Drove the Mk2 twice today. Earlier in the AM started up fine after a few weeks sitting. After breakfast it started back up fine and drove home. Late afternoon started up fine and drove to meet friends at a brewery. Not sure if it’s relevant but when I got there (10 minute drive) I noticed I had left the manual choke switch on. On the way out, tried to start once without the choke switch on then tried again with it on. No start. Waited a little and tried again. No start. Cranking seemed normal.

I checked a float bowl and there is fuel. I pulled a spark plug and there is spark at least at the front plug. Pulled off the air cleaner just in case that was restricting air. Hard to imagine I lost compression in the span of one beer but didn’t have a way there to test. I pulled the distributor cap and it looks clean and new. Ran a nail file between the points. No start. Not even any partial firing in any of the above.

I got a ride home, ate dinner and went back for one more try. Same result. Called AAA. Waited for 3.5 hours, got rescheduled for 2 hours later, got frustrated and went home leaving the poor old girl in the parking lot by herself.

Any suggestions for when I go back? I figured I’d test compression, and test spark on all plugs. Also charge up the battery as maybe it was not cranking strong enough to turn over. If I can find a spare condenser I can change that out but I wouldn’t expect spark if that was bad?

Could the choke solenoid be the culprit? I can hear a click when it is engaged (ignition on) but don’t see any external movement. Can it be manually actuated for a test start?

 

I have had a similar scenario. I have a friend who drives my S Type occasionally for me when I have a double booking with the S Type and the Alvis at a wedding. Steve is not mechanically minded and on this particular day I started the S Type for him but left the choke on. My mistake. Whilst I was picking the Bride up Steve had dropped the Groom off at the church but was supposed to join me to transport the Bridesmaids. He stopped at the church and could not restart the car. I turned up about ten mins later switched off the choke and the car started. Too rich to actually fire on a hot engine. That would be your first problem.
Now that the car has cooled you should be able to start the car but as the car has been cranked a lot to get it to start you might find that the problem now is battery. There might be enough charge to turn the engine over but not enough to turn the engine over and send a spark. Again without telling the story this has happened to me. I jumped the battery with a set of jump leads off another car and after a short wait to put some charge into the battery she started up straight away. If you still have the old generator even though the engine is being spun by the starter motor the generator is not helping to produce a spark as the engine is turning over too slowly. To produce power the generator needs to be rotating at about 1000 RPMs. All your draw on the battery with a low charge is not enough to power the starter motor and supply a spark.
An Alternator is completely different and produces power from very low RPMs and in this scenario would possibly start the car for you.

 

Sorry to hear of your untimely issue ! I think that you've maybe fouled the spark plugs. I would see if you can find another set of plugs to install this morning. that and some jumper cables should get you going. I will not be surprised if it starts up on its own this AM without any more fiddling on your part . Good Luck ! I hope the old girl was not molested during her night out.
Schmitty

 

Thanks for the responses! I went back today and tried to start with jumpers connected and got a brief sign of life, but then couldn't get it started. Since it's now raining I decided to go ahead and call AAA again. This time they showed up quickly and I'm back home. I'll dig back into troubleshooting after we both dry off and I'll report back what I find.

 

if an engine is run with full choke on it is bound, as mentioned in a previous post, to foul the plugs. they can simply be cleaned off with some brake cleaner, a toothbrush and rag in an emergency.

AFAIK (and i could easily be wrong, as usual) there is no standard "choke switch" on these cars. if so, then the manner in which it is rigged may determine how much of a problem it would be if it were left "on".

 

Good point. I'll pull and clean all the plugs. The one I tested for spark with looked OK, but I didn't check carefully. I do know the "hissing" continues no matter engine temperature until I cut the switch off. Because of that I suspect I'm in more danger of fouling by leaving it on too long than other setups that seem to still allow the auto cutoff function to work.

 

If the auto choke is set to start in a heated garage or even in an unheated garage, and then left outside overnight in the cold, the engine will not fire very well because the ambient temp will be too cold.

Geoff, where is the car normally kept at home upon first start ?

If it's in a garage, try again next day, after cleaning the plugs up.

I checked the temperature in VA last night, according to the report it got down to 35 degrees, that's cold enough where it will not start if the choke is set to start at 50 degrees.

About fouling, the choke will and does enrichen the mixture, but it also has it's own air intake (the hissing you hear), so fouling is not such a problem as you may think.

 

Usually in an unheated, uninsulated, unattached auxiliary garage.

Ah, interesting. I’m reading up on the choke in the workshop manual. Does that blue SU carburetor book cover the choke function? I feel like I understood the SU from experience on the MG but the auxiliary starting carb is still mysterious to me.

 

These autochoke devices gave trouble when the cars were in production in the 60s, and a lot of people replaced the auto with a manual switch on the dash. The culprit is normally the "Otter Switch" that detects coolant temperature and thus switches the choke device off when the temperature gets to a certain level. It is a fairly common failure item. I had a 2.4 Mark 2 which was manual choke anyway.

https://www.sngbarratt.com/uk/#!/Eng...20340&f=4&m=25

 

I have it on a charger now and poked around a little under the hood. I noticed fuel at a high level in the body of the auxiliary starting carb. Will try to attach a picture. I’m finding discussions online about whether this is normal or not. It does seem higher than the float bowl level and seems to be above what I thought was the air intake. Is this fuel height normal in the Mk 2? Could this be related?

 

If you happen to flood it go to wide open throttle. Foot to the floor. Ensure fuel pressure does not exceed about 3psi or go too low. SU's are fussy. Pressure too low & still won't start. Don't be mislead by fuel in the filter. Does not mean a bucket of beans. Constant depression carbs have their own foibles. e.g. Quite the opposite to a Weber sidedraught carb. My car is still using it's original red genuine Otter brand switch & works perfectly. 90,000 miles before concours rebuild. Luck of the draw.

Reset needle on your AED for ambient conditions. Different Summer to Winter in many climes.

 

Buy this book. ~ cheap.

 

Just ordered - thx.

 

A flooded engine and a weak spark is a recipe for not starting.
Glyn's advice for a flooded engine is correct and I have also used this technique dozens of times on aircraft engines.
One thing I have introduced into my MK 1&2 Jaguars is resistor starting.
The 12 volt coil is replaced by and 8 volt coil.
An ignition resistor is wired into the power feed to the coil.
A relay is wired with the points across the resistor and one side of the relay coil wired to the output of the starter solenoid and the other side to earth.
When the starter button is pressed the relay shorts out the resistor and full battery voltage is fed to the 8 volt ignition coil producing a really "hot" spark.
When the starter button is released, the relay opens, and the coil only sees a running approx. 8 volts (and doesn't get burnt out).

I didn't invent this idea and I first encountered it in Datsun 120Y (Nissan 1200?) cars. My first "experiment" used parts taken off a Datsun wreck to try on a Jaguar.
This may not be as sophisticated as modern electronic spark systems, but it is cheap and reliable and certainly makes starting a lot easier.

 

If the car has been flooded, sometimes I have then removed the plugs and used a blow gun on my air compressor down the plug hole and that blows the excess fuel out of the cylinder. After cleaning and drying the plugs, reinstall them and the car started.

That being said, I much prefer the manual choke of the E Types over the automatic choke of the S Type. The Daimler DS420's like mine kept a manual choke up to 1992!

 

So how many ohms is on the primary winding of the 8 volt coil, .7, .8 or 1.5 ohms ?
And what's the ohms resistance of the resistor you're using ?

I'm guessing that a 1.5 ohm coil is essentially meant for 8 volts, and therefore needs a 1.5 ohm resistor wired in series with the primary winding under regular driving conditions.
This all assumes that a 12 volt battery is being used.

I just never heard of an 8 volt coil before or referred to it as an 8 volt coil.

 

Jeff, You've probably heard of it as a ballast resistor coil. A ballast resistor and 7 or 8 volt coil as described by Bill were pretty well the standard arrangement for the last 'traditional' coil and contact breaker ignition systems.

Sometimes we unconsciously develop best routines for starting engines. For SUs with a conventional ignition system, opening the throttle while cranking and closing it as you release the starter can help the engine to fire up. As others have said, if the engine might be flooded, a wide open throttle usually clears things.

 

I have tried to stop using the term WOT on forums. It seems to confuse the uninitiated. And fair enough if I'm not achieving communication.

 

Yes, I know of a ballast resister and what it does.
Your statement does answer my question _ more or less, that an 8 volt coil (or 7 volt if you wish) is 1.5 ohms across the primary windings.
I've just never heard of any coil referred to as an 8 volt coil, when dealing with a 12 volt system.
When it comes to 12 volt systems, when discussing what type of coil is needed one looks for the ohms rating _ that's the way that I've always looked at it.

I understand quite well about opening the throttle wide open to get air into a flooded engine, but that has nothing to do with my volt/ohms question.

 

I think the coils in a ballast resistor system were nominally a "12V" coil, because they ran at 12V during cranking, but usually ran ~5V less during running. Chryslers used this system a lot in the 60's and 70's as a way of getting a hotter spark during crank. Chrysler spec was 7-9V at the coil, for a 1.5 ohm coil. That is for a points ignition.