How difficult is it to install a engin block heater in a John Deere 3720

marshallcro · Jul 15, 2014

How difficult is it to install a block heater in a JD3720 and is there anything I need to know before I tackle this job. Thanks in advance.

boggen · Jul 15, 2014

no clue about your tractor, i just had to nock out a plug on side of engine block, and make sure the heating element tip of the block heater was facing correct direction. i did use a zip tie for the short cord that came with the block heater. so the cord would not get tangled up into something it should not be in, or get grabbed by weeds/etc... when its not winter time.

i done forgot what direction heater element tip needed to be positioned, it showed in the instructions that came with the heater element.

drain coolant from system before hand. to make less of a mess when isntalling. if your tractor has a heater in it (example has a cab) you may need to run tractor 5 to 15 minutes to get thermostate to kick in, and turn heater on full heat / blast and run for a few minutes, then shut down and let it cool and check coolant levels again to see if you need top it off.
this is to remove any trapped air within the system, during installation of block heater.

mark02tj · Jul 16, 2014

A buddy of mine had the dealership install one in his open station 3320. I'm planning on installing one in my open station 3520. I think these two tractors share the same engine block as your 3720.

Looking at my buddy's tractor, it didn't look too hard. I don't think there are any freeze plugs to knock out.

On the other hand, this thread dismisses the idea of it being a DIY idea.

This thread is a little more specific. It does mention the turbo hardware on a 3720 that doesn't exist on my buddy's 3320.

oosik · Jul 16, 2014

I had a truck with a block heater. It worked fairly well - but it started leaking. Had the freeze plug replaced and installed an in-line tank heater. Worked much better and if it would have leaked, I could fix that. The in-line heater never did leak and it did a far superior job of heating the engine coolant and the engine block.