Hot start issue - Healey 3000
Discussion
Hello,
I have a Austin Healey 3000 BJ8 which has a small hot start problem.
When the car has been used and is warm every time you go to start it the first revolution of the engine is really slow, as though it's not going to turnover. It has never let me down and always burst into life but it feels as though it really doesn't want to. If you take the lead of the coil after the first struggling revolution it tuns over fine and nice and quick.
The starter has been rebuilt, new battery and seems to have plenty of earths but it is still doing it.
Any advice where to go from here?
Cheers,
Steve
I have a Austin Healey 3000 BJ8 which has a small hot start problem.
When the car has been used and is warm every time you go to start it the first revolution of the engine is really slow, as though it's not going to turnover. It has never let me down and always burst into life but it feels as though it really doesn't want to. If you take the lead of the coil after the first struggling revolution it tuns over fine and nice and quick.
The starter has been rebuilt, new battery and seems to have plenty of earths but it is still doing it.
Any advice where to go from here?
Cheers,
Steve
Russwhitehouse said:
Genuine question and at the risk of sounding stupid, what difference does the battery being in the boot make?
Resistance losses in the cable at a guess. The longer the cable, the more resistance, especially if the cable is not thick enough to carry the current.The problem really shows itself when you use cheap jump cables to try to jump a car, then the AA man comes along with his high quality cables and the car starts immediately.
healeyfan said:
They all tend to do this because the battery is in the boot. You can fit one of the new smaller lightweight high torque starter motors which cures the problem. I just wait a few minutes for it to cool down. As you say "it never lets me down".
If the issue us caused by the length/thickenss/internal resistance of the copper not providing enough current to the motor why would a new high torque motor fix it?Surely a better solution would be a newer high quality thicker copper supply lead?
Might be worth checking your engine earth return strap for good connection, take it off ,clean the ends and refit to ensure current flow. When these connections fail or become reduced the starter motor cannot achieve its full power and gets sluggish particularly on a first/morning start. Sometimes the current tries to find a different route (often inadequate) to carry the power and cooks things like the choke cable for example. Try feeling to see if the cable is getting warm after attempting to start . 
pingu393 said:
Russwhitehouse said:
Genuine question and at the risk of sounding stupid, what difference does the battery being in the boot make?
Resistance losses in the cable at a guess. The longer the cable, the more resistance, especially if the cable is not thick enough to carry the current. The problem really shows itself when you use cheap jump cables to try to jump a car, then the AA man comes along with his high quality cables and the car starts immediately.RichB said:
pingu393 said:
Russwhitehouse said:
Genuine question and at the risk of sounding stupid, what difference does the battery being in the boot make?
Resistance losses in the cable at a guess. The longer the cable, the more resistance, especially if the cable is not thick enough to carry the current. The problem really shows itself when you use cheap jump cables to try to jump a car, then the AA man comes along with his high quality cables and the car starts immediately.I suspect the hot start problem is more to do with fuel evaporation or perhaps an overheated coil. Internet diagnosis is next to impossible and I'm not sure whether throwing random suggestions around is helping the OP, so I'll stop now
.OK. O/P has asked for ideas so let's look at this. He says the issue it's the engine turning over sluggishly so we can rule out fuel evaporation or ignition problems, it's a voltage to the starter motor problem. Perhaps once the engine is hot perhaps expansion of the pistons and rings in the bores causes the compression to improve meaning the voltage isn't good enough to turn the engine? Don't know, but I'd try a new battery or at least borrowing one if I could first and as has been said, cleaning all the earth straps.
Again thanks for all your help.
To be clear it isn't anything to do with fuel evaporation, timing or anything like that. When hot it turns over sluggishly, fine when cold. It has a new battery of 80 amps, and the starter has been rebuilt. As far as I can make out it is either the cables running from the battery or possibly the starter motor has not been rebuilt correctly.
One thing that did come to mind is that I had trouble with the isolation switch in the boot (cheap crappy part) some time ago so I think it is probably worth bypassing this and see if that makes any difference.
Again thanks for your help.
A pic outside the pub to cheer me up!
To be clear it isn't anything to do with fuel evaporation, timing or anything like that. When hot it turns over sluggishly, fine when cold. It has a new battery of 80 amps, and the starter has been rebuilt. As far as I can make out it is either the cables running from the battery or possibly the starter motor has not been rebuilt correctly.
One thing that did come to mind is that I had trouble with the isolation switch in the boot (cheap crappy part) some time ago so I think it is probably worth bypassing this and see if that makes any difference.
Again thanks for your help.
A pic outside the pub to cheer me up!
Definitely bypass your isolator as a first stage. I would expect a dodgy isolator to be dodgy all the time, not just when hot, but you never know.
I'm assuming you have a solenoid that is separate from the starter and it is an inertia starter (like most BMC cars).
Try connecting the +ve pole of your battery directly to the live side of the starter solenoid. If you connect to the dead side, the starter will spin (as well as there will be some sparks). Try turning over on the key. The engine will turn over on the starter, but won't run, as there won't be 12v to the ignition after the key is released. You are only testing turn over speed.
Sluggish - YES - see below
Sluggish - NO - suspect the quality of the high current wires to the solenoid.
If YES, what was the starting voltage? How hot does the starter motor feel?
If you have a spare battery that you know to be good, do the same test. If it is still sluggish, your original battery is probably OK and the problem is "downstream" of the solenoid.
If the starter motor is hot AND the turn over is sluggish, this is probably your culprit, as heat indicates high internal resistance. A starter motor should have very low internal resistance. Can you measure the resistance of the starter (if it's an inertia starter, this can be done from the dead side of the solenoid to earth on the engine block)? You can also check for poor connections in the wire from the solenoid to the starter. And (as said previously) confirm that earth cables are good and secure.
I'm assuming you have a solenoid that is separate from the starter and it is an inertia starter (like most BMC cars).
Try connecting the +ve pole of your battery directly to the live side of the starter solenoid. If you connect to the dead side, the starter will spin (as well as there will be some sparks). Try turning over on the key. The engine will turn over on the starter, but won't run, as there won't be 12v to the ignition after the key is released. You are only testing turn over speed.
Sluggish - YES - see below
Sluggish - NO - suspect the quality of the high current wires to the solenoid.
If YES, what was the starting voltage? How hot does the starter motor feel?
If you have a spare battery that you know to be good, do the same test. If it is still sluggish, your original battery is probably OK and the problem is "downstream" of the solenoid.
If the starter motor is hot AND the turn over is sluggish, this is probably your culprit, as heat indicates high internal resistance. A starter motor should have very low internal resistance. Can you measure the resistance of the starter (if it's an inertia starter, this can be done from the dead side of the solenoid to earth on the engine block)? You can also check for poor connections in the wire from the solenoid to the starter. And (as said previously) confirm that earth cables are good and secure.
Most classic race cars have hot start problems , why ?
Isolators that are fitted and forgotten about !
Clean all the contacts or fit quality isolators and hey presto it starts also replace that battery that is on its last legs and will fail a load test .
I hate race cars that have simple starting problems it's soooooo embarrassing !!!
Isolators that are fitted and forgotten about !
Clean all the contacts or fit quality isolators and hey presto it starts also replace that battery that is on its last legs and will fail a load test .
I hate race cars that have simple starting problems it's soooooo embarrassing !!!
Huntsman said:
A thorough understanding of ohms law helps, a voltage reading on a meter won't tell you much about current flow.
Why is it worse when hot? Because the resistance of metals increases with temperature. More resistance means less current flow.
Not many people have access to ammeters that can handle starter motor current. DC inductor ammeters are VERY expensive. Hence, the advice to test cranking voltage and the resistance of the starter motor (if it's inertia type).Why is it worse when hot? Because the resistance of metals increases with temperature. More resistance means less current flow.
Gassing Station | Classic Cars and Yesterday's Heroes | Top of Page | What's New | My Stuff