Car overheating a bit and other observations - Page 3 - PeachParts Mercedes-Benz Forum

BillGrissom · #31 05-06-2015, 02:48 PM

Lookup my post where I dealt w/ the T-stat in my 1984 300D. I give info on the coolant temp sensor too, since that could be in error. Turned out the T-stat was working, but "sluggish", causing the engine to run ~60 C. Replacing it gives ~82 C. I bought citric acid on ebay and use to flush. It is the active chemical in some stronger Prestone flushes. Both my 300D's have Evans Waterless Coolant now, so no more corrosion concerns. Highest temp I saw was 104 C climbing the I-5 "Grapevine" on a ~100 F day w/ AC on. It might work in Alaska (turns slushy if very cold). You might find you need a block heater in the winter if you must park outside. It would be on passenger's side, just below the manifolds, w/ a red silicone connector on a 120 VAC cord that runs beside the radiator. If just a plug there, good luck. I tried removing that plug w/ engine on a stand and no-go, even with propane heat and a cheater bar on a big allen wrench (19 mm?). I was trying to swap a block heater from my old engine.

I too would like to know a PN for this AC filter/drier temp switch with a lower setting. It is a common problem that they don't switch on the electric fan until too hot.

Ceristimo · #32 05-06-2015, 03:14 PM

Yeah, I was planning on doing the Citrus flush and replacing the thermostat, so hopefully this will all be sorted out this weekend.
The Mercedes has a block heater, oil pan heater and battery heater. Every car here in Fairbanks has one. My daily driver and my wife's car are fully winterized as well, because without a block heater a gasoline engine won't start at -40f either, and without the transmission heater you can't shift at all.

I'm not planning on driving the Mercedes in winter though. Even with a block heater I don't think it'll start in the middle of winter. The plan is to just park it outside during winter. As long as the anti-freeze is up to par (I'll mix it 70-30, so it'll go down to -65f or so) I don't really foresee any problems.

I had a question though: The citrus flush says to fill the radiator with the stuff, but my radiator does not have a cap. Only my expansion tank does. Can I just remove the upper radiator hose and pour in in that hole to fill the radiator?

renaissanceman · #33 05-06-2015, 03:15 PM

I'd probably end up taking this little guy up if I drove the highway:

It's 4x4, dead reliable and (fairly) comfortable.

The switch I was mentioning was a coolant temp switch for the w124 engines that switches the fan on at 100C and cuts the compressor at 110C. You could bias the sensor to a lower switching temperature with an inline resistor. (Assuming resistance increases with temperature)

Ceristimo · #34 05-09-2015, 07:09 PM

@renaissanceman
Ah, I didn't realize you'd be driving your own vehicle up to Alaska, if you were to go. Yep, that thing'll get you through Dalton high way. Make sure to make that trip, it's amazing!

I picked up a pound of Citric Acid today at the bulk section at Fred Meyer and 4 gallons of distilled water.
I'm going to flush everything tomorrow I think and install the new radiator hoses and thermostat and gaskets etc.

I already got 2 gallons of Zerex G-05 full strength, that I can mix 30/70 to get it to -65F.

Of course, everything is conspiring against me actually driving this vehicle, because my new lower oil line is leaking. I'm trying to get a new one for that now as well, and hopefully all of that will be sorted out in the next week or two or so (though I'm really dreading having to do that job again), but at least the overheating issue will hopefully be taken care off tomorrow.

Slowly getting there.....I hope.

leathermang · #35 05-09-2015, 08:13 PM

Your first lesson in Quirky Mercedes Rules.....
with any other car I know of ....that 70 /30 mix on the antifreeze would be just fine...
but you need to check the manual for your car....
because if you mix it wrong..... you can cause corrosion enough to eat out your heater core.... your wife would be delighted..... replacing that would probably be the last straw...
Mercedes gives a way to check the specific condition of your coolant mix with a VOM.... yes.... that is a crazy deal.... but they do not put warning into the FSM for kicks....
If you use an infrared thermometer... read the instructions well..... as sometimes the color of the item you are measuring must be taken into account....

Ceristimo · #36 05-12-2015, 12:43 AM

All right, went to drain the car to do the flush, etc. I removed the thermostat to make it easier to flush with the SHOUT liquid gel and the citric acid stuff, and drained the radiator.

I ran into a small snag with the block drain. It requires a 19mm socket, but the only 19mm sockets I have are 1/2", and I don't have an extension for my 1/2" wrench. I have extensions for my 3/8" wrench, but no 19mm socket. The adapters that I have all go from big to small, I don't have a 3/8>1/2 (though I do the other way).

Oh well, I'll get a 1/2" extension tomorrow (probably should have already gotten one months ago anyway) and finish the job. I wasn't feeling like rushing to the store tonight to get it all done. Besides, flushing the car means running the engine for a while, and I'd rather not to that late(r) at night. My neighbors might not appreciate that too much.

The good news is that the coolant came out looking very clean and not rusty or brown looking, so that's good I guess. Means it got changed at least at some point in its life

.

Lucas · #37 05-12-2015, 04:03 AM

19mm=15/16"

Or maybe its 7/8"

Cant remember. But most larger sizes are universal.

I know I used my sae impact socket on the bolt on mine. The front crank bolt as well. But nothing that big will be 3/8"

Just an interesting note.

Wear rubber boots! So overlooked. Happens so much.

Not sure about citric acid. But I'm a little ocd with safety.

funola · #38 05-12-2015, 10:22 AM

I'd recommend bypassing the heater core before the citric acid flush. Surely you have read of new leaks that were not there before the flush? R&R heater core is probably a 40 hour job for first timer. I've never done one myself so that number is a WAG.

funola · #39 05-12-2015, 10:24 AM

Quote:

Originally Posted by Lucas

19mm=15/16"

Or maybe its 7/8"

Cant remember. But most larger sizes are universal.

I know I used my sae impact socket on the bolt on mine. The front crank bolt as well. But nothing that big will be 3/8"

Just an interesting note.

Wear rubber boots! So overlooked. Happens so much.

Not sure about citric acid. But I'm a little ocd with safety.

19 mm is 3/4"

Maxbumpo · #40 05-12-2015, 10:27 AM

Quote:

Originally Posted by Ceristimo

I removed the thermostat to make it easier to flush with the SHOUT liquid gel and the citric acid stuff, and drained the radiator.

Do you have a copy of the FSM, or found access to one online?

The thermostat needs to be forced open and installed for the flush, otherwise you may not get much flow through the radiator.

Simple way is to cut a short length of fuel hose, slit the long way and insert while hold the t-stat open, then secure with a hose clamp to make sure it doesn't escape into the cooling circuit. You could also just wrap some stiff wire around it a few times and twist the ends together.

TnBob · #41 05-12-2015, 10:49 AM

19mm .748"
19.05mm .75" 3/4"

Ceristimo · #42 05-12-2015, 11:59 AM

@Maxbumpo
No, I found the 'remove thermostat' procedure on a how-to on how to do a citrus flush.

@Funola
Yes, I've read of a few folks that have had that happen. What do you recommend? Just connect the heater hoses in the engine bay together?

Ceristimo · #43 05-12-2015, 12:20 PM

Hmmm, based on what Funola said I've been doing some more research on leaking radiators and heater cores, and it seems that it happens more frequently than I wanted to know...

So...since my coolant came out looking good and not rusty brown.... I think I'm going to just flush it out with my garden hose, put the new thermostat in and fill it back up.
Now, the coolant was green, but that doesn't necessarily mean it's bad. Sure, the "traditional" green coolant used a long time ago in all iron engines/radiators is bad in our W123's.
However, my daily driver Mazda has an aluminum radiator and aluminum engine parts as well, and it uses green coolant that is safe for aluminum. So while it looks like the "traditional" green stuff, it is in fact safe to use in aluminum, and I'm sure it would be fine in our W123's as well. So just the fact that the coolant was a nice bright green, does not immediately worry me that much.

If after I just flush it out with a hose it would still be running too hot, I can always consider the citrus flush at that point. Agreed?

I thought that having your radiator or heater core leak after a citrus flush was just a freak occurrence that happened to an unlucky few, but it seems to happen more frequently than that, which makes me doubtful about doing it.

Thanks for the advice, guys. I'm learning something new every day here!

renaissanceman · #44 05-12-2015, 12:41 PM

Quote:

Originally Posted by Ceristimo

Hmmm, based on what Funola said I've been doing some more research on leaking radiators and heater cores, and it seems that it happens more frequently than I wanted to know...

So...since my coolant came out looking good and not rusty brown.... I think I'm going to just flush it out with my garden hose, put the new thermostat in and fill it back up.
Now, the coolant was green, but that doesn't necessarily mean it's bad. Sure, the "traditional" green coolant used a long time ago in all iron engines/radiators is bad in our W123's.
However, my daily driver Mazda has an aluminum radiator and aluminum engine parts as well, and it uses green coolant that is safe for aluminum. So while it looks like the "traditional" green stuff, it is in fact safe to use in aluminum, and I'm sure it would be fine in our W123's as well. So just the fact that the coolant was a nice bright green, does not immediately worry me that much.

If after I just flush it out with a hose it would still be running too hot, I can always consider the citrus flush at that point. Agreed?

I thought that having your radiator or heater core leak after a citrus flush was just a freak occurrence that happened to an unlucky few, but it seems to happen more frequently than that, which makes me doubtful about doing it.

Thanks for the advice, guys. I'm learning something new every day here!

Yes, exactly why I forgo the flush on old vehicles unless I'm geared up to replace a lot of parts. My buddy has a CJ5 that would not cool at all (in the 100F+ heat of central CA) and we flushed as a last ditch effort to save the $500 cost of a real jeep radiator. After the flush, you could watch water weep out of hundreds of pinholes. Ended up putting a $80 all metal radiator intended for an old mustang, and now that thing runs really cool.

I imagine everything will be cool (ha) after you get the new thermostat in.

Ceristimo · #45 05-12-2015, 12:48 PM

Ha! I see what you did there. That's a cool play on words!

I'm not so sure anymore the old thermostat was stuck. I pulled it out yesterday and while I haven't tested it in hot water yet, I can move it with my fingers, so it isn't really stuck I guess. We'll see.

Yep, at this point tonight I'm just going to disconnect all hoses, flush it out with just normal water and fill 'r back up with Zerex G-05 and a new thermostat. Oh, and new radiator hoses, since I bought those as well.