Summer Project (mechanic minded people appreciated!)

[kmount]

Evening folks,

 

I have a summer project of restoring a 1978 MGB Roadster.

 

At the moment every now and again it will 'cut out' and attempts to start it again return lots of battery clicking and no attempts at turning over. (Internal lights function fine throughout suggesting battery is OK, no fading etc, replaced battery with spare just inc)

 

Leave it alone for a bit and it will start up fine (and wow does it sound lovely). Not so helpful when it does it mid run though

 

So, I figured I'd ask here (seeing as everyone who lurks in 'General Chat' is an expert on everything ever asked about) for ideas on what it could be

 

I was thinking fuel pump originally but I'm not much of a mechanic so I figured I'd keep my trap shut and let someone who knows what they are talking about offer up some assistance.

 

Grateful for some thoughts.

 

Cheers very much.

 

Kim

[CyberNerd]

I suspect there are two problems. It's likely that the 'clicking' is the starter solenoid, try and bypass it (I use a screwdriver on my kawasaki!) and see it that turns the engine.

The cutting out could be fuel related, or it could be a pickup relay. sometimes damaged pickup relays cut out as they heat and expand, measure the resistance against the book value when its hot. I understand that some cars have things called distributors, being a motorcyclist I'm unfamiliar with these but being a vintage car it may not have pickup relays - in which case check the fuel pump and that the fuel lines have not degraded, an old bike of mine used to run out of fuel if I did over a mile at 120mph, the fuel lines were so soft they constricted fuel flow.

[kmount]

CyberNerd,

 

Thanks for that

 

I had heard someone else mention solenoid (the old man I believe), I will check it out when we get to a day off with some reasonable weather!

 

 

Thanks again

[cpjitservices]

Cutting out.,... When exactly ? Pulling away ? or steady driving - could be a timeing issue.....

[Brucy]

Does it ever cut out on choke? could be the idle speed/mixture setting. Could also be your points (check the gap) or the condensor in the distributor.

 

Andy (Herald owner)

[laserblazer]

I had a similar problem with a Vauxhall Senator. That was the fuel pump relay. Giving it a light wack with a spanner sorted it until I replaced the relay. Also, check the connections to the starter motor, it could be a dodgy earth. Edited April 2, 2012 by laserblazer

[Sirbendy]

Ha, we have a science head here who has an MG, whho had to go to the garage last week because it did exactly this, and the garage couldn't get it running...

 

First - hammer. Whack starter/solenoid a few times, see what happens. I've known them jam in the gear, needing the car to be rocked in gear to free. Also known non-engaged starters to stick on their pinions (good fun). If the solenoid clicks, check it can pass voltage out to the starter. Burned contacts might cause it. Check your wiring and especially your earths - starters like a good, fat earth in good nick. If in doubt, add another braided earth strap from the engine block.

 

In fact, if you have jumpleads...next time it does it, use the jumplead to earth the block as a test.

 

Worst case, you've got an iffy starter motor...not done much on repairs with them, but I'd imaging they have brushes that can be cleaned/checked/replaced...I KNOW the alternators of that period have..it may be a stuck carbon brush.

 

Cutting out when running..hmm. You need to crack off a fuel fine and check for spurts of fuel on turnover..it'll be mechanical I'd think. I've had one fail and pump fuel all over the engine before on my Maestro..much cursing was had.

 

If you have fuel delivery, crank it over a few times and pop a plug out and have a sniff/check - it should be damp and smell petrolesque. If it is, fuel is not your issue, probably.

 

Grab a multimeter, check your wiring...it'll be a simple system. Check the coil isn't breaking down and going open circuit under heat/load - had that on the Reliant. Check your distributor - as I recall they had a suppressor/capacitor that was apt to go intermittent...but apart from that check your points, the rotor arm and the cap.contacts for damp/tracking/damage/wear.

 

If you have any spare HT leads, you could try swapping them out...I'd suggest for a total stop cutout doing the king lead first (centre of the dizzy cap to coil).

 

Is it a 1.8? The science guys is the 1275..heh..my Maestro had a 1.6, and the Reliants (god bless 'em) have an 848cc lump that's a clone of the A series..so I'm fairly used to these engines.

[Sirbendy]

I had a similar problem with a Vauxhall Senator. That was the fuel pump relay. Giving it a light wack with a spanner sorted it until I replaced the relay. Also, check the connections to the starter motor, it could be a dodgy earth.

 

you'll be gald to know the fuel relays can still give issue even on MK4 Astras...haha!

[laserblazer]

you'll be gald to know the fuel relays can still give issue even on MK4 Astras...haha!

 

I had my Senator in 1990, so I expect they'll get round to sorting the problem soon

[Sirbendy]

I had my Senator in 1990, so I expect they'll get round to sorting the problem soon

 

I doubt it...heh.

[alan-d]

To me it sounds like a solenoid problem but I'm no expert either

 

However on a slightly different note, when I had my kit car I found Rimmer Bros to be very good at supplying parts.

[3s-gtech]

1.8 B-Series in these, the 1275 A-Series was in the Midget/Sprite. Not the best, but fairly reliable. All the salient points have been covered, check your distributor and make sure each plug is giving a good strong spark too.

[kmount]

Wow, thank you for your thoughts everyone!

 

Lots to read and try :>