Re: engine dies after 3 min

Discuss fixes, upgrades and modifications to your M37

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jim lee
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Re: engine dies after 3 min

Post by jim lee »

Now that's an interesting little tidbit.

Thanks!

-jim lee
MSeriesRebuild
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RULE OF THUMB

Post by MSeriesRebuild »

Only a few minutes to spend right now, although I have not read this full thread, I could have missed something. I did not see any definitive solution to the original problem mentioned. First thing, DO A COMPRESSION TEST before spending $$$ on repairs / rebuilds of accessory components. Low compression will exhibit many of the same symptoms as problems with fuel and electrical. If compression readings are good (105 PSI or higher) then you can feel good about looking for possible fuel flow, carb, and distributor issues. If compression readings are 100 PSI or less, then go ahead a realize that there is internal engine issues with ring / cylinder wall wear or valves and spend your $$ where it will do some good.

A couple of facts, the original M37 fuel tank vent system is at the cap which has a valve to open and close the cap vent. For normal operation the system vents via the open cap valve. In fording operations, the valve is set to the closed position and venting takes place through the hard line that connects at the carb elbow creating a closed system IF the correct fording gear is in place. NEVER leave the cap loose to establish a vent, this is a CROCK. Non-vented caps were used on 2 1/2 and 5-ton trucks and some other vehicles that have systems in place, and are designed to establish tank venting in systems that are designed to work with non-vented tank caps. Either cap will fit the tank fill spouts on many vehicles, so it is easy to install a non-vented cap on a vehicle that has to have a vented one or vice-versa. A non-vented cap can work on a M37, but ONLY if the original vent system has been modified so the system can vent appropriately without the vented cap being used.

CHECK that cap vent valve, we have had some caps new out of the box that were defective, and did not have an open vent when the valve selector was set to the OPEN position.
Charles Talbert
www.mseriesrebuild.com
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