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pump issues and carbie choke 35 hp chrysler

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  • pump issues and carbie choke 35 hp chrysler

    gday, new to this site but its so helpful i had to sign up!
    have aquired a 35hp chrysler mid seventies, model #357H8M, got her running ok however 2 small issues if anyone can help..

    1) am in the process of cleaning out the carb and notice that the choke flap seems to be broken or placed incorrectly.
    it is split into 2 flaps, the upper one is loose and sits back and does its own thing. and the other half is stuck closed, im used to motorcycle engines where there is a single circular plate that closes and opens the same way as the throttle. im assuming theres meant to be 2 halves however do chryslers leave the bottom half permanently closed? any ideas or even on how to get the pin out without breaking it?

    2) i have taken the lower unit apart and checked the impellor and housing everything is in pretty good knick however when i run it in the garbage bin it will spit out a fair bit of water in neutral, but as soon as i put it into gear it doesnt seem to pump any water. is that odd or what. i notice that there is another exhaust port at the bottom near the prop under water level, could most of the water be exiting here or should i still be getting plenty through the top exahust.. any ideas would be greatly appreciated!!
    cheers

    ps at the top of the gear selector under the powerhead there is a little button that gets pressed down when in neutral.. anything to do with it?

  • #2
    Re: pump issues and carbie choke 35 hp chrysler

    Click image for larger version

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ID:	6985925OK! First, both halves of the choke plate should move, therefore the shaft is stuck in the carb body and needs to be free. Be careful when trying this as the shaft is split and brass, thus very easy to break. The pin inside the carb need not be removed. There should be a screw on the side holding the shaft in, and, of course, two screws holding the bottom plate into the shaft.
    The top half of the choke butterfly should be spring loaded with a "soft" spring around the shaft and centered between the two halves. When the choke is closed, if there is too much vacuum, the top plate will thus open a bit against the spring. It should NOT remain open at all times but with the choke closed, you should be able to push it back with gentle finger pressure.

    Be careful to note the orientation of the two plates and the spring to save youself some time when reassembling them.

    The rear hole is not an exhaust exit per-se. It is an idle relief . When the engine is sitting low in the water, like when the boat is at rest, this releives back pressure and improves the idle. It also keeps the engine from stalling due to too much backpressure against the exhaust ports. Thus, water and some exhaust will exit this hole at all times. However, the bulk of the exhaust will always exit through the exhaust snout. Look closely at the attached photo and you will see a steram of water exiting the idle relief at speed.

    If your engine has the water intake above and behind the prop, there should be a bent plate with a bunch of holes above the prop and on the back of the exhaust snout. This allows the prop wash to enter the holes and supply the pump. If this plate is missing, negative pressure behind the prop when in gear will starve the pump for water, yet when in neutral, it will get plenty, so check that.

    If I understand you correctly, the white button that is depressed in neutral is an interlock that prevents engaging the starter motor while in gear. It is in a brown switch with two yellow wires, one on each end.

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    • #3
      Re: pump issues and carbie choke 35 hp chrysler

      Here is a parts list for your engine and it is a 1978 model:

      http://www.crowleymarine.com/mercury-outboard/1757.cfm

      Gerry

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      • #4
        Re: pump issues and carbie choke 35 hp chrysler

        I d/n see the attachments indicated. Here is a carb that I feel is as my 1970 35 HP Chrysler's or close. Also attached also is a pic of my neutral switch and cooling water discharging. The dept of the leg in the barrel of water will affect my out-put flow or not flow period. I have many other pics if others related to my motor will help. Good Luck! jow
        Attached Files

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        • #5
          Re: pump issues and carbie choke 35 hp chrysler

          wickware;

          On the link I gave you, you click on Carburetor and this is what appears:

          http://www.crowleymarine.com/mercury...ts/1757_80.cfm

          This is for a 357H8M which you stated your model is and this comes up as a 1978:

          357H8M 35 1978

          http://www.iboats.com/basics/chrysler.html

          Gerry

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          • #6
            Re: pump issues and carbie choke 35 hp chrysler

            Thanks carholme! I need to save these 2 links. jow

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            • #7
              Re: pump issues and carbie choke 35 hp chrysler

              cheers! you blokes are tops very much appreciated, photos and links were very helpful, i fixed the carbie up no worries now that i understand the proper function of the flaps, someone had a pretty poor go at putting it back together at some stage..

              as for the water issue there is a water inlet above and behind the prop on the leg (which i blasted with an air hose through the pump housing when i had it apart) but the metal plate directly above the prop behind the muffler snout doesnt seem to be an inlet, it is a solid flat plate and cant take any water is this correct? i tried to take it off but one of the screws is stuck in there pretty good, i took a photo of this but when i go to upload it to there it wants a url location...

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              • #8
                Re: pump issues and carbie choke 35 hp chrysler

                Click image for larger version

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                ahh thats it there^ you can see the inlet and the plate im talkin about behind the snout

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                • #9
                  Re: pump issues and carbie choke 35 hp chrysler

                  does anyone know where exactly where the top of the water line is under the powerhead so i can give it a blast of air and make sure its not clogged?
                  am i best changing the entire impellor and water pump housing? i dont really think either of these would fix it as it pumps water fine in neutral but open to suggestion...

                  Comment


                  • #10
                    Re: pump issues and carbie choke 35 hp chrysler

                    The plate you are referring to in post #8 looks like the anode, seen here as item # 40 and your water line is item # 7:

                    http://www.crowleymarine.com/mercury...s/1757_150.cfm

                    As far as blowing air through anything, the easiest thing for you to do is drop the LU again and ensure the water tube is clear and you will see where it connects to the powerhead. Also at this time check the O ring and washer.

                    If you are sure that the impeller is pumping correctly and the head does not feel dangerously hot with your hand, when operating in the bucket, have you tried it in open water yet to determine if the cooling system is working?

                    Are you operating in salt?

                    Gerry

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                    • #11
                      Re: pump issues and carbie choke 35 hp chrysler

                      Tips:

                      1. Have you checked your over-heating sensor to see if it is ready to sound an alarm when it reaches over-heating temps? In my case the sensor is to the left of the bottom spark plug with an orange wire attached. The sensor acts as a ground to sound my horn if it gets too hot with the switch on. I test my system by grounding the orange wire with my switch on to see if the horn sounds.

                      2. Add A Tell Tale System! This might let you see a better flow and easier seen on the side vs back while operating.

                      3. A bad or weak impeller could reduce your flow at higher RPM. A diagram in a Clymer Manual shows impellers bend at higher RPM but with a good impeller I still notice good or better flow. The pump works as a displacement type at low RPM and centrifugal at high Rpm.

                      4. Last! A good question was asked in a post. Have you tried the motor in a full body of water vs a barrel? jow
                      Attached Files

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                      • #12
                        Re: pump issues and carbie choke 35 hp chrysler

                        i cant find the overheating sensor or alarm, the orange wire is in the harness but the rest may have been removed at some stage, im assuming the sensor would be some kind of screw near the pistons..

                        in you picture where youve installed the tell tale is that a hex bolt that seems to run down the centre of the head? have you simply taklen that out and run a hose line?

                        it is a sound theory on the impellor however if i rev it up in neutral it seems to still pump water at high RPM it just seems to be as soon as i put the resistance of the gear it stops..

                        in regards to barrel vs open water what is the difference? is it a mater of the water circulating differently around the intake? ive put everything back together so hopefully i can take it out on the lake tomorrow and test this theory so hopefully it will pump fine once on the water... however it will eventually be run in sydney harbour so yes salt. will that make a difference again?

                        Comment


                        • #13
                          Re: pump issues and carbie choke 35 hp chrysler

                          Taco;

                          Be careful about revving too high when testing in the barrel as you don't have the prop loaded. Best to get it on the water for a test at higher rpms.

                          The reason I ask about salt is that you could still have blockage issues in the water cooling passageways in the powerhead and dependant on your water test, you may want to consider having a look at this anyway.

                          The warning system, telltale etc., can be taken care of once you find the reults of your water test.

                          Gerry

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                          • #14
                            Attached Files

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                            • #15
                              Sign up today
                              Re: pump issues and carbie choke 35 hp chrysler

                              thanks for ther input very appreciated, put it all back on to take out on the lake but ran into a bit of trouble with the controls had to wire up a new ignition barrel and now trying to get a hold of gear shaft coupling and pin barrel for selector plate as one is buggered and missing. runnign it in the barrel i think ive noticed some water pumping in gear so eager to get it on the water to see what happens, however i wish i put a new impellor in when i had it apart to be safe cos it was particularly difficult to get the shaft back in i had to take the whole upper leg off. wil keep you guys posted once again thansk for all the info very helpful

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