Unusual problem

[R.White]

My car is only able to drive for about 1/4 of a mile and then it begins to back fire through the exhaust; looses power and eventually packs up altogether. If I leave it for, say, 10 to 15 minutes it starts up again and pulls away no problem. After a while, the backfiring then starts and the engine soon stops again.

I am pretty sure she is running too rich and I was wondering if the vacuum tank is still not quite right. Could it be that the vacuum valve is somehow being overpowered and fuel is being drawn from the vac tank down the vacuum pipe and into the manifold? The engine gets flooded and drowns? Unburnt petrol explodes in the exhaust?

I checked the vac tank valves by sucking/blowing through them when I restored the tank and they seemed to work O.K. so maybe it's something to do with the carb. If the piston was sticking would this happen?

At the moment, I am not sure what to do with it as I have never experienced a problem quite like this before. Perhaps someone could point me in the right direction. Thankyou.

Ray.

Edited April 10, 2013 by R.White (see edit history)

[keiser31]

Sometimes a coil will act like that when it shorts out.

[Grimy]

Following Keiser's line of thinking, try substituting a coil known to be good.

Another potential cause is a clogged exhaust system. Here's how I diagnose that: After the engine has been shut down half an hour or more, hook up a vacuum gauge then start the engine. Run the engine at 1200-1500 rpm in place (stationary, no load) and watch the vacuum gauge. The vac gauge will take 30 seconds or so to stabilize at speed. If, after two minutes the reading begins to drop markedly, a clogged exhaust system component may well be the cause. Clogged muffler or critter nest in a pipe may be at fault.

[R.White]

Thanks guys. That gives me a couple of things to try.

[gundog99]

Have you examined the hot and cold adjustable shutter on the inlet tube ?I think Australian cars tend to be fitted different shutters for warm / hot climates than cars running in cold/ warm climate. look in your manual under the heading "Air Inlet".

[lozrocks]

It may even be the spark plugs. I had a similar problem with my Chrysler using NOS plugs. Mine would idle for 10 minutes without missing a beat. But 10 minutes on the open road and it would backfire like crazy.

After numerous attempts changing things I discovered the new plugs were stuffed.

[MikeC5]

I vote for the partially plugged exhaust system especially if the car has been sitting for a few weeks. The critters around here just love intakes and exhaust systems..

[JACK M]

The unburned fuel is a good theory, Rich running would yield black smoke. Backfiring usually means lean condition to me.

[R.White]

The different ideas from you guys have certainly given me something to work with. Interesting that none of you think it is the vacuum tank valve not cutting off the induction and drawing surplus fuel down the pipe into the manifold. I am not familiar with using the Stewart Warner but the English 'Autovac' has a design advantage to prevent this from happening. Having said that, the American unit is a much sturdier and better quality affair. If I can discount the vac tank then that will be a bonus.

The situation is that I acquired this car as a non runner and from what I can gather the previous owner was unable to get it running in the years that he owned it. At least I have got it to the stage of running now. One of the difficulties, from my point of view, is that there are few correct parts available over here (or in Australia) for Dodge Brothers cars, and that many non original parts get used probably because of the expense of getting the proper parts from the States. I am certainly not complaining but I think it helps to explain the situation. I will get to the bottom of this problem and the car will be worth it eventually.

Gundog 99, that is an interesting idea; the hot/cold shutter is on the off side above the exhaust - I presume it should be closed to best suit these cold conditions? I will experiment with this and see if it makes a difference.

Mike C5, I have never had the problems with vermin that you and Lozrocks seem to have. Perhaps they sense that this place is a cattery and stay away! Only the really stupid critters find their way into the cats' accommodation! There is little chance of the exhaust being blocked with the ferocious back fires which have virtually ripped the thing apart.

Lozrocks - if you are right and it is the plugs, then I will eat my hat! Having said that you will turn out to be right!!

Jack, the running seems rich. I only need to have the choke out for cold starting then when it fires up the choke knob can be pushed home. The engine seems to run fine but it seems to hunt and there is certainly some black smoke from the exhaust but it seems to disapear as the engine warms up. The back fire only occurs after about a 1/4 mile and is in the exhaust. There is no popping back through the carb.

If the problem turns out to be a failing coil then John will win all the credits. That would be a nice cheap fix and like you, John, I would always normally suspect an electrical fault over a fuel one but as I have been meddling with the vacuum tank tank I thought that would be the most likely cause.

I will need some time but I will get back to you all in due course. Thanks for the help.

Ray.

Edited April 10, 2013 by R.White (see edit history)

[Guest occrj]

Hi Ray,

I had problems with the truck expiring when I took it out, usually 1/4 mile down the road, in the end I found a tiny hairline crack in the distributor cap. I've not had it down the road since, but it could be something like that as you're on coil ignition aren't you? As already said, I'd be swapping out ignition parts to try and find a culprit. Backfiring could be wayward engine timing couldn't it?

RJ

[R.White]

Hello Richard. I well remember the problems you had with the truck. I followed your restoration story - every word of it! That distributor cap caused you a lot of grief. I'm glad you sorted it out O.K.... A process of elimination I expect. On my car, however, I think the very loud backfire and rich running are linked to the eventual expiry. After a few minutes waiting, the situation seems resolved - like I think you found with the truck - and the car starts up again like nothing was wrong. That is why I don't think the problem can be down to ignition timing; although the timing is spot on it can never be right while there is some wear in the distributor shaft/bearings. Nevertheless, it wouldn't just show up after every 1/4 mile or so and then resolve itself.... or at least I wouldn't think so? What do you think?

I really do appreciate all the good ideas. A coil on the way out would, as John said, show up with these symptoms and I like your dist. cap idea - this is something I have experienced before - but it only produced a misfire which is not happening this time. I just hope it is something simple like that. If it's the vac tank then I am in for another big bill. I dont think you can restore the valves yourself? I need to find some time to really get stuck into it.

Thanks for all the advise.

Ray.

Edited April 9, 2013 by R.White (see edit history)

[1936 D2]

I can maybe throw out another idea here, just to help confuse things further. :confused:

I had an issue many years ago with my '36. I was having what seemed to be timing issues. I checked all the usual things I could find related to timing and they all checked out. But any time the engine ran for a while and heated up, or was under strain (like letting the clutch out), the "timing" issue cropped up. Long story short, I found a valve spring was cracked (broken) but was still in place. It was holding the valve closed tightly enough that while I was doing manual a compression check the cylinders checked out normally. But when the running engine speed was increased the timing issue seemed to come and go! Very odd.

So eventually I was in there checking the valve adjustments and when I moved the retainer on that valve spring the coil came out of alignment and the break showed itself with the collapse of the spring! You could visually see nothing odd about the spring until it broke fully.

I replaced the valve's coil spring and all was fine! Odd, very odd indeed!

[Pete K.]

Ray, Here's my 2 cents; Take hold of the copper vac. line from intake -to- vac. tank after engine is warmed up. If it's cold, there's fuel going through it to your engine with a problem of the valve in vacuum tank not closing and engine siphoning fuel out of the tank. Your problem of any loud backfire from tail pipe sounds to me of another source,--- IGNITION! This could be anywhere in the ignition system, from the key switch to the plugs and all in between. Sounds either like some component is either breaking down with engine heat-up or shorting out with the same heat induced scenario. If your vacuum tank was at fault and gas was siphoning into engine big-time, you would see the fuel pouring out of the pre-heater adjustment at carb and you'd be blowing out more black smoke than ever out of exhaust pipe.

[R.White]

1936D2 That's what I call sod's law. If it can go wrong it will go wrong! I guess we all get thrown a curved ball from time to time. I will check my valve clearances anyway.

Pete, your 2 cent's may be worth a lot more than you think! You have separated out the two issues for me. Thanks. I can check the temperature of the vacuum pipe like you say but as there is no leaking at the carb (and I did check the vac tank valves, honestly!) I don't now think it can be that for sure. I really don't know just how much black smoke is too much? It's not that bad and it get's better as the engine warms up but I don't know if that is due to evaporation or I am barking up the wrong tree altogether! I would normally have bet on ignition - like you said - but with the problems I have had with this vac tank I guess my judgement has been clouded.

What I think I will do is sort out the worn distributor which is looking much worse than I first thought it was. Once that is right, I can go through the ignition system again and substitute the coil etc..

We will get there eventually!

Ray.

[Pete K.]

Ray, Usually a back fire from exhaust pipe means there is RAW gasoline fumes in the exhaust system that are ignited and exploding once engine produces fire or sometimes the heat from the exhaust system itself. It sounds to me the ignition is intermittently shutting down and starting back up causing this problem. As mentioned earlier, the coil, condenser, points grounding out or wiring is the culprit. I do remember reading a service note about the distributor we have, not being grounded to car, where the two main iron bodies meet of the distributor housing and the coil housing. Grease and oil were the culprits there. Dodge suggested to run a separate wire from dist. body to frame, or other good, known ground. I had a '38 Chevy as a kid for everyday driving and one day in downtown traffic a backfire blew the muffler completely open. My feet were jolted 3 inches off the floorboard and a woman on the sidewalk almost fainted from shock. I found it was my key switch at fault. An intermittent on-off situation. Anyway, I'm thinking your vacuum tank may be OK.

[R.White]

Hi Pete. Well I checked out the vacuum pipe with the engine warmed as you suggested and it is warm compared with the feed pipe. Also there is no sign of a leak at the carb so it looks like you are right and the vac tank is not at fault. I have not had long today to check out the problem but I did manage to have the fault manifest itself while the car was standing in the garage. When the engine is warmed up it continues to tick over but refuses to pick up. And I mean refuse! The back fire is produced when I try to get the engine to pick up. The last time this happened to me it was down to a split diaphram in a modern(ish) Stromberg carburettor, so unless the piston is sticking in the carb - and I have checked it out not too long ago - the only other route must be like you suggested - ignition.

So I am thinking you are right and the ignition is breaking down when it gets hot. Tomorrow (if I get time) I wll check out everything and change the coil and condenser. Separate grounding of the distributor is not something I have come across before but its logical enough and worth a try. As to ignition switches - tell me about it!! Some of those old Bakelite switches develop hairline cracks and together with cracks in the distributor cap (which need darkness to see them ark) are among my least favourite problems.

Your tale about the backfiring '38 Chevy made me laugh and reminded me of the time I had a single cylinder bubble car. It happened just as an old chap was leaning over his hedge with a pair of shears. When the bang sounded it was so fierce it tore off the muffler and made a sound like a machine gun. The guy jumped off his step ladder and promptly disappeared over the hedge! He probably thought the Germans were coming after him like in the War!

We shall see what tomorrow brings.

Ray.

Edited April 10, 2013 by R.White (see edit history)

[keiser31]

With each thing that you try as a remedy, you should attempt to start and go through the motions as before so you can narrow down the cause. In other words....one "fix" at a time will tell us what happened and why the problem arose.

[R.White]

Good advise is always welcome, thankyou John. Tonight, I tried running the engine. Again it was fine until warm. Then I noted that when I tried to open the throttle, not only would the motor refuse to increase in revs, it would in fact die down and stall. Does this indicate anything? Why does it run and pull like a train until it gets warmed up and only then have a problem? I have yet to check the valve clearances. This involves removing the casting with the air filter which is situated directly over the exhaust manifold. If the exhaust valves have too tight a clearance they may not allow sufficient flow when hot. I know this to be a fact with my Austin but not sure about the Dodge. Insufficient air intake is possibly another cause but how it is temperature related I don't know. Perhaps the carb piston is sticking? It seemed fine when I checked and cleaned it up.

The air intake arrangement on this engine is unlike anything I have seen with the air being warmed as it is drawn through a passageway in the middle of the block. It obviously should work - it's just not knowing quite what is going wrong and why which is making my life interesting to say the least!

Ray

Edited April 10, 2013 by R.White (see edit history)

[robert b]

Good advise is always welcome, thankyou John. Tonight, I tried running the engine. Again it was fine until warm. Then I noted that when I tried to open the throttle, not only would the motor refuse to increase in revs, it would in fact die down and stall. Does this indicate anything? Why does it run and pull like a train until it gets warmed up and only then have a problem? I have yet to check the valve clearances. This involves removing the casting with the air filter which is situated directly over the exhaust manifold. If the exhaust valves have too tight a clearance they may not allow sufficient flow when hot. I know this to be a fact with my Austin but not sure about the Dodge. Insufficient air intake is possibly another cause but how it is temperature related I don't know. Perhaps the carb piston is sticking?

The air intake arrangement on this engine is unlike anything I have seen with the air beingwarmed as it is drawn through a passageway in the middle of the block. It obviously should work - it's just not knowing quite what is going wrong and why which is making my life interesting to say the least!

Ray

hi Ray have tried changing your condensor in the distribuitor, common problem when engine gets hot condensor breaks down and low spark out put to plugs.

[MikeC5]

Ray, I think someone mentioned that coils have been known to break down only when warmed up. I've not had this happen to me personally but you might try swapping in a 'modern' cylindrical coil and see if that cures things. I had a friend who used to purposely create backfires with his '67 Chevy. He would put the AT into low gear, run up the revs and then shut off the car and coast down. When he turned on the key again, boom! I was surprised how many times he was able to do it on one muffler...

[keiser31]

My 1949 Dodge did that very same thing. It would go a few blocks, sputter and lose power and die. Would not re-start until it cooled. Wait 5-10 minutes and it would start right back up. Turns out that the coil was getting hot and shorting out. That caused it to lose power and die. After the coil cooled a bit, it would start right up. Sold the car because I was 17 and did not know about that sort of electrical problem. The new owner replaced the coil and the problem was solved.

[R.White]

Mike, the coil on my car is a modern cylindrical one. I don't know what an original 1926 coil would look like. I will change it for another 6 volt coil as I have a new one waiting to go on. I will also replace the condensor.

That practice of deliberately backfiring; it used to go on near where I grew up. Gangs of feral youths would continually 'bang' their exhausts under a low bridge and keep everyone awake at night.

John, I hope you are right - it would be a cheap and simple fix. Just change the coil.

The best lessons are hardest learned. I am sure you slightly regret loosing out on the '49 Dodge like that, maybe not regret, but things like that stay with you don't they? There are things like that which niggle me if I care to think about them. I guess we live and learn.

Ray

[keiser31]

Ray...to add....yes, selling the '49 was a bear for me. It was completely mint with the exception of the rocker panels needing some work. The interior, including the dashboard, was like new. The woodgrain stood out beautifully and the seats, panels and headliner were perfect. The chrome was excellent. It was a very low mileage car. It even had two new rocker panels with it when I bought it for $200.00. I sold it for $400.00, but it was NOT enough.

[Guest brian j]

Hi Ray. First of all........any backfiring would usually launch a mouse nest, mouse and all out the tail pipe. When an engine runs fine, and then suddenly backfires, it sometimes means there is a failure of the spark plugs to ignite the fuel during an engine cycle, and then in another cycle the spark plug fires, making a "backfire", from the excess of fuel that was shoved down the exhaust pipe without being burned. Working backwards, i would test/check the plugs for intermittent firing or fouling(causing intermittent firing), and then outdoors i would place a dark tarp or blanket over the engine compartment area so in the darkness you can witness any sparking or shorting out of the plug wires,cap, or coil, or associated wiring. Make sure you have proper ventilation, so there's no carbon monoxide danger. Then i would attach a timing light to each plug wire to watch for intermittent firing. You can visually see that the light will either blink steady, or "skip" a beat.If "all" the plug wires are miss firing i would place the timing light sensor over the coil wire, to see if it's the distributor or coil causing the problem. Sometimes the distributor cap inside terminals get corroded, along with the rotor terminal, causing a slight timing change, which can cause a backfire. If there is no intermittent firing, it could be excessively rich fuel mixture, or possibly a timing issue. Any backfiring itself is enough to load the plugs up and cause the engine to "choke" itself, and making the engine die out untill it sits for a few minutes to allow the fuel to evaporate, clearing the plug. I hope this helps. Good luck.

[R.White]

I am delighted to say that I have replaced the coil and that seems to have fixed the problem so thankyou to everyone who pointed me in the right direction.

One thing which has come to light is a leaking exhaust manifold. Perhaps the backfire has made it worse but I knew there was a leak since first starting the engine. I will have to fix this before I can use the car because of the fumes. Having once nearly died from carbon monoxide poisoning due to a faulty gas fire, I have a deeply held suspicion of leaking exhausts where ever they may occur. Someone has smothered the manifold in some kind of exhaust sealant presumably in an attempt to mask the problem. If the manifold is cracked or burned through I may need a replacement so if anyone has one spare perhaps they could consider me as a potential buyer. I would not really

trust a weld in a rusty old cast iron manifold but if I am in luck I will only need a gasket. Fat chance!

Another point is the rich running. The exhaust does produce some black smoke and "hunts". A little carburettor adjustment is required I think.

Again many thanks to you guys who gave me some good advice.

Ray.

[keiser31]

Excellent to read that you got it fixed.

[Guest brian j]

Hi Ray. You should pull the spark plugs anyway, and assess their condition. Running the car for a time with that misfiring problem may have sooted them up, so they won't perform as well.

[R.White]

John. You were the first to respond with the solution - one originally born out of your own experience with that '48 Dodge.

Thanks again.

Ray.

Brian. Yes they had become sooted up but cleaned up easily. Thanks.

[Guest occrj]

I've bought new copper rings for when I re-fit my manifold, hopefully later this week. The ones that came out, not the copper type but the type made from coiled-up wire, were leaking badly.

RJ

[R.White]

Unfortunately my manifold branches have worn very thin around their mating edges and I feel the crush rings would be too thin to make a reliable seal. There is always the option of using the felt type but I prefer something a little more substantial. Fortunately, Yamaha 250/350 motorbike exhaust gaskets have a flat mating surface and an internal diameter of 43mm, external 53mm, and are just the ticket!

Someone has welded on a three point flange to take that type of exhaust down pipe. I shall not alter this and now I have relieved the surplus weld from around the holes, I can now use the correct size bolts to attach it.

Ray.

[Guest occrj]

I'd be interested to see the Yamaha gaskets, in case I need to resort to them also My downpipe and manifold have also been adapted to take a pair of bolts, it looks like an off-the-shelf conversion. When I had a new exhaust made up, I left it like this also.

[Guest occrj]

Hi Ray,

I attempted to re-fit my manifold this evening, but like you the mating edges aren't 100% on the manifold and I can see gaps in places. I daren't tighten them up any further, so I'll have a look for some of the gaskets you mention (thanks).

RJ

[R.White]

Exhaust Gasket Yamaha RD250LC & RD350 LC 1980-84 Alloy Fibre Non-Asbestos | eBay

It would seem they have all been sold. There are other people offering what looks like the same gaskets but I would check out the size first. Some have too small a diameter (internal).

By the way, I was really pleased to see your Dodge Transporter featured in the Automobile magazine. I thought they made a pretty good effort and gave it the coverage it deserves. That really is a marvelous vehicle. Made my day!

Ray.

[Guest occrj]

Hi Ray, yes I had a look and found someone selling 53mm/43mm gaskets so I ordered a few, ebay to the rescue once again (hopefully). The article in The Automobile did come out well didn't it, glad you liked it. Michael Ware came over in October 2011 to see the truck and prepare his notes, so quite a gap between then and it appearing in the mag - worth the wait though! rgds RJ

[Guest 1930]

Hi Ray, yes I had a look and found someone selling 53mm/43mm gaskets so I ordered a few, ebay to the rescue once again (hopefully). The article in The Automobile did come out well didn't it, glad you liked it. Michael Ware came over in October 2011 to see the truck and prepare his notes, so quite a gap between then and it appearing in the mag - worth the wait though! rgds RJ

There was an article that you posted a link too for me about your truck a few months ago, is this the same article that you guys are referring too? If it is than maybe post the link again, it was a very good article and a great story that I enjoyed reading and would like to do so again.

[R.White]

Hi Richard. Unfortunately, the gaskets that I received did not match the description. They should have been 43mm internal diameter but actually measure 38mm. This would restrict the exhaust too much for my liking and I have contacted the seller for a full refund. I am sorry for giving misleading information but I was not expecting this.

I would be interested to see where your 43 mm gaskets are being sold. It is quite urgent.

Many thanks.

Ray.

[Guest 1930]

Hi Richard. Unfortunately, the gaskets that I received did not match the description. They should have been 43mm internal diameter but actually measure 38mm. This would restrict the exhaust too much for my liking and I have contacted the seller for a full refund. I am sorry for giving misleading information but I was not expecting this.

I would be interested to see where your 43 mm gaskets are being sold. It is quite urgent.

Many thanks.

Ray.

Innacurate description on E-bay????? Why thats un-heard of !!!

[Guest occrj]

There was an article that you posted a link too for me about your truck a few months ago, is this the same article that you guys are referring too? If it is than maybe post the link again, it was a very good article and a great story that I enjoyed reading and would like to do so again.

Hi 1930, the article made it into The Automobile magazine in the April 2013 issue, it was based on content that features on my site, at the following location which describes the rebuild and the history of the truck: Restoring a '40s race car transporter. rgds, RJ.

[Guest occrj]

Hi Ray,

I had a look around and plumped for these: 110811057188 (not listed as being specific to any one vehicle).

They look like the gaskets I took out when I removed the manifold. For reference the ones I took out were 53mm OD, 40mm ID which are probably a bit restrictive too but given that the manifold seating is quite thin in places I'd prefer to sacrifice a little power, to get a good seal. Time will tell if they're suitable or not....!!! A few people are selling these gaskets, ref EXG53.

RJ

[Guest 1930]

Hi 1930, the article made it into The Automobile magazine in the April 2013 issue, it was based on content that features on my site, at the following location which describes the rebuild and the history of the truck: Restoring a '40s race car transporter. rgds, RJ.

Ok thats right, it was your site I was directed too. Great job