318 hard start when hot

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NJen42

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Hey folks, new to the forum, and to mopars in general. Just recently inherited a 79 power wagon w150 with the 318 2bbl. Not very familiar with dodge or chrysler products in general... I seem to have an issue where my truck will have a hard time starting when it's hot.

From a cold start, it will run and drive fine, and sit and idle fine. After I've driven it any amount, my first test was a half mile little stroll around the block, then let it sit for about 5 minutes idling. When I went to hop back in, I threw it in gear, and it immediately stalled out. When I went to start it again, it cranked about half a turn, maybe a full crank, and is acting like it's got a dead battery, very very sluggish crank. Checked battery, still 12.3, little low but nothing I'd imagine would give issue to start. Just to be sure, I tried jumping it with another running vehicle, to which it acted the same way.

Seems almost maybe like a vapor lock issue, or possibly timing? I'm not really sure.

Let it cool down for an hour or two and it starts right back up as if nothing ever happened. I've spent the last probably 4-5 days now reading just about every forum thread on here and other similarly mopar based forums, watching every youtube video I can find, and I'm just not sure, no exact answer or way to figure out what's going wrong here.


If anyone could give me a little assistance, I would appreciate it a lot. Cheers and thank you.

Edit: Also, the first time I noticed this issue (I have had the issue about every time I've driven it) of hard cranking, it also seemed to lose power at the key in the start position. I had buzzers, good lights, all the inside electronics, but no starter. It cranked hard, but did crank, by jumping the starter relay. This issue with loss of starter at the key only happened the first time I experienced the hard cranking issue, never again since.

Edit 2: I may have placed this in the wrong subforum, I meant to post it in the

Small Block Mopar Engine​

subforum


-NJen
 
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Make sure you have 8-10 volts at the coil when cranking on the positive side with the key. When running should be about 6 volts. If good there, maybe insulator under carb to prevent heat soak of carb.
 
Need to do the Dodge Dakota Mini Starter upgrade.

High torque, fast spinning starter. They rob way less juice from your ignition too, so naturally it will also start easier.

Enjoy, it's the very first upgrade to every mopar....


☆☆☆☆☆
 
The first think to check is the battery. 12.3 is discharged. Charge up the battery, either with a charger or idling the engine, then let sit for a few hours to dissipate the surface charge. Good battery should measure 12.6-7 v. If lower, I would get a new battery.
 
The first think to check is the battery. 12.3 is discharged. Charge up the battery, either with a charger or idling the engine, then let sit for a few hours to dissipate the surface charge. Good battery should measure 12.6-7 v. If lower, I would get a new battery.

Battery was at 12.6 until trying to start it hot. That half a crank to full crank brought it down to 12.3. Is a new battery, just bought it pretty recently. I wouldn't consider 12.3 discharged though, a bit low, but not discharged until under 12v. I can still start my chevy with a 454 on that 12.3 like it's nothing.

As far as the suggestions go, I'll be checking out the coil and checking all my grounds today. Reading into the dakota starter switch, seems pretty quick and easy, so I'll be buying one of them here soon as well.

Appreciate the advice so far guys, thank you.
 
I would charge and test the battery, do a starter draw test and a alternator output test. If you don't have the testers to properly do that, find someone or some shop that does. It does sound like a starter/ battery issue but unless you test it properly, my guess is no different than yours. By throwing parts at it you may find the cause eventually.

For example, here is a good video about testing just the battery. The battery, starter draw, and alternator output all need to be tested before any other testing. Never overlook the obvious and start at the beginning.
 
Here's an alternator output test using the same type of carbon pile tester.
 
I would charge and test the battery, do a starter draw test and a alternator output test. If you don't have the testers to properly do that, find someone or some shop that does. It does sound like a starter/ battery issue but unless you test it properly, my guess is no different than yours. By throwing parts at it you may find the cause eventually.

For example, here is a good video about testing just the battery. The battery, starter draw, and alternator output all need to be tested before any other testing. Never overlook the obvious and start at the beginning.

Battery is known good. It's been sitting on the floor in my house for about 3-4 days now because it's been cold out and I haven't been messing with the truck. It's currently sitting at 12.74v

Is there any way to do a starter or alternator load test with a simple multimeter instead of a carbon pile tester? I have a Fluke 107 multimeter, not a clamp style. Most of the videos I've looked at show using a clamp style multimeter or a carbon pile tester.

If I have to take it to a shop I suppose I can, but considering if I drive it anywhere it won't start for at least an hour or two, I'm trying to leave that as a last resort.
 
Battery is known good. It's been sitting on the floor in my house for about 3-4 days now because it's been cold out and I haven't been messing with the truck. It's currently sitting at 12.74v

Is there any way to do a starter or alternator load test with a simple multimeter instead of a carbon pile tester? I have a Fluke 107 multimeter, not a clamp style. Most of the videos I've looked at show using a clamp style multimeter or a carbon pile tester.

If I have to take it to a shop I suppose I can, but considering if I drive it anywhere it won't start for at least an hour or two, I'm trying to leave that as a last resort.
You will need a tester that measures amps and it will have an induction clamp on it. That's why the bog testers have the large clamps and cables to carry the load. You can't put 200 amps through a multimeter with 18 gauge leads and probe tips (for example. Search you tube for videos. Look at a few different ones to understand the basics they all have in common.
 
Battery is known good. It's been sitting on the floor in my house for about 3-4 days now because it's been cold out and I haven't been messing with the truck. It's currently sitting at 12.74v

Is there any way to do a starter or alternator load test with a simple multimeter instead of a carbon pile tester? I have a Fluke 107 multimeter, not a clamp style. Most of the videos I've looked at show using a clamp style multimeter or a carbon pile tester.

If I have to take it to a shop I suppose I can, but considering if I drive it anywhere it won't start for at least an hour or two, I'm trying to leave that as a last resort.
The only thing the 12.74v reading is telling us is the static charge of the battery and nothing else.
 
The Sun Vat 40 tester is probably the best for the complete system test. Many shops still have them after 50 years of use.
 
The connections at the battery, starter, and grounds at the block are all suspects for hard cranking. A set of headers cooking the starter will do the same thing. A weak starter and or a weak battery with a dead cell will also cause the same symptoms. Last but definitely not least is the initial timing. Too much initial will cause the exact thing you’re describing when hot.
 
Not to forget those replacement battery-post ends that are held on by a strap, that, when you take them off, they are packed full of corrosion, sometimes a few inches up inside the insulation.
Or the skinny cables that barely light up your dash-lights.

About the only things that make for slow cranking of a fully warmed up engine would be as already discussed, or
tight skirts, butted rings, or water in the cylinders.
Bad timing ? maybe but not usually, if it idles nicely.

A long crank time, on the otherhand, could be a sign of a flooded engine, or a weak coil supply voltage, or one in the which the Transfers slots are nearly closed.

As to the one time that it would not crank by key, here's the secret;
That circuit has so many potential trouble spots that you absolutely NEED to check it out or risk burning down the truck.

Here's another trick.
turn the headlights on before cranking it. If they go out during cranking, then your starter is robbing all the battery has, OR the power-supply line is compromised.

The first clue you gave was that boosting it did not change the slow cranking. That's usually because the boosting car was jamming all it had into a bad battery, leaving nothing for the starter. When that happens to me, I disconnect the bad battery, and just use the one from the boosting car, thru caples that I have jammed hard into the lead cable ends. If it now cranks normally, the battery is compromised. OFTEN, I find them low on acid, or dry
 
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The connections at the battery, starter, and grounds at the block are all suspects for hard cranking. A set of headers cooking the starter will do the same thing. A weak starter and or a weak battery with a dead cell will also cause the same symptoms. Last but definitely not least is the initial timing. Too much initial will cause the exact thing you’re describing when hot.
And it starts ok after it cools off so it's heat related.
 
Not to forget those replacement battery-post ends that are held on by a strap, that, when you take them off, they are packed full of corrosion, sometimes a few inches up inside the insulation.
Or the skinny cables that barely light up your dash-lights.

About the only things that make for slow cranking of a fully warmed up engine would be as already discussed, or
tight skirts, butted rings, or water in the cylinders.
Bad timing ? maybe but not usually, if it idles nicely.

A long crank time, on the otherhand, could be a sign of a flooded engine, or a weak coil supply voltage, or one in the which the Transfers slots are nearly closed.

As to the one time that it would not crank by key, here's the secret;
That circuit has so many potential trouble spots that you absolutely NEED to check it out or risk burning down the truck.

Here's another trick.
turn the headlights on before cranking it. If they go out during cranking, then your starter is robbing all the battery has, OR the power-supply line is compromised.

The first clue you gave was that boosting it did not change the slow cranking. That's usually because the boosting car was jamming all it had into a bad battery, leaving nothing for the starter. When that happens to me, I disconnect the bad battery, and just use the one from the boosting car, thru caples that I have jammed hard into the lead cable ends. If it now cranks normally, the battery is compromised. OFTEN, I find them low on acid, or dry
headlights stay nice and bright when cranking, even the plow lights. I will check all the connections again but have checked the battery and starter connections, solid and I have cleaned them all. I've been reading into the ignition circuit and it seems simple and everything seems clean, not really sure what's going on there. The battery I have in it (that I posted earlier was at 12.7v) was bought in december, like I said earlier it will start my chevy 454 at 12.3v after trying to crank this thing over. Have not tried cranking from a good running vehicle yet, but will try that as well.

I did try to crank it again earlier after running (idling) in my driveway for about half an hour, and it wouldn't even engage the starter. I'm starting to believe that is the culprit, and ordered a new one. I'm not super against throwing parts at it if they seem like they may be failing, but I'm not made of money either.
 
Take the jumper cable and hook it up to the battery neg and then ground to the block with other end. See if it starts easier.

Bad cables will act like your situation. Heat reduces load carrying capacity.

If the light stay bright when cranking, look closely at the pos cable.
 
Take the jumper cable and hook it up to the battery neg and then ground to the block with other end. See if it starts easier.

Bad cables will act like your situation. Heat reduces load carrying capacity.

If the light stay bright when cranking, look closely at the pos cable.
so negative battery jumper (from other vehicle) to negative battery on the dodge, and positive jumper to block? Seems sketchy, or I'm not understanding..

Or you mean jumping negative from my dodge battery to the block?

Sorry if I seem a little ignorant, I'm not much of a mechanic but am trying to learn and also this is one of very few pre 90s vehicles I've messed with. Mopar in general for sure though. Lot different than the chevy's I've worked on
 
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so negative battery jumper (from other vehicle) to negative battery on the dodge, and positive jumper to block? Seems sketchy, or I'm not understanding..

Or you mean jumping negative from my dodge battery to the block?

Sorry if I seem a little ignorant, I'm not much of a mechanic but am trying to learn and also this is one of very few pre 90s vehicles I've messed with. Mopar in general for sure though. Lot different than the chevy's I've worked on
You are just using the jumper cable as an extra ground.
 
Battery is known good. It's been sitting on the floor in my house for about 3-4 days now because it's been cold out and I haven't been messing with the truck. It's currently sitting at 12.74v

Is there any way to do a starter or alternator load test with a simple multimeter instead of a carbon pile tester? I have a Fluke 107 multimeter, not a clamp style. Most of the videos I've looked at show using a clamp style multimeter or a carbon pile tester.

If I have to take it to a shop I suppose I can, but considering if I drive it anywhere it won't start for at least an hour or two, I'm trying to leave that as a last resort.
"Battery is known good" - By WHAT method? If it's just you saying it's good, then no, it's not "known" at all. Has it passed a load test? I always do 3 in a row allowing about 3 minutes for the battery to recover between each test.

You can use a simple VOM to see amp draw. Most of those clamp type cost a bit for a VOM, so I would just get a small handheld carbon pile tester. You can do a lot more with one. Carbon pile to me is the best. It's simple, affordable and they last. I got this one when I worked at O'Reilly several years ago and I've abused it quite regularly.

LOAD TESTER
 
"Battery is known good" - By WHAT method? If it's just you saying it's good, then no, it's not "known" at all. Has it passed a load test? I always do 3 in a row allowing about 3 minutes for the battery to recover between each test.

You can use a simple VOM to see amp draw. Most of those clamp type cost a bit for a VOM, so I would just get a small handheld carbon pile tester. You can do a lot more with one. Carbon pile to me is the best. It's simple, affordable and they last. I got this one when I worked at O'Reilly several years ago and I've abused it quite regularly.

LOAD TESTER
Known by the fact that it is good voltage, will start my 454, and was bought less than december. I'm pretty sure if it wasn't "good" I couldn't start a chevy 454 on 12.3 volts
 
As I've obviously said I'm currently without a good amp tester, just a fluke 107. I can promise this is a solid and good battery. It starts engines much larger than a 318 on a much lower draw than it starts the 318 on at full capacity.
 
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