Testing Block Heater
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Freshman User
Joined: Oct 2004
Posts: 37
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From: Toronto Canada
Testing Block Heater
-25 Celsius last night here in Ontario. First time I left her plugged in all night. Gauge was still dead cold in morning. Turned over till I killed battery. No go until I recharged battery and squirted a little WD 40 into intake. Fired right up.
How can I properly test my blocker heater? If it needs replacing is the dealer my only option?
Dont really like to open her up every cold morning and remove air cleaner cover (with soup bowl), spray WD, fire up, warm up, shut down, refit air cleaner, etc etc!!!
thnx jvc
94 F250 7.3 IDI 4X4
How can I properly test my blocker heater? If it needs replacing is the dealer my only option?
Dont really like to open her up every cold morning and remove air cleaner cover (with soup bowl), spray WD, fire up, warm up, shut down, refit air cleaner, etc etc!!!
thnx jvc
94 F250 7.3 IDI 4X4
Posting Guru
Joined: Sep 2002
Posts: 1,897
Likes: 0
From: Northeastern Pa - USA
it may not be the heating element itself. I had a mouse eat the wiring to the heater. Follow the wire and determine if the wire is solid. If the wire is ok, drain the radiator and there should be a water plug in the block to drain the block and you can change the element yourself. I got my last one at NAPA auto parts or International dealer. I beleive the hole is metric in size. The element is L shaped and will slip into the soft plug hole up near the starter. When you install the new one, insert it and twist it both directions until there is resistance ,,,determine center (this keeps the element from rubbing internal walls of the engine) and tighten the element. You may have to use emry cloth to clean the seal area on the block, but should be able to do it yourself. Install correct coolant and have at it. Dont plug the heater in with no water in the block. Good luck and let us know how you make out.
Post Fiend
Joined: Nov 2004
Posts: 5,638
Likes: 1
From: Manitoba
Whoa up there guys..........don't change anything yet.
First make sure the BH red power plug is in the BH, then do a continuity test with a meter on the main 120V plug wires. If there is no continuity check the wires for breaks right at the 120V plug, check by wiggling the plug and you may see continuity come and go possibly. By pulling the plug away from the wire you may see one side of the wire looks different. If it's a broken wire(s) just cut the plug off and if the 2 wires now show continuity through the BH, then replace the 3 prong plug .
This is the most common type of failure on a block heater....lets face it if your plug is hanging out flopping around at -30F, it too would freeze and break off.
First make sure the BH red power plug is in the BH, then do a continuity test with a meter on the main 120V plug wires. If there is no continuity check the wires for breaks right at the 120V plug, check by wiggling the plug and you may see continuity come and go possibly. By pulling the plug away from the wire you may see one side of the wire looks different. If it's a broken wire(s) just cut the plug off and if the 2 wires now show continuity through the BH, then replace the 3 prong plug .
This is the most common type of failure on a block heater....lets face it if your plug is hanging out flopping around at -30F, it too would freeze and break off.
Last edited by PLC7.3; Jan 19, 2005 at 09:10 AM.
New User
Joined: Jan 2002
Posts: 7
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block heater was not working on my wife's truck,
no continuity when checked with an ohmmeter,
about 4 inches from the plug the power cord was like a wet noodle,
cut it open...copper wires had been stretched and broken!!!
can happen when you back up while still plugged in.
second story...a coworker showed up at work one morning with an orange extension cord trailing from her car, about 10 miles.
I like to loop the extension cord around the driver's side mirror as a little reminder to unplug.
no continuity when checked with an ohmmeter,
about 4 inches from the plug the power cord was like a wet noodle,
cut it open...copper wires had been stretched and broken!!!
can happen when you back up while still plugged in.
second story...a coworker showed up at work one morning with an orange extension cord trailing from her car, about 10 miles.
I like to loop the extension cord around the driver's side mirror as a little reminder to unplug.
Post Fiend
Joined: Nov 2004
Posts: 5,638
Likes: 1
From: Manitoba
My setup/proceedure I have used for several years, I have 10' of extension cord exit between the grill and headlight assy. I back into my spot next to the garage and plug the BH cord directly opposite the drivers side fender. My first task in the morning is start the truck, then remove the cord and wrap it around the license plate holder, then clean the snow off before driving away.
Sorry but when I see cords flapping up and down on fenders or hung off mirrors it makes me think those people have no concern for their vehicles appearance..... but they would be the one's looking for top buck a sale time for their POS.
Sorry but when I see cords flapping up and down on fenders or hung off mirrors it makes me think those people have no concern for their vehicles appearance..... but they would be the one's looking for top buck a sale time for their POS.
New User
Joined: Jan 2002
Posts: 7
Likes: 0
yes, my truck probably qualifies as a POS in your eyes. It's a 1990 F250 and too many Ontario winters (road salt) have taken their toll. As an example I replaced the differential cover yesterday because it had a pinhole leak caused by corrosion from the outside!
But I run good tires, brakes, exhaust...everything works and it's paid for.
BTW, it's not for sale.
But I run good tires, brakes, exhaust...everything works and it's paid for.
BTW, it's not for sale.
Trending Topics
Hotshot
Joined: Feb 2004
Posts: 11,697
Likes: 3
From: Marengo, Iowa
I would say the mirror trick would work great, and then I would undo it all and not drive it with the cord still on, but maybe that's just me... Also, my guage won't show anything when it has been plugged in, and I didn't think it should show anything. The heater won't bring it up to operating temp, just warm enough to fire well. If it were up to temp, you couldn't touch the block for long, I think it gets it up to maybe 70-80 degrees. Ususally, after being plugged in for a minute or so, you can hear the heater working, kind of a hissing like sound, like you plugged in the coffee pot. Otherwise, after a few minutes, you can touch the heater to feel if it is warming or not. then if not, it's diagnosis time.
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Senior User
Joined: Aug 2004
Posts: 201
Likes: 0
From: Los Angeles
i had a question on the block heater. I have a 1987 F250 diesel. it's a california truck and always has been. I'm wanting to take it to go snowboarding in the nexted few weeks, during which it'll proably see some very cold temps, and i want to check to make sure the heater is working. (the plug has never been used). what do you guys think, should i just not run the heater?
Junior User
Joined: Feb 2004
Posts: 64
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wd-40 in intake??
Don't spray anything like wd 40 or ether into any diesel that has glowplugs or an intake heater. It's just a bomb waiting to go off. i have seen a few aluminum intakes with holes blown through them and the odd cracked head.
Senior User
Joined: Aug 2004
Posts: 201
Likes: 0
From: Los Angeles
hummm i'll check those things, will it make a difference if the truck is only going to be seeing weather of about 60-70 ish degrees? eh i'll check it anyways. 
can't right now cause i'm in the SD but when i get home
can't right now cause i'm in the SD but when i get home