Block Heater Resistance

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Sep 20, 2007 | 11:58 AM

powrstrkr

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Fleet Mechanic

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From: Rio Rancho NM

Block Heater Resistance

My block heater quit this past spring and now is the time to fix it. I ohmed it w/a Fluke and it reads 15ohms DC resistance through the power cord and element. Pulling the cord out of the wall outlet gives a spark, just like it always did when working. I could always hear the coolant bubble within about 15sec of plugging it in but it doesn't do that any more. Didn't someone post a while back that they are supposed to read somewhere around 200ohms DC resistance? Can they short like this internally? I have not left it plugged in long enough to see if it still heats the block. I just assumed it was bad since it no longer boiled the coolant.

Sep 20, 2007 | 01:21 PM

powrstrkr

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From: Rio Rancho NM

Searching through some old threads reveals that the heater draws about 1KW or 9A. 1KW/110V = 9A. 110V/9A = 12ohms. Would a change in element resistance to 15ohms indicate failure, or just not heat the block up so much? Should I try leaving it plugged in for a while and see, or just replace it anyway even if it still warms the block? It is drawing current.

Sep 20, 2007 | 01:27 PM

powerstroked162

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From: Ellensburg, Washington

Those little fuggers are a pain in the rear to exchange out. I did mine on a car lift and it made it much easier, but it was still a pain.

Cowboy Steve

Sep 20, 2007 | 09:21 PM

plowhand

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From: Southwest Georgia

I would plug it in for a couple of hours and see if it still heats. Like steve said, they are a pain to change out. Just remember that like a hot water heater element they do loose some efficiency over time but still heat up the coolant.

Sep 21, 2007 | 04:56 AM

Cuda_jim

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From: MICHIGAN

I agree with plowhand, it's probably working, you're just not hearing it. Especially if you are getting a spark at the wall outlet. If you have any continuity between the two flat prongs on the plug the element is still intact. BTW: what is DC resistance? I didn't know AC or DC made a difference in resistance (ohms).

Sep 21, 2007 | 11:30 AM

powrstrkr

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From: Rio Rancho NM

I'll try it tomorrow. Hopefully it still works. But what is so difficult about replacing it? It's easy to drain and refill the coolant. It looks easy to get to and like it just screws out of the block once you pull the cord off. NAPA has them for $42.

By DC resistance I meant I checked it with a Fluke meter. It uses a DC battery to check resistance. Since the element uses AC power I thought I'd say that. I've been doing elecronics way too long I guess. For fear of there possibly being a problem I didn't use it once I couldn't hear it boiling anymore. And summer got here. I'll post up if it still works or not.

Sep 23, 2007 | 10:18 PM

powrstrkr

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From: Rio Rancho NM

I plugged it in for 3 hours this morning and it did indeed warm up the block. Not quite as warm as it used to but apparently it still works. At startup, the temp needle was halfway between the C (cold) line and bottom of the normal range. Garage temp was about 70. But it doesn't get hot enough to boil the coolant any more. With the resistance getting slightly higher, could the element be on its way out? And what is so difficult about replacing it? It looks easy to get to.