Fred K-OR
Well-known member
These ideas sound good to me also. They should find the problem. If you have a hot coil, you may have a short somewhere.
Mystery problem-won't re start when hot
- Thread starter WrenGB
- Start date
These ideas sound good to me also. They should find the problem. If you have a hot coil, you may have a short somewhere.
steve s
Well-known member
Good idea.
Try a tank of good gas instead of the ethanol laced crap gas, and also add 4 ounces of MMO per 10 gallons of gas.
That's what worked for me.
I agree that it sounds like a heat soak problem. During the first several minutes after shut down, heat from the engine's innards will move out and warm the peripherals in the engine compartment, like the carb, fuel line, and sediment bowl, and condenser, distributor, and various other nearby electrical contacts including firewall junction box mounting bolts (since they run hot, I'm not sure which way net heat flow at coil is during this period).
I'm betting the problem is vapor lock, but since weak electrical contacts can sometimes be temperature sensitive, and it's easy, it makes sense to first check for spark, as others have suggested. If spark is good, then you're into a whole world of vapor lock lore and controversy, ranging from total denial to clothes pins to Marvel Mystery Oil, diesel fuel, heat shields and insulation, and--ideally, as Tom suggests--avoiding ethanol containing fuel. See the archives.
A few straws to grasp at:
A short term quicky fix might be to leave the hood open after engine shutdown.
If the troublesome vapor bubble is forming in the carb fuel inlet, maybe adjusting the depth to which the fuel line is inserted will help. You don't want it jammed right against the filter thingy (Zenith carb). Similarly up at the sed bowl.
In any event, your problem may subside a bit as your gas station switches over to summer blend fuel, which is less volatile.
good luck!
Steve
Patrick L.
Well-known member
A couple things.
If the air temp is warm and you think its a heat soak issue, make sure the fuel line from firewall to carburetor is pitched correctly downhill with no portion of it pitching up at all.
As far as the coils are concerned, don't use an oil coil. They hate being mounted upside down and will let you know that in short order by leaking and then not working. Use an epoxy coil, there is nothing to fall out of them so they'll keep on working.
If the air temp is warm and you think its a heat soak issue, make sure the fuel line from firewall to carburetor is pitched correctly downhill with no portion of it pitching up at all.
As far as the coils are concerned, don't use an oil coil. They hate being mounted upside down and will let you know that in short order by leaking and then not working. Use an epoxy coil, there is nothing to fall out of them so they'll keep on working.
One step at a time - good advice! Will try your suggestions tomorrow. Many thanks for reply.
Kaptain Karl
Member
Happened to me with my AA in the inspection station. How embarrassing. Waited 40 min and it started fine. Left it running and completed the inspection and passed
Barry B./ Ma.
Well-known member
Check the polarity at the distributor center coil wire I had a problem like that and the coil polarity was wrong. The vendors sell a gadget with LEDs to check the polarity.
Marshall V. Daut
Well-known member
Well, from my "Why does everything happen to me" personal history files, I'll give you a weird possible cause for the no-start scenario when the engine is warm, i.e., after the Model A has been driven. But do check out all the other good suggestions posted so far first! The following is to be considered only as a last resort possibility - but it DID happen to me in 1974 in Germany. I wrote about this incident in my "Model A Trader" magazine column in the early 1990's, so stop me if you've already heard this
one.
I won't go into the whole story as it appeared in that magazine, but I will tell you what the problem turned out to be after exhausting all the usual tests. I took my 1928 Roadster to Germany with me to tour the country while I lived there for a year. Before leaving Arizona and driving the car to New York City (and personally loading into the cargo ship!), I changed everything that I thought might fail or that looked a little suspect. The original terminal box looked kinda crusty, so I installed a brand-new, shiny terminal box ordered from Rick's Antique Auto. THAT alone should have been a red flag. This was before the Model A community discovered what lousy junk parts were being sold by the now-defunct parts house.
Anyway, the car ran fine across country to New York and for some of the driving from
Hamburg down to Munich in Germany, although I was deluged for three days straight by liquid European sunshine, to be read: "RAIN!!!". The engine ran well each morning, but after a while, it misfired and wouldn't start when I coasted to a stop along the Autobahn, mostly making it to rest areas for repairs. The danged thing would not start for about 20 minutes, no matter what parts I swapped around. And then almost like clockwork, the car would start and be fine for another few miles before it began to miss. Cutting to the chase here, I removed my brand-new shiny Rick's terminal box from the firewall and found the problem. There, beneath one of the two long round-head bolts were signs of electrical arcing. The slotted roundhead bolt installed in that Taiwanese terminal box was way too big to fit down inside the hole in the terminal box for it. It's head was sticking out just enough to allow arcing when the firewall got hot after driving for a while. While the car sat and wouldn't start, the firewall had cooled and contracted, creating enough of a gap between it and the round head of the terminal box bolt to allow the car to start and run well until the firewall got hot again after a while driving, and expanded to cause the arcing again. While the engine was running, it misfired. When I shut the engine off, it wouldn't start for 20 minutes. Apparently while the engine was running, the ignition system still functioned, although with a miss. By shutting off the engine, it wouldn't start. It was undoubtedly shorting out.
To fix the problem, I don't recall whether I filed the head smaller or put rubber
between the bolt head and the firewall. Anyway, that solved the problem and the car ran fine for a year until I sold just before returning to the States.
A once-in-a-lifetime occurrence, you say? Nope! The same thing happened to a friend's 1930 Coupe in the 1990's and a friend's Fordor here in Iowa 10 years ago. Guess what the problem was? That same &%^#%&* cheap-*ssed Taiwan terminal box with the wrong-sized bolt head! Rick's must have sold a ton of these lower priced boxes in the 1970'-1980's because I still come across them on older restorations. If your Model A's previous owner/restorer shopped with his wallet instead of his brain, your car probably has one of these worthless (but shiny!) terminal boxes.
As I say, it's a weird cause, but it definitely ruined the first week in Germany for me!
Marshall
one.
I won't go into the whole story as it appeared in that magazine, but I will tell you what the problem turned out to be after exhausting all the usual tests. I took my 1928 Roadster to Germany with me to tour the country while I lived there for a year. Before leaving Arizona and driving the car to New York City (and personally loading into the cargo ship!), I changed everything that I thought might fail or that looked a little suspect. The original terminal box looked kinda crusty, so I installed a brand-new, shiny terminal box ordered from Rick's Antique Auto. THAT alone should have been a red flag. This was before the Model A community discovered what lousy junk parts were being sold by the now-defunct parts house.
Anyway, the car ran fine across country to New York and for some of the driving from
Hamburg down to Munich in Germany, although I was deluged for three days straight by liquid European sunshine, to be read: "RAIN!!!". The engine ran well each morning, but after a while, it misfired and wouldn't start when I coasted to a stop along the Autobahn, mostly making it to rest areas for repairs. The danged thing would not start for about 20 minutes, no matter what parts I swapped around. And then almost like clockwork, the car would start and be fine for another few miles before it began to miss. Cutting to the chase here, I removed my brand-new shiny Rick's terminal box from the firewall and found the problem. There, beneath one of the two long round-head bolts were signs of electrical arcing. The slotted roundhead bolt installed in that Taiwanese terminal box was way too big to fit down inside the hole in the terminal box for it. It's head was sticking out just enough to allow arcing when the firewall got hot after driving for a while. While the car sat and wouldn't start, the firewall had cooled and contracted, creating enough of a gap between it and the round head of the terminal box bolt to allow the car to start and run well until the firewall got hot again after a while driving, and expanded to cause the arcing again. While the engine was running, it misfired. When I shut the engine off, it wouldn't start for 20 minutes. Apparently while the engine was running, the ignition system still functioned, although with a miss. By shutting off the engine, it wouldn't start. It was undoubtedly shorting out.
To fix the problem, I don't recall whether I filed the head smaller or put rubber
between the bolt head and the firewall. Anyway, that solved the problem and the car ran fine for a year until I sold just before returning to the States.
A once-in-a-lifetime occurrence, you say? Nope! The same thing happened to a friend's 1930 Coupe in the 1990's and a friend's Fordor here in Iowa 10 years ago. Guess what the problem was? That same &%^#%&* cheap-*ssed Taiwan terminal box with the wrong-sized bolt head! Rick's must have sold a ton of these lower priced boxes in the 1970'-1980's because I still come across them on older restorations. If your Model A's previous owner/restorer shopped with his wallet instead of his brain, your car probably has one of these worthless (but shiny!) terminal boxes.
As I say, it's a weird cause, but it definitely ruined the first week in Germany for me!
Marshall
Barry B./ Ma.
Well-known member
Same thing happened to my brothers 30 coupe back in the 90s Marshall. In his case it seemed to happen every time it rained, we thought it was a bad fuse mount on the starter as it kept blowing fuses so we by-passed it, well now the wiring started to burn and melt. We made it home from Rhinebeck with some bare wires and when we removed the shiny terminal box the rear of those screws had shorted out on the firewall. Apparently the rain water got between the heads of the screws and the firewall and when it dried out it ran ok. A good tightening and recessing of the screws and some black silicone on the heads of solved the problem.
Purdy Swoft
Well-known member
Too cold heat range spark plugs may be the problem.
BILL WILLIAMSON
Well-known member
MANY older cars I've owned, do better on a HOT restart, if I hold the throttle WIDE open until it ROOOARS & "cleans" itself out, attracts a lot of ATTENTION too!
I "think" the later old Fords, with the fatter air cleaners, get lots of fuel fumes in them, from HOT carbs sorta like "BOILING"! SO, basically, it's sorta' FLOODED!
Bill Jones' '47 Ford, restarts with NO throttle, if the air cleaner's OFF, BUT if it's ON, he has to hold the throttle WIDE open, then all is well, after the KZHAUST pipe gives out a little puff of BLACK smoke.----Bill W.
I "think" the later old Fords, with the fatter air cleaners, get lots of fuel fumes in them, from HOT carbs sorta like "BOILING"! SO, basically, it's sorta' FLOODED!
Bill Jones' '47 Ford, restarts with NO throttle, if the air cleaner's OFF, BUT if it's ON, he has to hold the throttle WIDE open, then all is well, after the KZHAUST pipe gives out a little puff of BLACK smoke.----Bill W.
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steve s
Well-known member
Bill,
I can see how a downdraft carb sitting on top of the block could flood the motor by boiling over, but how would that work with an updraft Zenith, especially with that big vent hole on the inside top for the fuel to boil out of? In my experience with overheated updraft fuel setups, the engine is starved for fuel.
Steve
BILL WILLIAMSON
Well-known member
Well, Steve, "ONLY THE SHADOW KNOWS FO' SHO"! Old cars, jist like OLD MEN, have their QUIRKS & you gotta' lurn their QUIRKS, to "OUT FOX" them. Even with an updraft, the manifold runners "might" be full uf fuel vapors that "might" be sizzled out of the jet tubes??
I once had an old Datsun pickup with a big glass window over the float chamber & within 2 minutes after hot shut off, thet sucker looked like a pot boiling!--Bill W.
(I can just hear Chief saying, "There's sure a lots of MIGHTS in your statements"!)
I once had an old Datsun pickup with a big glass window over the float chamber & within 2 minutes after hot shut off, thet sucker looked like a pot boiling!--Bill W.
(I can just hear Chief saying, "There's sure a lots of MIGHTS in your statements"!)
sidhartha
Senior Member
I had this same problem last summer. I had changed the engine. Put a used one in the car and it run fine until I shut it off and tried to start it with the engine hot. After checking all possible causes I did a compression check with the car cold and all was fine. But when I did it hot I got quite different readings. I guess the guy I bought the engine from hadn't re-torqued the head after he rebuilt the motor. I assumed it was and didn't check it. I had a high compression head I wanted to run anyway and changed them. Most of the head bolts were so loose I could almost take them off by hand. New head and gasket and no more problem..
mot
Registered User
i had an old chevy 55 years ago
it started just fine when cold,every time
but when it was hot ,no way
it would turn over but wouldnt fire
i finally traced it down to a bad ground connection on the frame
cleaned the cable end and sanded the frame ,and it fired right up everytime
just wasnt enough current to both start the engine and fire the coil
it started just fine when cold,every time
but when it was hot ,no way
it would turn over but wouldnt fire
i finally traced it down to a bad ground connection on the frame
cleaned the cable end and sanded the frame ,and it fired right up everytime
just wasnt enough current to both start the engine and fire the coil
Growley bear
Well-known member
Heat causes resistance to electron flow. More heat/more resistance. A hot engine when shut down will experience an increase in temperature before cooling down. On diesels unless idled until a temperature drop is noted on the gauge the engine can increase in temperature enough to melt the bearing Babbitt.
Chet
Chet
George Miller
Well-known member
Well, from my "Why does everything happen to me" personal history files, I'll give you a weird possible cause for the no-start scenario when the engine is warm, i.e., after the Model A has been driven. But do check out all the other good suggestions posted so far first! The following is to be considered only as a last resort possibility - but it DID happen to me in 1974 in Germany. I wrote about this incident in my "Model A Trader" magazine column in the early 1990's, so stop me if you've already heard this
one.
I won't go into the whole story as it appeared in that magazine, but I will tell you what the problem turned out to be after exhausting all the usual tests. I took my 1928 Roadster to Germany with me to tour the country while I lived there for a year. Before leaving Arizona and driving the car to New York City (and personally loading into the cargo ship!), I changed everything that I thought might fail or that looked a little suspect. The original terminal box looked kinda crusty, so I installed a brand-new, shiny terminal box ordered from Rick's Antique Auto. THAT alone should have been a red flag. This was before the Model A community discovered what lousy junk parts were being sold by the now-defunct parts house.
Anyway, the car ran fine across country to New York and for some of the driving from
Hamburg down to Munich in Germany, although I was deluged for three days straight by liquid European sunshine, to be read: "RAIN!!!". The engine ran well each morning, but after a while, it misfired and wouldn't start when I coasted to a stop along the Autobahn, mostly making it to rest areas for repairs. The danged thing would not start for about 20 minutes, no matter what parts I swapped around. And then almost like clockwork, the car would start and be fine for another few miles before it began to miss. Cutting to the chase here, I removed my brand-new shiny Rick's terminal box from the firewall and found the problem. There, beneath one of the two long round-head bolts were signs of electrical arcing. The slotted roundhead bolt installed in that Taiwanese terminal box was way too big to fit down inside the hole in the terminal box for it. It's head was sticking out just enough to allow arcing when the firewall got hot after driving for a while. While the car sat and wouldn't start, the firewall had cooled and contracted, creating enough of a gap between it and the round head of the terminal box bolt to allow the car to start and run well until the firewall got hot again after a while driving, and expanded to cause the arcing again. While the engine was running, it misfired. When I shut the engine off, it wouldn't start for 20 minutes. Apparently while the engine was running, the ignition system still functioned, although with a miss. By shutting off the engine, it wouldn't start. It was undoubtedly shorting out.
To fix the problem, I don't recall whether I filed the head smaller or put rubber
between the bolt head and the firewall. Anyway, that solved the problem and the car ran fine for a year until I sold just before returning to the States.
A once-in-a-lifetime occurrence, you say? Nope! The same thing happened to a friend's 1930 Coupe in the 1990's and a friend's Fordor here in Iowa 10 years ago. Guess what the problem was? That same &%^#%&* cheap-*ssed Taiwan terminal box with the wrong-sized bolt head! Rick's must have sold a ton of these lower priced boxes in the 1970'-1980's because I still come across them on older restorations. If your Model A's previous owner/restorer shopped with his wallet instead of his brain, your car probably has one of these worthless (but shiny!) terminal boxes.
As I say, it's a weird cause, but it definitely ruined the first week in Germany for me!
Marshall
Yes I remember Rick's junk packs. He talked a good story but he sold a bunch of junk.
mshmodela
Well-known member
WrenGB,
4oz per 10 gal of MMO has helped me with warm starting... Also, 1/4 open GAV and no chock at first... if my engine does not start on the 4th crank, I stop, try again and on the second time around, a chock on the 4th crank if needed... Don't chock at the firsts like a cold engine, floods mine...
4oz per 10 gal of MMO has helped me with warm starting... Also, 1/4 open GAV and no chock at first... if my engine does not start on the 4th crank, I stop, try again and on the second time around, a chock on the 4th crank if needed... Don't chock at the firsts like a cold engine, floods mine...