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Honda HT3813 - starter problem ?

20K views 16 replies 6 participants last post by  RCP Designs  
#1 ·
Hi, my trusty Honda 3813 lawn tractor has developed a weird starting problem.

On a fully charged battery, it will spin and start fine on first go from cold. But ...

1. Switch it off after a minute or two and try to restart and it turns very slowly and wont start.

2. Removing the spark plugs makes negligible difference to the spin speed off the starter

3. When keeping the starter turning slowly, after a minute or two smoke starts issuing form the solenoid to starter cable and both solenoid terminals get very hot.

4. Solenoid does it's clunk engagement noise fine

4. After the above the battery still reads 12.9V across its terminals ... and <> same reading across solenoid terminals

5. If I put the battery onto a 4amp charge for a coule of hours and refit, it will again spin the starter and start the machine.

6. Its deffo NOT the battery by the way


Any ideas before I go to the major hassle of removing the engine, to remove the starter to check it out ?

Its sunday, it's 3:15pm in Scotland, I'm back at work first thing tommoroww morning and the grass is growing so fast you can see it moving skywards :crybaby:
 
#2 ·
You say it is definitely not the battery because it reads 12.9 volts and the same at the solenoid, but what does the voltage read as the engine is cranking? Sometimes a battery may fail by loosing cranking amps and just wont have enough power to supply the amps needed. When this happens the voltage will drop below 10 volts and cause the starter to crank slow. This may also explain how after charging the battery it will start fine.

If the battery is good, I would check the voltage on the solenoid as the engine is started. The solenoid may click in fine but have faulty contacts and cannot pass enough current from the battery. Bad contacts will create a lot of heat. Be sure to measure the voltage on the heavy wire going to the starter. It would also be a good idea to be sure the battery and solenoid connections are clean and tight, but you probably have already done that.
 
#5 ·
You say it is definitely not the battery because it reads 12.9 volts and the same at the solenoid, but what does the voltage read as the engine is cranking? Sometimes a battery may fail by loosing cranking amps and just wont have enough power to supply the amps needed. When this happens the voltage will drop below 10 volts and cause the starter to crank slow. This may also explain how after charging the battery it will start fine. If the battery is good, I would check the voltage on the solenoid as the engine is started. The solenoid may click in fine but have faulty contacts and cannot pass enough current from the battery. Bad contacts will create a lot of heat. Be sure to measure the voltage on the heavy wire going to the starter. It would also be a good idea to be sure the battery and solenoid connections are clean and tight, but you probably have already done that.
Did a bit of testing this morning , with following results:

1. Voltage across battery terminals with battery stratight off the charger = 14.8V
2. Put battery on machine and it starts no prbs first go
3. Switch machine off after a couple of minutes and try and start agains and the starter turns very slowly and machine fains to start
4. read V across battery agian and it is 12.8V and V across solenoid (ignitions swithch on ) = 12.8V. Turn key round to enagage strater and V across solenoid drops to 8.5V
5. There is constant continuity across the solenoid terminals both when battery -ve lead is disconnected at the battery and laso when it is reconnected.

Does the voltage drop across the solenoid when the starter in engaged and the fact that continuity is constant across the solenoid whether or not battery is connected indicate a faulty solenoid ... which is only overcome when the battery is at 14.8V straight off the charger.

All battery connections are fine, but battery to solenoid terminal gets very hot very quicky when starter only turning very slowly and machine not starting.

Anything I can do to further check the solenoid with the engine still in the machine and the solenoid still on the starter ?:drunkie:
 
#4 ·
Sounds like this could be the problem to me, too.

But something else bothers me:
3. When keeping the starter turning slowly, after a minute or two smoke starts issuing form the solenoid to starter cable and both solenoid terminals get very hot.

5. If I put the battery onto a 4amp charge for a coule of hours and refit, it will again spin the starter and start the machine.
#3. Don't spin the starter for more than 15-20 seconds. Then wait at least that long before spinning it again.
#5. While the battery is on the charger doesn't everything else cool down?
 
#8 ·
Here is a photo of the back of the solenoid. If you measure the voltage on the solenoid from the heavy wire going to the starter motor (covered by the rubber cover) and the other heavy terminal connected to the battery, and then turn the ignition switch to start, you should measure less than 1 or 2 volts. If you measure a higher voltage, the solenoid is bad. If you measure less than 2 volts and the engine is turning over slowly, then the battery is probably bad. To check that, measure from the heavy terminal that connects to the battery and the starter metal case as the ignition switch is turned to start. The voltage must be greater than 10 volts if the battery is good.

The confusing part of this problem is that the engine will start up fine just after the battery has been charged. This indicates that a fully charged battery with enough cranking amps and volts will start the engine once. Then it will not a second time. To me this seems like a bad battery.
 

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#11 · (Edited)
Here is a photo of the back of the solenoid. If you measure the voltage on the solenoid from the heavy wire going to the starter motor (covered by the rubber cover) and the other heavy terminal connected to the battery, and then turn the ignition switch to start, you should measure less than 1 or 2 volts. If you measure a higher voltage, the solenoid is bad. If you measure less than 2 volts and the engine is turning over slowly, then the battery is probably bad. To check that, measure from the heavy terminal that connects to the battery and the starter metal case as the ignition switch is turned to start. The voltage must be greater than 10 volts if the battery is good. The confusing part of this problem is that the engine will start up fine just after the battery has been charged. This indicates that a fully charged battery with enough cranking amps and volts will start the engine once. Then it will not a second time. To me this seems like a bad battery.
Tested as above. results are; 1. Voltage across battery, just off the charger = 13.7V. Put battery on the tractor and it no longer starts at first attempt. 2. Voltage across the two big solenoid terminals when cranking = 0.9V 3. Voltage between solenoid battery terminal and starter body when cranking = fluctuating between 2.5V & 8V So ..... prognosis = battery knackered. Reason that I didnt think it was the battery before is because I was getting the same problem with another battery out of my '69 Triumph Herald, and it still strats the Herald fine. So, maybe the Herald engine is just requires much less effort to turn it over. Will get a new battery tomorrow and let you know if it solves the problem. :thanku:
 

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#13 ·
... and the latest is ...... New battery hasn't arrived yet, but while in the shed getting something I turned the key on the way past and hey presto the machine started ..... and then died after about 10 seconds and lots of smoke issuing from the deck drive clutch area behind the radiator fan. Then , trying to start again and the starter is again very sluggish and engine wont start. We'll see what a new battery brings ... but the smoke from the deck drive clutch is a worrying new development ..... after the machine has been working absolutely fine for the past 12 months :(
 
#14 ·
Hi Folks

New ÂŁ60 battery arrived this morning . Fitted it and it's exactly the same as before. Starter turns very slowly and engine wont fire up. Bearing in mind the amount of smoke coming from just in front of the engine when it did start up yesterday for a very short period, before refusing to start again ..... anyone got any more ideas ?
 
#15 ·
A wee bit more info...... there is an isolater switch connected to the PTO lever. The effect of this is that you cant start the engine with the PTO engaged. I've disconnected that switch and put a temorary wire across the two terminals so that the switch no longer acts as an isolator ... ie so that you can start it whether or not the PTO is engaged. result is .... with PTO lever forward (PTO engaged) the machine starts no problem at all. If, while it's running, I disengage the PTO by pulling the lever back to its upright position the engine starts to labour, smoke starts issuing from the PTO clutch in front of the engine and the engine eventually gives up. If I try starting with the PTO disengaged (PTO lever in upright position), the starter labours and engine wont start. So, it looks to me as if the starting problem is something to do with the PTO clutch . Anyone got any ideas on how to sort this ?
 
#16 ·
All sorted now folks. So, the problem that was causing a sluggish engine turn over when trying to start (and which superficially seemed like a dud battery) was none of the following: it wasn't the battery, it wasn't the starter, it wasn't the starter solenoid, it wasn't the starter relay, it wasn't the valve clearance. IT WAS ... a sticky clutch that meant that when trying to start the engine that the engine was trying to overcome an engaged clutch brake while the clutch was seizing on... DIAGNOSIS/TEST FOR THIS: (If engine turns over very slowly when trying to start it) 1. undo the PTO lever switch connectir block just under the ignition key barrel. 2. short circuit the two terminals in the PTO lever switch wiring connector on the wiring harness side of the terminal block 3. Engage the PTO by pushing the PTO lever forward. If the engine starts fine with the lever in this position, but not when the lever is in the vertical (PTO disengaged ) position then your starting problem is due to a seized PTO clutch mechanism SORTING IT: 1. take the radiator off 2. take the cooling fan off 3. undo the centre bolt that holds all the clutch componets on. (this may be well stiff, such that all that happens when you try to undo the bolt is that the enngine turns . If so give the bolt head a dousing with penetrating oil then put a spanner on it and give the spanner an anti-clockwise belt with a rubber mallet) 4. Remove all clutch parts from the spindle 5. Clean all clutch component surfaces with emery paper - 24 - 600 - 1000 grit in sequence. In my case the clutch plate was not riding free on the three dowels of the PTO pulley. To clean the dowl holes on the clutch plate, wrap the emery paper round a pencil , stick pencil in each of the three holes in turn and while holding each end of the pencil , twirl the plate round and round. Repeat with 240, 600 1000 grit. Also clean the surfaces of the three dowels themselves. 6. Reassemble In my case the above has completely sorted the problem, although the friction pads on the friction disc are starting to come away from the disc , so in the longer term I'll need a new clutch friction disc. The other buggeration is that prior to using a spanner and rubber mallet on the central spindle bolt, I'd bolted a brace onto the fan boss to prevent the engine turning when trying to undo the central bolt.... when I put a bit of force on the bolt, the tip of the fan boss snapped where I'd bolted the brace onto it .. see photo. At the end of the day , its all working again at zero cost and I'm happy as a happy Larry. The shop even refunded the ÂŁ60 I'd spent on a new battery. Think I'll go and celebrate with a large malt whisky and ginger :) :) :)
 

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#17 ·
I had the same problem and had completely forgotten that the PTO clutch is also a brake. If it fails it can keep the motor from turning over. I fixed this very problem about 20 years ago and had this vague idea it was probably the problem again but couldn't quite remember how. Glad I found your excellent post as it all came flooding back as I read it.