Testing a block heater

Soundguy · Jan 7, 2014

Industrial Toys said:
YES, common problem as I mentioned. The contacts are often not up to the task and are burned, providing poor contact. How do the heater prongs look, if you can see them? What about the cord. Is it melted around the socket openings?

A little curious though. Seems the heater has very low resistance. My calculations at 120 volt would be that the heater has 1309 Watts! Could that be? Never heard of an element going lower resistance then it should be, only burning up, going open circuit.

Depends on the element type.

1309w doesn't make me blink at all. i was figuring even 1500w.

add to that that the measurement device is likely a consumer grade meter.. thus not very accurate at low ohms. also figure that a DC 'ohms law' wattage check on a heating element that may not be fixed resistance vs impeadance.. it not 100% the same..

Industrial Toys · Jan 7, 2014

I'm thinking that 11 ohms is the COLD resistance. Possibly a chromium or tungstin type element changes resistance, going higher with temperature. Probably 11 ohms is OK.

allen6634 · Jan 7, 2014

speaking of battery chargers i have a automatic charger , i leave mine pluged in all year , one thing i would think about , is the engin block warm? touch it with your hand if it is 0 then you should feel warmth

Pipestone Kid · Jan 7, 2014

Latest update--First off, thanks to everybody who responded. Second, As I lay in bed this am, hesitating to get up, I began to think of what is my problem. I then realized I was being dumb in my testing process. Those of you who are familiar with these heaters know that the two prongs that the cord attaches to are quite close together and also quite close to the actual case of the heater. Well, to make a long story short I thought maybe in trying to get the meter prongs onto the posts, I may be grounding them out. I made some "insulating" covers out of small plastic tubing and tested again--no reading. I tried this 5 or 6 times to be sure I was making contact and got a zero reading every time. Now does anybody know where I can get a heater besides JD? Not only are they expensive at JD, but the nearest dealer is 50 miles away. I called Zerostart, but they don't have one for my engine. It is a Yanmar model 3TNE74. (3 cylinder diesel)

Mechanos · Jan 7, 2014

Pipestone Kid said:
... I called Zerostart, but they don't have one for my engine. It is a Yanmar model 3TNE74. (3 cylinder diesel)

Yes they do... they just don't know it. #3100003 1" NPT 400W 120V

Industrial Toys · Jan 7, 2014

Curious. If you had shorted the leads, you should have gotten closer to zero resistance, usually an ohm or so. This is however the (I have some really nasty language for this) murphy's law of troublshooting.

You get erroneous results and readings to confuse you!

There's actually more then one thing wrong! Why? Everything worked before!

The wire in your meter lead or clip lead jumper breaks at the moment you try and take a reading!

Your meter times out and shuts off, or the battery dies!

You've been switching between ohms and volts and are on the wrong setting.

You accidentally choose AC and not DC or vice versa (All these STUPID products have symbols and not English Language to accomodate markets on the other side of the globe!) and get false information.

Someone has switched around wires trying to "fix" it unbeknown to you!

Alliens are hovering over your place, just messin with ya, having a good laugh at your expense!

Sometimes I think the last, happens most often!

Welcome to Troubleshooting!

Pipestone Kid · Jan 7, 2014

MECHANOS--I called Zerostart back with the JD part # and sure enough, they came up with 3100003. It will be here tomorrow. Thanks again everybody.

Henri88 · Jan 7, 2014

Soundguy said:
did you read his post? he said he tested about 11 ohms on the heater element. that's not OPEN!!!

the 11 ohms is about what i expected as well.

Yep, miss that completely! Very very short term memory. :confused2:

Pipestone Kid · Jan 10, 2014

I hate it when an OP doesn't follow through with the final outcome, so here is mine. The new block heater arrived Wed. afternoon (too late to start on the replacement) I had a Dr. appointment and other errands on Thur, so this morning I went to the shop, drained the radiator and block, replaced the heater and tested for leaks--none. So, I decided to test the old heater where I had it out where I could see exactly what I was doing. Result-- Dead as a doornail! Thanks again for everyones help.