Insulating block heater?
 

Hello all, I have recently installed a block heater on my 2004 Honda Civic 2.4 (the kind that replaces the block drain plug) and I quickly noticed that the outside brass part of the block heater around the heating element gets incredibly hot within seconds of plugging it in. Never used a block heater before but I would assume that this is normal. Anyways, I am thinking about wrapping the exterior of the heater in a piece of a fiberglass insulation strip I have to keep the heat in the coolant directly surrounding the element and therefore keeping more of the heat in the engine. A decent size chunk of brass can dissipate quite a bit of heat at a well over 100 degree F delta T and I would much rather have that heat in the engine than wasted heating the air surrounding the heater.



The only concern I have is whether insulating the exterior of the heater could cause the element to overheat and fail prematurely, boil the coolant in the heater around the element, etc. I wouldn't expect that this would be a problem since I would think the coolant in the engine block is more than enough to adequately cool the element with or without the exterior of the heater dissipating heat to the air, but I don't have much experience with block heaters so I wanted to check first and any advice is greatly appreciated.



This is what the block heater I installed looks like. As you can see, quite a bit of the heater is exposed to the outside air.

Let us know how it turns out?

If I end up trying it (and I probably will) I definitely will :) What's the worst that could happen? The element is still surrounded in coolant

Try spraying it with eight coats of Plastidip.

What would be the benefit of Plastidip over wrapping it with fiberglass insulation? I'm not sure Plastidip would tolerate that much heat for long, it's only rated for 200 degrees F. I doubt it's a great insulator either compared to fiberglass.

Don'r know about high temps. I thought a spray-on coating would fit better than wrapping with tape.

Then how about shrink tubing? It comes big enough to fit over the sensor.

I'm not sure if shrink tubing comes that large but even if it did I doubt it would have much insulating value as thin as it is. I thought about trying to find a piece of foam pipe insulation that size because I hate fiberglass, but as hot as that thing gets it might melt foam insulation so I think unfortunately my best bet for insulation would be a piece of fiberglass pipe wrap held on by a couple zipties. The brass part gets hot enough to boil water and it's right under the exhaust header, so I don't want to put anything flammable or meltable on it.

I'm probably going to wrap it tonight, leave it plugged in overnight, and see if it gains any noticeable heating efficiency. If it survives that is ;)

Edit: This is what I came up with. Not very pretty or permanent, but effective. There is definitely more heat transfer to the block now. The part of the block that the heater screws into is now burning hot for the first time after just a couple minutes, normally it's just warm. There isn't noticable heat radiating off the heater anymore either. I will report back with results in the morning.

Update: The block heater survived the night. Just not sure about what long term effects insulation may have on it. I think it should be fine since the element is still submerged in coolant but I'm no engineer.

As for whether it worked any better, it may have by a few degrees. Last night we had a low of 46 degrees and the coolant heated up to 101 degrees according to my Scangauge. Night before last, we had a low of 49 degrees and the coolant reached 100 degrees.

I certainly wouldn't call a 4 degree difference over a single test conclusive by any means though as many other variables as there could have been such as varying winds.

I think the block heater is boiling the coolant because now as the system doesn't fully depressurize after using the heater. I haven't used the block heater or run the car for a couple days and the cooling system was still under pressure when I took the cap off from when I last used the block heater. Not good.

I think I may know what the issue is. On my engine, there is a small plug inside the large hole for some of the blocks that don't have an oil cooler. Although I removed the plug, the hole is still quite a small diameter and the block heater is a couple inches away from the water jacket so I wonder if the small hole is restricting the convective flow of warm coolant out of the block heater and into the block, causing the block heater and the coolant within it to overheat. Since convection is the only force circulating the coolant, it's path needs to be pretty unrestricted for flow to be decent.

I bet if I bored out the small inner threaded hole so it was the full size of the outer threads that would help a lot, but I can't think of a way to do that without getting a lot of crap into the block. I wish I thought to do that while I had the block torn down before I put it in the car :mad:

Might be simpler to add a small pump to some circuit like the cabin heat. Doesn't take much. The remaining pressure thing is odd, however.

That might work. I thought about getting one of the heaters that circulates warm coolant through the heater hoses, but I chose the OEM style screw in heater instead to avoid the extra bulk, complexity, and points of failure.

I think the remaining pressure issue may be caused by the block heater boiling the coolant and creating steam in the system. The outside brass part of the block heater gets hot enough to boil water within seconds, so I bet the inside gets more than hot enough to boil the water/coolant mixture.

Ended up taking the insulation off the brass and it definitely got hot, the silicone dielectric grease I coated the connector and the pins with to prevent water intrusion/corrosion melted out of the connector and burned up/turned black. According to 3M's data sheet, that silicone paste is rated for use up to 400 degrees F so it's pretty surprising that that brass part got hot enough to burn up the silicone paste. I'm not so sure that's good.

I wonder how hot it would get if I plugged it in with the coolant still at 200 degrees like a lot of people do! :eek:

Your 2004 Civic - which trim is it? I'm trying to figure out what engine yours actually is. To my knowledge, 2004 was the 7th generation and all trims except the Si came with a 1.7 D series single cam. The Si had a 2.0L K series dual cam. From your picture, it really looks like the back of my K series.

In my car, I personally installed the oil cooler from a K series that had it. All said and done it cost maybe $120 in parts, and I got a new water pump out of the deal while I was at it. Maybe it would help with the coolant circulation, by giving the coolant both an inlet and an outlet?

I wouldn't try to bore the hole out.

https://i.imgur.com/MmNvD5o.jpg

It's an LX but I swapped a K24A2 from an Acura TSX into it. It did in fact come with a D17.

The USDM/JDM K24's don't have an oil cooler although the European/Australian market K24A3 did. Only the K20 in the Acura RSX-S and 06-11 Civic SI comes with an oil cooler here. I could add one but I would need to change the water pump and housing and get the oil cooler as well as the coolant hoses and fittings, so easily $300+ in parts. Where in the world did you manage to get the whole setup for $120?

Also, do you have any data on how well the OEM oil cooler actually works like oil temps before and after installing it? I do not have an oil temp gauge for it yet so I'm not sure how much I would benefit from a cooler but oil pressure/temp gauges are definitely on my list of things to get for it. I'm spoiled because my 05 Civic has had gauges for years now.

Nice, my Insight's is a K24A(2) as well.

I found my setup on eBay, waiting until there was one for a reasonable price. Mine had both hoses, the longer oil filter stud, and one of the elbows, but was missing one, so I got the missing elbow from Honda. The housing I paid $35ish for from some other source, and I used a higher quality RockAuto water pump. I probably spent more like $150-160 in total tbh but I think $120 is likely possible. The worse part of the entire install was getting the oil filter stud off because there's noting to grab onto it with.

https://www.ebay.com/itm/22477178805...EAAOSweyxh0iE3

I don't have any hard data on how well it works. My water temperature seems better buffered after installing it so it seems to be doing something. More than anything I was looking to warm my oil up more quickly on colder days, and it definitely achieves that. All of Honda's lean burn engines have these installed (even the Insight 3 cylinder) and I suspect they're more meant to get oil up to temperature rather than down, during typical driving.

Depending on what alternator you're using, you might need a stack of washers because the post lengths are different between RSX and TSX.

That's an awesome deal! Can't believe how much people are charging for used parts, often times almost as much as/more than new OEM parts. As for the housing, I know the 06-11 Civic Si housing is compatible with the K24 alternator but the RSX alternator is a bit different as you said.

I think you are right about the oil cooler heating the oil up more than cooling it. When I installed an oil temp gauge on my 05 Civic I was shocked to see how long it takes for the oil to heat up especially in cooler weather. Sometimes it refused to get any warmer than about 150 degrees and sometimes took 30+ miles of driving to get that warm. In the summer, the oil temp maxed out at around 200-210 degrees during sustained high speed cruising. But since I installed a huge 30 plate oil to coolant heat exchanger setup, the oil temp is much more stable and now always ends up at around 180-185 degrees regardless of outside temp. Temp measurements will be required to decide whether to get the OEM style cooler or a more elaborate setup like I have on the 05.

But from what I have read, the K24 will likely heat the oil up faster/hotter than the D17 does since it has piston cooling jets, so the oil is always being directly sprayed at the underside of the hot pistons.

I added the OEM oil cooler last spring and recently started using the block heater again now that the weather cooled off a bit. The oil cooler didn't seem to noticeably affect the operation of the block heater. It still heats the coolant to the same ~50 degrees over ambient temp and gets hotter than heck, but I guess it must be fine since it's still working perfectly.

In case anyone wonders how much I paid to add the oil cooler:
$80 for the oil cooler with center bolt, new O ring, and coolant fitting
$160 for a 2011 Civic Si water pump/housing
$28 for new OEM hoses
$4 for new coolant fitting O rings
$65 for a new OEM thermostat (not needed, just preventative maintenance while it was apart)

Total cost: $337 including new thermostat

I'm not sure if it was effective yet since I still don't have an oil temp gauge, but I feel better about driving on those very hot/cold days having it there to help warm up/cool off the oil and at the very least I don't have to worry about it causing any problems since it's a 100% OEM setup.

As soon as I have an oil temp gauge, I'm definitely going to do some testing to see how effective the OEM cooler/warmer really is and report back since I haven't been able to find any data at all on its effectiveness and I have wondered about it for so long.