontrol black control box?
    Thanks for the reply.

    It is the Mercontrol black control box. I did notice there was quite a bit of slop in there when I took it apart yesterday to put the new ignition switch in. What exactly do you mean when you say "the throttle is all the way to it's stop in slow"?

    I believe that when the engine is off and the control handle is straight up neutral and the fast idle lever is all the way down the prop will spin freely in both directions but I'll double check to make sure.

    Thanks again.

  4. #4

    Default Re: No Reverse on 1970 Mercury 500 Thunderbolt - Help Please!

    Quote Originally Posted by fastjeff View Post
    Common problem after an impeller change. Assuming the remote cable is properly adjusted, then the top and bottom shifting is simply misaligned.

    Jeff
    I'm not sure if there was a recent impeller change, but I am 100% sure that the control box was taken apart yesterday as I did it myself so I'm thinking this is most likely the issue. Is there a common adjustment that might need to be made in the control box that would fix this (ie making sure the throttle was in straight up neutral and the fast idle lever is all the way down and then putting the box back together)?

    Thanks for your help guys,

    I'm pretty new to this.

  5. #5

    Default Re: No Reverse on 1970 Mercury 500 Thunderbolt - Help Please!

    Quote Originally Posted by kimcrwbr1 View Post
    There should be a detent roller that tells you when the control handle is in neutral. The same with the motor you should feel it set in neutral then adjust the cable to fit. As far as the throttle it is probably best to adjust the cable when running using the fast idle lever you should get it to idle around 2000 rpms with the fast idle lever just make sure it returns to slow with the lever all the way down. I take it you cleaned and greased the controls? did everything seem nice and tight going back together?
    I did notice the roller when I took the controls apart. I'm thinking that I made adjustments to either the throttle lever or fast idle lever when I had the box apart and then put them back together in some sort of incorrect position. I'm going to go take a look at it today and see if I can figure it out, although it is supposed to be raining all day, so I'm not sure how much work I'll be able to do. One last quick question and this may be self explanatory when I go take a look at the boat: where to the throttle controls connect to the engine? In the same place where the wiring harness goes in?

    Thanks again.

    Sam

  6. #6

    Default Re: No Reverse on 1970 Mercury 500 Thunderbolt - Help Please!

    So, I took apart the control box and made sure everything in there was good, which it seemed to be. I also checked to see if it needed adjustments on the motor end of the cables and that doesn't seem to be the issue. I feel like the controls are definitely clicking into reverse but the gear isn't engaging or something. Is it most likely something in the lower unit linkage? I've heard that if something comes disconnected in there, people run into this issue where they. This may be what related to what fastjeff said:

    Quote Originally Posted by fastjeff View Post
    Common problem after an impeller change. Assuming the remote cable is properly adjusted, then the top and bottom shifting is simply misaligned.

    Jeff
    Is this a relatively easy fix if I drop the lower unit?

    Thanks so much, I really truly appreciate all your help.

    Sam


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  7. #7

    Default Re: No Reverse on 1970 Mercury 500 Thunderbolt - Help Please!

    Quote Originally Posted by kimcrwbr1 View Post
    Getting it right can be a challenge even for the experienced mechanic. Did you try shifting it without the cables connected? You need to spin the prop if the engine is not running to line up the clutch dog ears. In forward gear it will ratchet in one direction and reverse it locks the prop in both directions.
    I honestly can't even really figure out how to disconnect the throttle and idle lever cables from where they run into the engine. Sorry, like I said, I'm not a super experienced boat mechanic. I like to think of myself as being handy, but maybe this whole thing is just beyond me. I'd love to fix it myself but am not sure I have the ability to. Are you saying that spinning the prop will help this problem in some way? It does ratchet one way when the controls are in forward and spins freely in neutral, but it also seems to spin freely in reverse as well, or at least definitely isn't locked in both directions.

  8. #8

    Default Re: No Reverse on 1970 Mercury 500 Thunderbolt - Help Please!

    I think that I'm actually starting to understand a little better now after reading some other forums and I'm starting to think it might be that both my throttle and shift cables are old, worn, and stretched out. For one, the shift control is exceptionally hard to move in either direction. It's possible, but really really hard. Secondly, I have to push the throttle to an almost 90 degree position forwards relative to neutral for the throttle cable to start to fully engage and bring the boat up to (full) speed. And lastly, with the fast idler lever or whatever you want to call it, I also have to pull it up really far for it to start to have any effect on the engines RPM's which I believe is directly connected to bullet point number two. I'm thinking that perhaps the shift cable just doesn't have enough backwards push to fully engage the engine into the reverse gear but this is just speculation. Which kind of leads me back to the issue of disconnecting my shift and throttle cables which I didn't see a flaer when I looked today. Anyways, any input would be greatly appreciated. I'll try to do some more research and figure out how to remove those cables and try to manually shift it into reverse and confirm that the prop locks in both directions and then I'll have a better idea if it's something in the cables or in the lower unit.

    Thanks guys.

    Sam

  9. #9

    Default Re: No Reverse on 1970 Mercury 500 Thunderbolt - Help Please!

    Quote Originally Posted by kimcrwbr1 View Post
    Yea pull the cables off of the motor and see if the controls work easily also maybe take some pics first inside the motor so you know how the cables go I have never worked on that year 50hp merc. But your headed in the right direction tho.
    So I finally figured out how to get the cables off the engine yesterday and turns out it was super easy and I was kind of just being an idiot. Got them off, slid the little gear selector thing by the bottom of the engine back into reverse and TA-DA, prop was locked in both directions! Neutral spins freely both ways, and forward ratchets in one direction so it appears as though everything in my lower unit is okay at this point which I'm quite happy about. The cables were still pretty darn stiff after disconnecting them from the engine, so I think I'm gonna go ahead and replace both the throttle and shift cables and hope that the controls a bit easier to handle as well as the throttle more responsive. The West Marine close to me sells each cable for $28 or something (way less than I expected). Probably gonna go ahead and take the control box apart again as well and properly clean and grease everything in there, just to make sure everything is free and easy when I'm shifting and accelerating. Do you think replacing the cables will help with this?

    Thanks again for the advice guys; it has been so amazingly helpful.

    Sam




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  10. #10

    Default Re: No Reverse on 1970 Mercury 500 Thunderbolt - Help Please!

    Quote Originally Posted by kimcrwbr1 View Post
    http://www.ebay.com/itm/NOS-OEM-MERC...ded788&vxp=mtr
    http://www.ebay.com/itm/New-OEM-Merc...1d9b0a&vxp=mtr
    Put new bushings in when you replace the cables. Did you check the cable adjustments? Put both the engine and controls in neutral and see if it fits. The threaded part of the cable is the adjustment. Do the same with the control handle in neutral and the lever on the motor all the way slow.

    Sweet, thanks for the tip. I had to put the little adjustment thing the whole way forward to even be able to get the controls to be able to push the shifter thing into reverse gear so I know that the cables need to be replaced. I did the same thing with the fast idle lever and basically got the same results. When I adjusted the threaded part to the tightest position, my throttle response got a little bit better, but clearly still needs replacing. As far as those bushings go, I was planning on replacing them too. How can I be sure that those ones on ebay will fit? Are they pretty universal as far as Mercury outboards go? The ones you sent me the link to definitely look exactly like the ones in my control box but I just want to make sure before I order them.

    Thanks again,

    Sam

  11. #11

    Default Re: No Reverse on 1970 Mercury 500 Thunderbolt - Help Please!

    Hey guys,

    Update here for you. I finally got a chance to replace both the shift and throttle cables on my Mercury which was fairly straightforward. I thought I had adjusted the cables properly at the motor as all the shifting was doing what it was supposed to when I spun the prop. In neutral, the prop spins freely both ways, in forward it ratchets one way, and in reverse it's locked both ways. This is all on muffs which leads me to my problem now.. In the water, neutral and shifting into forward both work great, but when I try to put the boat into reverse, I get a loud clicking noise in the engine that gets faster and slightly louder as I push the controls further backwards, revving the engine. It sounds like the engine is trying to shift into reverse, but isn't fully clicking into gear. I guess my question now is: Should I try to keep adjusting the cable more, in the hope that it gives it extra push into reverse? Should I try to quickly put the boat into reverse as I usually do it pretty slowly? Or is something most likely horribly wrong in my gear box / lower unit? Again this is only something that happens in the water when under load.

    Any suggestions?

    Thanks guys,

    Sam




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  12. #12

    Default Re: No Reverse on 1970 Mercury 500 Thunderbolt - Help Please!

    Try this... Disconnect the SHIFT cable from the engine. Slide the shift linkage(on the engine) to its full reverse position. Make sure propeller is locking in both directions. Check your shift limkage (on the engine) again to make sure it is still in the FULL reverse position. Next.. put your control box in reverse. Now adjust your cable (on the engine) to fit. After you have done this.. check to see if you still have neutral, forward and then again reverse. Have someone spin the prop when you are shifting to reverse. Hope this helps.

  13. #13

    Default Re: No Reverse on 1970 Mercury 500 Thunderbolt - Help Please!

    Quote Originally Posted by kimcrwbr1 View Post
    Did you try disconnecting the cable and shifting manually to see if it goes into gear fully in both forward and reverse? Did that make the throttle respond better with new cables? Did you replace the bushings in the control box? Can you hear the gearbox click into neutral when the control handle is in the neutral detent? When shifting do it quickly, yea adjust the cable a little more in the reverse direction and see how it does.
    I did disconnect the cables and it does seem to go manually into forward and reverse fully. The throttle is definitely a whole lot more responsive with the new cables as well. I didn't replace the bushings in the control box when I replaced the cables because as far as I can tell, the bushings in there actually seem to be in decent shape. I can hear the gearbox click into neutral when it's in the neutral detent. At this point the only things I can do is adjust the cable more but I'd say I'm only about 6-8 turns from being as far as I can go to adjust it, and try to shift into reverse quicker as I've been doing it pretty slow. If none of this helps, what's the next step?

    Thanks,

    Sam

  14. #14

    Default Re: No Reverse on 1970 Mercury 500 Thunderbolt - Help Please!

    Quote Originally Posted by woodsman243 View Post
    Try this... Disconnect the SHIFT cable from the engine. Slide the shift linkage(on the engine) to its full reverse position. Make sure propeller is locking in both directions. Check your shift limkage (on the engine) again to make sure it is still in the FULL reverse position. Next.. put your control box in reverse. Now adjust your cable (on the engine) to fit. After you have done this.. check to see if you still have neutral, forward and then again reverse. Have someone spin the prop when you are shifting to reverse. Hope this helps.
    I did already kinda try the first thing you mentioned. When I'm not in the water, all the gearing seems to be working perfect. When I shift it into reverse (whether the cable is connected at the motor or not), the prop is locked in both directions. When it's in neutral it spins freely, and forwards it will spin in one direction (regardless of whether it's connected at the motor or not, or I put it in manually or use the controls). When you say FULL reverse position, do you essentially mean that I can't slide the little slider thing back any further on the little guide rod thing that it's on?

    Thanks for all the help guys. I didn't realize this was going to be an issue, but it is, and I would like to deal with it, as just about everything else on the boat is working perfectly.

    If anyone else has any other ideas, feel free to let me know.

    Thanks a bunch,

    Sam




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  15. #15
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
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    Default Re: No Reverse on 1970 Mercury 500 Thunderbolt - Help Please!

    Sounds like the LU is lined up okay. That slider has to go ALL the way back with the cable hooked up.

    Jeff

  16. #16

    Default Re: No Reverse on 1970 Mercury 500 Thunderbolt - Help Please!

    Hey guys, sorry for the delayed response. Hadn't had a great chance to do more adjusting on the engine but finally got around to it yesterday. So I adjusted the shift cable to make it so that when I put it into reverse it essentially pushes the littler slider shifter thing under the engine cover back as far as it will possibly go and it still won't engage into reverse in the water. Still shifts perfectly on muffs out of the water but something about the added load of being in the water just is not letting the engine engage into reverse. What would be the next step at this point? Could it be adjusted to far backwards? Would changing the throttle adjustment do anything? I've read a bit about worn clutch dogs and reverse gears, could it potentially be this? I don't have any experience with removing the lower unit or assessing damage to the dog or gears.. Any ideas or input would be greatly appreciated.

    Thanks again,

    Sam





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  17. #17

    Default Re: No Reverse on 1970 Mercury 500 Thunderbolt - Help Please!

    Hey Sam,

    My mercury is doing the same thing after I replaced the cables the shifting is all messed up and when it does shift it is bogging out when the throttle advances. I am suspecting there is something wrong with the way I put the controller back together...did you ever figure out what was wrong with your situation? Please let me know! I will save me alot of frustration and money most likely...

  18. #18
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    16,836

    Default Re: No Reverse on 1970 Mercury 500 Thunderbolt - Help Please!

    Bogging has nothing to do with shift cables.

    Add another 1/4 turn OUT (richer) on the idle mixture screws.

    Jeff

  19. #19
    Join Date
    May 2020
    Location
    Stokesdale NC
    Posts
    261

    Default Re: No Reverse on 1970 Mercury 500 Thunderbolt - Help Please!

    If the lower unit has been dropped the shift shaft could be one spline off. I had to put both the remote control shifter and the trans in reverse before reinstalling the lu to get mine right. Hopefully the shift shaft didn't get bent by engaging reverse with the engine not running.

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