Author Topic: Engine issues  (Read 301 times)


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Engine issues
« on: May 01, 2019, 06:56:56 AM »
For a while now I have been having issues with keeping my halftrack running.  This past weekend at an event we swapped out the carb and it idled great.  I let it idle for 30 minutes or so without a problem.  After shutting it down for a while I started it back up and when I tried to drive with a load I started having issues.  I had no power and it seemed to be like it was starved for fuel.  Afterward I was told black smoke was coming out of the exhaust.  This weekend I had people who I considered mechanical experts looking at it and they threw up their hands on it.  Does anyone have an suggestions?  There were a couple of suggestions to check the vacuum line to the hydrovac and plug it or check the exhaust for leaks.

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Schafer's Folly - Halftrack Restoration


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Re: Engine issues
« Reply #1 on: May 01, 2019, 07:40:07 AM »
Could be a vacuum leak at hydrovac.
Could also be sucking some brake fluid.
But would think that would also screw up your idle......but you said idle was ok??

Unhooking/plugging that line at the intake would probably be a good place to start.

« Last Edit: May 01, 2019, 07:42:40 AM by spillmk1 »
1955 M38A1
1952 M100
1941 M2A1
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Re: Engine issues
« Reply #2 on: May 01, 2019, 07:54:49 AM »
Keith is on a good track. Try eliminating the vacuum variable.
1941 White M2
1942 White M4A1 was M4
1942 Autocar M2A1
1942 Autocar M3-75
1943 White M13 rebuilt as M16
1943 Diamond T M3A1


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Re: Engine issues
« Reply #3 on: May 01, 2019, 03:49:46 PM »
If you are blowing black smoke you have too much fuel. Could be brake fluid also check float level. Also check your points and timing.

Lots of green "junk" as my wife likes to call it.
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Re: Engine issues
« Reply #4 on: May 02, 2019, 07:57:07 AM »
I had the same issue with mine, found that the air cleaner oil level was over full and had water in it. I couldn’t figure out where the water came from. I wonder if the water  is condensation from the engine? Anyway once I serviced the air cleaner it ran fine.
1941 M2A1 not restored
1942 M3 Diamond T Mostly restored
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1967 M51A2 Tractor
1945 WC 63 needs restoration
1967 M36 Long wheel base duece
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Re: Engine issues
« Reply #5 on: May 04, 2019, 09:21:35 AM »
If you have the same or similar problems with 2 carbs the carbs are most likely not the not the problem. If you have too much fuel you will have black smoke, If you are seeing lite blue smoke you are burning oil. If you see white Vapor/smoke you are seeing water. And dot 3 brake fluid makes white smoke until the brake fluid is depleted then no brakes (long story). Sounds like you have a carburetor that is set pretty rich and when you try to accelerate you cannot burn all extra the fuel. I think you should check the timing. It might be right at idle maybe the spark advance is not working properly. A vacuum leak would make the mixture too lean and so you should not see black smoke. 

How and when did the problem start? slowly over time, suddenly, after storage or was it always this way? Did the carburetor you put on work good on another vehicle?

If your spark is too late you will have all the symptoms you describe except the black smoke. Good idle and no power. Too early and you will have popping backfiring and engine will sound labored when it is idling.

When you solve this please post what you found I would like to know



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Re: Engine issues
« Reply #6 on: May 15, 2019, 11:36:15 PM »
Mine did some weird things similar to this on three occasions and for three different reasons. The first time was a stale battery. It had enough life to crank it over and start the beast, but it dragged the system down and the motor ran weak especially at idle. A new battery got me a much hotter spark and better power.
  The second time was vacuum leaks. Pinch everything off at the carb as a test.
  The third time was a damaged “economize” valve in the carb. And loose carb. Screws. This fix really woke the beast up. I got it up to 40 mph before I chickened out.
  Are you hearing much ticking from the valves / lifters. If all else fails, pull the side covers off and see if all your valves are returning or check compression


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Re: Engine issues
« Reply #7 on: May 15, 2019, 11:42:17 PM »
Also, check the butterfly on your exhaust manifold. Make sure it opens when hot and moves freely