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Help me Diagnose no start condition

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Help me Diagnose no start condition
#1
sswarin Avatar
sswarin Steve Swarin
West Bloomfield, MI, USA   USA
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1974 MG Midget
My 1966 MGB-GT has been giving me fits lately. In a separate thread I described my fuel pump problems, but those are now solved and my backup Facet pump has been running fine.
But today I wanted to take a short drive to test everything before Cars and Caffeine tomorrow. The car started fine and ran for about 30 seconds before spontaneously shutting down. And when I try to re-start, all I get is a soft clunk from the vicinity of the starter. Although the fuel pump is running and the lights and wipers, etc. will all come on, when I turn the key to start, everything shuts down and I get the clunk.
So what can this be? Ground? (it's always a ground problem, right?) Starter solenoid? Help!!
Thank you.
Steve

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Re: Help me Diagnose no start condition
#2
joron Avatar
joron Silver Member Michel Joron
Roxboro, QC, Canada   CAN
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1977 MG MGB "Victoria"
2018 Jaguar XE "Meghan"
I suspect your battery is just dead. Recharge it and/or let it be tested for charging capability. If you remove the battery clean the connections to the battery and verify everything is tight including the ground connection and the positive cable to the starter.


1977 MGB Red 'Victoria' and 2018 Jaguar XE 'Meghan'
All Classics:
Married, 2 children, MG MGB May to December, Jaguar the rest of the year.

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Re: Help me Diagnose no start condition
#3
billymgb1000 Avatar
billymgb1000 william gaulin
harrisville, harrisville RI, USA   USA
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1973 MG MGB
1974 MG MGB V8 Conversion "Sweet Thing"
If your battery turns out to be good I would suspect a ground issue

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Re: Help me Diagnose no start condition
#4
beedlejpott James Pott
Corvallis, Oregon, USA   USA
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The first thing I would do is pull the spark plugs and check that you don't have a hydraulic lock in the engine. It sounds like the engine won't turn. If it still won't turn with the starter, try turning it by hand as your starter may be locked up.

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Re: Help me Diagnose no start condition
#5
rntanner Avatar
rntanner Roger N. Tanner (Disabled)
Oxnard, CA, USA   USA
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1970 MG MGB
1977 MG MGB
You and/or your friends or a professional mechanic have a lot of electrical connections to clean up.

My suggestion is that you go to your local auto supply store and buy at least two sheets of 3M (brand) Scotch-Brite #7447

Scotch-Brite™ General Purpose Hand Pad Maroon, 6 in x 9 in

Since this electrical cable connection cleaning is not "rocket science" you can work your way through very many connections between the starter and the batteries, that are probably in "less than great condition."

The pads are quite large. I would first cut a two (2) inch strip off the short end of one of the pads, and work cleaning up your less than great electrical connections.

You may find that it is too long, and then cut that piece in half.

With three British sports car, I would have hoped that you have been exposed to these great MGB electrical schematics, online, at no cost:

http://www.advanceautowire.com/

Click on "STOCK SCHEMATICS ON THE BLACK BAR ON THE LEFT"

Open up the file to Sheet 2, for DIAGRAM 2 - 64/67 MGB

First, remove both battery cables, and make sure the ends on the battery are shiny and clean and the ground cable is attached to a shiny part of the body where it is attached.

Yes, those many years have been able to cause these connections to be in "less than great cleanliness" because of corrosion.

Clean the Negative (-) cable at the Solenoid in the upper left corner of Sheet 2.

Clean the Positive (+) cable connections at battery and where it is attached to the body metal.

Assuming you "don't every want to do this cleaning again.", after every battery cable connection is clean, and you have successfully started the MG:

Then sparingly spray each connection with:

http://www.amazon.com/Permatex-80370-Battery-Protector-Aerosol/dp/B000BOKML2

Your local auto supply will also have this in stock or an equivalent.

Roger N. Tanner, Professional Engineer

. . . and if you are still using two six (6) volt batteries, make sure the cable between the two batteries, and the connections at the batteries are also freshly cleaned up.


Roger N. Tanner
Professional Engineer, Retired

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Re: Help me Diagnose no start condition
#6
tomkatb Avatar
tomkatb Larry Baygents
Dayton, Ohio, USA   USA
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1963 MG MGB
One should troubleshoot one item at a time.

Do the battery maintenance that should be done every few years.

Remove battery connections. Clean them. The AutoZone tool for this should be in your tool box

Clean the battery top.

Check levels. Top up with distilled water.

Check connectors for clamp tightness and corrosion. Sometimes the connectors will break off.

Place clean connectors on clean battrery terminals.

Charge the battery overnight. Check voltage. Around 12.6. Check running. Should be a little higher.

This half hour effort eliminates the battery as the issue.

If no start, perhaps the starter is jammed. With the lights on try the starter. If they essentially go out I would verify the starter is free of the flywheel.


L.W.(Larry)Baygents
63B
77 Spit

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Re: Help me Diagnose no start condition
#7
rulonsw Avatar
rulonsw Rulon W
Logan, UT, USA   USA
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1967 MG MGB "Old Boy"
1967 MG MGB GT
1969 MG Midget MkIII "Oddjob"
1970 MG MGB GT "James Bondo"    & more
X2 for what Larry advised. I only just recently got my '67 starting consistently, and all it took was brushing the wires and contacts clean. Went from a 'clunk' to a 'clunk-clunk-whirr' in no time flat.

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Re: Help me Diagnose no start condition
#8
sswarin Avatar
sswarin Steve Swarin
West Bloomfield, MI, USA   USA
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1974 MG Midget
Well, after getting all that "tough love" from Roger and Larry, I bought a new battery for the MG this morning.
And the car started right up. Amazing what 12+ volts will do!!!
And to top it all off, 12+ volts also cured my SU Solid State Fuel Pump. It is now clicking away.
Thanks for all your help. I love this Forum!
Steve

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