Max4Me Posted December 22, 2021 Share Posted December 22, 2021 I started and ran my 1925 Maxwell/Chrysler in early to mid November of this year, and it ran perfectly. About 3 weeks later I went to start it to prep for a local Christmas parade and it would crank, but not fire. I have the vacuum fuel pump and there is gas going to the carburetor (clear glass filter just prior to carb is full). I did rebuild the carb about 18 months ago and it's been working fine. I pulled the coil wire and grounded it and got a clean spark. I then pulled the #1 plug wire, grounded it and got a spark. I even did one thing I am usually against- I gave the carb a quick shot of starting fluid and no indication it even wanted to fire up. Today I cleaned the distributor cap contacts and the rotor. I also pulled, cleaned, and reset the gap (.020 according to the manual) on the points. I also pulled a plug and it looks OK (no heavy soot or fouling apparent). When not in use I have a battery tender on the battery so that should not be an issue; besides, it cranks fine. Any thoughts on what I've missed or what I should check next will be greatly appreciated. Link to comment Share on other sites More sharing options...
MaxwellFox Posted December 22, 2021 Share Posted December 22, 2021 Does it spark a timing gun when all hooked up? Compression test? Have you adjusted your valves? I think a bad condenser would just be a flat no spark. If you have a port available try an intake vacuum test, or figure out a way to listen to the manifold for leaks while cranking, maybe you have a leaky intake gasket or carb flange gasket. I just fixed my moped that was sparking when tested but didnt have enough oomph under compression, so sparking can be frustratingly misleading. Link to comment Share on other sites More sharing options...
Max4Me Posted December 23, 2021 Author Share Posted December 23, 2021 MaxwellFox, Thanks for your reply. I have not tried a timing light, but can. I thought of the condenser but I agree that a bad condenser would just be no spark, but might change it anyway. As for compression; I will do a test but I just can't see how the car has been running fine for years, and had started and run it just 2 1/2 weeks earlier and it started and ran fine. What would happen it 2 1/2 weeks such that all cylinders lack compression? I can hear the carb sucking air when an intake stroke comes up, but that doesn't necessarily mean it's sucking enough. Checking gaskets is a good thought as stuff happens so.... I hope to get to this tomorrow, but will post results as I can. Thanks again for your thoughts! Link to comment Share on other sites More sharing options...
Max4Me Posted December 24, 2021 Author Share Posted December 24, 2021 Regarding my Maxwell that won't start:I've been trying to track down a 6 volt coil and condenser. Got one at a parts house that said they were 6 volt but the insert in the coil box says it's 12 V. I have some electrical knowledge (if you grab one wire and nothing happens, leave the other one alone!) I can use a multimeter and understand ohms and volts OK, but coils are another story. Will a 12V coil/condenser work in a 6V system without causing damage? Parts are Standard coil #UC15T and condenser is Standard DR90T. Info from internet searches are all over the place and no help. Thank you for your help! Link to comment Share on other sites More sharing options...
Bloo Posted December 24, 2021 Share Posted December 24, 2021 Measure the primary resistance of the coil, from one small terminal to the other. If it is something close to 1.5 ohms, or a little less, it will likely at least work on 6 volts. If it is closer to 3 ohms, probably not a good idea. Don't forget to subtract the resistance of your test leads from the coil reading. Short the leads together and read ohms to find out what the lead resistance is. Voltage (at least 6 or 12 volts) is not any sort of a rating on a condenser. If it is a good condenser, the ignition will work even if it is the wrong condenser. The rating that matters is microfarads (uF) and they hardly ever tell you what that is in the automotive ones sadly. If it is wrong your points wont last very long, because one point will lose metal and the other will gain it, looking like a mountain on one of the points. If the condenser is too big (in uF) the mountain will build on one point, and if the condenser is too small it will build on the other. Old MOTOR manuals have a picture of this. Link to comment Share on other sites More sharing options...
Max4Me Posted December 24, 2021 Author Share Posted December 24, 2021 Bloo: Thanks for your input.I have seen the 'mountain building' before but wasn't sure as to cause. Thanks for the explanation. Internet search and my owner's manual turn up nothing on capacitance for the Maxwell. Crapshoot I guess. Link to comment Share on other sites More sharing options...
Bloo Posted December 24, 2021 Share Posted December 24, 2021 (edited) It is a crapshoot. Decades ago, i was working in a gas station that had on old cabinet where we stocked common ignition parts. The old original card in the door for the brand of parts it originally held gave you the uF ratings for a bunch of common 1950s-1960s condensers. Even though the supplier had changed, it was possible to go a little bigger or smaller based on that chart when you needed to. You never see this information anywhere today. New correct-for-the-application parts varied in quality as well as uF too. The unwritten rule in those days when doing a tune up was if the old points were staying about flat, leave the old condenser in. If the points had mountains, put a new one in. Maybe the new one will be better. For what it's worth though, any *good* condenser out of any points ignition system will make another points ignition system run. For the Maxwell, I would start with one for something with a 6 volt ignition and a fairly slow turning four cylinder engine, and hope I hit it pretty close on the first try. Maybe a 1950s tractor? There seems to be 2 threads and I am not sure where the other one went. Regarding coils, Yes you want a 6 volt coil if you can get one, assuming the Maxwell is a 6 volt car. NAPA should have that, as should most other parts stores. If they insist on make model and year, say 1953 Chevrolet Bel-Air if the Maxwell is negative ground, and 1953 Plymouth Cranbrook if the Maxwell is positive ground. Even the ground detail probably makes no difference in the real world. Hook the (-) terminal to the points on a negative ground car, (+) to the points on a positive ground car. I am not completely convinced there is any difference between a 6v and a 12v coil as used on typical common American cars with points. Many 12 volt American cars use a separate ballast resistor or resistance wire, and run the ignition on about 7 or 8 volts. 6v American cars typically do not run a resistor, and the system voltage with a full battery and the generator charging is about 7.5 volts. That idea comes with a whole bunch of caveats and exceptions. It certainly does *not* necessarily apply to all 12 volt coils, and especially does *not* typically apply to European 12v coils or aftermarket universal 12v coils. If a 12v coil passes the test in my earlier post, it will be close enough to run on 6v. Edited December 24, 2021 by Bloo (see edit history) Link to comment Share on other sites More sharing options...
MaxwellFox Posted December 28, 2021 Share Posted December 28, 2021 The way you were describing it as progressive makes me wonder if your valves went out of adjustment, carbon build up, or a valve seat wore out. My mini ate an exhaust valve and a seat on separate occasions. It started and ran for a while but eventually the leak got bad enough it would just woosh out all the air-fuel when it compressed and not start. A compression test would show a bad valve or seat real quick, just have to get the 7/8 adapter. Link to comment Share on other sites More sharing options...
Max4Me Posted December 30, 2021 Author Share Posted December 30, 2021 Update: I put a new 6V coil and condenser in today and still a no start. Distributor rotor is turning, spark between the points seems to be a good spark at plug, but no start, even after a squirt of gas in the carb. The thing that gets me is I had it out for a 50+ mile drive in late Sept./mid Oct. and it ran beautifully. Then I started it just before Thanksgiving (I try to start it periodically to keep oil on the internals) and it started right up and ran fine. When I shut it off it shut down and sounded just like it did every other time I turned it off. When I tried to start it about 3 wks later for a Christmas parade it wouldn't start. My next step is clean plugs (not really yucky and only have about 300 miles on them, but who knows), compression test, and squirt a bit of gas in each cylinder and try starting (that should indicate a possible carb float issue). It will have to wait, though, holiday, out-of-town guests and a garage that's currently 40 degrees have put me off. Thanks again to all for the suggestions! Have a SAFE New Year's! 1 Link to comment Share on other sites More sharing options...
Max4Me Posted January 10, 2022 Author Share Posted January 10, 2022 (edited) Another update: I pulled all the plugs and, though not really bad, gave them a good cleaning and checked the gap. Before installing them I drizzled a little gas in each cylinder. Once the plugs were installed and reconnected I cranked it over, and it fired up for about two seconds. I then disconnected the fuel line to the carb and drizzled gas in it and it seemed to take a fair amount. Unfortunately it still did not start or even fire. So next chance I get, the carb comes off for further inspection. Edited January 10, 2022 by Max4Me (see edit history) Link to comment Share on other sites More sharing options...
Max4Me Posted January 12, 2022 Author Share Posted January 12, 2022 Still another update: OK, I checked fuel transport system. Fuel in tank, in fuel lines to the vacuum fuel pump, fuel from the pump to the glass filter ahead of the carb and fuel in the float bowl (removed drain plug on the bottom and fuel ran out). Before removing the carb to work on it, I checked the mounting bolts thinking if they were loose the intake manifold could be sucking air ahead of the carb and there wouldn't be enough vacuum in the carb to pull fuel through. Well, it was worth a try. So now the question is what is the carb doing with the fuel once it gets there? Carb is on the workbench ready for inspection once I get the chance. Link to comment Share on other sites More sharing options...
Max4Me Posted January 14, 2022 Author Share Posted January 14, 2022 A further update/problem: So now I have a bigger problem that probably is not part of the issue. After removing the carb I noticed carbon build up on the top near where it mounts to the intake manifold (which bolts to the exhaust manifold). Yep. Gasket leak. The worst part is while taking the manifolds off I noticed what looked like (and is) a hairline crack in the exhaust manifold. It is so small I doubt it is interfering with combustion. Top pic is outside of manifold, bottom is inside. Interesting block set up, it appears only two ports are intake. They appear wet, but it is gas not oil (not slippery and smells distinctively of gas). Bottom pic is the exhaust manifold. Notice the intake port is glazed. Thoughts? Still working on the no-start issue. Thanks to all for your advice! Suggestions as to whether or not I can get the manifold welded to prevent more cracking or leave it alone? Sources for new exhaust and intake manifold gaskets? Link to comment Share on other sites More sharing options...
MaxwellFox Posted January 21, 2022 Share Posted January 21, 2022 Hold your hand over each of the manifold ports while someone cranks it over. See if they only suck or suck and blow. If you have a vacuum gauge stick it in a rubber stopper and shove it in each port and see if you have appropriate vacuum and pressure. 1 Link to comment Share on other sites More sharing options...
Max4Me Posted January 24, 2022 Author Share Posted January 24, 2022 On 1/20/2022 at 9:27 PM, MaxwellFox said: If you have a vacuum gauge stick it in a rubber stopper and shove it in each port and see if you have appropriate vacuum and pressure. Great idea! Had not thought of that. It certainly would be worth a try just to see what the results are. Link to comment Share on other sites More sharing options...
jamesborn14 Posted February 4, 2022 Share Posted February 4, 2022 (edited) Most likely a problem with the ignition coils or engine oil. I think it's worth checking everything. Well, it's best to replace, especially since a new set is not expensive. I advise you to buy 6.7 cummins diesel oil here https://davesoilchange.com/best-oil-for-cummins-6-7/ .I have been buying there for many years, a very reliable manufacturer, I think what your retro car needs. Edited February 10, 2022 by jamesborn14 (see edit history) Link to comment Share on other sites More sharing options...
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