block heater not working - PeachParts Mercedes-Benz Forum

pkmorgan17 · #1 12-07-2002, 01:19 PM

Plugged my 82 300 TD in last night using a heavy duty timer set to kick on at 6am. At 10am I went out and felt the engine by the oil cap with my hand. Ice cold. In the past it was always warm. I tested the extension cord and timer and both are working fine. Checked the block heater cord all the way to the block and it looks intact and in good shape. Block heaters are so simple I am wondering what it could be. Am I wrong to expect the top of the engine to be warm after a cold night (20 degrees)?

#2 12-07-2002, 02:59 PM

Hey Paul, did you try to start the car? If so, what happened? I've never touched the valve cover after heater block has been on.

#3 12-07-2002, 03:31 PM

Did you do a continuity test on the heater cord itself?? Unplug the orange connector from the passenger side of the block and test each of the three terminals for cord continuity.

I had to replace the male connector on my because it was shorted out on one of the terminals. The male plug is usually the culprit as that is what you pull on to disconnect your extension cord.

#4 12-07-2002, 04:57 PM

Paul, valve cover slightly warm to touch after a couple of hours plugged in.

190D22 · #5 12-07-2002, 10:53 PM

When I used mine, the radiator, the hoses, and the valve cover were all warm to the touch. I actually felt the heat even before I opened the hood to put the cord back in.

pkmorgan17 · #6 12-08-2002, 09:05 AM

went out again this morning - cold. I guess I have to check the cord. Man this car is killing me lately, I'm averaging 2-3 issues a week.

#7 12-08-2002, 09:22 AM

plug a light bulb or something into your extension cord or timer to see that it is hot. Then use an ohmmeter or continuity tester across the two flat pens of the plug at the car, with it disconnected from the electricity source of course.

I understand your frustration, but it's just like anything else that gives trouble, you just have to be dilligent in working through the issues and don't let them pile up. That is what ruins cars for many people. They just say, well I can get by without that accessory, or oh well I replace that broken handle some day. Before you know it the car is run down and they want another one.

It is much more cost effective to analyze and correct problems as soon as you can as they come. If you take this attitude, you can keep a car going forever. You will go through some periods of everything seeming to break at once, and then you will go through long periods of no troubles at all.

Best of luck,

pkmorgan17 · #8 12-08-2002, 10:39 AM

Larry, thanks for the encouragement.

A development this morning - with block heater plugged in I leaned over and listened close and heard what I would describe sounded like a tea kettle at low, low simmer. Then I unplugged it and sound stopped. Tried it with and without timer in the loop and always heard the sound. Does that mean it is working? I would think so, but then how come the valve cover does not get warm like it used to? One note, I have found antifreeze in the driveway recently after a night of being plugged in - could that have anything to do with it? Antifreeze still resevoir reads within safety.

Thanks,
Paul

BoostnBenz · #9 12-08-2002, 12:34 PM

Yea my 83 300d makes that same kind of noise, I've never felt the hoses though to see if it gets warm or not. I noticed when I plug this heater in it makes a nice spark so it must be using a decent amount of energy for something.... I haven't noticed if my 84 300d makes that noise or not, I figure it is just to much of a pain to drive a diesel in the winter time.

As for the antifreeze leak, do you ever notice it after getting home after a drive? I'm new to these diesels but it only makes sense that the heater is pumping the coolant around and heating it at the same time, how else can things get warm. So I imagine it just found a leak you had. I noticed a ever so small drip of coolant on my 83's thermostat housing after leaving my heater on for a couple hours, so it'll be time for a new gasket there soon.

~jm

pkmorgan17 · #10 12-08-2002, 12:37 PM

It's a little puddle after plugging in for a night - I figured it's because coolant is heating up with no where to go - is it indicative of a leak - if so, where?

#11 12-08-2002, 07:12 PM

WHERE is the puddle? Is it under the waterpump? It is not ridiculously uncommon for the waterpump to seep a few drops through the weep hole in cold weather.

In 30 degree weather, the valve cover should be slightly warm to the touch after 2 hours of block heating. If the temperature is colder, it may take much longer for the valve cover to feel warm.

Good luck,

190D22 · #12 12-08-2002, 08:51 PM

The problem with these cars (I can't say for the 123, but I'm betting the 124 is the same as my car due to them being so close) is they have the belly pans that cover the whole engine bay and the entire transmission including the front flex disk. So it's tough to tell where a leak is comming from when there is in fact a drip in the driveway. Do the 123s and others all have the belly pans?

lrg · #13 12-08-2002, 11:43 PM

190D22,

The 123 do not have the belly pans (actually I believe they are called sound encapsulation panels). They were sound deadeners added with the start of the 124 model in '87. They helped make the car quieter but were a pain to R&R everytime you needed to do even a simple job. Some DIY owners just took them off and left them off, also they're expensive so if you loose one you might not replace it so lots of 124s don't have them anymore.

#14 12-09-2002, 07:58 AM

No, you can't block heat too long, but it just wastes electricity if you go past a few hours. Leaving it on all night won't hurt anything.

The belly pans prevent water from splashing up on the underside of the engine, particularly the alternator. R&R of the belly pan takes all of three minutes. They are very worthwhile to leave in place.

If you are having problems tracing a leak, just leave them off temporarily until you locate the leak.

My $0.02,

190D22 · #15 12-09-2002, 09:58 PM

I also agree with larry. The belly pans are very good to keep water from getting up in your engine bay, and it also helps protect everything in the event of something flying up in there. It also helps when you bottom out on a driveway. Mine's got scrapes on it.

They are a pain to take on and off, but they are worth having. Especially since they are expensive!