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Old 10-31-2011, 10:58 PM   post #1 of 51
flash5153
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Default Hard starting 20hp briggs

Its a twin,,no OHV. 461707

When I got it ,,it would not roll over. The guy told me it started hard. But like I said,,,when I got it , the starter would not turn the engine over.

I had a used starter on the shelf,, that I knew nothing about it,,other than was on a engine for parts.(I never put juice to it). But I put it on the 20 hp

And it will start ,,but rolls hard still. Although it starts every time,,I want to fix it.

Can the valves be adjusted on this engine?? Or do you think I (still) have a weak starter??

I have other (good)briggs starters on GT's,,but it is a pain to change to this 20hp. Starter has to be taken apart and a bracket put on the top of it for mounting.Although allot of work,,this might be the best move for me at this point.

What do you think???
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Old 10-31-2011, 11:12 PM   post #2 of 51
RED-85-Z51
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Default Re: Hard starting 20hp briggs

Common thing on these engines to buildup a ton of carbon on the pistons and heads. You can try to seafoam them, or pull the heads and scrape it off...the carbon actually bumps the compression up and can make for difficult starting.

Ive seen these come in knocking from the carbon on the head hitting the piston at top dead center, on both cylinders...not smoking, not using oil, running excellently.
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Old 10-31-2011, 11:28 PM   post #3 of 51
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Default Re: Hard starting 20hp briggs

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Originally Posted by RED-85-Z51 View Post
Common thing on these engines to buildup a ton of carbon on the pistons and heads. You can try to seafoam them, or pull the heads and scrape it off...the carbon actually bumps the compression up and can make for difficult starting.

Ive seen these come in knocking from the carbon on the head hitting the piston at top dead center, on both cylinders...not smoking, not using oil, running excellently.
What are my chances of doing this without new head gaskets?? I guess I could try ,,and if the gaskets don't look good/reusable,,,,just go and get new.
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Old 10-31-2011, 11:34 PM   post #4 of 51
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Default Re: Hard starting 20hp briggs

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What are my chances of doing this without new head gaskets?? I guess I could try ,,and if the gaskets don't look good/reusable,,,,just go and get new.
Ive never had to replace one.

I loosen all the bolts like a turn..then smack the head from the side with a mallet, then pull the head bolts and remove the head, usually the gasket is stuck to one side or the other, with only a few small spots of rip....
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Old 11-01-2011, 12:40 AM   post #5 of 51
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Default Re: Hard starting 20hp briggs

just take it slow I have taken heads off many a number of these motors and never had to replace them(I say that now and it will happen) just have a knife or something to separate the gasket from the head or the block which ever will come off first and the easiest.
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Old 11-03-2011, 02:19 AM   post #6 of 51
flash5153
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Default Re: Hard starting 20hp briggs

I cleaned the heads,,,was pretty bad. I had no problem with gaskets,,they come off clean.

It did help,,but didn't solve the problem. Still starts slow. Some times will turn over just perfect. Others,,,,,,,,,,,,,, not so good,,,but always starts.
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Old 11-03-2011, 03:16 AM   post #7 of 51
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Default Re: Hard starting 20hp briggs

Well, now that thats out of the way, clean your battery to frame ground point, and check your hot wire from the battery to the solenoid, and from the solenoid to the starter for damage.

One way I check for resistance in the field is to pull the plug wires off, crank the engine for 10 seconds...then start at the battert and feel all the wires to their termination points for hot spots. a Hot spot indicates increased resistance, which is basically bleeding off amperage.

If the battery terminals, ground, wires, solenoid, etc arent hot after say 20 seconds of cranking (10s 1 minute cool down, then 10s more) then go to the starter...is IT hot at the hot wire, or is the case hot, lower cap hot?

These starters and wiring systems were just adequate to crank over these twins new...any loss of efficiency can make problems.

Also a dragging PTO belt can make problems too.
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Old 11-03-2011, 08:34 AM   post #8 of 51
Walt 2002
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Default Re: Hard starting 20hp briggs

"Can the valves be adjusted on this engine?"

Of course the valves can be adjusted but not easily. The valves on these engines very seldom need adjusting and then usually after someone has "done a valve job" and flubbed it. Unlike OHV engines, there is little wear in valve train and then what there is makes the compression release system used become more efficient, not less as in OHV engines.

IF you have reason to think it may have had a valve job, it is entirely possible whoever did it left too much clearance as many people still go by the old myth that it is better to leave more "just to be sure".

IF you would like a Service Manual for the engine, contact me at address below, put in proper format and remind me what you want.

And I always use new gaskets. Even though the gasket surface may appear good, the gasket has been compressed, is no longer pliable.

Walt Conner
wconner5 at frontier dot com

Last edited by Walt 2002; 11-03-2011 at 08:39 AM.
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Old 11-03-2011, 10:04 PM   post #9 of 51
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Default Re: Hard starting 20hp briggs

Quote:
Originally Posted by RED-85-Z51 View Post
Well, now that thats out of the way, clean your battery to frame ground point, and check your hot wire from the battery to the solenoid, and from the solenoid to the starter for damage.

One way I check for resistance in the field is to pull the plug wires off, crank the engine for 10 seconds...then start at the battert and feel all the wires to their termination points for hot spots. a Hot spot indicates increased resistance, which is basically bleeding off amperage.

If the battery terminals, ground, wires, solenoid, etc arent hot after say 20 seconds of cranking (10s 1 minute cool down, then 10s more) then go to the starter...is IT hot at the hot wire, or is the case hot, lower cap hot?

These starters and wiring systems were just adequate to crank over these twins new...any loss of efficiency can make problems.




Also a dragging PTO belt can make problems too.

I had a little time to look at this tonight. Just starting it,,rolls very slow at first,,then will take off. Just doing this ,,the neg cable is getting hot. I removed battery,,and cleaned the connections,,to battery and to frame under battery. Didn't help!!
The cable looks good. It has a small wire going from the connection at frame ,,to 25 amp fuse,,then to solenoid.
Positive cable is not getting hot at all.

No belts are moving with brake applied,,so can eliminate that,,,I think?? Not sure if there could still be some resistance..

Do you think this short negative cable is the problem?? Or could it be something more??
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Old 11-03-2011, 10:06 PM   post #10 of 51
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Default Re: Hard starting 20hp briggs

Quote:
Originally Posted by Walt 2002 View Post
"Can the valves be adjusted on this engine?"

Of course the valves can be adjusted but not easily. The valves on these engines very seldom need adjusting and then usually after someone has "done a valve job" and flubbed it. Unlike OHV engines, there is little wear in valve train and then what there is makes the compression release system used become more efficient, not less as in OHV engines.

IF you have reason to think it may have had a valve job, it is entirely possible whoever did it left too much clearance as many people still go by the old myth that it is better to leave more "just to be sure".

IF you would like a Service Manual for the engine, contact me at address below, put in proper format and remind me what you want.

And I always use new gaskets. Even though the gasket surface may appear good, the gasket has been compressed, is no longer pliable.

Walt Conner
wconner5 at frontier dot com
I'm really hoping I do not need to get into this engine.lol

I also do not believe anyone has had it apart through the discussion with previous owner.
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Old 11-03-2011, 10:27 PM   post #11 of 51
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Default Re: Hard starting 20hp briggs

I have both versions Horz and Vert 18hp briggs. All fully rebuilt, Valve adjustment usually takes replaceing the valves and grinding the stems.

1. I experiance the "hit the key" and the starter enguages but the eng dosn;t start to spin right away.... then it will turn slowly, then fire. Mainly when Cold Cold, or after a stall when hot. Other times it will spin fine. (Both engines do this).

2. I would supect the neg cable may be the issue if getting hot.... Or the starter needs a clean and lube as it may be drawing too many amps.

3. I always try the cheeper fixes before tearing into the engine.
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Old 11-03-2011, 10:34 PM   post #12 of 51
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Default Re: Hard starting 20hp briggs

I take it that this is an opposing twin? If so, leave the choke off before you start cranking. Once the engine made one full turn, pull the choke while you're still cranking the engine. I have an 18 hp this way. I can have jumper cables hooked up and it doesn't help. But if I start cranking and then pull the choke it will keep spinning to start. Good luck in your venture.
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Old 11-03-2011, 10:41 PM   post #13 of 51
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Default Re: Hard starting 20hp briggs

Took a quick video, this mower hasn't been started in 2 weeks, Second try is a classis example when the engine stops dead like the battery is low then takes off.
http://www.youtube.com/watch?v=mu7dqqIYTkI
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Old 11-03-2011, 10:58 PM   post #14 of 51
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Default Re: Hard starting 20hp briggs

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Originally Posted by monteman_73 View Post
I take it that this is an opposing twin? If so, leave the choke off before you start cranking. Once the engine made one full turn, pull the choke while you're still cranking the engine. I have an 18 hp this way. I can have jumper cables hooked up and it doesn't help. But if I start cranking and then pull the choke it will keep spinning to start. Good luck in your venture.
I will give it a try ,,,why not huh??
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Old 11-03-2011, 11:03 PM   post #15 of 51
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Default Re: Hard starting 20hp briggs

Quote:
Originally Posted by larrybl View Post
I have both versions Horz and Vert 18hp briggs. All fully rebuilt, Valve adjustment usually takes replaceing the valves and grinding the stems.

1. I experiance the "hit the key" and the starter enguages but the eng dosn;t start to spin right away.... then it will turn slowly, then fire. Mainly when Cold Cold, or after a stall when hot. Other times it will spin fine. (Both engines do this).

2. I would supect the neg cable may be the issue if getting hot.... Or the starter needs a clean and lube as it may be drawing too many amps.

3. I always try the cheeper fixes before tearing into the engine.

Of course,,cheaper fixes are always better. lol

But if a have to I will do valves. Although I have never done it. First I will change cable,,,if no help I will change starter,,,then onto valves if needed.

I don't mind ,,usually a small hesitation in starting,,but this pretty bad and not acceptable.
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