Cranking way too slow experts question 4.0

[Ecomike]

Trying to help a lady 1500 miles away..... 4.0

So far replaced the battery, replaced the starter, was sure that solve the problem. Cables and clamps are good. Same problem we had with 1 year old starter and 1 year old battery.

While cranking the battery voltage drops to 9 volts, and the engine is doing maybe 5-10 rpm at best.

When they first started they jumped the old battery/starter and got it to run and the battery voltage was 13.7 volts while running.

Oh, it is 97-98 ish rig.

But then I had the person helping her clean the clamps and cables, test the cranking voltage. it was dropping to 9-10 volts while cranking and that is why we replaced the battery and starter. Battery first, then later the starter. Even with new Battery and Starter, it will now barley turn over.

Plan is to tow it and have the valve cover removed, look for obvious issues and than hand turn the crank shaft to see what might be wrong top side.

Keep in mind, it ran earlier after having an initial issue (unclear what the original issue was).

The last 2 start tries, it was like it made 2-3/6ths of a full rotation, second try was worse 12 then it was like it was trying to rotate but was bushing on a brick wall, fully bogged down.

Since the 4.0 is not an interference engine, and it ran after the earlier problems, with a jump start, I leaning towards a valve/valve spring/lifter/rod issue, but I am not even sure that could cause this problem.

So I am a bit stumped. Looking for expert ideas from engine experts on what could happen internally and cause this. I do not think a stuck closed exhaust valve could do this? As that would be the same as a compression stroke right? The engine should still rotate / crank way faster then 1-5 to 10 rpm????

 

[Ecomike]

What if a valve spring busted and the valve fell and is jammed up on the piston top creating a bind???

Anyone ever heard of that happening? Sounds possible to me, but the keeper at the top of the spring would have had to fail too for the valve to be able to fall???

 

[Anak]

Do you have full confidence in the person who is helping her?

I ask because I have too much experience dealing with people who go through the motions without actually performing the task, and with other people who simply don't seem to see what they are looking at.

 

[8Mud]

I'd start with the basics, air filter full of water. Possibly water in a cylinder or two. Pull the plugs and then try turning it over. Make sure the A/C is turned off. Check the A/C and power steering etc. to make sure nothing is binding.

Less likely is the new starter isn't any better than the last starter.

 

[Ecomike]

I had not considered water as two people verified the oil, on the dip stick looked new (which it is), no water in it at all, no reports of water in the exhaust, or coolant loss (yet), but it adds to the reason to pull the spark plugs for sure.

I would like to hope the brand new durajunk starter is the issue, but everything so far points to something that is going wrong, intermittently top side.

Thanks that gives me some ideas.

I'd start with the basics, air filter full of water. Possibly water in a cylinder or two. Pull the plugs and then try turning it over. Make sure the A/C is turned off. Check the A/C and power steering etc. to make sure nothing is binding.

Less likely is the new starter isn't any better than the last starter.

 

[Ecomike]

Yes.

Do you have full confidence in the person who is helping her?

I ask because I have too much experience dealing with people who go through the motions without actually performing the task, and with other people who simply don't seem to see what they are looking at.

 

[Tim_MN]

What is the condition of the alternator ? What is the battery CCA rating ? New batteries are not fully charged so a new battery is not a diagnostic tool.

Set the DVM (Digital Volt/Ohm Multi-Meter) on the 20 volt scale. First check battery voltage by placing your multi-meter's positive lead on the battery's positive post ( the actual post, not the clamp ) and the negative lead on the negative post. You need a minimum of 12 volts to continue testing. 12.4 volts is perfect. Next, leave your meter connected and take a reading while the engine is cranking. Record this voltage reading. Now connect your positive lead to the battery terminal stud on the starter and the negative lead to the starter housing. Again, crank the engine and record the voltage reading. If the voltage reading at the starter is not within 1 volt of battery voltage then you have excessive voltage drop in the starter circuit.
　
Typical voltage drop maximums:
• starter circuit (including starter solenoid) = 0.60 volt
• battery post to battery terminal end = zero volts
• battery main cable (measured end to end) 0.20 volt
• starter solenoid = 0.20 volt
• battery negative post to alternator metal frame = 0.20 volt
• negative main cable to engine block = 0.20 volt
• negative battery post to starter metal frame = 0.30
• battery positive post to alternator b+stud = 0.5 volt with maximum charging load applied (all accessories turned on)
　

 

[Ecomike]

Tim, please re-read the post. Please do not make me type a 50 page report/PhD thesis paper on my experience, know how, and what we have tested, painful blow by blow.

I was repairing old style Tube style TVs in the early 1960s.......

It is not the starter, the battery or the cables. I am 500% sure of this. It is something in the engine. I am looking for advice as to what could cause the crank torque required to go through the roof. 8-Mud nailed one, I had not seriously considered, because there has been zero signs of coolant leaks or over heating etc.... oil looks perfect and almost new etc. But a sudden loss of coolant in the piston chamber could have hydrolocked it. At this time I have no other reason to suspect that, but will pull the plugs and verify.

I am leaning towards a busted, loose part in the engine, but what part and why would it crank and run one minute, and later bog down so bad to where the starter is fully loaded and stalls after 2 piston-compression trips (like 1-2 seconds at almost a stalled cranking speed). Tried two new and almost new starters, tried two batteries and jumped system, Ran all the DVM tests.....

What is the condition of the alternator ? What is the battery CCA rating ? New batteries are not fully charged so a new battery is not a diagnostic tool.

Set the DVM (Digital Volt/Ohm Multi-Meter) on the 20 volt scale. First check battery voltage by placing your multi-meter's positive lead on the battery's positive post ( the actual post, not the clamp ) and the negative lead on the negative post. You need a minimum of 12 volts to continue testing. 12.4 volts is perfect. Next, leave your meter connected and take a reading while the engine is cranking. Record this voltage reading. Now connect your positive lead to the battery terminal stud on the starter and the negative lead to the starter housing. Again, crank the engine and record the voltage reading. If the voltage reading at the starter is not within 1 volt of battery voltage then you have excessive voltage drop in the starter circuit.
　
Typical voltage drop maximums:
• starter circuit (including starter solenoid) = 0.60 volt
• battery post to battery terminal end = zero volts
• battery main cable (measured end to end) 0.20 volt
• starter solenoid = 0.20 volt
• battery negative post to alternator metal frame = 0.20 volt
• negative main cable to engine block = 0.20 volt
• negative battery post to starter metal frame = 0.30
• battery positive post to alternator b+stud = 0.5 volt with maximum charging load applied (all accessories turned on)
　

 

[Anak]

It sounds like time to pull the plugs and see if that changes how easily it turns over.

If not I would then pull the valve cover and turn the engine over by hand (socket on the crank) and start going through the opening/closing of all the valves.

Another thought: What about pulling the serpentine belt? Is it possible an AC compressor or some other driven accessory has bound up and is fighting the starter?

 

[Rockwood]

It sounds like time to pull the plugs and see if that changes how easily it turns over.

If not I would then pull the valve cover and turn the engine over by hand (socket on the crank) and start going through the opening/closing of all the valves.

Another thought: What about pulling the serpentine belt? Is it possible an AC compressor or some other driven accessory has bound up and is fighting the starter?

Yep, but I'd pull the plugs, then pull the serpentine belt. Just easier and more likely the problem, especially if it's running fine after starting (which it sounds to be the case).

Loose engine part usually makes LOTS of unhealthy noise...

 

[Ecomike]

I ruled out the serp belt as they would slip and squeel.

It sounds like time to pull the plugs and see if that changes how easily it turns over.

If not I would then pull the valve cover and turn the engine over by hand (socket on the crank) and start going through the opening/closing of all the valves.

Another thought: What about pulling the serpentine belt? Is it possible an AC compressor or some other driven accessory has bound up and is fighting the starter?

 

[denverd1]

Do you have full confidence in the person who is helping her?

I ask because I have too much experience dealing with people who go through the motions without actually performing the task, and with other people who simply don't seem to see what they are looking at.

This. Was getting good voltage now 10?

Also have the person check the wires and terminals on the starter itself for good connectivity and no corrosion. Although new starter should've fixed that issue.

Still question the helpers skill

Sent from my SM-G975U using Tapatalk

 

[denverd1]

Tim, please re-read the post. Please do not make me type a 50 page report/PhD thesis paper on my experience, know how, and what we have tested, painful blow by blow.

I was repairing old style Tube style TVs in the early 1960s.......

It is not the starter, the battery or the cables. I am 500% sure of this. It is something in the engine. I am looking for advice as to what could cause the crank torque required to go through the roof. 8-Mud nailed one, I had not seriously considered, because there has been zero signs of coolant leaks or over heating etc.... oil looks perfect and almost new etc. But a sudden loss of coolant in the piston chamber could have hydrolocked it. At this time I have no other reason to suspect that, but will pull the plugs and verify.

I am leaning towards a busted, loose part in the engine, but what part and why would it crank and run one minute, and later bog down so bad to where the starter is fully loaded and stalls after 2 piston-compression trips (like 1-2 seconds at almost a stalled cranking speed). Tried two new and almost new starters, tried two batteries and jumped system, Ran all the DVM tests.....

The odds of dropping a valve or some other mechanical problem sounds unlikely to me. It also wouldn't create the same issue high compression issue either.

Agree let's pull plugs and see if she spins

Sent from my SM-G975U using Tapatalk

 

[Down under]

I would agree totally with cranking without plugs. Charge new battery to full.
And pop cover off and watch the rockers! If y ou have the slow motion app on your phone. Film rockers even

 

[trippled]

I ruled out the serp belt as they would slip and squeel.

Not true at all. Seen many locked up ac compressors that cause slow crank/no start without making a sound.

Removing the belt would be my first thing to do and one of the easiest thing to do.

 

[old_man]

A voltage drop during cranking is normal. 9 volts is a bit more than normal but within tolerance. If the drop is measured at the battery, then it can't be cables. It could be that the starter is pulling more than typical current or the battery does not have as low an impedance as most. The best way to tell is to get a clamp on meter and measure the cranking current and compare it against another XJ.

I would be surprised if the motor itself is dragging things down. If it had that much resistance, you would see some performance difference.

I converted over to large gauge welding cable for my battery cables and the starter spins way faster. The starter will spin when there isn't enough juice in the battery to run the ECU.

 

[FlyNNN]

... A voltage drop during cranking is normal. 9 volts is a bit more than normal but within tolerance.

This is normal operation for me with my 90' RENIX. Measured at the cigarette lighter port, usually just a little over 9v. With a new AGM battery, I usually also experience a longer crank of 3-5 sec's if the vehicle has sat for awhile. If the battery is fully recharged or I have a solar panel setting on the dash plugged in, I usually get a quick start which I prefer. Just thought I would share my experience with this 30 year old jeep.

 

[FlyNNN]

This is normal operation for me with my 90' RENIX. Measured at the cigarette lighter port, usually just a little over 9v. With a new AGM battery, I usually also experience a longer crank of 3-5 sec's if the vehicle has sat for awhile. If the battery is fully charged or I have a solar panel sitting on the dash plugged in, I usually get a quick start which I prefer. Just thought I would share my experience with this 30 year old jeep.

Only way to fix typo's (???)

 

[four_shot]

I'm in the "pull the serp belt" camp. When my compressor locked up, it actually spun the outer ring on the balancer!.

Worst case...you can say you told us so. Best case...it cranks normally and diagnosis is narrowed down.

 

[BIG1RED9]

You shared that it was running is it 100% a starting issue or when it ran it did so like crap and made other engine noises?

If once started it runs fine then that points to items related to the starter circuit.

Not suggesting it is the issue, but when I just changed my starter for slower than typical turnover rpm I found the stud on the starter and the cable to be coated with rust. Although I changed out the starter, it is possible that by itself would have solved the problem. Engine grounds clean and tight?

It was running like crapola then I join the suggestions of pulling plugs - looking at them for clues, try to turn it over by hand and finally pop the valve cover.

Good luck.