Running too cold?

[Floating VW]

Anyone else ever have this problem? You hear a lot about running too hot, but what about the opposite side of the coin?

When I set out to build an engine that would run as efficiently as I possibly could make it (I achieved 39% efficiency and 40+ mpg, thank you very much!), I was living in the south where cold weather wasn’t really a concern. Five years later, now I’m back in the Midwest where below-freezing temps are the norm this time of year. In the summer, things were fine and engine oil reached operating temp quickly, and it hovered between 180 and 220 degrees F regardless of how I drove it. But when autumn came and ambient temps started to dip below 50 degrees F, I noticed my wonderfully efficient engine, which was designed to shed heat as quickly as possible, was struggling to get its oil temps up to 180 degrees F. And when ambient fell to around 40 degrees F, the oil barely got into the 160’s F - what I consider to be the absolute minimum operating safe zone. And now that it’s regularly below freezing outside, the oil temp barely registers on my gauge, which starts at 140 degrees F, and this is after driving 30-minutes to and from work, at more or less constant 60-65 mph speeds. I never in a million years would have guessed I would ever have a problem with an engine running too cold!

Now, before I get the usual commentary, let me make a few things clear:

1- All the cooling tins are in place.
2- The flaps and thermostat are there and in proper working order.
3- The oil bypass valve is not stuck and uses the OG spring.

To resolve the problem, the first thing I did was to adjust the thermostat to its minimum setting and make sure the bypass valve was not stuck shut. This had little to no effect (mostly because the thermostat was already at its lowest setting). Next, I covered the louvers in the deck lid to reduced some of the air flow into the engine compartment. This helped some, but not much. Then I decided that if I couldn’t make the oil itself hotter, I could at least use an oil that was designed to work well cold, so I switched from 10W-30 to 5W-20, both synthetic. But even with the 5W-20, at start-up with ambient temps in the 20's, the oil pressure would peg the pressure gauge at 100+ psi, at less than 2000 RPM. This is not acceptable to me, so something had to be done, and I looked to our cousins in the aircraft industry for inspiration.

Here’s what I found: The E-Z Heat model 360.

I ordered mine from Aircraft Spruce. It wasn’t cheap, but that’s the aircraft industry for you. The idea is to stick it to the bottom or side of the oil sump. It only uses 300 watts at 110 volts and is thermostatically controlled, so you can leave it on all night if you want. According to the manufacturer, it will raise 12 quarts of oil from -40 to +60 degrees F in one hour. I had to have it! The only problem is that the oil sump of an ACVW engine is finned, not flat, so sticking the heat pad to the bottom of the case is going to require some engineering. They do make a model that is designed for use on a Porsche 912 engine, which would probably work on an ACVW, but I didn’t like the idea of permanently sticking the heat pad to my case, so here’s what I came up with:

My idea was to stick the heat pad to the sump plate, but the Model 360 measures about 5 inches in diameter, which is slightly too big for the stock sump plate, so I got some half-inch thick steel plate for the sump and a 1/8" aluminum plate to attach the heat pad to.

Some cutting and drilling:

I only had an old drill press and a hand-held angle grinder to work with out in the shed (which is not heated and it was only 22 degrees F in there that day!). Here is the result:

I left most of the mill scale on the steel plate to keep the corrosion off, but I did sand it down to a very thin layer to prevent flaking. And I wanted to attach a magnet to the sump as well (that's the little round thing between the sump plates in the picture), since I don't use the screen and a magnet is cheap and very effective protection from ingesting ferrous metal fragments. I used a simple ceramic magnet from the hardware store and a stainless steel button-head bolt to secure it to the sump plate:

I definitely don't want that bolt to vibrate loose inside the engine:

In addition to red locktight, the end of the bolt was peened and sanded flush with the bottom surface of the sump:

Here is the aluminum plate. I had to make some notches to clear the stud bosses in the case:

The heat pad comes with an adhesive on one side that forms a permanent bond to whatever you stick it to. The manufacturer recommends sealing the edges of the pad with RTV to prevent any solvents or petroleum products from getting under it. The RTV comes included in the kit.

I painted the parts of the steel sump plate that will be exposed to the air:

Here is the new steel sump plate on the engine. As you can see, I also added a little drain plug to make oil changes a little easier:

It's a very solid piece and it fit perfectly (if I do say so myself), but it was almost a shame to have to remove my trick anodized aluminum JayCee sump!

I applied a thin layer of thermal paste to help promote heat transfer between the hot plate and the sump plate.

And here is the aluminum hot plate secured to the new sump plate:

The electrical cord was just long enough to run along the horn, over the passenger-side torsion bar tube, and under the pan to the bottom-front edge of the passenger-side rear fender. This makes it easy to reach the socket to plug it in. Oh, in case you're wondering what the orangish-colored globe is at the top left corner of the picture, that's part of my PCV system. I'll go into that more a bit later.

After some simple testing, here are the results:

I measured the oil temp in the sump with a long turkey thermometer in the dip stick hole, and several key spots on the engine with an IR gun at 15-minute intervals for one hour, then at one-hour intervals for an additional six hours. Ambient air temp in the garage was 43 degrees F, with no wind. My turkey thermometer doesn't register below 60 degrees F, even though the dial goes down to 50 degrees F, and only the bottom three inches of the stick were actually in the oil, so accuracy is a bit suspect. The IR gun is right on, though.

In addition to the oil (3.5 quarts), I measured the heat pad itself, the bottom of the case at the rear stud boss closest to the sump plate, the top of the case just below the "O" in Zundefolge, the passenger-side intake manifold, and just for giggles, I measured the temperature of the oil filter, which on my engine is located here:

After 15 minutes, the temps had risen to:

Heat pad- 319 F
Oil- 70 F
Lower Case- 76 F
Upper Case- 46 F
Intake Manifold- 43 F
Oil Filter- 46 F

After one hour:

Heat Pad- 312 F
Oil- 80 F
Lower Case- 80 F
Upper Case- 51 F
Intake Manifold- 44 F
Oil Filter- 43 F (What the...?)

After 4 hours:

Heat Pad- 298 F
Oil- 90 F
Lower Case- 91 F
Upper Case- 64 F
Intake Manifold- 53 F
Oil Filter- 50 F

After 7 hours (end of test):

Heat Pad- 327 F
Oil- 92 F
Lower Case- 91 F
Upper Case- 66 F
Intake Manifold- 55 F
Oil Filter- 53 F

My conclusions:

The heat pad cycles between a minimum of about 150 and a maximum of about 330 degrees F. After about 3 to 4 hours, the oil in the sump and the case around the sump plate reached a maximum temp of about 90 degrees F, but the extremities continued to rise, albeit at a very slow rate. My theory is that the case, being made of an AS-41 magnesium alloy, is wicking away the heat from the oil a bit faster than what a steel sump full of 12 quarts of oil would, hence the slower rise in oil temp and lower max temp than what the manufacturer claimed.

All in all, the engine fired up and idled just as well as it does on a warm summer day, even though the ambient temperature was only 43 degrees F, so I can say I'm quite satisfied with the result.

And if you're still reading this, here's some more details on my case ventilation and oil filtration system:

Of course, there is the full-flow system as shown the oil filter pic above. But in addition to that, I'm using an air box/oil separator from CB Perf that, if set up right, is perfect for removing liquid as well as blow-by contaminants from the oil. The CB Perf piece has a series of baffles cast into it that separate evaporated liquid contaminants from the oil:

And here is how mine looks:

The stainless-steel braided hose at the bottom of the box runs down to a sealed, glass jar where condensation and other liquid contaminants go after they are separated from the oil in the case. Here is what it looks like when it's clean and empty:

After a week of driving, which is the equivalent of about 300 miles for me, this is how much water and other nasty stuff would have been in my oil without this system (I should add that this is winter-time accumulation; in the summer, the jar stays dry as a bone-io):

The jar in this picture is actually hanging about an inch or two below where it normally is located, because I had the hose disconnected from the box at the time I took it. Any un-burned hydrocarbons or other gaseous or liquid contaminants that didn't get separated by the baffles then continue on into the intakes via the hoses at the top of the air box, where they are ingested and burned up in the the combustion chambers:

In case this concerns you, I personally have never noticed anything making it past the baffles and into the air filters/carburetors, but I run Total-Seal rings, and they perform exactly as advertised, so I have very little blow-by in my engine. Depending on the condition of your engine and the amount of blow-by you have, how much crap gets sucked into your intakes may very well differ from mine.

Ok, I hope this gives the rest of you poor people who live in the frigid north like me an idea or two on how to keep your engine happy in the winter months. I'll try to report back in a couple of weeks after I get some more real-world testing done of my latest upgrade.

Questions or comments, feel free!
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[oprn]

I hate to be the one to break it to you but VW sold pan heaters for their engines way back in the '60s, maybe earlier. We had one on every car in the family. Yes they make a huge difference for starting the engine right down to -40!


The effects though wear off the longer you are on the road and at highway speeds after about 30 minutes or so the engine will have cooled off to the same temperature as it would have been had you not had the heater at all. Around town and short trips it's the cat's butt!

[nextgen]

The sump heaters were really popular back in the 60's and 70's when we ran straight 30 w oil in the winter. At temps below freezing the oil was like mud. Starting was hell.

The biggest advancement was Synthetic, the oil would come out of the can like water and still protect like a 30 40 or even 50 weight.

BTW I would always tie my extension cord to the drivers side door handle, so I remembered to unplug the heater before I took off for work. .
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[Pruneman99]

What heat range thermostat are you running? There are a few different flavors.

[mark tucker]

they also have sump heaters that go in the dip stick location. also why did you go with a steel plate? aluminum transfers heat way better and no rust also it expands and contracts with the case the same amount. I drive my bug in all weather as it was intended to do.5-20 syn all year. yes it does take a while to get up to temp,I do not know how hot it will get in cold weather, but I duct my oil cooler to the car for heat so i know when the motor is starting to heat the oil and how long till it gets good and warm air comming off oil cooler.

[madmike]

That's the "Kats ass" no more drivin VW's in the winter for me ,,just too much salt on them roads and I don't do body work
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76 Drag/Street bug 2180cc 'Turbo' 11:85 @113 mph"If I go any faster I'll burn up the Hamster" ,gets 28 mpg. also 10/09/22 11.90 @115 mph
"If I'm ever on Life Support,UNPLUG Me, Then Plug me back In see if that Works"

[Floating VW]

[nextgen]

Funny I am with Madmike, NY is just as cold and they use just as much salt, plus they now spray Brine- liquid salt.

When my bug as daily driver, I used electric sump heater, kept fixing my heater boxes .

Then went to gas heater. That thing will kill you in bug. No more cabin heat just drive it till it gets too cold and up on blocks.

Just headers no heater boxes. Ripped out the heater channels installed 2" galvanized steel pipes full length both sides, not for heat, bolted to the body for Extreme support. Covered them with stainless steel sheet metal, with 3/16" Stainless steel rivets.
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[Boolean]

[jpaull]

Nice job on that engine! You clearly take time and care about all the little details.

[mark tucker]

we have salt sprayed all year long...so...I should just stop driving all togeather.
personaly I think a accusump will do more for"start up wear" than a heater will do. but yes I do agree they are good to have in cold weather climates.I put one on my daughters new prius 10 years ago( she just traded it in last month as it's been smoking some lately....) as for running too cold...I doubt it, but it may need some hot weather attn to cool it better.

[FreeBug]

Chrome valve covers and sump plate could help a little.

What's the combo? What's the tune like? By playing around with fuel and timing, you could get more heat, but mileage, reliability and drivability could suffer...

One issue with ultra-efficient engines is just that: they convert more of the energy in the gas into kinetic, and therefore less into heat. The idea behind efficiency is to shed as little heat as possible, and it seems to be working.

How big is the engine? Gears, tires, weights? This plays into how much it's loaded. A big engine works less to go the same speed, so could produce less heat, and they are revved less in general.

Could it be that oil viscosity, OG control spring and whatever oil pump you have aren't playing well together? Do you have a way of measuring the air temp coming out of the doghouse exit?

Probably just a coincidence, but I had this problem once, a long time ago, and that engine case was painted black, too.

[FreeBug]

And since everyone here knows that if you leave out just ONE of the original tins out, your engine will go into instant meltdown...what happens if you leave out the rear apron tin?

Air intake pre-heat would be nice, but hard to do with your set-up. It's a crazy idea, but you could point the exits from the heater boxes towards the intake filters, à la Porsche 356. Sorry, too crazy.

[[email protected]]

Putting a heater on the engine is only useful to keep it warmER so it starts easily. It does virtually nothing for running warmer. If the engine is running too cool, try a warmer thermostat, or a power pulley for the colder times.
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[nsracing]

that pad idea is not bad. But there are better block heaters out there for diesels or tractors that can go in a VW if you want to keep the oil warm overnite in winter. They come in all flavors. All over Amazon.

My diesel starts really nice in dead of winter if the block heater is plugged in.

Also, when I was stationed in Minot, ND - we ran an old VW bug for our ride to work. Same stock configuration cooling w/ thermostat, heater boxes, got fairly warm. But this car had HOT air feed into the carburetor...collecting the warm air from the exhaust header pipings. NOt from under the head.

The collector was from an import car and it was just wired in place. The carb took air from the collector full time. The carb and intake manifold stayed warm. Car ran nice. Matter of fact it was probably the only one running on base when it was minus 70 outside.

[74 Thing]

Sump heater
https://www.thesamba.com/vw/forum/album_page.php?pic_id=1283913

[oprn]

[Howard 111]

Nextgen, my BIL has a Thing with the gas heater, and you will end up cracking the window, even on the coldest days, to cool it off inside.
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[nextgen]

Howard,
I had one if I remember it was a BN2 Too Freaking hot and no thermostat to control it.. ON top of that I had it exhausting on the Drivers side wheel well.

So If I opened the window because it was too hot THe Fumes would kill me.
I came to my senses and said WTF am I doing, I just won't drive the car in the winter.

Actually used a Electric heater with a 12v car battery.
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[oprn]

One of the biggest deficiencies of the air cooled VWs was the heating system was inadequate in our northern climates. VW's answer to the problem was to offer a gas heater as an option sometime in the early '60s. These mounted over the transaxle and were not very dependable to say the least. They had a habit of back firing a lot and occasionally catching fire! Then they came out in the late '60s with the ones we see today that mount in the engine compartment of the Bus or the smaller one under the hood of the sedans. They were much better but cut your fuel mileage in half and still did not blow warm air in the defrost vents.

The stock heating system on the later cars were adequate when at highway speeds but short trips around town would not keep the windshield clear or the cabin warm enough in our climate. You could always spot a VW owner in the winter by what they wore! My Dad used to say it was a good thing as we were the only ones on the road that were prepared for the worst every time we went out!