Block heater short life

[desert_rat100]

My 1986 GMC K1500 Suburban is used as a daily driver. This winter has been colder than normal and I plug the block heater in below a forecasted temperature of 25F. I use a timer and the block heater has been on for 2 hours before I start the engine. Block heater was first replaced Oct., '06. Replaced in early Dec., '06. This in turn failed and 2 were applied last month. At that time, the additional block heater was put on the passengers side. Block heater then failed on the driver's side within 2 weeks. This morning, I found that the heater on the passengers side failed. I measured 120V on the end of my extension cord (14 gauge). Verified failed by using an ammeter. Verified ammeter by plugging in a drill and running the drill. Previous block heaters were made by KATS and bought from NAPA. Work done by a reputable local auto repair shop. Block heaters that are currently applied were purchased from Carquest by the local repair shop. Cords to block heaters are integral to the heater, i.e., not replaceable w/out replacing the entire block heater asm and were wire tied to the grill to prevent damage to same. Cords are wire tied to prevent flopping around and being torn off also. Anti-freeze mixture is 50/50 ethylene glycol with distilled water.

[john8662]

Sounds like the aftermarket block heaters aren't quite up to the task.

You mention the type heaters that have the cords permanently attached to the heater itself.

I have had good luck with the other type, solid brass-looking construction, basically look identical to the OEM.

The only place I have been able to find those has been at Napa.

The heater you acquired from Napa previously that failed, did it have the cord attached just like the ones you're using now?

Just curious.

The one I got for my last engine looked like the OEM, they had a picture of it in their computer for me to identify that it was the one i wanted.

Might also lie to them and tell em it's for a 6.5 in the mid 90's, Same heater.

Of the burned out ones you already have replaced, could you physically identify what failed, the element or the connection on the cord somewhere?

Always thought of installing two, just didn't find it necessary.

Good practice with the timer, just make sure it's a Heavy Duty one, that's what i've used (for this colder-than-usual winter here).

J

[Artworks]

It sounds like the heaters are 'running dry' i.e. out of the 'water' and over heating. If you start your truck while it is still plugged in, you may be causing an air lock and burning out element. Check coolant levels / rad cap also. Same thing happens with your home electric water heater. I have two block heaters in mine, but I live in great white NORTH.

[desert_rat100]

All the block heaters that I have tried thus far have been of the built-in cord type. No apparent damage to the cords have been seen to date. As a replacement this go around, I will include one of the types with a replaceable cord from a different manufacturer that I obtained off ebay. This one is a zero-start by Phillip and Temro Industries.

I have been starting the engine sometimes while the heater is still plugged in, so I'll change my practices to pull the plug as suggested by artworks below. Radiator is full as checked, no leaks & no useage out of the overflow reservoir. Cap holds pressure. In Canada where you're colder, do you put something in front of the radiator to get your engine to operating temperature faster and if so, what do you suggest?

Thanks for the suggestions!

[DmaxMaverick]

The element is located at about the lowest point in the cooling system between the cylinders, so if you are "drying up", you have bigger issues.

Some past discussion indicated an improperly installed element could be short lived if it contacts a cylinder wall. That would shorten the effective element, and cause it to burn up early. I don't have any experience with the permanent cord models, but on the OEM types, the pins should be parallel to the bottom of the block. If it's rotated any, the end of the element could be in contact, or close enough, with a cylinder wall, to cause a short in the middle of the element, as well as a corrosion issue from the contact.

[desert_rat100]

As I contacted Car Quest this morning, who was the outlet that my local repair shop used, I was told that they use the Zero Start brand and it is likely to have the cable separate from the heater element. Sure enough, that's what is present. The element is also such that the pins are parallel to the block and pan rail. Thus, the cable as attached is perpendicular to the block and thus qualifies as an OEM type.

So, I used the Zero Start element that I bought from ebay and plugged it in to the cable on the vehicle, and the circuit is open. I then qualified the ebay element with the ohmmeter and I have a circuit, thus the cable is good. I only performed this task on the driver's side element as the passenger's side is hindered by the starter motor.

What you state makes sense re: element contacting the block may wear a hole in the outer copper shell and causing the element to short out. I'm not so sure that it would effect the overall resistance as the outer copper shell (heat transfer surface) is isolated electrically from the pins. But your point is well taken.

[john8662]

Great point about proper positioning of the element.

I've always taken great care to make sure it's perfectly aligned.

J

[DmaxMaverick]

Many things come into play when the element is in contact with a cylinder. Probably the most influencial would be the comustion pulse, hammering the shell against the heating element, or causing a significant vibration. That, in my informed opinion, could certainly cause premature failure. Couple that with the galvanic corrosion that would occur at the contact point between the cast iron cylinder and copper heater element, and any weakness will surface. If the element were under electrical tension during a start, it could exaggerate the condition, even if it were not in physical contact. Water (coolant) is a pretty good conductor of concussion.

Outside of that, it's anyone's guess. I know if some folks that have to replace them every year, and others that never have an issue. There doesn't seem to be a common ground among them. Mine have always leaked before failing electrically, and I have no explanation for that, either.

[arveetek]

Mine have always leaked before failing electrically, and I have no explanation for that, either.

That's been my experience as well. I once had a block heater pop out of the block while driving! Turns out it was due to a corroded center bolt that clamps it to the block. Apparently, after a long period of time, the center bolt corroded and simply let go. The end result: no water in the block! Luckily, it didn't happen too far from home and no engine damage resulted.

I have used the permanent-mounted cable type of heater for many years with no problems. The one on my '81 has the cable permanently mounted to the heater.

Casey

[desert_rat100]

I made the decision to install a lower radiator hose heater - at least for now. Perhaps my problem with the block could be some crud or the buildup on the internal walls??. The heater is rated @ 800W vs. the 600W immersion types & doesn't seem to heat the block as well either. Today was very cold, reached -15F this morning, coldest thus far this winter. Timed it for 3 hours before I tried to start it. It took 3 attemps before she finally started to come to life. I'll see how much current it draws later as a comparison.

[desert_rat100]

I removed the lower radiator hose heater and installed 2 new GM block heaters. The lower radiator hose heater was trying to heat the coolant in the radiator more than the engine. Had to replace the starter motor as it failed. Starts much easier now. Wait and see what happens.