Correct sequence for thermostat install - PeachParts Mercedes-Benz Forum

mbzr4ever · #1 04-03-2008, 05:28 PM

Can someone please enlighten me on the correct order of the parts to replace the thermostat?

There is an arrow on the t-stat (old one had a small hole in same position) - points up?

I did not know to order a new t-stat housing gasket and will reuse the old one until I get the new one. It appears to fit around the t-stat, because there is a slot.

So where does the new o-ring go?

This is for my 79 240D. Took the old t-stat out, looked like the original, did not look bad except for some lime scale and superficial rusty spots. I guess I'll keep it for a spare.

Edit: I looked at dieselgiant's tutorial, but he did not use the o-ring, just a new housing gasket. He also drilled a bunch of holes in the new t-stat - I don't think I need to do the same.

http://dieselgiant.com/thermostatreplacementandmodif.htm

Inside the housing had more lime scale, scraped it off. Wish I had some citric acid to do a full flush. As it is, I'm planning to flush with distilled water about 9 times, because I could not get the engine block bolt off.

79Mercy · #2 04-03-2008, 05:38 PM

the arrow should point up once installed.

mbzr4ever · #3 04-03-2008, 05:57 PM

OK, thanks, 79Mercy.

Found another thread asking the same about the o-ring seal, but no answer was ever given:

thermostat leak

DeliveryValve · #4 04-03-2008, 06:17 PM

Quote:

Originally Posted by mbzr4ever

....

There is an arrow on the t-stat (old one had a small hole in same position) - points up?

I did not know to order a new t-stat housing gasket and will reuse the old one until I get the new one. It appears to fit around the t-stat, because there is a slot.

So where does the new o-ring go?

This is for my 79 240D. .....

There are two different thermostat housing styles - varies by years. Your thermostat kit should also have the gasket that matches the one you currently have. The o-ring that is included is not used for your application. Just toss it aside for a rainy day. Go back to the place you purchase the thermostat to see if the gasket was missing from the box.

mbzr4ever · #5 04-03-2008, 06:25 PM

Hi DeliveryValve,

Thanks for confirming what I was thinking - o-ring is for another model.

Well, I got the t-stat from Phil (this site) , so it might take a while to get one. BTW,I did order what I thought was the housing gasket, but it was something totally different. No big deal, however, it was a small, inexpensive mistake.

Thank you.

This damsel (that was in distress) can now finish her project, took the radiator off yesterday, wish I had bought a new one, but seems to be in good enough shape. A bit paranoid about those plastic necks though. A good exercise in taking one out and in again.

In my haste, am leaving of the fan guard. May replace the hoses/clamps as I do this flush, gives me more room with that guard out of the way.

Lycoming-8 · #6 04-04-2008, 01:51 AM

Would not leave the fan guard off once you go back and replace the correct t-stat o-ring etc. The shroud is there to properly duct the air thru the radiator and should not be left off.

mbzr4ever · #7 04-04-2008, 08:26 PM

Lycoming-8,

I understand, but do you think it would be ok for about a week or so?

I'm planning to change the t-stat housing gasket and the bottom hose clamp, and drain/refill about another 6 times over the week.

My driving range will be very limited to 10-15 mins max each way, and about half at night, so as not to cause the engine to overheat. (Running it now, during the day, after about 15 mins, is a bit over 175 degrees F, with just water. This is my 3rd flush, just after the prestone super flush).

If makes a big difference, maybe I should just get the gasket and clamp at the dealer, would be much quicker and be done with it?

But I was hoping to get these with some other parts on an order with Phil, and it might take a week to get them, at the soonest.

Lycoming-8 · #8 04-05-2008, 01:02 AM

Should be OK. Just did not want you to be leaving it out on a permanent basis.

lietuviai · #9 04-05-2008, 01:20 AM

My shroud was missing from my 300D and doesn't make any difference cooling.
I am looking for another one if someone has a spare to sell.

mbzr4ever · #10 04-05-2008, 02:00 PM

lietuviai,

Perhaps a missing fan shroud/guard is not a problem if you are not driving in hot weather? I'm not sure how hot the ambient temp is where you are?

For me, the temperature never gets below 50, but I have to worry about the heat, all the time.

mbzr4ever · #11 04-15-2008, 01:38 AM

OK, I've flushed this radiator at least 8 times the past 2 weeks. I even did a prestone "super flush" and used the garden hose for about 1/2 hour, even though I was going to avoid the tap water. AS I mentioned earlier, I did change the thermostat, housing gasket, upper and lower hoses, put the fan shroud back on. I could not, however, unbolt the block drain. Too hard.

The water is still a very rusty brown, looks like unfiltered apple juice. I can post a pix, if someone wants to see the color.

My question is: How many more times do I flush/refill this? Will it EVER get to a clear (er) color?

Lycoming-8 · #12 04-15-2008, 02:51 AM

Are you running the car at operating temp for a while after each drain and refill? If not that will cause it to take a long time to clear out.

mbzr4ever · #13 04-15-2008, 02:55 AM

Yes, for at least 15 - 20 minutes (when the gauge gets to about 180 degrees F).

Maybe that is not considered a long time?

Lycoming-8 · #14 04-15-2008, 03:05 AM

Well if it was really bad in there it might require the citrus acid flush and I believe there is a deoiling flush that should be run before that. It can be tough when a system has been left to deteriorate by an uninterested PO.

Also noted that you had originally considered the acid flush but don't have the chemical at hand.

mbzr4ever · #15 04-15-2008, 03:23 AM

Quote:

Originally Posted by Lycoming-8

Well if it was really bad in there it might require the citrus acid flush and I believe there is a deoiling flush that should be run before that. It can be tough when a system has been left to deteriorate by an uninterested PO.

Also noted that you had originally considered the acid flush but don't have the chemical at hand.

Yes, I did not have the citric acid available, but found the Prestone "super flush", which I understand has citric acid in it. The "super flush" was at wal-mart, and only about $3, so I bought it.

I guess I could order the citric acid over the internet, and try the flush again. How many pounds do you think I'll need?

If there is anyone to blame, it is me, as I have been the owner for the past 19 years, and call it ignorance and/or lack of a good mechanic...there really is not a good reason, just poor excuses.... in spite of the neglect, however, the cooling system never gave me any problems, and consequently, was forgotten about.