Engine block heaters and uneven temperatures...

[rustypigeon]

The recent below 0 temperatures had me looking at engine block heaters. While looking for one for our Rav4, I noticed that Toyota puts a hole in the engine block specifically for a OEM heater. The hole is located at the very top corner of the engine by the #4 cylinder. The heater get coated in silicone grease and directly heats the aluminum block, without direct contact with the coolant.

What I am wondering... Will this uneven heating stress the head gasket? There would be a hot spot in one corner of the block, instead of a more even and distributed heating that you would get with a freeze plug style heater. This, I would think would cause an uneven metal expansion around the head gasket. Do vehicles running these block heaters have more head gasket problems, or am I over thinking this?

I settled for a magnetic oil pan heater in the mean time.

 

[Lead Shoes]

Good question, I have always wondered the same thing about that type of heater... in for results.

 

[zrxkawboy]

If Toyota put the hole there for that purpose, it will be just fine. Aluminum dissipates heat quickly, and when it is cold outside, the engine will get no where near operating temp just by using the heater.

 

[mclasser]

Is it consistently at zero degrees or below where you live in the winter? If not, I wouldn't be so quick to go out and get a block heater. This cold snap is temporary and will pass soon enough.

 

[Donald]

Why do you need a block heater for a gas (I assume) vehicle in PA?

 

[dparm]

That's odd that it heats the block directly -- I thought the heaters warmed the coolant up?

 

[Clevy]

Block heaters typically are installed in a frieze plug. They are a simple electric element and are typically standard equipment on every single vehicle sold in Canada.
So the uneven heating concern and gaskets failure would have presented itself by now I'm sure,so not likely a problem.
Then there are recirculating heaters which actually circulate heated coolant. These are not standard oem equipment however they can be purchased and plumbed into any vehicle.
The recirculating type is the best. You've got instant heat blowing.
Then there are removable magnetic oil pan heaters as well as oil pan blankets which are epoxy'd on the bottom of the oil pan and are permanent. And to top off oil preheating options one can buy a dipstick heater.
Lots of options.
We all know how metal dissipates heat,so a drilled element type will get very hot and the block absorbs then distributes/dissipates the heat the ought the entire block. In extreme cold this is enough to prevent the block bores from shrinking so tightly around the piston it hinders travel.
Recirculating heaters can be plumbed into a water line in 15 minutes,and easily accomplished by a bitoger.

 

[Clevy]

Originally Posted By: dparm
That's odd that it heats the block directly -- I thought the heaters warmed the coolant up?


Wouldn't that be called a coolant heater not a block heater.

 

[dparm]

Originally Posted By: Clevy
Originally Posted By: dparm
That's odd that it heats the block directly -- I thought the heaters warmed the coolant up?


Wouldn't that be called a coolant heater not a block heater.



Agree that the terminology isn't the best, but by heating the coolant it does heat the block, obviously.

 

[SuperDave456]

You don't need THAT much heat to help.

I know guys who used to put a shop light (with a 100 watt bulb in it) under the hood for 20 minutes in the , and the difference was night and day with their cold starts.

It's a simple electric heating element, not a propane or acetylene torch.

 

[The_Jeff]

Think of the thermal stress of your thermostat opening a crack and letting in all that subfreezing coolant where 180' coolant used to be.

The block heater has nothing on this.

 

[Kira]

I'd love to see heater options in a place like "Inner Canada". The selection of such heaters in New Jersey is nonexistent.

A local Ford dealer had a part listing for a block heater for the 4.6L V-8 but the lead wire from the heater was a discontinued part....all but completely off our radar.

With all the concerns relevant to start-up wear, you'd think there'd be a market for block heaters anywhere the temps dropped below 25℉ (-4℃) Kira

 

[sciphi]

Get an oil pan heater. That way the oil is heated instead of the coolant, and there are fewer hot spots to worry about. Heat rises, so putting a heater onto the lowest point on the car will help.

Both our cars have 40 watt oil pan heaters installed, but we've been unable to use them due to not having a convenient outdoor plug. Back when we could use them, they made a noticeable difference in how quickly the engine heated up.

 

[Clevy]

Originally Posted By: Kira
I'd love to see heater options in a place like "Inner Canada". The selection of such heaters in New Jersey is nonexistent.

A local Ford dealer had a part listing for a block heater for the 4.6L V-8 but the lead wire from the heater was a discontinued part....all but completely off our radar.

With all the concerns relevant to start-up wear, you'd think there'd be a market for block heaters anywhere the temps dropped below 25℉ (-4℃) Kira


Pm me. I'll send you whatever you want.

For our southern neighbours:

If you need some kind of block heater that's unavailable to you locally shoot me a pm. I can walk up to the local co-op and we've got recirculating fluid heaters that simply plumb into a coolant line or if you like they've got both the magnetic oil pan heaters as well as the more permanent blanket type.
I've got PayPal so receiving payment is a snap and I'm sure express shipping can get it to ya in 2 days.
The recirculating type come in sizes from 100 watts to 1000 watts,magnetics are roughly the same.

Originally Posted By: SuperDave456
You don't need THAT much heat to help.

I know guys who used to put a shop light (with a 100 watt bulb in it) under the hood for 20 minutes in the , and the difference was night and day with their cold starts.

It's a simple electric heating element, not a propane or acetylene torch.


This comment is correct. I've seen guys put cardboard around the bottoms of their cars and a small 750 watt heater pointed at the oil pan which got the car started in 15 minutes.
Just gotta take the edge off

 

[Number21]

Originally Posted By: sciphi
Get an oil pan heater. That way the oil is heated instead of the coolant, and there are fewer hot spots to worry about. Heat rises, so putting a heater onto the lowest point on the car will help.


I agree. A big enough oil pan heater will do more for you than a block heater will. Factory block heaters don't do anything for the cold oil way down low in your pan. Or most of the bottom half of your engine. Oil pan heaters are really cheap.

 

[TiredTrucker]

I like the oil pan heaters also. When thing really get cold I will use both engine and oil pan heaters on my diesels. When I lived in Alaska, oil pan, engine, battery all got a heater. For my gassers now where I live, the oil pan heater works fine. Notice a trend? Oil pan heater is always the first line for me, then I move onto other heaters as the temps get progressively lower. And oil pan heaters are very economical to use on a regular basis. Many engine heaters use several multiples more electricity compared to oil pan heaters.

 

[CurtisB]

Originally Posted By: Number21
Originally Posted By: sciphi
Get an oil pan heater. That way the oil is heated instead of the coolant, and there are fewer hot spots to worry about. Heat rises, so putting a heater onto the lowest point on the car will help.


I agree. A big enough oil pan heater will do more for you than a block heater will. Factory block heaters don't do anything for the cold oil way down low in your pan. Or most of the bottom half of your engine. Oil pan heaters are really cheap.


I'm going to disagree with both of you on this, a frost plug coolant heater is way more effective than an oil pan heater by design. I am well aware that heat rises from the heated oil, but that heat must use air convection to reach the block. With a frost plug heater, the element uses fluid convection through the coolant veins to transfer directly into the block/cylinder heads and raise the overall core temperature. The cooling system on any water cooled engine is designed for maximum heat transfer efficiency (or at least should be), and using that system in design reversal is equally efficient.

On most vehicles the largest pan heater that can affix to the oil sump is 125 to 250 watts, most frost plug coolant heaters are in the neighborhood of 1000 watts. While the oil pan heater may be more cost effective/easy install it doesn't produce near as much heat. I have a Wolverine 250 watt heat pad installed on the sump pan of my '08 F150. It's adhered to the lowest/largest part of the sump on the very bottom, the most efficient place. I installed it to supplement my coolant heater/battery warmer and I put it's only value at that. When used on it's own It makes very little to no discernible difference to cranking power, most likely because I use a 0w-xx full synthetic oil come winter.

I agree 100% with Clevy, circulating pump style coolant heaters are by far the best providing they are plumbed properly. They are predominantly a diesel mod, but I'm sure one could be plumbed up on a gasser. With a properly installed circulating pump style coolant heater you will have cabin heat almost immediately after start-up. I had thought of doing a circulating coolant heater install on my newer truck, but I find the frost plug heater to be sufficient enough. As the old adage goes "if it ain't broke don't fix it". Cheers.

 

[Lapham3]

I've been using 'frost plug' heaters for 45 years-most are 400-600 watts and make an engine 'think' it's a summer day. Lots of chatter on this site about start up wear being the major wear component. I agree and feel the heaters help with that.

 

[Number21]

Originally Posted By: CurtisB
On most vehicles the largest pan heater that can affix to the oil sump is 125 to 250 watts

That's not really true. You should be able to fit at least a 250 watt into a pretty small engine. If you have a six or eight cylinder, you should be able to fit quite a bit more than that. I could probably use four 250w heaters on my old truck with a small block Chevy. My new truck will take quite a bit more, but it's a diesel so it has a giant oil pan.

You also have to ask yourself why are you using any kind of electric heater? Is it because it is so cold outside you can't get your car started? Or is it because it's cold outside and you want to minimize startup wear? For the first question, any sort of heater will do. The second question, an oil pan heater will do much much more for you than a coolant/block heater can.

The best option of course is to use both, which is what I do.