Case tractor troubles

Well, Case backhoe troubles actually. I think it's a CK 74. Anyway,
here are the symptoms: The 1970s engine (gasoline) starts right up,
idles well, and runs OK when it's not too warm. After fifteen or
twenty minutes it starts running poorly. It misses badly. If I let it
die it is very hard to start until the engine has cooled some. What I
have done: replaced the plugs, rotor, cap, coil, and wires. At first I
thought it was the coil. I had another laying around so I swapped
coils. This seemed, at first, to solve the problem. When I replaced
the plugs the only brand available on the island that were the proper
type were Champion plugs. I have been told by several mechanics to
avoid Champion plugs. The old plugs were Champions and they looked
like they were burning correctly when I pulled them. Now maybe the
replacement coil I had kicking around is junk and I need to get
another one, brand new. The ignition system uses a ballast resistor
and the coil is just warm to the touch, not hot like it would be if
the coil was wired wrong and getting the full 12 volts all the time. I
checked that too. The ballast resistor is only bypassed when the
starter motor is energized. The engine is not getting so hot that it
boils over, in fact, sticking my finger in the radiator neck to feel
the coolant temp tells me that the engine really isn't running too
hot. Steam and bubbles don't come out of the open radiator neck when
the engine is running so I don't think I have a bad water pump that is
letting the engine cook while the coolant in the radiator stays only
warm. I do have to run the engine with a little choke for it to run
half way well. I have adjusted the carb, which is a very old design
similar if not exactly the same as the one on my '39 Ford 9N,
according to the directions for this type of carb. That seemed to help
some, but even if I adjust the carb so that it runs rich I still get
the missing problem after the engine has run for 15 or 20 minutes. I
am going to buy a carb rebuild kit but I don't expect it will fix the
problem. So, any ideas? I'm stumped and I know there several folks
here who know about old engines.
Thanks,
Eric
Reply to
etpm
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Have you checked the points to make sure they're gapped correctly. I had an issue years ago on my frogeye where it would misfire and stall when hot and I discounted the points as a problem because I had only changed them a few months earlier. Seems the points heal on that set wore more initially than any other set and the gap closed up. It started fine and ran well until hot then died, resetting the points gap to the correct setting cured the problem immediately and it didn't come back.
Reply to
David Billington
Greetings David, I have not checked the points again. That may indeed be the problem. Thanks for the suggestion. If your suggestion is the solution, and your going to be travelling to the Seattle area the first week of August, then you can come to my pig roast and play with the backhoe. Cheers, Eric
Reply to
etpm
Can you pull individual plug wires when it's running to see if it's only missing on a certain cylinder or two? (Carefully, Eric. It's quite shocking. ;)
One really common problem for an engine to run OK when cold and then crappy (or quit altogether) when hot is a plugged gas tank vent. Take the gas cap off when it starts running crappy. If it immediately runs better, that's your problem.
Since you've played with the manual choke, we can somewhat rule out the carb. AAMOF, that seems to somewhat confirm the plugged tank theory. Doublecheck all the rubber portions of the fuel lines so you can rule out air leaks, too.
Misadjusted points usually make it run crappy even when cold, but do a quick doublecheck that they're still set right. I've had new sets of points close up on me due to swarf on the end of the rubbing block. Man, that was a whole lifetime or two ago, I think. I don't miss carbs or point sets at all. Vive la EFI and ECMs!
Reply to
Larry Jaques
Nobody has mentioned the condenser yet either (capacitor) - quite common to fail hot. Check for a good hot blue spark when cranking hot. _ most likely you will have a sick yellow spark. As for the Champion plugs - as long as they are the right plug, you are OK. The Case engine came with Champions from the factory. You COULD put in AC plugs - but I would not use Bosch or "boutique" plugs in it.
Reply to
clare
I'm not a tractor guy... never worked on one. However, from the little I've see of them, they look to have gravity fuel systems... and I agree with Larry about checking the fuel cap vent. Someone could have even replaced the cap with a modern non vented one.
I've also seen an ignition capacitor or two that act up when warm.
(BTW, fuel tank vents are a required pre flight inspection item on most, if not all light aircraft.)
The fuel cap reminds me of a story... if I've told it here before, just stop me. :)
Worked a place in the 70's, and they hired a new guy who was a biker type wanna be. He looked all tough, stopped shaving, had the shiny oil soaked pants, boots, vest, and even had a chain on his wallet! But he didn't have a Harley yet... or even know how to ride.
Anyway he found a bike, and as he knew little if anything about them asked me to look at it with him. I knew little about bikes in particular, but agreed.
We get there... IIRC they said it was a 40 something Panhead. The thing had chrome everywhere, 19' forks, 5' sissy bar, suicide shift, multiple chrome skulls, long dangling leather tassels hanging from stupid high handle bars, and all the other intellectual accoutrements. A true beginners bike if there ever was!
Anyway the owner dude said he'd had it for ages, but hard as he tried, could never run more than 5 or 7 minutes. The first thing that popped in my mind was the vent. So in looking it over, I took the cap off, and sure enough, a long dead spider had it plugging.
They deal, they bicker, wannabe forks over cash... they do paperwork, and wannabe gets a quick riding lesson. I followed him home (scary to watch), and soon as we were out of ear shot (quite a ways actually), I flagged him down and cleaned out the vent with a twig. It never stalled again.
But sadly wannabe immediately had another issue... mainly he lacked the 275lb beer gut necessary to start the damed thing. But he worked hard acquired one in short order.
Guess you had to be there. :)
Erik
Reply to
Erik
Get some additive that is for Alcohol in gas. The Alcohol is hygroscopic and absorbs water like nothing else. The additives help attach to the water (that makes misses) and binds it to something that will burn.
The nasty is the water will corrode floats and carbs.
Cars that are made for Alcohol are different. They - the government - are forcing the Alcohol on us, depleting our national trust in corn when it could be made from sugar cane grass or many other non-eating crops.
Chainsaws and mowers of most kinds - old time equipment. All are being destroyed if you leave fuel in it for any length of time. Run them dry.
Martin
Reply to
Martin Eastburn
this sure sounds like condenser, it costs like $2 to replace.
or do it right, put in an electronic point upgrade. Genesee products. the machine will run like new.
Karl
Reply to
Karl Townsend
I've worked on lawn mowers, that failed when warm. That's one concern.
Another, oddlly enough, is motor oil gone bad. Many years ago, some engines didn't run on cheap oil. Change the oil, and use a good brand like Penzoil or Castrol. A couple vehicles ago, Castrol was the only brand that quieted the piston rod knock for more than a couple days. . Christopher A. Young Learn more about Jesus
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Check to make sure you have valve clearance when the engine is warm.
Reply to
Stormin Mormon
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With a solid valve train, when the poppet valve wears, it starts seating deeper and deeper up into the head...eventually, thermal growth of the pushrods causes there to be no valve lash whatsoever, result being a loss of compression at the affected cylinder(s) but only when the engine is fully warmed.
--continued running under this condition will rapidly cause both the valve and seat to burn.
Easy rudimentary check is warm it up then remove valve cover and make sure you can at least spin the pushrods by hand when the piston are at TDC of ignition stroke.
Reply to
PrecisionmachinisT
Thanks everyone who responded to my post. This weekend I will use the info to try to figure out the problem and will report back with any solutions. Thanks, Eric
Reply to
etpm
Oh, you betcha! That's a simple check, and you REALLY don't want that big Air Conditioner Fan on the front of an airplane to stop turning, the moment it stops everyone is sweating buckets.
Might be easier to retrofit a decent electric starter... Some of us are already far too close to 275 for comfort.
Reply to
Bruce L. Bergman (munged human readable)

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