Testing Block Heater
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
That works out to 850 watts.
How long is your extension cord?
You may need a larger AWG cord.
3 volts of drop to 118 volts is not bad, but 110 volts is to low.
You should supply a minimum of 115 volts to the heater.
In the electrical business,
Almost all devices are designed for a minimum of 115 volts.
The supply voltage at the electric panel is usually aroung 120 volts.
So when you wire something, you take the length of the circuit and the amp load to figure out what size wire you need to to keep the voltage drop under 5 volts from the panel to the device.
Any device running on low voltage will fail before one that has the proper voltage supplied to it.
You may also notice the cord gets warm, which is putting heat out where it is wasted instead of in your engine where you want it.
How long is your extension cord?
You may need a larger AWG cord.
3 volts of drop to 118 volts is not bad, but 110 volts is to low.
You should supply a minimum of 115 volts to the heater.
In the electrical business,
Almost all devices are designed for a minimum of 115 volts.
The supply voltage at the electric panel is usually aroung 120 volts.
So when you wire something, you take the length of the circuit and the amp load to figure out what size wire you need to to keep the voltage drop under 5 volts from the panel to the device.
Any device running on low voltage will fail before one that has the proper voltage supplied to it.
You may also notice the cord gets warm, which is putting heat out where it is wasted instead of in your engine where you want it.
Thread Starter
|
Mountain Pass
Joined: Mar 2004
Posts: 102
Likes: 0
From: Wilmington, NC
So apon further testing it pulled 105.7 this time. Length is 6 foot. Is it possible that it is the right cord and just worn out? I have used it a lot. Yes I noticed it was getting quite warm to the touch before it quit working. Is the heater plug inter cahngeable, so I can build a cord or must they be ordered as a unit? Also can one just order a heavy duty one? Thanks again!
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
My question was how long is the extension cord you are plugging into?
I have a friend that had a diesel, and tried to plug his block heater into an 18 gauge 100 foot extension cord.
The cord got hotter than the block heater did.
I have a friend that had a diesel, and tried to plug his block heater into an 18 gauge 100 foot extension cord.
The cord got hotter than the block heater did.
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
You need to test it while the block heater is also pluged in.
You don't get voltage drop until you put the amp load on the cord.
14 AWG wire just barely should be big enough, 12 AWG would be much better.
You don't get voltage drop until you put the amp load on the cord.
14 AWG wire just barely should be big enough, 12 AWG would be much better.
Thread Starter
|
Mountain Pass
Joined: Mar 2004
Posts: 102
Likes: 0
From: Wilmington, NC
Dave, I pulled the heater. It is 120v and 1000w. It tests at 15.6 ohms which you said was 800w or something. Does that mean the heater is going bad too? Thank you.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Ford Super Duty: 5 Things Owners LOVE, 5 Things They LOATHE!
Joe Kucinski
Every 2026 Ford Truck Engine RANKED from WORST to FIRST!
Michael S. Palmer
The Best F-150 Deal of Every Trim Level (XL through Raptor)
Joe Kucinski
Thread Starter
|
Mountain Pass
Joined: Mar 2004
Posts: 102
Likes: 0
From: Wilmington, NC
Ok here is the latest. Ignore the last post. I put in a new cord an heater. Under load with the same extension cord I am getting 120.1 where the cords meet. Seems likr problem solved. Thanks.
Junior User
Joined: Mar 2009
Posts: 94
Likes: 1
Yeah in my experience cords go more often than heaters. I have seen them snap right off at 40 below or colder and the contacts in the heater end are crap. I made a cord for the loader from 12ga. wire and bullet connectors cable tied on close by to prevent damage in the event of the dreaded "oops, i forgot to unplug". I have seen people driving down the highway dragging 20 or 30 feet of extension behind them. I've also picked up those extension cords with the locking female plugs, that had most of the block heater cord still attached.
Thread Starter
|
Mountain Pass
Joined: Mar 2004
Posts: 102
Likes: 0
From: Wilmington, NC
Here is another issue. I put in the new heater, cord and tested the extension cord. All seem good. My antifreeze does not seem to be heating the block. I did refill all the way without running it obviously. Could the block still be empty of antifreeze after draining to change the heater? If so how to I get around this Catch 22? Thanks.
Thread Starter
|
Mountain Pass
Joined: Mar 2004
Posts: 102
Likes: 0
From: Wilmington, NC
Help!
Now this GD thing will not start. Is it possible to have a bad heater? I just crawled under it and have 120 volts to the heater plug. Hard to get my leads on it but the heater only seems to be testing at about 5 ohms. Funny, before I installed it it tested good. 20 or something. Gonna pull it out later to see for sure as it is hard to test installed. What gives? I am so pissed right now. This is my work truck and I have no $ to take it to someone! Anyone want a deal on a truck right now? #%^**$#&*(())&^^###!!!!!!!!!
Senior User
Joined: Mar 2010
Posts: 140
Likes: 0
Block heater come in a variety of wattages.
Because of that, resistance can vary.
26.4 ohms = 500 watts
13.2 ohm's = 1000 watts
8.8 ohm's = 1500 watts
That is three examples, I have seen 600, 750, 900, 1200 and several other wattages over the years on top of the ones I listed above.
Because of that, resistance can vary.
26.4 ohms = 500 watts
13.2 ohm's = 1000 watts
8.8 ohm's = 1500 watts
That is three examples, I have seen 600, 750, 900, 1200 and several other wattages over the years on top of the ones I listed above.
Today I went out after it was pluged in for 1 1/2 hr and it was only a little worm by the block heater, I guess its a little sleepy!
Thread
Thread Starter
Forum
Replies
Last Post
Whitey Ford
1999 - 2003 7.3L Power Stroke Diesel
1
Nov 25, 2016 09:36 AM
