Anyone familiar with block heaters?
 

My car came with a big 110v AC plug behind the grill and today I figured I'd plug it in. I had always thought that block heaters were just electric blanket deals so I was surprised that mine made noise. It sounded like an electric motor running. The wire just goes into a big plug screwed into the block behind/under the turbo. It was puling some current because the cord was warm after a few minutes.

So how do these things work?

Normally just a heating element similar to what you would find in an electric kettel. Plug it in and it gets hot. After 30+ years it may have corroded (most are copper) or have large deposits on it causing the noise and excessive current draw.

Or it could be operating normally. I've had ones I could hear and the cord does get warm since it's drawing current through it.

yours could be an aftermarket one. some are in the heater hoses, with pumps to circulate the coolant.
but like mentioned, you are likely just hearing the water boiling off the elements.

The standard MB Block heatyer is just a little heating element that heats the coolant in the water jacket. fits into the side of the engine on the right side in front of the starter.

http://img.eautopartscatalog.com/liv...1619895OES.JPG
this is one shown in Fast Lane.

Charlie

I just had an OEM block heater installed and it works great! Little expensive, but definitely worth it in a cold climate like mine.

As the others have said, check for corrosion since all the fittings are at least a quarter of a century old. A bunch of parts on mine were corroded so I had everything replaced.

My blockheaters have always made a little sizzling noise from the coolant being in contact with the heater element.

The noise is analogous to a kettle "singing" when it's on the stove. Has to do with tiny water bubbles forming and breaking, I think. Click and Clack would know.

The block heater should take about 4 hours from stone cold to easy-start warm. You'll also have heat in the cabin almost immediately. If you don't want to leave the block heater on all night (it draws a good 400 Watts and the aftermarket ones even more) you can set up a timer to turn on the block heater 4 hours before you need the car to start.

Jeremy

Be sure that your extension cord is an appropriate gauge for a block heater. They do draw a lot of current and the longer the run of cord the bigger gauge wire it should be. If the gauge is too small it could be the reason the cord is getting hot.

Thanks for the pic Charlie!! I'm thinking about adding one to my 240d.

They are nice to have on those cold mornings. I have a lower radiator hose heater in my 240, it was free and convenient. It helps but it's not as good as a real block heater. Also getting the freeze plugs out of the block and be REALLY hard, so a lower radiator hose heater is easier to install.

The PO of my car installed a small battery trickle charger and wired it to the same cord as the block heater, so plugging the car in both preheats the engine and tops off the battery. I thought that was pretty clever.

That's a pretty damned good idea actually.

Quite clever.
Is there any downside to trickle charging a battery constantly?

I think it would depend on the rate of charge. I mean people put battery tenders on their motorcycles all winter to save the battery's so it cant be bad for them.

The pre start trickle charge possibly just basically helps the battery to deliver more current when it is time to start. Kind of agitates the battery electroylite a little perhaps. Simular to pre warming a battery a little maybe. . THe slight top off charge does no harm either.

The pre start trickle charge possibly just basically helps the battery to deliver more current when it is time to start. Kind of agitates the battery electroylite a little perhaps.

A stone cold batery is way down in ability to deliver current compared to a warmer one.

I connected my block heater using this cord...
 

My vehicle had a factory installed block heater. I purchased a cord on Amazon (see link below) and was able to install the cord from above. I tied off per other members suggestions and terminated the cord at the hatch under the bumper. Starting is much easier 45F or below. I connect to an external AC receptacle which has an internal switch in my house. I turn the switch on about 3 hours before I anticipate traveling.

I bought the cord on amazon for $14.49 and it was listed as a "Fleetguard Coolant Immersion Heater 6' Replacement cord 120V 251919":

Block heater power cord

It was a perfect fit for the factory plug and threads :)

A trickle charger left on a battery 24/7 will eventually dry out the electrolyte but 4 to 8 hours a day while the block heater is running on cold winter nights won't hurt the battery at all. And as others have posted, a warm and fully charged battery makes a great deal of difference in starting a diesel. In really cold climates (north of Winnipeg, say) the trickle charger helps keep the battery from freezing. This relatively rare situation typically cracks the plastic case and then the electrolyte leaks out all over the car's chassis.

Because my car has about 30 milliamps of "phantom load" (not really phantom because I know what it is and want it to be there) I have a trickle charger built in to the engine compartment and plug it into a timed outlet almost every night. The charger runs for only two hours but that's enough to keep the load from gradually discharging the battery, especially as this car isn't driven every day. [10 milliamps of discharge current is generally considered the safe limit.]

Jeremy

I installed one in our 85 about 2003, they really do help to get things up to operating temp when cold. I had a shop do it after looking at the difficulty it would have been for me at the time. this was before I discovered the Forum. on an older engine, I still might pay some one to do it.

When I purchased the Metric Motor, I had them install one. they threw it in with the price of the engine. "That was easy". :D

Charlie

Seems that every year I've belonged to this forum, the subject comes up. I printed out previous threads, and brought an after-market block heater (plaices into the radiator hose) to the mechanic recommended to me in the Fargo, ND area that I found myself and car located at for the upcoming winter. After calling AAA twice in one week, I was determined to block heat my engine. I showed the mechanics what other MBZ owners said about the installation. They did not believe that even in a car as old as mine, they would need to use a torch and get the bolt red-hot to remove it. They insisted on installing an OEM block heater, which was fine with me, as long as they gave me a written estimate of the work. They were not happy to see me the next day. Seems that even with four lumberjack swedes hanging off a cheater bar with the car on the rack . . . they could not break that bolt loose (guess they never heard of "zincing." Hey . . . but what do I know . . . am just a woman and a dumb truck-driver . . . LOL.

Unless you have a torch to loosen that bolt, take it to a mechanic and have them install it, and warn them to get the torch out to START the job. ROFL

BTW, mine block heater was a life-saver, literally. Gave longer life to my glow plugs and battery, and the car had no trouble starting up in the -40 deg. F weather, if it had been plugged in overnight.

X2

overkill
 

here's my winter prep thread from a while back.

overkill to the extreme.. but it was fun. works great.

http://www.peachparts.com/shopforum/diesel-discussion/167546-ultimate-artic-mb300sd-pictures.html

My understanding is alot of the name brand("Battery Tender" for example) chargers are considered smart chargers, which charges untill the battery is full then switches into a monitor mode only charging if it drops again.
I have a little Battery Tender for the motorcycles. I use it on the truck and the Mercedes if i let them sit. Wiring one into the heater plug is a great idea!! I don't have the experiance with brutal cold like you guys up north but seems like a awesome idea! And these darn diesel batteries are not cheap!!!

My 240 is.one of those that did not have a factory block heater. I didn't want to take the chance with the potential block issues and a huge lack time. I installed a Katz k500 hose heater. So.far it is a big difference in how it starts. Not quite like it Is 80 degs, but one glow cycle and she fires up.

it'd be nice if the pictures were still in the thread...
any chance you could upload them to the PP server?

pics
 

I'll try to grab a few tomorrow morning.

I'm gonna sell the car in the spring. but I'm gonna pull the espar first.

JP