The Stovebolt Site Forums The Shop Area Engine Shop Turning over too slow... Maybe?

So I havent done much since the last time i was on here, but my shop teacher made a good point to me. My truck is running off of a 6V battery, everything is 6 volt. we've got the timing set, points gapped, spark ect. but still no start. i havent done a compression test b/c i cant find my tester and i really dont wanna go spend $40 on a new one. When we've been cranking the engine over its almost started. it'll turnover at a medium pace, then it goes fast and we hear a couple small tings in the engine, and we hear compression. then it turns over really slow and will repeat this over and over again. when i tested my battery it was at 5 volts... ive charged it and filled it up with destilled water and it'll charge back up to 6 but keeps draining to 5. i dont have a amps tester with a big enough scale, so i dont know what they might read.

Josh,

Are you using heavy duty jumper/battery cables? You will need 2 gauge or thicker battery cables to get the best spin out of your 6v starter.

If it is just nearly starting, I would try this: Try powering the coil separately with your battery charger. That way it will get the full voltage while the starter is drawing current. Also, you might want to move the timing in very small amounts either way to see if that helps.

I agree with timing being part of the issue. You should not have to crank an engine long once you have fuel at the carbs. Its not starting for a reason. Sometimes you need another set of eyes on a situation of just double check everything.

I would also put another battery in parallel with starting battery.

The variation in cranking speed indicates one or two cylinders may be firing. Possible causes
low compression on one or two
double check that distributor is in right way and not 180 out.
Double check that you have the right wires going to the right plugs (dun that one)

A short shot of propane down carb while cranking may help.

Dan Bentler

Sorry this took so long, been a bit busy with my dogs getting surgery.

Anyways, my dad bought me all the battery cables which are 7 or 8 gauge, im trying to find a place that carries 2 or 0 gauge.
Ive found TDC by taking off my valve cover and waiting for the first exhaust and intake pistons to be up, i remember somebody telling me to make sure my rocker arm is lose? can somebody clear that up for me? i'm a little lost. i would put another 6 volt inline but moneys tight right now so i cant afford one.

By checking to see if the distributor is in the right way, how do i tell?

Here's a link to a vid of the truck turning over (I'll upload another one with a fully charged battery and when it catches), just so you all can see how slow it turns
: Flickr

sounds like the cables might be the problem [as well as a weak battery] - the usual cables around now are for modern 12V systems, if you can't find heavier at any FLAPS, get some welding cable and make your own - and make sure you have a good ground cable direct from the battery to one of the starter mount bolts

Bill

Why not use a 12 volt battery temporarily just to get the thing running? I did that with mine and it fired right up.
Chris.

Ive tried a 12 volt battery but it just does the same thing, and smoke my starter....
What kind of compression should I be looking for when I do a test?

Josh, I'd like to hear that you have pulled the starter , cleaned the commutator and brushes and made sure the brushes floated freely in their holder . A bit of lube on the bushing too

Then I have an observation.

On all my 6 cyl chev car/trucks, the #1 plug lead goes to the 4 o'clock position on the dist cap. I see yours goes to the 12 o'clock position.

I have no idea if this is influencing your lack of go , but that's a thing I see.

Did the bigger cables help spin the engine faster? It sounds REALLY slow on the vid.

I have used 12v on my truck for over 14yrs. just short stands on the starter. It's ok.
For me, short stands is 3 to 5 seconds , if it hasn't started by then , there is a problem. (latest being weather related , damp in the dist cap)

Compression pressures I have noticed range around 110 to 130, for an engine that drives fine, but its more important that they are all similar , say within 5 pounds of each other.

Remember to have all the plugs out so it spins freely when doing the test.

I wouldn't bother doing anything until you get big cables on there. A compression reading at that speed probably wouldn't even register.

worn bushings in the starter will cause it to crank the engine slower than normal.

it is easy to time these engines 180 out.

Dusty, If I read your post correctly you run a 12V battery in your 6V system and you have not converted it to a 12V system, correct? I've always wondered if you could and what would happen if you did. My truck turns over slow (not as slow as Josh's) and always wish I could make it spin faster. If simply dropping in a 12V battery would fix my problem and not hurt anything I'd do it today!

Spot

When i put my dad's 12 volt off of his truck and tried starting my engine, the battery cables got hot and my starter started smoking... I think i remember a guy at Lordco saying if the battery cables get hot there's is something wrong with the cables.
i can see why the cables where so hot when using the 6 volt battery on the 7 guage cables but why still with the 12 volt battery?

I'd say worn bushings. The 12 volt battery should not smoke the starter and nothing should even get warm unless you ride on her for more that say 20 seconds at a time. The 12 volt batt should spin the starter really fast...unless the starter has issues.

The max voltage of the 6 volt is 7.5. The engine timing may be far advanced. If the ignition fires when the piston is deep into the stroke, the pressure is high. This will cause the starter to drag. Set the timing at TDC. You can set the spec timing after you get the engine running. You may be 'hearing' pre-ignition.

Josh, Dusty said "On all my 6 cyl chev car/trucks, the #1 plug lead goes to the 4 o'clock position on the dist cap. I see yours goes to the 12 o'clock position." Do you know for a fact that your plug wires are on in the right order? I looked briefly at your pictures and noticed that your plug wires are not run anything like mine. I would double check that, look at pictures of other trucks in the Gallery section if it helps, I do.

Twotone, i have no idea if I have it at TDC, ive never worked with a distributor so thats all foreign to me. i believe im close to tdc only because i have it set to where the first intake and exhaust pistons are up with the valve cover off. maybe my distributor is advanced or retarded too much... HOW DO I TELL??

which is the correct timing mark on the flywheel for my '51 gmc 228?
The triangle, the bb, or the UDC letters?? so far everybody has told me something different.
when i set what i believe is tdc from the exhaust and intake way, the mark closest to the pointer is UDC

I shall take the starter off tomorrow after school and check the bushings... anything specific i should be looking for?

Stick a piece of wire in your #1 spark plug hole and feel for the piston to top out. At that point you will be on #1 or 180 degrees out of time. you should be able to check your plug wires and make sure they aer in the rite position. lud

UDC =Upper Dead Center
the BB is set at 5 degrees before UDC

5 degrees before UDC is where you want to set the distributor for a stactic timing. Leave the distributer clamp loose so small adjustments can be made while you crank the engine over.

OF COURSE THIS WILL BE DONE AFTER A COMPRESSION TEST.

Below is a link to the 1955-1959 GMC maintenance Manual. This online source gives specs and tune up sequence for the gmc 270 and 302 motors. The 228s aren't much different, so these spec's will be close. Best bet for you would be to get the Maintenance Manual for your specefic truck.

http://chevy.oldcarmanualproject.com/gmc/5559mm/5559mm365.html

From previous posts, there was an uncertainty to which engine you have, and if your truck was American or Canadian.

Have you confirmed your engine is a 228 or is it a 216 as was used in Canadian trucks, or some other motor that has been replaced by a previous owner?

John

Edit: I just saw your video and pictures of your engine. Your motor is not a 228 GMC. It is very likely a 216 Chevy motor as was standard equipment on a Canadian GMC trucks. As such, the specs for the GMC motors I linked will not due you any good. Search for the timing spec's for a 216 chevy motor. The BB should be close enough for static timing on the 216.

"i can see why the cables where so hot when using the 6 volt battery on the 7 guage cables but why still with the 12 volt battery?"

Simple answer: When Electric current travels through a conductor, it produces Heat and Magnetism. 12 volts will push twice as much current as 6 volts. Therefore it stands to reason that it will produce more heat in the conductor than would 6 volts.

Measure cranking voltage at the starter, one lead on starter frame and the other lead at the copper post where the cable connencts. Should measure 4.5v or more. You can measure voltage drop on each cable and each connection while cranking. Doing this you can determine you're losing voltage. Any hot connections or cables are trouble points. Don

I'm assuming the truck is a 51 GMC. It's my understanding that GMC's of that era are POSITIVE GROUND. Has this been taken into consideration throughout battery jumping exercise?

I don't know the history of this truck, but if it was running when parked, it should run now. Why not charge up the 6V, and tow start it.

Good luck

sfsutton

This truck is Canadian, and therefore 6 volt negative ground. In an earlier thread, it was sugested the truck was positive ground. Canadian gmc was more like a chevy than our American gmc

How would I tow start it?

My battery cables got hot too when I used 4 gauge. Now I have 2 gauge cables for both the positive and negative and don't have that problem.

You have a nice truck. Don't give up hope

Josh, Tow starting your truck is not a very good idea. The idea is to strap it to another vehicle using a tow rope, and dump the clutch with the transmission in 3rd gear to turn the engine over. While this will work on some trucks, it is not reccomended for a truck that has been sitting for some time with questionable mechanics and even more questionable brakes.

Best advise for you would be to get the proper guage cables, get a new/rebuilt starter, or rebuild yous starter if possible. It is likely the windings on your starter are starting to fail from trying to crank the engine too much.

When you are satisfied with the operation of the starter, run a compression test on your motor.

1st thought, You have not stated when the last time the truck has run? Has it had work completed since it was last run, like main bearing caps roped and shimmed? Can you turn the engine over by turning the fan by hand? Hopefuly yes?

2nd thought, Could there be corrosion internally in the cylinder walls?

If it hasnt been run in a long time, its not bad to pull all the plugs, squirt a few drops of oil in each and try turning it over with out the plugs. The engine should spin very well with no compression.

If you are still turning slowly and the answer to the 1st 2 thoughts are "no" you have starter issues and need a rebuild.

good luck, looks like you have a great truck!

Ive taken apart my starter and it looks like it was rebuilt sometime just before the truck was parked to sit, ill through in a link at the end of this message.

Oldblue, the last time the truck was on the road was in in 1982, i have no idea what work has been done since the originally owner has passed. and yes i can turn the engine over by hand from the fan blade.
For corrosion in the cylinder walls, i will be draining the engine of oil and pouring some diesel fuel through the spark plug holes... hopefully that will clean some things up.

For when i get my proper gauge cables, i should run one positive from the starter to the battery, but for the negative, should i just by-pass grounding on the frame and go straight to the battery or go with a ground cable on the frame??

Heres a link to some pics of the starter: Starter

Sorry the vid is so blury

The ground cable on the frame is good to assist the lights etc .

Ground the battery to the starter mount bolt for best effect for starting.

edit, if your battery falls to 5v quickly as you said in your first post , then I think it is dead.

I agree, the battery shouldn't quickly drop in voltage after being chargedbut I would check that with the cables disconnected. Take it to any battery shop they can give you a health check if you leave it with them for a day. If you need a new battery, don't go for low cost, you need lots of cranking amps.

The slow turning of the engine may be the results of the friction drag at the cylinder walls/pistons. I will suggest bench testing the starter. Jump it with a 6 or 12 volt battery. pos to the switch lug, neg to the starter body. the short test should have the starter turning with high RPM's. Any friction drag with-in the engine will cause the 'too slow' condition. With the plugs removed, try turning over the engine.
If the commutator is dirty, it may be cleaned with a piece of wet/dry 400 sandpaper. However, if the commutator is rough, pitted, or out-of-round or if the insulation between the commutator bars is high,this condition suggest a rebuilt starter may resolve your problem.
Good luck

Just some quick information to find Top Dead Center.

First remove all the plugs, so you can turn the engine easy and get a good look at them.

Get a 12" long small diameter wood rod or length of wire that fits through the spark-plug hole.

Remove the valve cover.

Rotate the engine by hand and watch in the first two rocker arms. The very first one is the exhaust valve rocker arm, the second one in line is the intake rocker arm. Go two complete turns of the engine watching as rockers move up and down. You have compression stroke (rocker arms not moving,piston coming up), power stroke (still not moving, piston going down), exhaust stroke (first one in line opening, piston coming up), and intake stroke (first one closing and second one opening, piston going down).
As the second (intake) rocker arm is opening, put your stick in the first spark-plug hole. The intake valve should be closing as the piston reaches the bottom of the cylinder. Now slowly turn the engine till the piston reaches the Top Dead Center.

You should be able to wiggle the two front rocker arms just slightly. You should also see the UDC mark in the opening.

Back the engine up 1/8 turn and return toward UDC but stop when you see the BB marking. This is the 5 degree timing mark.

Pull your distributor cap off and look to see where the rotor is pointing. Wherever its pointing is #1 spark-plug wire post.

Return the cap to the distributor and start the firing order from number one post you just found. In a counterclockwise wise direction, #1 4 2 6 3 5.

Reinstall all but number one plug and wire according to the firing order. Install the #1 plug in the wire and lay the plug across the head someplace so its grounded. Use a jumper lead if you have to, just make sure the steel body of the plug is grounded.

Turn the key to run, DON'T rotate the engine, just have key on, engine not trying to start.

Rotate the distributor in quick short turns to see if the spark-plug fires. Keep twisting in short spurts as the plug fires trying to get closer and closer to the point of intersection between firing and not turning the cap anymore.

Once you get as close as you can with the distributor and the plug firing, lock it in place semi tight and install the plug and wire.

You should now be with in a few degrees of the proper timing, on top dead center, #1 plugm and have the firing order correct.

Joe

A couple of more ideas or suggestions.

First, you need 1-0 or 2-0 welding cable for battery cables. The bigger the better. Six volt takes twice the current of 12 volts so you need the large cable to handle the huge current load.

Ground the battery right to the starter. Run secondary grounds from the engine to the frame and engine to the cab sheet metal. Clean the metal of all paint and rust, and use star washers to bite into the metal and cable end.

Charge the battery overnight, have it check if theres any doubt about weathers its good or not. Useing a good charged 12 volt battery will work for test runs. Be sure to shut off any lights and accessory's, 6 volt things don't like 12 volts. I would unhook the fuel gauge to, they really don't like 12 volts.

Spin the engine with the plugs out and motor oil in the holes. Not so much it sprays across the engine bay, just enough to lube the cylinders.

Change the oil in the pan if its old and dirty.

Have the engine full of coolant, be sure and burp the coolant system. Drilling a small hole in the thermostat lets the air out but doesn't effect the cooling. 216, 235's are bad about holding air in the engine.

Have fresh gas in the carb. Use a clean fuel jug with line going to the pump, bypassing the trucks fuel system. Once running you can swap it back to the trucks.

Have fire extinguisher handy, timing light, wet towel (to snuff out small carb fires), and some help close by.

Joe H,
Great info and explanation!!! That should clear it up for him pretty well.

Chris

Thanks Joe!
i'll Give that a try once the weather clears up.

thanks to everybody else for all there help too!

"Your motor is not a 228 GMC. It is very likely a 216 Chevy motor" {edit by bigswingdaddy} post #749378

If the engine is infact a 216, the firing order is 153624. Note: The firing order should be cast in the intake manifold. The rotation of the distributor on the 216 is clockwise.

would my engine have "Chevy" Stamped into the side of the block then? because mine has GMC stamped into the block, and intake manifold....

Josh - you sure there's a "C", not just GM?

they're both made by General Motors, as I'm sure you're aware

Bill

Im aware that they're made by GM, just thought it would've made sence if they stamped chevy or gmc in the block.

Ill check again to see if it says GM or gmc