35 hp, 1978, recent rebuild but won't start

sam03v

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May 10, 2006
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27
Hello,

The power head on this motor(model 35R78) was recently rebuilt and I can't get it to start. I've done the synch and link and everything I can do without the motor running . It has good spark and the fuel pump is working, there is fuel at the carb, compression is 120psi in both cylinders. I'm using a 25:1 mixture by the way(just for the break in period-if i ever get that far).

It seems to be flooding( the plugs are wet with fuel after attempting a start) and it also backfires after about 5 seconds of running the starter. Also, when I have the manual choke pulled and try to start the motor, the choke plate flutters(opens and closes) as the motor tries to start...thats not normal is it?

One other thing. I had old fuel(>1 year) in the tank which I replaced, I thought I was good to go, but the tank or line still had old fuel in it when I initially tried to start. The fuel looked like mud water(anyone ever see that before?). So I bought a new tank and line and flushed the whole system by removing the drain plug in the carb bowl, tilting the motor, and pumping the fuel bulb until the fuel draining out was "clean". I thought that would do it but nothing changed. I had also rebuilt the carb before trying to start the motor.

Anyone out there have an idea what might be going on with this thing?

thanks in advance,
Sam
 

JB

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45,907
Re: 35 hp, 1978, recent rebuild but won't start

The backfire suggests that either the plug wires are reversed or the flywheel key is sheared.

Fluttering of the choke plate suggests a broken or leaky reed valve.

Do the plug wires first. The rest may disappear.
 

sam03v

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Re: 35 hp, 1978, recent rebuild but won't start

I double checked the plug wires and they are correct. Mabye it is the woodruff key. A long time ago I tried to remove the key when I had the flywheel off, but couldn't. It looks like only a 1/16 of an inch of the flat side of the key is sticking out of the crank shaft, does this mean it had been sheared off? How much should stick out of the crank?

thanks,
 

Paul Moir

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Re: 35 hp, 1978, recent rebuild but won't start

You cannot tell unless you remove the flywheel or check the timing with a timing light.

Are you absolutely, 100% certain the plug wires are the right way round? If the ignition coils are separate, are the powerpack connections connected to the right coils?

Just to be clear, you rebuilt the carb after the bad fuel incident right?
 

sam03v

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Re: 35 hp, 1978, recent rebuild but won't start

You da man!

I took the flywheel off and the key had been completely sheared. The flywheel was about 180 degrees from where it should have been. Now i have a new problem, what remains of the key is stuck in the crank shaft. Do you have any tricks for removing it? I'm thinking dremel tool time, I tried using a scredriver, knife and chisel to no avail.

The fuel problem was after I rebuilt the carb, but the bad fuel was only in there for two days at the most. I'd bet 5 bucks it'll run once I get the flywheel positioned correctly.
 

fireman57

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Aug 24, 2004
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Re: 35 hp, 1978, recent rebuild but won't start

Whatever you do don't heat the shaft. You might try a very good pointy chisel to get in behind whatever is left of the key. Otherwise the dremel will work with a lot of patience.
 

clint

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157
35 hp, 1978, recent rebuild but won't start

I agree with the Lieutenant Commander do not use heat! I would try the dremel Idea with a tempered steel grinder wheel and a tempered steel punch. Once you get this back together, this engine will purrr! Good Luck!
Clint 8)
 

i386

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3,548
Re: 35 hp, 1978, recent rebuild but won't start

I've done the same on my old '72 Chrysler...

It shouldn't take more than a few LIGHT taps with a punch and hammer to get it out. It's a tight fit by design and shearing the key distorts the key some so the piece left in the keyway gets stuck.

I ran a piece of emory cloth around the top of the crankshaft to clean up the marks my flywheel made while rattling around with a loose nut and no key.

I know if I'd torqued it properly it wouldn't have left me stranded but I still keep a spare key on the boat now.

I think you'll have her running again in no time. Good luck.
 

sam03v

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Re: 35 hp, 1978, recent rebuild but won't start

I got the rest out using a punch and hammer, it wasn't that bad after all, the key way is in good shape too, so hopefully we'll be in business soon.

thanks!
 

Paul Moir

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Re: 35 hp, 1978, recent rebuild but won't start

Before you put it back together, you're going to have to repair the taper fit. Lightly grind out any burrs on the crankshaft taper, then lap the flywheel to the taper with a little lapping compound. Just go lightly until you've got a good contact patch - you do not want to be aggressive with this stuff. Then clean the taper and crankshaft perfectly. Don't let any of that stuff down into the seal area.

Torque the flywheel to spec and it won't break again.
 

Solittle

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Re: 35 hp, 1978, recent rebuild but won't start

Be prepared to go through the carbs again. If the mud water got in them crud may have gotten where crud ain't supposed to be. Years back I bought a boat and the gas in it looked like brown orange juice and smelled like turpentine.
 

sam03v

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Re: 35 hp, 1978, recent rebuild but won't start

Yeah, brown orange juice pretty much describes what I saw in my tank. \

Now I'm trying to find a woodruff key.. I assume its a standard item, but I ordered one from the dealer anyway.
Now I gotta find some lapping compound.
 

sam03v

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Re: 35 hp, 1978, recent rebuild but won't start

Hello again,

I got the key today. Is there any difference between valve lapping compound and valve grinding compound? Autozone has the latter....
 

Paul Moir

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Re: 35 hp, 1978, recent rebuild but won't start

No difference. It's just grease mixed with a fine grit.
 

iwombat

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Re: 35 hp, 1978, recent rebuild but won't start

Coat the bottom of the shaft with a thick line of grease before lapping. That'll stop the lapping compound from going anywhere you don't want it to. Wipe it all clean when you're done.
 

sam03v

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Re: 35 hp, 1978, recent rebuild but won't start

Well, that's done.

The flywheel key I got from the dealer was actually much smaller than the standard woodruff key I was considering.

That $3 tube of grinding compound will last a while considering I only used about an 1/8 teaspoon at most.

Torqueing the flywheel nut was fun. I couldn't find my shop manual(was under a tackle box) so I initially torqued to 90 ft/lbs.. then I found the manual and it said 100-105..>o.. so I found a better strap wrench and got the extra 15 ft/lbs. on it. I also put some blue loctite on the threads.

I'm guessing the key originally sheared because I didn't torque it down enought the first time(didn't use a torque wrench...BOOT to the head!)and i didn't do the lapping.

Anyway, tonight I'll see if she wants to run.

Cheers!
 

sam03v

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recent rebuild Idle/synch/link

recent rebuild Idle/synch/link

Got it running last night! The idle was missing a little though, I didn't want to run it to long on the ear mufffs so I didn't mess with it too much-maybe still bad gas? Three questions left ....

Question1: should I be able to shut the motor off just by rotating the throttle(its a tiller model) all the way clockwise or is it normal to use the kill switch each time? I haven't actually used a tiller outboard since I was 13 years old so I don't remember.

2:The manual I have is a little vague when it comes to the linkage adjustments so i'm not sure i'm doing it right. Specifically I'm not clear on this statement - "when in forward gear the throttle rod should be touching its stop". I can't find any diagrams showing the throttle rod stop, and I'm not sure which rod they are talking about. If anyone has suggestions I'd appreciate them

3: I've got water coming out the pee hole, it is slightly warm but the crankcase seems to be much hotter, I dribbled water on it and it doesn't steam, but it is very hot to the touch. Is this normal? Also water comes out almost as soon as the engine starts. I thought with the thermostat it would take a few secs/minutes before water would come out the pee hole. Am i wrong?

Thanks for all the help! 8)
 

fireman57

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Aug 24, 2004
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3,811
Re: 35 hp, 1978, recent rebuild but won't start

1. No, you have to use the kill switch otherwise each time you throttled all the way down it would die.

2. Don't know.

3. You should be able to hold your finger(s) on the flat spot of the head for a good five count with cussing. If you can't then you have a blockage in the water jackets somewhere. Sounds like your impeller is working. Check for junk behind the tstat and flush the powerhead with a garden hose.
 

sam03v

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May 10, 2006
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water pump and flushing device/ear muffs

water pump and flushing device/ear muffs

I took the ear muffs off and put a plastic can under the motor, filled the can with water and then started the engine. This time no water came out the indicator hole. So I took the thermostat out, didn't see any blockage, left the t-stat out, and started the motor...still no water out the hole. Shut off motor right away.

Apparently something is wrong with the water pump and I'm guessing when I had the ear muffs on, the water pressure from the garden hose was forcing water thru the system and a weak water pump helped it along? Does this sound reasonable? At any rate, i'm taking the lower unit off ...again ..to see what's happening. Its a new pump assembly so i don't get it.

I've come full circle with this motor. Got it for free cause the previous owner thought it was dead, but he really only burned up the water pump. For kicks I rebuilt the power head and now I'm back to water pump problems!
 

Paul Moir

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Re: water pump and flushing device/ear muffs

Re: water pump and flushing device/ear muffs

The water pump was submerged was it?

What did you do precisely when you serviced the water pump? Has it got a plastic housing and was it replaced?
 
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