Mahindra Max 25

   / Mahindra Max 25 #1  

Engineergeek

New member
Joined
Nov 27, 2021
Messages
1
Tractor
Mahindra max 25 HST
Thought I’d share how I fixed my tractor’s starting problem. It is 7 years old and has about 500 hours on it. It recently developed a cold starting problem. I could start it with a very small shot of ether with no glow plug heat up time, but it would not start from cold on the glow plugs. Note: if you choose to use starting fluid on a glow plug engine, use a very small dose of starting fluid into the air cleaner. Crank the engine without heating the glow plug. A hot glow plug will cause literally an explosive effect on ether.

I used a test light to check the glow plugs, and they were getting power. Each plug was individually tested and each was ok. I cleaned the precombustion chamber with carb spray through the glow plug hole. I let it sit for a minute and then bumped the engine over to prevent liquid lock, before reinstalling the plugs. No difference.

I found a wiring schematic online. The controller is a fairly simple switch device, and the plugs are fed power directly from the main battery feed to the fuse block. There isn’t t much to it.

Since the glow plugs normally receive full battery voltage according to the diagram, I hot wired the glow plugs to the positive side of the battery for five seconds and then I disconnected the hot wires and hit the key. It started immediately. This told me it was not an engine or a glow plug problem. The glow plugs were getting voltage (I checked it, and it was about 0.2 volts below battery voltage), but they were not getting sufficient power. There had to be a bad connection somewhere upstream preventing high current flow.

I pulled the air cleaner and coolant overflow out of the way and inspected the wiring. I removed the wires from the split conduit, and it all looked good. No burning or other degradation. Online, I had read about a 10 amp online fuse in the eMax 25 that sometimes has a loose connect, but neither the wiring diagram nor my inspection revealed any such thing on my older 25 Max. Moreover, the diagram shows nothing that would indicate a need for another fuse. It is already properly fused, at least on this model.

I checked the fuses and the fuse block. There was nothing out of the ordinary there. No burning or carbon marks, and the fuse felt tight.

I pulled the connector for the power side out of the controller. I noticed it had almost no contact marks on the spades. I bent them slightly towards the contacts on the opposite connector and applied a little dielectric grease.

I got on the tractor, turned on the glow plugs until the light went off, and it started right up. I waited about six hours, and it started again.

This system is much simpler than many of the threads I have read online. I hope this helps someone.
 
 
Top