View Full Version : Block Heaters-Sources, Types, Costs?

11-28-2008, 07:56 PM
Been reading all the info and comments here on block heaters. I think we have a gap in our threads. I'd like to see some information and discussion of the types, sources, and costs of these devices. Any takers?

11-28-2008, 09:23 PM
You should be able to find versions of all these heaters from $20 to 60.

-Dipstick heater
Easy yes, but not going to get much heat. Any heating element small enough and flexible enough to fit down a dipstick tube is not going to be able to produce enough heat.
The smaller it is the hotter it would need to be, at a cretin point it is no longer safe.

-Magnetic or Adhesive heater, Block or Oil pan
If you can find suitable mount location this seams like it would also be easy.
Large heating element, But not efficient as the heat is applied outside the engine.

-Frost plug heater
Hard one to install, but good efficiency. Large heating element installed inside the engine. Heating the coolant inside the engine where the heat will also spread out to more of the engine. Simple heating element providing reliability. Factory installed by many manufactures.

-Circulating coolant heater
Moderate installation difficulty, and good efficiency. Using heater hoses to circulate warmed coolant thought the engine. The most through engine warming.
Down side is not too bad. Need space to install heater tank and complexity of pump possibly failing at some point.

Ok these next 2 are just silly, but people have used these methods.

-Drain oil and keep it warm.
Cheapest by far, but defiantly not a desirable method.
Drain the old and keep it warm in the house with you. Warm oil to be re-added in the morning when you need to start the car.

-Hot coals under the engine
ya less not recommend this one. I have seen it done, NOT by me.
I can do without the car fire thank you.

11-28-2008, 09:44 PM
I'll add...

The freeze(frost) plug type heaters are the most effective because they provide the most direct approach- heating the coolant that is in the block, thus all energy is directed towards internal engine components. The coolant is not circulated because it doesn't need to.

However, engine coolant temperature sensors are usually outside the block and near the top of the engine. Since the coolant is not circulating, warm coolant will not pass by the location of the sensor. Eventually, the coolant by the temp sensor will be warm if the Ebh is plugged in long enough, but by then the internal engine components have been heated for a while.

Temperature gauges read the coolant temperature, not the engine temperature. Our temperature gauges are just telling us if the coolant is keeping up. So when we start a freeze plug heated engine, the temp gauge may drop (if it was registering any temp at all) as cold coolant is circulated near the sensor. The first two hours the heater is plugged in provides the most benefit. After that the benefit is mostly warm toes.

The lower radiator hose or tank type heaters are also effective. Circulating coolant heats the engine rather than take heat away from the engine. But we're more interested in heating the block than the coolant (for FE purposes, not warm toes purposes). The circulation is provided by the physics of thermo-siphoning. There is no mechanical pumping involved, that's why it is important to have these types of heaters installed correctly, as low as possible. The heated coolant rises, and cooler coolant is drawn into the heater.

As stated above, oil pan or dipstick heaters are least effective. They are comparatively far removed from where the heat is needed- in the combustion chamber.

Roughly- a 400watt freeze plug heater is as effective as a 600watt tank type heater.

Maximum benefit for energy used is usually achieved at 2 hours.


12-06-2008, 09:09 PM
great info guys.

I was thinking about the options and I think I will go for the OEM honda coolant plug heater. I was also wondering about oil heaters as well.

However, those that might want the others check these out for a reasonable price:

12-08-2008, 11:33 AM
The only thing I have to add is that VERY RARELY a frost plug heater can cause damage to the engine. Only in very extreme conditions, and here is why:

You unplug the heater, and start the car. It's nice and warm, but once it gets to thermostat release temps, your engine gets subjected to immediate, very cold, coolant.
The 200+ degree temp change can cause some problems (it's been known to crack blocks; again, it is very rare). It's very rare that this happens, but it is why I preferred the radiator hose heaters. They circulate the water while heating it. It doesn't heat the engine up as much, but doesn't subject the engine to that sudden temp change.

Right Lane Cruiser
12-08-2008, 11:46 AM
I don't think I'll ever seen that problem... the warmest the block heater gets my engine is in the low 100s. The thermostat opens fully at 180F and I don't think it even really starts until at least 130F.

12-08-2008, 02:26 PM
Right Lane,
Like I said, it is very rare. The only time I know of it happening, the outside temp (without wind chill) was -50F.

The thermostat started to open at whatever temp (we can use your 130F). Once that -50F water hit the 140F to 150F block, part of the engine shrank with the lower temp, but the rest didn't due to it's higher temp.

Is it possible there was already a weak spot (like my truck's windshield that had a ding that turned into a crack last winter)? Entirely possible.

Would it have happened without the block heater? I think so, as the temp difference would have been the same.

It was very rare. Not like the people that didn't check their radiator fluid and overheated their car in the middle of winter. The fluid in the radiator had frozen solid!

Then you had the people that tried to use 20W-50 oil... Those engines really didn't want to turn over in <-20F weather.

Right Lane Cruiser
12-08-2008, 05:02 PM
Ah... -50F is a bit lower than I've seen. My block heater has only really been used inside my garage, too. It isn't insulated but it does tend to stay a bit warmer than ambient outside temperature.

Copyright 2006 Clean MPG, LLC. All Rights Reserved.