has my alternator seized or my engine?
- Thread starter colin100
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- alternator bearings seized
H Peasource
Injector King
Great news, Colin. Now go and buy yourself some hair restorer to celebrate.
When I first saw this a couple of years ago I too couldn't believe it and it niggled away in the back of my mind for quite a while until the penny finally dropped.
We all know that it takes a fair amount of torque to turn over a piston engine and that diesels are worse in this respect than petrols because of their higher compression ratio. That torque is applied at the flywheel end of the crankshaft and most of it is absorbed in overcoming the friction and pumping losses. The amount of torque available at the other end of the crankshaft (the excess torque if you like) is much smaller. With that in mind it becomes much easier to understand how a siezed alternator can do this.
The old trick of using the starter motor to undo the crankshaft pulley bolt could almost have been designed to mislead us into thinking there's a lot of torque available at that end of the crankshaft. In reality there are two factors which explain how this trick works. The first is that much of its success is due not to the torque of the crankshaft but to the shock loading applied to the bolt. It's basically the same as the way an impact wrench manages to use a relatively low torque motor to undo tight bolts. The second is that, when doing this, there's inevitably some rotation of the crankshaft before the breaker bar (or whatever you're using) smacks into something solid. That's important because there is a big difference between the static friction, when the engine is stationary, and the kinectic friction when the engine starts to rotate. Indeed the static friction will be over twice the kinetic friction. The combined effect of both these factors is to produce a shock loading big enough to shift the crankshaft pulley bolt or snap the crankshaft if you're really unlucky!
Alan
When I first saw this a couple of years ago I too couldn't believe it and it niggled away in the back of my mind for quite a while until the penny finally dropped.
We all know that it takes a fair amount of torque to turn over a piston engine and that diesels are worse in this respect than petrols because of their higher compression ratio. That torque is applied at the flywheel end of the crankshaft and most of it is absorbed in overcoming the friction and pumping losses. The amount of torque available at the other end of the crankshaft (the excess torque if you like) is much smaller. With that in mind it becomes much easier to understand how a siezed alternator can do this.
The old trick of using the starter motor to undo the crankshaft pulley bolt could almost have been designed to mislead us into thinking there's a lot of torque available at that end of the crankshaft. In reality there are two factors which explain how this trick works. The first is that much of its success is due not to the torque of the crankshaft but to the shock loading applied to the bolt. It's basically the same as the way an impact wrench manages to use a relatively low torque motor to undo tight bolts. The second is that, when doing this, there's inevitably some rotation of the crankshaft before the breaker bar (or whatever you're using) smacks into something solid. That's important because there is a big difference between the static friction, when the engine is stationary, and the kinectic friction when the engine starts to rotate. Indeed the static friction will be over twice the kinetic friction. The combined effect of both these factors is to produce a shock loading big enough to shift the crankshaft pulley bolt or snap the crankshaft if you're really unlucky!
Alan
freddofrog
won 16.4k on Euro lottery :)
tbh Alan, your description flies in the face of basic mechanical gearing. Firstly, a diesel's starter motor has a much bigger torque than a petrol engine (which is why diesel engines have bigger batteries, to provide the current, which the starter motor requires to provide its torque). When the starter rotates, its pinion is engaged on the ring of the flywheel, which gives a massive increase of torque onto the crankshaft. It is the rotation of the crankshaft that causes the pistons to move, so I fail to see how you can say that the torque available at the pulley end is less. If you apply torque to one end of a shaft, you cannot lose the torque at the other end of the shaft unless the shaft twists. So the torque provided by the gearing of the pinion onto the flywheel will absolutely and always be available at the pulley end while the current is being drawn into the starter motor. The only thing that can reduce that torque is to reduce the voltage (and hence the current available) across the starter motor (or to disengage the pinion from the ring).H Peasource said:
immy786
Members
hmm interesting guys so much technical talk going on here 
H Peasource
Injector King
I won't get into a slanging match Brian. Suffice it to say that I do understand ¨basic mechanical engineering¨, indeed I have a degree in the subject and am a member of the relevant professional bodies.
A torque is no more than a force and, like any force, it can be absorbed - in this case by the internal engine friction and, once the engine is turning, by the pumping losses too.
Perhaps we should just agree to disagree.
Alan
A torque is no more than a force and, like any force, it can be absorbed - in this case by the internal engine friction and, once the engine is turning, by the pumping losses too.
Perhaps we should just agree to disagree.
Alan
TheHole
TAF Member
I for one am not supprised a seized alternator stopped the engine turning.
I presume the aux belt is the old longer one? With the belt comming off the compressor down to the alternator then making an almost 180degree turn up to the idler pulley... There is alot of force on the alternator (enough force as many of us know to kill the bearings in the alternator)
To settle the argument above.
The starter motor is able to provide a huge amount of torque to get the engine turning... But with all electrical motors, torque drops off quickly when the motor starts spinning.
The initial current rush in to the starter can turn the engine over its compression points.
Once the engine has started to rotate the torque from the starter motor is turned in to kinetic energy to turn the crank and therefore the internals and auxiliaries.
As this happens torque has dropped off in the starter motor, but the now given kinetic enegry of the engine internals help alleviate this issue of loss in torque in the starter motor.
Plus add in to the factor that once the engine has done less that 1/4 of a rotation, fuel is already being injected in to the next corresponding bore to attempt the start of the engine using combustion.
With an issue here where the alternator was seized, the start motor was not able to overcome the extra resistive force of the stuck belt and was not able to start.
I presume the aux belt is the old longer one? With the belt comming off the compressor down to the alternator then making an almost 180degree turn up to the idler pulley... There is alot of force on the alternator (enough force as many of us know to kill the bearings in the alternator)
To settle the argument above.
The starter motor is able to provide a huge amount of torque to get the engine turning... But with all electrical motors, torque drops off quickly when the motor starts spinning.
The initial current rush in to the starter can turn the engine over its compression points.
Once the engine has started to rotate the torque from the starter motor is turned in to kinetic energy to turn the crank and therefore the internals and auxiliaries.
As this happens torque has dropped off in the starter motor, but the now given kinetic enegry of the engine internals help alleviate this issue of loss in torque in the starter motor.
Plus add in to the factor that once the engine has done less that 1/4 of a rotation, fuel is already being injected in to the next corresponding bore to attempt the start of the engine using combustion.
With an issue here where the alternator was seized, the start motor was not able to overcome the extra resistive force of the stuck belt and was not able to start.
TheHole
TAF Member
Alan.
Torque is a force and can be absorbed / transfered in to another object or body.
As you say pumping losses is a perfect example.. Even more so with the delicate but very functional oil pump the accord has, the contra-rotating pump requires torque from the engine (via chain and sprocket from the crank)
This torque is absorbed by the oil therefore giving it enegry and pumping it around the engine...
Provide a thick enough oil to that pump and it wont be able to transfer the power in to the oil as the oil is too viscous.
The pump will try and turn but the torque required is too great, therefore a weak link will be found and this is the chain.
Torque is a force and can be absorbed / transfered in to another object or body.
As you say pumping losses is a perfect example.. Even more so with the delicate but very functional oil pump the accord has, the contra-rotating pump requires torque from the engine (via chain and sprocket from the crank)
This torque is absorbed by the oil therefore giving it enegry and pumping it around the engine...
Provide a thick enough oil to that pump and it wont be able to transfer the power in to the oil as the oil is too viscous.
The pump will try and turn but the torque required is too great, therefore a weak link will be found and this is the chain.
Jon_G
No Longer Active
But the engine wasn't turning, so the series-wound starter motor would have carried on delivering the maximum possible torque and there would have been no pumping losses as the engine wasn't turning.
Nevertheless, the seized alternator DID prevent this engine from turning. So I suggest that there was a combination of faults, with a discharged/poor condition battery being a contributory factor.
Nevertheless, the seized alternator DID prevent this engine from turning. So I suggest that there was a combination of faults, with a discharged/poor condition battery being a contributory factor.
freddofrog
won 16.4k on Euro lottery :)
I think it is important that we get this right, as otherwise "maybe the alternator is seized" will become a never ending piece of advice dished out to people whose engines are not rotating.H Peasource said:
I don't want to be rude, I honestly don't, but if you are an IMechE (which you imply) then I would have expected a better description than you gave in your previous post. You are also not really understanding pumping losses properly. If the pistons move slowly, then the pumping losses are very small. On that basis, it is possible to rotate most engines slowly by hand, or to put the car into gear and push the car slowly. The starter motor provides most power when the engine is rotating at around 600 rpm (10 revs per second), but its static torque (and even slow rotational torque) is immense. I would expect a belt to make it very difficult, if not impossible, for the starter to provide sufficient rpm to start the engine, but not to stop the crankshaft from rotating totally. If the crankshaft does not rotate at all, then either the engine is seized, or there is not enough current getting into the started motor. I would bet my house on this.
As I've put above, you're confusing the rpm for starting the engine with the static torque. The rpm for starting is around 600rpm (10 revs per second), at which point the starter motor is providing maximum power, which is not the same as its maximum torque (at zero or very low speed). So if a starter motor cannot rotate a crankshaft at all, then it implies that either the engine is locked solidly (seized) or that the starter motor is not getting enough current (battery or cable issue).TheHole said:
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Both (and anyone else) .....I do not and will not "agree to disagree" on a subject like this. In economics and politics that is a well-used statement, but in engineering that statement cannot be used, and IMO it is very important to get things stated properly in engineering topics.
It is quite possible that the "recovery man" simply went down the recovery route because he quickly realised that recovery was the easiest option for him at that time, he may even have seen/heard the engine rotating very slowly with his battery pack attached and decided that it was not up to him to remove the belt to check (which he could have done if he wanted to give a 100% diagnosis).
freddofrog
won 16.4k on Euro lottery :)
A more concise answer than my one Jon, I would probably not have posted had I seen it, but I was too busy typing those longer descriptions at the time (and no point me editing out what I have put time into posting IMO)Jon_G said:
edit: and moderators, I don't think this thread needs moderating, and I don't think it requires intervention, it is a useful thread IMO
TheHole
TAF Member
freddofrog said:
You glanced over my ****ysis somewhat and its difficult on a phone to get a concise reason across.
Lets get some basics here that we all should agree on;
1) max torque of a motor is a 0 rpm.
2) the starter attempts to move the flywheel.
3) flywheel is attached to a crank with (in our case 4 pistons).
Turning an engine to compression point by hand is relatively easy. I would like to see someone go over compression point on the accord by hand though... Its not that easy with out a tool...
Anyway back on topic. The aux belt is known to kill our alternator. This is due to it being rather tight. I know i bent a metal bar trying to loosen the idler pulley.
The way the aux belt is routed over the alternator means that over 1/3 of the surface area of the pulley is being utalised by the belt.. Also add in the mix the belt pulls the pulley up (by design).
This has now added a huge static frictional force on to the engine, and to turn it over you need to over come this force.. We can all agree thus far surely?
The gearing on the starter / flywheel is designed thus the max speed is IIRC (and im happy to be corrected) is about 100 rpm over starting rpm of the engine.
This allowd some leway when starting and provides for a battery volt drop etc.
I think what is a very important factor that is being missed is the effective 'gearing' from the crank pulley on to the aux belt.
The crank pulley is fairly big compared to everything else.
The size of the alternator pulley is tiny.
So what happens when you drive a big gear and this big gear is thus driving a small one?
The effective torque to turn that small gear is effectively much greater.
So we have a small gear from the starter driving a very big fly wheel = nice and easy.
Then we have a nice big crank pully turning a tiny little alternator puller that is seized.. = not easy at all
Its all in the gearing of the pully system... Again going back to my original post of me not being supprised about the lack of torque to overcome a seized bearing in the alternator
Jon_G
No Longer Active
The crank pulley isn't particularly large compared to the alternator pulley, maybe twice the circumference? But, for me at least, the surprise isn't that a seized alternator can withstand the torque of the stationary starter motor, it's that the drive belt didn't either slip (despite maybe having the longer belt) or simply snap!
TheHole
TAF Member
If you look at the routing though,its not easy to slip as the contact patch coupled with belt tension was too great.
I think the crank pulley is about 20cm dia and the alternator is less than half this size...
The OP complained of a screeching noise before it stopped and this could have been the belt / alternator.
Now reading back and the OP says he was driving... I bet the belt was squeeking over the seized pully.. But when the clutch was depresse or the OP came to a stop... The engine wasnt able to idle and hence ground to a stop...
Then obviously trying to overcome this friction when re-starting just wasnt going to happen
I think the crank pulley is about 20cm dia and the alternator is less than half this size...
The OP complained of a screeching noise before it stopped and this could have been the belt / alternator.
Now reading back and the OP says he was driving... I bet the belt was squeeking over the seized pully.. But when the clutch was depresse or the OP came to a stop... The engine wasnt able to idle and hence ground to a stop...
Then obviously trying to overcome this friction when re-starting just wasnt going to happen
Jon_G
No Longer Active
Seems a reasonable theory.
freddofrog
won 16.4k on Euro lottery :)
TheHole said:
ha, no I did not Adam
...you said ....which is mainly about the starter getting the engine to run up to starting speed i.e. running up to a point where "pumping losses" start to become large, but my reply to you was that this is not the case when the starter motor is initially rotatingTheHole said:
TheHole said:
"by hand" I meant on the flywheel ....I, or anyone, could turn an engine very slowly by hand on the flywheel (if the flywheel was accessible), through each of its "compression points" ....if you turn it slowly enough then there is very little compression. The point is that the torque from the starter motor does not have to overcome compression initially, it only has to do this as the rotational speed picks up.
TheHole said:
No, that is not how an engine is started. The engine has to get up to sufficient rotational speed before it can start, else there is not enough compression in the cylinders. That is why a slightly flat battery, that only provides enough current to rotate the engine slowly, will fail to start the engine. As I say, ir has to "inhale" and then compress the "gas" to provide enough explosion to get the process going. If you want to call it 100rpm (let's say 120 to make the numbers easier) then that is still 2 revolutions per second. I doubt if most modern high-compression engines will get enough gas and compress it, as only 2 revs per second. My understanding is higher rev/sec than that.
Also, if some of the components have not been serviced properly (spark plugs on a petrol, inlet manifold on a diesel) then it may take several seconds of spinning to get sufficient spark (SI engine) or gas (CI engine) to start.
But as I say, we are not talking of getting the engine up to starting speed, we are talking of the stalled torque from the electrical starter motor.
TheHole said:
As Jon pointed out, it's not that much of a gearing, especially when you compare the gearing of the starter motor's pinion and the flywheel ring. The starer motor on its own has massive stalled torque, which is then geared up by the pinion.
If you're admitting that the engine was causing the belt to slip when it was running, then I don't see why you're not seeing that the starter motor's torque has enough to cause the belt to slip, although as I say, I doubt if the engine will achieve sufficient rotational speed to compress enough gas to start the engine.
Basically the static torque on the crankshaft through the flywheel ring and pinion is far greater than the peak torque of the engine when the engine is running. But once the flywheel is rotating, the starter motor's torque falls away, usually when it reaches maximum power (at the rotational speed of the starter and flywheel that was in the design)
the point for me was when the op described his engine cut out while running or similar. I wouldn't have thought a seized alternator would overcome a running engine crankshaft? I've driven miles with a failed alternator, no power or lights in my diesel.
It must be more at play, for example a failing alternator plus weak battery why it wouldn't turn?
who knows, I'm just drawing from experience my MR2 seized and it shredded the belt and bellowed out smoke but engine did not stall and has much less torque.
It must be more at play, for example a failing alternator plus weak battery why it wouldn't turn?
who knows, I'm just drawing from experience my MR2 seized and it shredded the belt and bellowed out smoke but engine did not stall and has much less torque.
freddofrog
won 16.4k on Euro lottery :)
aye, you have to make sure the missus hasn't left the windscreen wipers on, and you have to shut the door too ......joke about Skoda from the 70's .....rhinogolf said:
what do you call a Skoda driver who shuts the door before turning the key in the ignition ...... deluded
I tried to check that one but found these instead http://skoda-jokes.blogspot.co.uk/
I used to drive a skoda Estelle. The lawnmower engine was in the back and everything. It always over heated and often stalled and didn't start again. I became an expert at push starting cars with the skoda! I was strangely fond of that car. Maybe because it was my first car or maybe it was because the alternator always worked
freddofrog
won 16.4k on Euro lottery :)
I decided to put some numbers to what we've been talking about, and I've gleaned the following data from the Honda CD for the 7th-gen pre-facelift 2.4 Accord Tourer.
There are 3 different makes of starter motor, of various kW ratings. I've constructed this table from the cranking tests in the "Starter Circuit Troubleshooting" section.
.....Denso 1.0kW >8.0V <200A
.....Denso 1.1kW >8.7V <230A
...Mitsuba 1.2kW >8.5V <350A
...Mitsuba 1.6kW >8.5V <380A
Mitsubishi 1.7kW >7.7V <400A
Before I continue, can anyone (e.g. Jon) check on the Honda CD for the 7th-gen pre-facelift 2.2 Accord Tourer, to see if the info is the same ???
Also, the battery in the 2.4 is 45 Ah with CCA of 330 Amps, what are the figures for the battery in the 2.2 ???
There are 3 different makes of starter motor, of various kW ratings. I've constructed this table from the cranking tests in the "Starter Circuit Troubleshooting" section.
.....Denso 1.0kW >8.0V <200A
.....Denso 1.1kW >8.7V <230A
...Mitsuba 1.2kW >8.5V <350A
...Mitsuba 1.6kW >8.5V <380A
Mitsubishi 1.7kW >7.7V <400A
Before I continue, can anyone (e.g. Jon) check on the Honda CD for the 7th-gen pre-facelift 2.2 Accord Tourer, to see if the info is the same ???
Also, the battery in the 2.4 is 45 Ah with CCA of 330 Amps, what are the figures for the battery in the 2.2 ???
Jon_G
No Longer Active
Hmmm, I just tried to have a look but it seems my Honda service manual won't run under Google Chrome (a pop-up is telling me to run I.E.)... I still have a laptop running I.E., but that can't post on TA!!! Will obviously have to sort this out.freddofrog said:
My 'genuine Honda' (actually made by Johnson, formally Delphi's battery concern) has a CCA rating of 780A and a capacity of 77Ah.
freddofrog
won 16.4k on Euro lottery :)
CCA of 780 Amps is hugeJon_G said:
, 77 Ah is a lot too. I am now very interested to see the data on the starter motors in the diesel !!
One of my laptops is also "preset" to open html files in Google Chrome, but it is still possible to get the Honda service CD to open in IE. You have to put the CD into the drive, then open a "file explorer" window at the "computer" level, which lists all the drives. Right-click on the CD drive in the file explorer, then click on either "open" or "explore" (do not click on "autoplay"). Another "file explorer" will then open up, and you will see "HONDAESM.HTML" listed. Right click on that, go to "open with", then select Internet Explorer, and hey presto.
Jon_G
No Longer Active
Thank you Brian.... you are clearly more knowledgable about computers than you are about feeding a cat!
However, I can't find any details for my CN2 similar to the ones you have for petrol models (although the 400A ammeter suggests that <400A would be expected:-
_________________________________________________________________________________________
Starter Circuit Troubleshooting
NOTE:
YES -
The starting system is OK. Go to Step 11 .
NO -
Go to Step 5 .
YES -
Repairing the loose connection corrected the problem. The starting system is OK. Go to Step 11 .
NO -
Check the following:
YES -
Go to Step 7 .
NO -
Remove the starter, and repair or replace as necessary.■
YES -
Go to Step 9 .
NO -
Replace the starter, or remove and disassemble it, and check the following:■
YES -
Go to Step 10 .
NO -
Replace the starter, or remove and disassemble it, and check the following:■
However, I can't find any details for my CN2 similar to the ones you have for petrol models (although the 400A ammeter suggests that <400A would be expected:-
_________________________________________________________________________________________
Starter Circuit Troubleshooting
NOTE:
Air temperature must be between 15 and 38 °C (59 and 100 °F) during this procedure.
After this inspection, you must reset the engine control module (ECM), using the Honda Diagnostic System (HDS), otherwise the ECM will continue to stop the fuel injectors.
The battery must be in good condition and fully charged.
Use a starter system tester.
Connect and operate the equipment in accordance with the manufacturer's instructions.
Hook up the following equipment:
Ammeter, 0−400 A
Voltmeter, 0−20 V (accurate within 0.1 V)
Connect the HDS to the data link connector (DLC).
Select PGM-FI, INSPECTION, and then ALL INJECTORS OFF function on the HDS.
Turn the ignition switch to START (III).
YES -
The starting system is OK. Go to Step 11 .
NO -
Go to Step 5 .
Check the battery condition. Check electrical connections at the battery, the negative battery cable to body, the engine ground cables and the starter for looseness and corrosion. Then try cranking the engine again.
YES -
Repairing the loose connection corrected the problem. The starting system is OK. Go to Step 11 .
NO -
Check the following:
If the starter will not crank the engine at all, go to Step 6 .
If it cranks the engine erratically or too slowly, go to Step 8 .
If it won't disengage from the flywheel ring gear when you release the key, check the following:
-
Solenoid plunger and switch malfunction
-
Dirty drive gear or damaged overrunning clutch
Make sure the transmission is in Neutral, then disconnect the BLK/WHT wire from the starter solenoid S terminal. Connect a jumper wire from the battery positive terminal to the solenoid terminal.
YES -
Go to Step 7 .
NO -
Remove the starter, and repair or replace as necessary.■
Check the following items in the order listed until you find the open circuit:■
The BLK/WHT wire and connectors between the under-dash fuse/relay box and the ignition switch, and between the under-dash fuse/relay box and the starter.
The ignition switch.
The starter cut relay.
While cranking the engine, check the cranking voltage and current draw.
YES -
Go to Step 9 .
NO -
Replace the starter, or remove and disassemble it, and check the following:■
Drag in the starter armature
Shorted armature winding
Excessive drag in the engine
Check the engine speed while cranking the engine.
YES -
Go to Step 10 .
NO -
Replace the starter, or remove and disassemble it, and check the following:■
Open circuit in starter armature commutator segments
Excessively worn starter brushes
Open circuit in commutator brushes
Dirty or damaged helical splines or drive gear
Faulty drive gear clutch
Remove the starter, and inspect its drive gear and the flywheel ring gear for damage. Replace any damaged parts.
Select ECM reset to cancel the ALL INJECTORS OFF function on the HDS.■
freddofrog
won 16.4k on Euro lottery :)
:lol: :lol: :lol:Jon_G said:
that section in my Honda service CD for the 2.4 is very similar, except it has a step "check the cranking voltage and current draw" which has this ........ (which is what I used to construct the table in #50)
Is cranking voltage greater than or equal to 8.0 V (DENSO 1.0 kW model)/8.7 V(DENSO 1.1 kW model)/8.5 V (MITSUBA)/7.7 V (MITSUBISHI),and current draw less than or equal to 200A (DENSO 1.0 kW model)/230A (DENSO 1.1 kW model)/350A (MITSUBA 1.2kW model)/380A (MITSUBA 1.6 kW model)/400A(MITSUBISHI)?
if you have time, there might be similar data in other sections, e.g. "Starter Performance Test" and/or "Design Specifications"
edgeoftime
Members
This has gone way over my head and possibly a lot more heads, re the ticking noise could it be that the "fitter" forgot to clean off the burnt old belt that the op mentions? and also why did the "short" belt not be fitted at the same time??