My Tractor Forum banner

1 - 20 of 31 Posts

·
Registered
Joined
·
26 Posts
Discussion Starter · #1 ·
Hello Gravely L Fans,

This unit is pretty original, except for the disposable oil filter system.

The past several years the machine just doesn't start once warm. The first start of the day is fine: I pull the choke out, move the crank/pulley to the start of compression, wrap the strap, pull and it generally starts on the first pull. I quickly shut down the choke (push it in) and do my work...until for whatever the reason the engine is shut down - including me shutting it down by shorting the magneto with the push-metal thingie. Then I simply cannot restart; I've got to wait for it to cool down at least several hours or the next day. Then it starts fine...

All the troubleshooting I've done turns up cold-starting techniques and tips for the L; nothing about hot-starting problems - can anyone help? I'm sure the problem is either ignition or gas or both, but why? if the unit cold-starts just fine?

Thanks in advance! Also, anyone know what year this was mf'd?
 

·
Premium Member
Joined
·
5,143 Posts
I'm sure the problem is either ignition or gas or both, but why? if the unit cold-starts just fine?
Could be a variety of things.

Is your mixture too rich? That would help with cold starts, but might cause flooding when hot.

Is the spark plug ok? I've seen some which are marginal, work ok when cold but get weak when hot.

For starters, I'd check the mag, timing and points. Also set the mixture according to the manual.

You could also check the impulse coupling; do you hear the impulse snapping at TDC?

What's the symptom when hot? Just cranking and no spitting or attempting to catch? Any puffs of black smoke?

Thanks in advance! Also, anyone know what year this was mf'd?
What's the exact serial number? You can look it up in the sticky topic at the top of this page. 2300B doesn't make sense, but if it's 23008, that would be 1947.

Where in mass are you?
 

·
Registered
Joined
·
26 Posts
Discussion Starter · #3 ·
OK I gotta admit one thing: the old-timer I bought this from back in 1976 told me to never never mess with the carb - and I haven't! Nor have I touched the magneto or points. Only oil and filter changes, and clean the air filter system and breather cap. Oh yes, I have occasionally adjusted the valves...

I have changed the plug and ignition wire more than once.

When hot, the engine just cranks no spitting or firing. No puffs or black smoke...

I'm not sure what the impulse coupling actually is and would not know if it is snapping at TDC.

I guess you're suggesting a tune-up, which after 30 some odd years I guess is necessary!

I just checked you're absolutely right about the serial # it's 26008

The machine only gets used around this time of year to do some light brush cutting with the 30" mower. Some years the rotary plow gets used but not very much, in the spring...
 

·
Premium Member
Joined
·
5,143 Posts
Dunno why to be scared of the carb, it's a way simple unit. As long as it's fairly clean, set it the way the manual suggests, and you're close enough that a little tuning will get you there.

If the mag hasn't been touched in eons, same thing applies, it's not that complex; check the manual and adjust accordingly.

BTW if you don't have the manuals, see http://www.oldgravelys.net There's every manual you could want in pdf form there.

The impulse coupling is part of the mag. When turning slow (like starting) it delays the spark a bit, and accelerates the rotor, to give a hotter spark. If you turn it over by hand, you'll hear a clank or snapping sound at TDC. That's the impulse. If you don't hear/feel that, odds are the impulse coupling is rusted or stuck. That'll make starting harder.
 

·
Registered
Joined
·
62 Posts
Thanks jrd, I'll take your advice and I'll post back here after i've done what you suggest.
One things for sure! They guys around here KNOW their gravelys!!!!!! They'll have you running like a champ in no time........ That is if you have the time to spare to tinker. Not that they require alot of time, I just don't have a u spare tight now :(
 

·
Collector of many tractors
Joined
·
15,274 Posts
Take a before and after compression test... The heat from the engine might be keeping the valves open...
 

·
Premium Member
Joined
·
2,732 Posts
I would suggest removing that spark plug and taking a look at it. Ideally, the tip should be a gray color. If it's black/sooty, you're running the tractor rich - which could account for some carb flooding and difficulty when starting warm. And make sure to ground that mag wire when checking the timing and spark quality - you don't want to damage any internal mag components, nor do you want to receive an eye-opening shock from that magneto!
 

·
Registered
Joined
·
1,711 Posts
Some people have suggested that when an engine gets worn like that, basically being on its last little bit of cylinder meat, the timing can change as the engine heats up, making restarting next to impossible once the machine is warmed up. The '37 that I sold to Peter (shoman666) is like that. If it runs for any period of time, it will not restart until cool. I had another L that did the same thing and when I had it bored .010 over and got a new piston, did a valve job, no more issues like that.
 

·
Premium Member
Joined
·
5,143 Posts
kbeitz, bluegoose, gm1276, +1; all worthwhile things to consider.

A related possibility is that the rings, particularly compression, may be marginal. I once had a car with rings that were just about gone, I could get it to start and run, but it was weak, and would get weaker with heat. I think the oil was the only thing keeping a seal there, and as it got hot, it stopped doing so well.
 

·
Registered
Joined
·
1,711 Posts
It can get pretty complicated. I forgot to mention in my example, but boring and a valve job could have alleviated a lot of problems that caused the no-restarting condition. In other words, it could have been anything. But after playing with that L, trying to figure out the problem, I'm convinced it was a timing issue. I basically performed every test possible and could not even get a pop using starting fluid in the spark plug hole.
 

·
Registered
Joined
·
26 Posts
Discussion Starter · #12 ·
Hmmm this gets more interesting - I went back to my L this morning (i had left it out overnight because I couldn't get it restarted) - pulled the plug before starting. Now it's coming back to me - this is an Autolite TT-10 - is that the letter "O" or a zero?

I'm not sure I ever replaced this plug, only cleaned it and regapped it. I had trouble obtaining it - so can someone help me with a modern-day equivalent plug to put in this unit? For what it's worth, the plug mounts at an angle in the head; i've read this means a 6.6 hp engine. All I know is the seller at the time told me it had been rebored several times. Also I'm struggling with just a plain ol wrench to remove and tighten the plug, is there really a spark plug socket that will fit this large plug and also clear a very close by cooling fin?

Not knowing what to replace it with and it's Sunday around here and town is a bit of a drive, I did what i'd been doing in the past - clean and re-gap. Plug wasn't fouled and the tip was definitely fairly grey in color - so I don't think it's running rich. Tractor started right up, I did my work, brought it into the garage, shut it down via the magneto shorter. Tried to start it back up, I got one cough, and that's it. Cannot start. Pulled the plug connected the ignition wire laid it on the head and manually cranked - spark was definitely observerd - I do want to mention this tractor runs very well, tons of power, and is very tight when manually rotating the pulley to prepare the start strap. I don't think compression is an issue unless something happens as the tractor heats up - but then why does it run so well?

So first, can someone tell me what plug to put in here? One manual I read says Autolite-1S or Autolite-15? Are these available or is there a modern equivalent? What's the correct gap? And also, what type of socket (as I mentioned previously).

I'm going to explore the timing and also carb but I first want to get a new plug in this machine. Off-topic, I think someone should write an American History curriculum around the Gravely Tractor and Company - would be great for High Schoolers.

Thanks everybody for your help! It's all good and appreciated...
 

·
Premium Member
Joined
·
5,143 Posts
The autolite plugs are still available. You can get them from Richard (www.gravelyparts.net) or on ebay, or other sources.

You want a 15/16 socket to get them in and out. Any decent tools outlet will have that.

It's not all black, so you're not running rich. And you said it has a nice spark when you crank it over, even when hot. How's the compression? You should feel a very definite compression stroke, enough so that it's hard to pull past it without backing up and getting some momentum going.

Timing: There are marks on the mag, one on the input drive and one on the case. They should line up when the piston is 3/8" BTDC on the compression stroke. If they don't, loosen the bolt on the shaft that comes out of the engine and engages the fiber coupler to the mag. Rotate the works by hand until you're at 3/8 BTDC with the marks aligned, then retighten, and you should be good to go.

Fuel problem? Hard to see how, if it's running strong until you shut down. Couldn't hurt to open the carb, clean, fresh gaskets anyhow, but that doesn't really sound like the problem.

These engines are basic; compression, spark, mixture, and they'll run.
 

·
Registered
Joined
·
1,711 Posts
For the record, if the timing is altered once the tractor is heated up, I don't really think there's a fix for that other than a fresh bore and a new piston and rings. Just seems to be the nature of the problem. I'd try all the other possibilities first and then worst case scenario, you've got a pretty well re-conditioned Model L to use for another 50 years!
 

·
Registered
Joined
·
1,711 Posts
Maybe I didn't explain myself 100%. The idea is not that the mag is going out of time, but rather the timing at which the engine will start actually changes as the engine heats up. This could be due to lost compression from wearing rings, or heated up oil, etc. etc. It's really a wear issue if this is happening.
 

·
I Love All Color Tractors
Joined
·
22,321 Posts

·
Registered
Joined
·
1,374 Posts
Check the intake manifold and gasket area. I had a similar, not exact, problem with my 48 L. I chased it down to that area. My guess was that something was warping due to heat. I double gasketed the manifold and the problem has sense disappeared.
 

·
Registered
Joined
·
26 Posts
Discussion Starter · #19 ·
coldone: sounds like you're onto something I will have to give the double gasket trick a try after replacing the plug - now the intake manifold is where exactly? It's gotta be after the carb but please point it out to me.

I started dealing with the timing. I've got an Edison-Splitdorf magneto which isn't mentioned in the Condensed Service Manual I pulled off oldgravelys.net but I did see three markings (lines) on the magneto housing and one line on the collar on the shaft. I would assume the middle line represents top dead center and the lines on either side either advance or retard the firing. So my assumption is that the first line is what I'm after but I'm unclear how to set it - do I pull the plug and measure from the cylinder top to the bottom of the head? And what should it measure? Any help here would be appreciated as I've never done this before on my L.
 
1 - 20 of 31 Posts
Top