MY 51 WON'T CRANK VERY FAST

[Raindance654]

I just got a 51 Plymouth Belvedere.

It's in great shape and runs fine but it will not start on the key.

I realise that this might be an often discussed topic here but I wasn't able to find too much in the tech section to help, so I'm hoping you guys will help a little.

The problem centers around the rate at which the starter spins the motor over..........it's just too slow and consequently will not draw any fuel/air mix into the cylinders.

 

I've checked the battery, the grounds, cables and most everything else I can think of. Taking the starter off and disassembly shows no obvious problems internally. Brushes look good, bushes have no undue slop, commutator is in great shape and there does not seem to be any obviously burned or damaged windings.

My Plymouth starts easily if I push start it down the street and runs just fine, so I'm reluctant to place blame on igniton or carburation at this stage and therefore my first goal is to get the motor spinning over at a decent enough speed to pull fuel into it.

Any of you early Mopar experts have thoughts on how to do this ........?

I'd rather not convert to 12 volt if I can avoid it as the car has survived all these years without being messed about with and I'd prefer to keep it that way.

 

[Los_Control]

you say your cables look good, what size cable are they?

6 volt systems need heavy 0 or 00 cable, the smaller 12 volt cables most cars have today are to small to work on 12 volt.

 

I just changed my cables to the correct size, I noticed a big difference in the speed it cranked over after the swap.

[Don Coatney]

Suggest you install an electric fuel pump near the gas tank with a momentary contact toggle switch to prime the carburetor prior to attempting to start the engine. 

[Plymouthy Adams]

when you had the starter apart did you check the end bushing for enlongation that will cause the armature to drag?  This will kill a battery very quickly...as you did not state, might I also suggest that you do test the amperage draw when starting and ensure your cable are of proper size, good terminal ends and clean solid connection with no voltage drops.  A voltage drop test is always first order of business in these cases.  Even if  you are to get the starter to spin a bit faster you still have to ensure that there is enough reserve for the ignition. 

Edited November 18, 2018 by Plymouthy Adams

[Raindance654]

15 minutes ago, Los_Control said:

you say your cables look good, what size cable are they?

6 volt systems need heavy 0 or 00 cable, the smaller 12 volt cables most cars have today are to small to work on 12 volt.

 

I just changed my cables to the correct size, I noticed a big difference in the speed it cranked over after the swap.

The cables look to have been replaced very recently and are pretty big gauge. They look to be OO or OOO gauge. I'm planning to add an extra ground cable of similar size to run direct to a starter bolt, for what good this might do. The photos show my cables and I have included an AA battery cell for comparison of size.

[Raindance654]

6 minutes ago, Don Coatney said:

Suggest you install an electric fuel pump near the gas tank with a momentary contact toggle switch to prime the carburetor prior to attempting to start the engine. 

There seems to be plenty of gas in the carbs, Don. I suspect that getting fuel to the carbs and priming them may not be the biggest problem at the present time. The motor does not seem to spin over fast enough to draw the fuel into the cylinders.

[Raindance654]

7 minutes ago, Plymouthy Adams said:

when you had the starter apart di dyou check the end bushing for enlongation that will cause the armature to drag?  This will kill a battery very quickly...as you did not state, might I also suggest that you do test the ameperage draw when starting and ensure your cable are of proper size, good terminal ends and clean solid connection with no voltage drops.  A voltage drop test is always first order of business in these cases

Whilst the starter was apart I checked the bushes, which looked like they had been recently replaced. No undue slop, elongation or other imperfections. I forgot to mention that I did an amp test whilst cranking, which came out at about 40 amps. No significant voltage drops either.

I removed checked and cleaned all cables and grounds, which all seemed pretty decent anyway, but I went though it all just to be sure. 

I also cleaned the starter mounting surfaces and bolts, again just to be sure.

In addition I have an extra cable in my plans to be fitted direct from the battery to a starter bolt, just as soon as I can get to a truck parts store during the coming week.

[Plymouthy Adams]

40 amps...this was off the car testing and not under load? 

[Raindance654]

4 minutes ago, Plymouthy Adams said:

40 amps...this was off the car testing and not under load? 

This was under load whilst cranking the motor with the plugs in. Admittedly, The battery was still recovering from several attempts to start............

[Plymouthy Adams]

you should draw a lot more amperage than that....free run test is 68 amps....was this amp meter inline with the cable or did you use a clip on indictive meter...again, a voltage drop test in in order based on this reading

Edited November 19, 2018 by Plymouthy Adams

[JerseyHarold]

Welcome to the forum.  Beautiful Plymouth! 

 

Does the engine crank faster after it is warmed-up?  If so, you may have a heavy weight oil in the crankcase that slows the starter when it's cold.

[Raindance654]

9 minutes ago, Plymouthy Adams said:

you should draw a lot more amperage than that....free run test is 68 amps....was this amp meter inline with the cable or did you use a clip on indictive meter...again, a voltage drop test in in order based on this reading

I used an inductive clamp meter to get that reading. Do you think perhaps the windings have a problem.........?

[Raindance654]

1 minute ago, JerseyHarold said:

Welcome to the forum.  Beautiful Plymouth! 

 

Does the engine crank faster after it is warmed-up?  If so, you may have a heavy weight oil in the crankcase that slows the starter when it's cold.

Thanks for the welcome.

No, the motor does not crank any faster after having been warmed up. It's always agonisingly slow.

I haven't had my plymouth long enough to investigate what oil is in the crankcase but the problem does not seem to be noticably temperature sensitive

[Plymouthy Adams]

did you test the windings....I suggest again that you follow the manual for testing the starter components, you have not stated if you did a voltage drop test either.....a number of things can be suggested but best advice is going through the starter in the sequence and testing procedures outlined in the manual and AGAIN...perform a voltage drop test!  This will tell you the condition of your cable and all connections in between...

[maok]

How old is the battery?

 

Also, check if the field winding wires that go to the main power input bolt are solder in place or not broken off.

Edited November 19, 2018 by maok
spelling

[greg g]

Looks like the engine was freshly painted.  Perhaps your starter is not sufficient!y grounded to allow it to draw properly!  Maybe some some star washers would give a sufficient path to ground.  Sit is however worth noting that as late as 41 these engines still had provisions for a hand crank.so the speed of the crank has little to do with an engines willingness to start. Is your timing set properly, do you have proper compression, are your choke/s operating as they should?  What spark plugs are you running?  Champions have been absolutely Jung for the last 15 years or so..

[9 foot box]

  I notice the starter to solenoid cable is smaller gauge and you have 6 volt pos. ground alternator? When you test as Plymouthy Adams suggests, you should have a service manual. I have a ground cable to the block, another engine to frame, on the lower right side. And another 10 ga. wire from the starter area to the firewall. It could be the solenoid. Your tests at various points on the system, might show lower voltage to the starter. Assuming the starter nose bushing isn't elongated. And causing starter drag, under load. If you don't have a manual, maybe someone with more knowledge  than me, can show page 93. Nice car, Raindance. Wire wheels look good. Where are you in Europe? More pictures of your car, would be nice. Your plug wire loom has an extremely long coil wire. Lots of resistance there. Or it could be timing?

[Dodgeb4ya]

I think I sold a Belvedere nameplate that ended up on your car several years ago....before it had wires on it...to a Mr Greer.

Edited November 19, 2018 by Dodgeb4ya

[Don Coatney]

Remember three things are required for an engine to run. Compression, fuel, and spark delivered at the correct time. What one is missing? I have seen these engines start at a very slow cranking speed as long as the 3 aforementioned things are in place. With the air cleaner removed using a flashlight can you see a good squirt of fuel in the base of the carburetor when you pump the throttle? Have you done a compression test? Have you done a static timing procedure? 

 

[Raindance654]

9 hours ago, greg g said:

Looks like the engine was freshly painted.  Perhaps your starter is not sufficient!y grounded to allow it to draw properly!  Maybe some some star washers would give a sufficient path to ground.  Sit is however worth noting that as late as 41 these engines still had provisions for a hand crank.so the speed of the crank has little to do with an engines willingness to start. Is your timing set properly, do you have proper compression, are your choke/s operating as they should?  What spark plugs are you running?  Champions have been absolutely Jung for the last 15 years or so..

Yes Greg, the engine looks freshly painted to me also.

With this in mind, one of the first things that I checked was whether the ground connections were good. So, I removed all attaching bolts, re-cleaned them (even though they were actually pretty good already) and re-attached with new star washers.  Whilst I had the starter off, I cleaned the mounting surfaces and mounting bolts.

I get the impression that this has been an ongoing problem for some time as everything that I check has already been renewed or refurbed.

Spark plugs are new NGK and other components in the ignition look new too.

Whilst I'm old enough to remember hand crank starting (we had cars here with hand cranking provision until the late 60's), I feel that the motor is not able to pull any fuel through since even after tipping significant amounts of fuel manually down the carb throat and attempting to crank, the plugs remain bone dry when I'd have thought for sure they would have been drowned by that time.

There doesn't seem to be a lack of compression, either........but it's on my list of things to check next. It will also be interesting to see how quickly the engine spins without any plugs fitted.

Chokes are manually operated and have no apparent problems with operation.

Until I can make this sucker run again I can't check timing but the one time I had this car running after push starting it down the street with the help of three buddies (gosh these cars are heavy, aren't they.....?), it fired easily and ran sweetly enough so I don't envisage any revelations when I check the timing.

See what I mean..........??

It's an odd situation with this car..........!

Edited November 19, 2018 by Raindance654
typo

[Plymouthy Adams]

get your voltmeter out, ohm reading a heavy duty large cable will be of little to no use to you, it will not show correct resistance since the meter internal resistor is so high and the voltage is so low on a conductor  this large.  That is the relevance of the voltage drop test.   Using your search engine you can find articles on this and the procedure online.  With the aid of a helper turning the ignition key you should be able to test all the cables (negative and positive) and the solenoid itself in under 10 minutes and KNOW for a fact the very condition of the cables, your many connections and the high current contacts within the solenoid.   Eliminate the guessing and possibility that the visual inspection shows a very clean cable terminal but be totally corroded internally beyond your vision.  Voltage drop test is always the GO-TO testing prior to removal of any components for rebuild/replace when the motor is turning slowly.  Many have rebuilt/replaced starter, solenoids and batteries when in fact an internal corroded cable was the culprit all the time.  These tests and easily obtained VOMs are essential tools and procedures that in short order define the condition of the system quickly.  anything else is just guessing.  Yes, it sounds so easy and simple it borders on mundane and foolish...BUT IT WORKS

[Raindance654]

7 hours ago, 9 foot box said:

  I notice the starter to solenoid cable is smaller gauge and you have 6 volt pos. ground alternator? When you test as Plymouthy Adams suggests, you should have a service manual. I have a ground cable to the block, another engine to frame, on the lower right side. And another 10 ga. wire from the starter area to the firewall. It could be the solenoid. Your tests at various points on the system, might show lower voltage to the starter. Assuming the starter nose bushing isn't elongated. And causing starter drag, under load. If you don't have a manual, maybe someone with more knowledge  than me, can show page 93. Nice car, Raindance. Wire wheels look good. Where are you in Europe? More pictures of your car, would be nice. Your plug wire loom has an extremely long coil wire. Lots of resistance there. Or it could be timing?

I just measured the cables and there doesn't seem to be any difference in the cable sizes. Perhaps the colors make them appear to be different sizes. The cables used are approx 100sqmm to 110sqmm in size. This equates to something like OO or OOO gauge in AWG terms i believe.  I do have a service manual which came with the car along with a lot of other documentation.

Whilst the cables all seem to be OK, I plan to supplement them with an additional ground cable of similar size to go directly to a starter bolt and also add a couple more body / frame grounds.

Yes, you did spot the 6 volt positive ground alternator, which is of 1 wire variety which I do not like as I personally prefer the 3 wire variety. Could the presence of this alternator be significant, other than being an attempt to keep the battery charge topped up more efficiently..........?

Stripping the started revealed no obvious issues with it. In fact it looked like the started had been worked on quite recently as the bushes looked new, as the the brushes, whilst the commutator looked like it had been turned in a lathe. Judging by the condition of the armature and its windings, it's even possible that this had been replaced or refurbed at the same time.

I don't think the started has an easy fix problem such as bushes or brushes although if I can't find any other problems with the car, the started may need to be stripped and checke dmore closely for shorts or segment damage.

Voltage drop tests didn't reveal any significant drop in the system ........but how much drop is likely to cause a problem with a 6 volt positive setup........?

Whilst the coil wire is admittedly quite long, when I check for a spark under cranking, I'm getting a pretty decent one........even with the battery having gotten past its best charge due to previous cranking.

I'm in England on the south coast in Dorset county...........not by any means the worst part of the world to live, lol.

I'll put up a couple more pics of the car shortly.

In the meantime, I'd appreciate it if the thoughts would keep coming, so I can try these one by one.

[Raindance654]

7 hours ago, Dodgeb4ya said:

I think I sold a Belvedere nameplate that ended up on your car several years ago....before it had wires on it...to a Mr Greer.

This would very likely to be one and the same car................!!

It's now with me in Dorset, UK..............right by the sea on England's south coast.

The last owner of this car in the USA was Mr Greer.

I wonder if he had the same problems with the Plymouth when it was in his care.................?

[Raindance654]

16 minutes ago, Plymouthy Adams said:

get your voltmeter out, ohm reading a heavy duty large cable will be of little to no use to you, it will not show correct resistance since the meter internal resistor is so high and the voltage is so low on a conductor  this large.  That is the relevance of the voltage drop test.   Using your search engine you can find articles on this and the procedure online.  With the aid of a helper turning the ignition key you should be able to test all the cables (negative and positive) and the solenoid itself in under 10 minutes and KNOW for a fact the very condition of the cables, your many connections and the high current contacts within the solenoid.   Eliminate the guessing and possibility that the visual inspection shows a very clean cable terminal but be totally corroded internally beyond your vision.  Voltage drop test is always the GO-TO testing prior to removal of any components for rebuild/replace when the motor is turning slowly.  Many have rebuilt/replaced starter, solenoids and batteries when in fact an internal corroded cable was the culprit all the time.  These tests and easily obtained VOMs are essential tools and procedures that in short order define the condition of the system quickly.  anything else is just guessing.  Yes, it sounds so easy and simple it borders on mundane and foolish...BUT IT WORKS

What you say makes perfect sense to me, Plymouthy. It's my next move to go over the whole lot much more closely. This would be in normal circumstance my "go-to", as you say ..........but in this case, it appears that this has already been done as all the cables, wires, etc lok new or almost new. I think that as an ongoing problem, my guess is that multiple persons have been down this and other roads in an attempt to solve this problem. What I have to do is be the one who finds what they didn't.................and this is what I'm hoping you good folks here will be able to help me achieve.

[Raindance654]

Here are a few more photos of my car, which according to the paperwork that came with her is named "Betsy" .

I was originally looking for a slightly later MoPar until I saw this 51.

You can see why I fell in love with her, can't you..................?