Topic: 1950 Mercury Hard To Start When Hot


keith_mercury    -- 11-23-2018 @ 6:26 PM
  Guys, I have a 1950 Mercury that turns over very slow when the engine is hot. It will barely start when warm, but turns over fine and starts normal when cold. If I wait 20-30 minutes after the engine has been shut off, it will turn over normal and start right up. I have a new Optima 6V battery, new starter, and new relay. I also have put a 2/0 ground cable from the positive battery post to the engine block. The engine only has around 1000 miles on it since it was rebuilt. What else should I try? I would like to keep it 6V. Thanks


cliftford    -- 11-23-2018 @ 9:54 PM
  Do you have a 2/0 0r larger cable from the block to the frame?


denofiniquity    -- 11-23-2018 @ 11:20 PM
  With 6 volt all must be perfect. Change to 12 volt, use 1-0 cables, negative ground, a known good starter, good ignition, (points etc or electronic), cap, rotor plug wires, plugs, good fuel, some compression, correct timing and it will start right away every time. May have left something out, but this will cover it. No need to bother with 6 volt.


CharlieStephens    -- 11-24-2018 @ 1:58 AM
  I would pull the starter and have it tested. New (especially today) is not always good, and what to you mean by "new"? Have the battery "load" tested. Then go back and check all of the grounds again (look for paint or rust), is anything getting hot? See if one of the cables is getting hot, maybe they (or their end connectors) are defective. Are there painted surfaces where there shouldn't be, like between the starter and the block? Measure the voltage drop across the solenoid when cranking. What was the last thing you did before the problem started? It wouldn't explain slow cranking but is the coil ok? Fix the problem, don't waste money going to 12 volts, especially since it sounds like everything is new. Put your general location in your profile, you can never tell how that might help. Post your results.

Charlie Stephens

This message was edited by CharlieStephens on 11-24-18 @ 2:40 AM


TomO    -- 11-24-2018 @ 7:53 AM
  If your starter has a hard time when you first push the button, and then starts to turn OK, check you distributor and carburetor. You may have a timing problem or a hydraulic lock due to fuel leaking from the carburetor.

Perform these checks when the engine is cold and the ignition is off with the high tension lead removed from the coil to prevent starting.

(1) Connect your voltmeter across the battery and crank the engine. The meter should read at least 5.5 Volts while cranking and return to at least 6 volts when you stop cranking. If it does not pass this test, slow charge the battery for at least 24 hours to bring it up to full charge and repeat the test. If it does not stay above 5.5 Volts this time, but goes back above 6 volts when you stop, your starter is probably bad. If it does not return to 6 volt or more the battery may be failing. Have it checked on a modern battery tester. If it passes the test, go on to the next test.

(2) Connect the voltmeter com or black lead to the NEG post of the battery and the red or + lead to the starter terminal and crank the engine. The meter should drop back to 0.3 Volts or less. A higher reading means excessive resistance in the starting circuit. To find the resistance, move the + or red lead to the other end of the starter cable and repeat the test looking for a reading of 0.2 Volts or less. The battery side of the solenoid should read 0.1 V or less. If any of these readings are high, replace the cable or solenoid and repeat the test. When this test is successful go to step 3.

(3) Connect the red or + lead of the meter to the POS cable of the battery and the COM or black lead to the case of the starter (a through bolt will work) and crank the engine. The meter should read 0.1 or less. If it reads more you have a high grounding resistance. This can be at one of the ground cable connections or where the starter mounts to the oil pan. Both the face of the oil pan mounting surface and the starter end plate should be clean with no paint.

(4) If you complete these tests and no problems were found, the starter is probably bad.

Good luck

Tom


51woodie    -- 11-26-2018 @ 4:13 PM
  Many years ago I bought two Amp testers from Snap-On. An MT110 Alternator current meter and an MT109D starter motor current meter. These simply fit over the respective cable and read the current by induction. These are easy to use and don't require disconnecting anything. There are some listed on Ebay


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