The Stovebolt Site Forums The Shop Area Engine Shop 235 Cranks Slow when Warm

I'm extremely frustrated. I have seen similar postings to this, but I am pulling my hair out. I have a 1962 235 in a 49 Ton-and-a-half. It cranks slowly when cold but I can get it started. It runs and idles fine at about 650 RPM but doesn't want to idle slower. It will die. Then is will crank like the battery is bad. However, reading voltage at the starter it will show 6.25 volts or so. Here is what I have done so far:
1. Pulled plugs when warm... cranks at very good rate.
2. Starter completely rebuild with brand new high torque coils and new armature, bushngs, switch (foot starter), washers, everything except the case... by a very good shop.
3. Brand new commercial 6 volt battery.
4. Cleaned all terminals, connections, etc.
5. Read voltage drop from battery to starter... exact same readings.
6. Welding cable 00 for both hot and ground.
7. Moved ground to top mounting stud on starter at block instead of on frame.
8. Confirmed good 1" wide grounding strap from starter to frame.
9. Compression tested with readings ranging from 100 to 115 on all cylinders.
10. Used jumper cables in addition to usual cables from battery to starter... no improvement.
11. Tried using 12volt booster on starter directly along with 6V batter... no improvement.
12. Have had 2 6V batteries in parallel to get more current... no improvement. I used an Optima with a separate set of cables going directly to the starter.

This is not a case of "it won't start". This is a case of "it cranks too slowly like the battery is dead". If I can get it to spin up it will start. It will crank to speed with the plugs pulled, but even doing a compression test on one cylinder can cause it to stop spinning momentarily each time the piston comes up.

Please don't tell me to clean the terminals, rebuild the starter, and get a new battery. I have spent over $300.00 on all that stuff in the last week. This has been a problem with this engine ever since I put it in 5 years ago and that is why I gave up for a few years. I have decided to give it one last chance before I throw in the towel. Any useful input would be greatly appreciated.

Could they have put 12volt coils or armature in the starter?

When you "put in in 5 years ago" was it after a rebuild? I am probably wrong on this but it sounds like maybe incorrect main bearings. It sounds like you've done all the external fixes so that makes an internal problem look more likely. I hope for your sake someone says I'm out of my mind and gives you an easy soulution.

No, it wasn't a rebuild, per se. It had been rebuilt at one time, but when I bought it it was in a running '55 that was being upgraded to a 350. My truck had a '52 in it when I bought it but it was blown up. It had water in 3 cylinders. I bought the '62 as an upgrade to a full oiler. I had to swap the ring gear to use the 6 volt foot starter which I wanted to keep. I also had to modify the water pump with the shortened shaft, but I never went through the bottom end. I did pull the head, have it milled to make sure it was flat and put on a new head gasket, set the valved, added a new fuel pump, swapped exhaust/intake manifold, put a Carter rather than a Rochester on it, etc. I am afraid you are correct that there is something wrong in the bottom end like bad bearings or missing/improper shims.

Can you turn it by hand? With the pugs out it should be easy to turn by hand.

I haven't tried that specifically. However, with the plugs out the starter spins it up at a high rate of speed similar to what I hear when the starter was on the service bench at the shop. Some other things to add...Remember that with the foot starter (at least on my truck) you can turn the starter over with the key off and it will not actually try to start because the rest of the distributor systen is shut down. SO the issue is not timing or kickback from being too far off on the timing. When it starts (when first cold) it will run pretty smooth. Vacuum when it is idling at about 650 RPM is around 21" at the carb port and it is steady.
Keep asking me questions... I am hoping to find something I am missing.

I would borrow a friends 6V starter and see if that works a little better. I'm thinking that if it spins OK with the plugs out, that your bottom end is OK.

You could try spining it over (hot) by hand with the plugs out and see what kind of resistance you get.

If your connections and battery are all good, then I would bet on the starter.

Kurt

I was thinking more along the lines of piston ring clearances...!!!??!!

You can check everything but piston skirt clearance and piston ring gap by pulling the oil pan. Drop the pan, and check rod and main bearing clearances with Plastigauge. The ideal clearance is somewhere around .001"-.002" for rods, and possibly slightly closer for mains. You might also try pulling the spark plugs quickly after a warmup, and checking the cranking speed with the plugs removed. If even a single compression test load slows it down, I suspect an internal problem in the starter after warm-up. Ditto on the suggestion to swap starters and see what happens.
Jerry

Did you check to make sure your plug wires are on in the right order?
I did this las year. Same symptoms. Drove me nuts. If you exchange the number one for the number two I think it's close enough to run ok above 1000 rpm. I worked on 5 cylinders for years though so my ear may be off a bit.

Just a suggestion befor you tear off the pan.
Jeremy

I think that although the starter is rebuilt, it may not have enought torque to turn it over when it is hot. You should be able to turn it over by hand when it is warm. I think you need to try that. I use the fan and pull on the belt to get it to turn. You need to establish whether the motor is too hard to turn when hot or whether your starter isn't doing the job.

I just went through the exact same thing exact same symptoms. You mentioned about spending $300 on battery, rebuids....etc I just want to clarify the starter is a recent rebuild? These were my symptoms. Would spin up ok cold and run fine. But even just warmed up it would spin like a dying battery. The starter would stall out as soon as I hit a compression stroke. With plugs pulled it spun like a champ. I went through the whole routine, new heavier cables, cleaned all connections, new higher cranking battery, checked timing a thousand times to make sure I wasn't to advanced and causing it to kick back. In the end it was my starter. the spring loaded arms that push the brushes aainst the armature were siezed so I was getting a high resisitance open across the brushes. It couldn't pull enough current to turn over a hot engine. I cleaned up the internals of the starter, freed up the arms and she spins like a champ now. I would be taking a look at the starter myself.

..yep, with compression on the engine I've seen many starters give up the ghost that I swore was good and rebuilt.

I'm just curious...if you let it roll off does it fire soon as you let the clutch out or does the engine have to turn over a few times before it fires??

Thanks for all the suggestions so far. I see I have a couple of things to try. I know it spins up fine with the plugs out using the starter. I haven't tried to spin it by hand with the plugs out after it is warm. That would be an easy test.
As far as trying another starter, that is a bit more problematic. I need to find one that will fit the ring gear and starter gear that I have in this one. I am not sure if it is the 62 match or the 52 match. I converted the engine from 12 volts to run on 6 volts...coil, starter, and I think ring gear but this was quite a ways back. I know the starter gear and ring gear match... there is no binding or grinding and it releases freely when you release the foot switch.
Checking the bearing/journal tolerances is more whee I am afraid I am headed.
By the way, I have checked for evidence of water in the cylinders and my plugs are consistently sooty black but not wet, oily or flooded. Just a dry black soot. I clean them after about every third start to help it start. I have a spark plug cleaner that runs on compressed air and grit from Harbor Freight.
I am off to give a few things a try from the suggestions above. I'll let you know what I find. Keep the ideas coming. I really appreciate the help.

The 6 volt starter has a larger-diameter armature shaft than the 12V model. I've got both examples stashed away in the shed, so I could do some measuring after it gets daylight tomorrow and let you know which one to look for. One possibility you might be encountering is some worn bushings in the starter that allow the armature to drag the pole shoes under load and bind up the starter after the armature gets hot and expands a little.
Jerry

If I remember from my starter drive hunt last year, the six volt and twelve volt have the same number of teeth but the diameters are different giving the gears a different pitch.

To the question of how recently the starter was rebuilt, it was done last week. Literally everything was replaced in two phases. First phase was everything but the armature. Last was the armature. Completely new armature, new high torque stator coils, new brushes, springs, bushings,spacers, foot switch, etc. The shop checked the Part Number of the case, confirmed it was for 6 Volts, then ordered all the new parts as specified for that part. As I said in an earlier post, I also have tried running it on 12 Volts and that didn't help when it was warm.
Based on some of the input I am getting here, I may see if I can work a deal with the local NAPA dealer to buy a rebuild starter with the understanding that I can bring it back if it doesn't solve my problem. That potentially could at least put to rest if it is still this starter. The main reason I did all the rebuild was that they told me it was probably a heat soak problem. Changing all the parts should have eliminated that possibility.
I still want to try some of the other suggestions if I can get some time tomorrow. I will let you know how things go since it seems that others have had the same problem but solved it in several different ways.
Thanks, again, for all the help. You guys are great and I can't begin to tell you how much I appreciate it. This has been a pretty humbling experience.

I had similar troubles on my 216.

Had me stumped for along time. In my case, it was that one of the springs which pushes the brushes onto the armature, had lost most of its tension. That brush wasn't being pushed to make contact hard enough. The truck would start when cold, but not hot-the weakened starter couldn't spin the engine against the increased compression.

A new spring plate thing solved my troubles, after much, much head scratching and bewilderment!

My starter had been rebuilt by a local shop, and they had missed the trouble!

It also wouldn't hurt to stick the hygrometer in the battery, and see how charged it is, although with the double battery, and 12v tests you did, I can't see that being the trouble. I've just learned to sometimes start from the beginning, after several humbling experiences like this!


The great news is, that you've been systematic and thorough so far, big cables and what-not. You'll get it solved.

I just did a copy/paste of the following phrase from your initial post- - - -

However, reading voltage at the starter it will show 6.25 volts or so.

Is this voltage reading being taken during cranking? If so, it tells me that the starter is not drawing enough current for some reason. A slow-cranking starter draws HUGE amounts of current, because the counter-EMF that's developed by the armature spinning at normal speed isn't being developed. That drops battery terminal voltage dramatically. I'd strongly urge a swap to a different starter as a diagnosis tool. Battery terminal voltage during normal-speed cranking should be somewhere in the 4.75-5.0 Volt range due to current load on the battery, even a new, commercial-grade 6 volt.
Jerry

If I had just purchased a truck with these symptoms without even knowing what services had ever been performed on it, I would suspect the starter.
I think the idea of a second starter for comparison is a good one. To me, because a starter spins on the bench doesn't mean it will deliver under load. I smell a rat... ha!
I know you'll get it resolved, buddy. Don't give up!
Jerry

Gentlemen,
Thanks for all your help. I think I have figured it out with all the input I received. By using several of your suggestions and testing virtually all of them, I have come to the conclusion the problem is in the bottom end of the engine. Especially using the test of turning it over by hand when it was cold and hot with the plugs out I have found that it is a bit harder to turn over when warm, but it is still tighter than I think it should be when cold, even allowing for an outside temperature of 43F. I also find that it will turn about 1/8 of a revolution and then grab. I then need to tick the starter to get it to move past this spot and then it will do the same thing... remember this is with the plugs out so there should be no compression to lock it up.
The electrical shop did some calling around for me and found out that swapping the starter gear was not an option. Their experts said if the 6V gear engaged with the 12V fly wheel gear it would bind within 1 rev and break something or lock up the starter. If the 12V gear were put on the 6V starter it would be loose, rattle a bit, and start chipping teeth off the flywheel. Neither would cause the symptoms I was having.
I also did find that a couple of plug wires were swapped for some reason, but that just made it run a bit smoother when I could start it. It didn't resolve the cranking issue either hot or cold.
Once again, thanks for all the help. It looks like either a swap or tear down is in my future. Kudos to you guys for jumping in and pointing me in the right direction.

Cleaning up a couple of things that I want to respond to:
1. I did not try to pull start it because I am working on it with nobody to help, so that is not a good option in general.
2. The answer to HotRod Lincoln regarding voltage. I was reading 6.14 - 6.25 volts when the batter was not being used, just installed with the key off. When I cranked it would drop to the 4.75-5.00 volt levels until it stopped rotating and then would drop even more, as expected. I also measured voltages across the cables to see if there was loss of voltage in the cable and there was no measureable voltage drop. Of course, current delivery would be a different question but I don't have a meter that could handle currents that high. If I checked the batter right after cranking it would pop back up to 6.10 - 6.20. I consider that pretty normal. When I had the charger on the batter in boost mode the voltage would be up around 6.75 - 6.9 volts and that didn't even help an appreciable amount.
My son has a 216 babbit pounder that will run. I may swap out the 235 for now and rebuild it later, once I can get the truck further along the rebuild path and can enjoy it some.

starter!

The thing that stood out to me is that the engine will not idle below 650 RPM. Now, this is a newer engine so I may be way off base but looking in the book for my '54, it calls for an idle speed of 400-500 RPM. This would seem to indicate that the problem could be something other than that of the starting system, couldn't it? Just an idea.

I hope for Bossman's sake that it's not the starter, because after all the work to swap in a new engine, imagine the frustration if it still won't start.

Kurt

Bossman,change the starter,if you can turn the engine by hand hot and cold it's NOT the bottom end,starters are much more powerfull than you're arms and hands.If the bottom end is that bad to hold a starter back it wouldn't run.


Pete

Per my comments on 1/10, I have started pulling the engine. Everything is disconnected except the engine mounts, tranny shifters and driveline. I am working on it as weather allows, but should have it out by this weekend.
I would like to clarify something from that post... when I turn the engine by hand with the plugs out it will turn but is tight enough that I have to use a glove to keep the fan blade from leaving a permanent dent in my palm. However, after turning about 1/8 turn it grabs much tighter. I need to use much more effort to get it over this point before it will turn tightly but smoothly for another short distance and grab again. You might want to say that this is because of compression, but I have all the plugs out so there will be no compression in the cylinders. I also don't think it is valves because there is no valve sound when it is running and the compression is up to snuff when I test that. Once I get it out I will take off the pan and see if perhaps the crank shims are wrong and it has too much play or has chewed up the bearings. I has never knocked like a rod or had any valve rattle.

Before you jerk it out, you might take the valve cover and side cover off and watch the pushrods etc which you turn it over by hand. Same thing with the oil pan. You might find the smoking gun!

Beginning to sound to me like it has a spun main bearing. Is that possible on a 216? Aren't the mains held in place by a small dowel pin?

I think if it were a rod it would have already started knocking after being run a few minutes.

Keep us posted on what you find.

I am more likely to believe you got a bad rebuild on your starter. The shop may be good, but they are most likely getting their stuff from china like everything else. And if the work ethic of most of the people I have worked with for the last 20 years or so is any indication, I wouldn't have that much faith in USA made parts either.(I can't believe the awful work that gets done that I have to clean up after) I don't know how long it has ran, but if you have something that tight it won't run long, and you would have large amounts of some sort of metal in the oil I would think. I mean if the guy before you was driving it and you have been driving it, I would tend to think it wasn't main bearings or piston clearances, I may be entirely wrong of course, but at least just drain the oil and see what you get. You can also have the starter tested for bad components. Your very good shop should be able to do that I used to know how to do that but its getting fuzzier each year.

if you are using welding cable for starter leads, verify your connections of the wire end and the cable you can get the proper voltage, but lose it when there is a heavy load. I saw nothing about you checking the timing, if it is way advanced it will give similar symptoms, and still run once it is started. I drove my truck around for about a year like that. also if you don't have the carburetor adusted properly (you said you replaced the carb) you will get weird idling symptoms. I also drove the truck around for the same year like that as well (the mustang too, I just didn't have the time to fiddle with it then) The one thing I am pretty sure of is that it isn't too tight bearings...

Broke,

he said he had pulled the spark plugs and tried to turn it by hand. That it was hard to turn, and would get harder then could turn it a little at a time.

With the plugs out it shouldn't be any problem turning that engine over by hand.

I think he has eliminated the starter. It sounds like something in the engine is binding.

may be but I would at least drain the oil and check for metal, if you got something binding that hard you will have shavings in short order. Also I don't know how he is attempting to turn the engine by hand, using the fan would give you a lot of leverage, however if you are just using the balancer you won't get much, I also don't know how long it has ran, 2 minutes, or has it ran for hours. (total run time) I seem to recall he said he had redone the head,there is another place to look for problems. He said it came out of a running truck, and he has ran it for some indeterminate amount of time, leading me to believe the lower end is fine. and he said it hangs up about 1/8 of a turn, (or is it about 1/12 of a turn when the next valve spring starts to compress making it harder to turn by hand) I'm still going with the starter, timing or carburetor (regarding the idle issue) I also don't know how well it ran before he did the extraneous work. There are many situations during reassembly when things don't get done correctly, I spend a considerable amount of time trying to figure out what someone else has done to any number of machines at work, that aren't working up to par. By his own statements he has changed several things at one time. I would go back through everything that has been changed and check that out before I tear it out of the vehicle.

oh there it is, he is using the fan, however I have a hard time believing if you are pulling that hard on the fan that the belt isn't slipping, are you sure it isn't the water pump? Or Generator/alternator. Or how tight is the belt? Too tight a belt can cause bearings to go bad in the above mentioned accesories. One thing to add is check inside the filter (if you have one) for metal. I always assume everyone knows this, but it isn't always the case. I also don't know what you consider "tight" if it is as tight as it would need to be for ME to hurt my hand it wouldn't spin as easily with the starter as stated in your comments. It may have been mentioned but there is a lot to cover here. How hard is it to turn by hand when it is cold? if it only gets hard when it is hot, there could be piston/ring clearance issues (already mentioned I know) but then again there would probably be metal in the oil, and here again I can't see it running for any length of time in this condition. There is no way I would tear an engine apart without examining the oil first. But this is all academic since the patient isn't in the room any more.

A bearing in the water pump or generator/ alternator could be a good candidate, but I think the starter would go ahead and turn it. The belt would likely slip. But it would be good to check those.

Checking the oil for metal is another very good idea too. If there is any in the bottom of the pan, it should show up when he drains it.

Be interesting to see what the problem is.

Hi Guys. STill lots of comments so I will see if I can fill in some of the blanks that are mentioned.
1. By tight, I mean that using the palm of my hand on a fan blade will leave a mark and is painful. Now, I don't have the strongest hands but using a shop rag will dampen the pain. I am using the fan blade to turn it, not the crank pulley.
2. Yes, the fan can be made to slip when the engine grabs. I use the old method of pressing down on the fan belt to help overcome the slipping when I am trying to turn by hand. When looking from the front of the engine, I am turning clockwise (same direction the starter turns it).
3. The plugs are pulled when I am turning by hand, so timing, I believe, is irrelevant. There is no compression so the actual position of the valves, distributor, etc. don't affect how it turns.
4. The driving I may have mentioned in the past was several passes at a time from the end of my driveway to the shop... about 200 feet, back and forth while I was testing the brakes, clutch, tranny, Brownie, etc. This gives the engine about 20 minutes of run time under some loads in forward and reverse since I can't turn the truck around on the driveway. I have done this maybe 5 or 6 times total.
5. At other times I have just started it and let it idle for 10 or 15 minutes to let it warm up. If I keep the idle above 600 RPM it will keep running. Once the RPM drops below that it will want to stall out and once it dies I can't get it started until it cools back down. When I say cools down, the temp gauge is showing around 180... it is not boiling over, steaming, etc.
6. There is no water in the oil or vice versa when checking the dipstick or radiator.
7. I do plan on pulling the pan after I finish pulling the engine to see what I can find. I have been stalled on pulling it because of snow and rain. The truck is outside since it won't fit in my shop. I currently have everything but the motor mounts and tranny mount undone. So it is coming out no matter what at this point.
8. This engine came out of a pickup that was being junked but I did hear it run before it was pulled. Unfortunately, I did not see it run for any length of time and they jumped it to start it. I installed the starter, new coil, etc. when I converted it to 6V for my application.
9. Bearings in Water Pump and Generator are fine. The water pump was gone through before I installed the engine because I had to convert it to a short shaft to fit in the '49 and I had a specialist rebuild it before I put it in. The generator spins smoothly and had good output to the regulator.
10. Again, my complaint is the slow turning when cranking even with cold. It just seems to turn even worse when warm. Timing is set with a timing light so the ball is on the needle on cylinder 1 with the unit idling at around 600 - 650 RPM. Vacuum advance is sitting around mid range and does move on acceleration. Distributor is on "0" for fuel compensation. Vacuum is around 21" at idle at the base of the carburetor where the hydrovac taps in. It starts right off if I prime the carb when it is cold and pull the choke. It then idles rough until I push the choke in and it will smooth right out but at the higher than desired idle.
I think that covers it for now. I am amazed at all the ideas that are flowing on this topic. I hope this thread will help others with similar problems.

let us know what you find, it still sounds like a starter to me, with a carburetor that needs adjustment, are you sure the one you put on is good? before you tear it apart see if it turns well by hand and isn't something on the other end, in the clutch or transmission area. I just have a hard time believing you ran and engine for 3 hours bound up that tight and it still runs.

Howdy from Bossman. I figured I would give you the latest update as of about 20 minutes ago. I was talking to a good friend who specializes in rebuilding old cars and trucks, especially rare ones. He also has been a heavy equipment mechanic for a few decades. He said he would be willing to bet me any amount of money (if he had any) it was the starter. Boy, that sounds familiar. He lead me into his shop and pulled a 12V starter off a 1960-ish pickup that he had sitting on the shelf. It was rebuilt, then put in his pickup and worked just fine. Then he pulled it off when he scrapped the engine for other reasons. He told me to put it on my engine and give it a try. I took my 6V off, installed the 12v and hooked it up with jumper cables. Remember, nothing else is connected right now because the engine is about to come out. I jumpered it to my 1994 Suburban so I know the battery is good. Guess what... it doesn't turn over any better than with the 6V that I had in it. It does make some extra gear noise that I don't get from the 6V so that tells me the other "experts" were right and my 6V is matched properly to the flywheel. I hope this puts an end to the suggestions that it is the starter, cables, battery, etc. By the way... the 12V starter did turn it over without plugs in it, just like the 6V, but actually not as fast. I think that is because of the expected clash between the starter gear and the ring gear. With the 12V starter it sounds like a chain drive instead of a gear-to-gear mesh.
The next step is to pull the engine out and shotgun the 216 in it. I can't do it this weekend because of a previous obligation. My luck it will be raining next weekend. I will keep you guys updated as I move on.

Because a 6 volt system operates on half the voltage it uses twice the amperage to run the starter.
I have seen a number of starters that acted as yours that only needed all the brush connections tightened.
All connections need to be as clean and tight as you can get them on a 6 volt system.

I just don't think this is starter related. With the spark plugs out he should easily turn the engine by hand using the fan. Even with the plugs in it should not take a lot of effort to turn that engine by hand.

My 261 turns by hand easily enough with the fan and it runs fine.

With a 6 volt starter and flywheel that matches if he were to apply 12 volts to the starter it should really make that engine whirl over. You can do this providing you don't just sit on the starter. You can burn it out fast if you crank for any length of time using 12 volts on a 6 volt starter. But I have run a 6 volt starter on 12 volts with no problems.

I'm still betting on a tight main bearing.