well if done properly, using the correct fluid, unless you have a clean radiator drain, and a clean catch basin, the cost of coolant dumped is a big waste, not to mention the chemicals dumped...
but it's your time, and money.
personally, I boil em to see what they do first...

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I just have a clean large oil pan $4, and I filter the coolant through a stapled shut jean pant leg, I often times have to do something that requires a partial drain on a system with clean coolant so that setup was worth my time..

Each is own I guess, but if I boiled one every time that it was good I would have spent way more hours than the time spent to replace a faulty one, or even a few. If it's a trend with Mercedes I'm sure it's worth it- I'll be boiling the new one(s) when they get here, that's for sure.

Don't forget, "properly" uses distilled water, always distilled- I've seen engines ruined from using the hard water we have here...

__________________
Jake, 15 years working on Toyota's for a living, self employed now- Landcruiser restorations.
1985 W123 300D CA emissions, 225K miles; deleted cat/oxidizer, all EGR removed
1997 Supercharged 4runner desert buggy
1993 Cummins D250 ~250hp 650 ft lbs, keeping it mild
1978 Honda CVCC Civic, the tiny collectable
1994 F350 4x4 crew (soon to receive the cummins)
2003 Tacoma DC, the wifes/camping
1983 John Deere 310C (Backhoe, for work)

Isn't that the truth, when I'm down in your neck of the woods I just buck up for 20 gallons of distilled water to flush the cooling system in my 7.3 Powerstroke truck, I won't even run tap water to flush it. It takes me a few days to get used to the scale it leaves on your skin, really makes my hair stand on end too! It's a small price to pay for that excellent weather, though.

Well your the exception to the rule. As a Toyota tech, it probably doesn't pay to do the extra step. Time spent is very important in the business. But for the fella who only changes them out once every few years, it is an important step to do to prevent that type of headache.

I'm guessing your 500+ change outs were done with a newer Toyotas, not cars 25+ year old cars. Those thermostats probably are made by the OE manufacture to strict guidlines. Eventually those parts become a 25 year old design, are pawned off to be manufactured either by a cheaper third party manufacturer and reboxed or the quality control becomes lackadaisical in a cost cutting move because the numbers are not there to produce the same amount as they were when the vehicle was in production.





.

__________________
1983 123.133 California
- GreaseCar Veg System

You're approaching this wrong. For many, Mercedes maintenance is a matter of religious dogma. There are rituals, "kosher" (for want of a better term) products, etc. Woe be unto you for being different.

Sometimes the 10 Commandments are mandatory, learned and re-learned and re-re-learned the hard way. Sometimes, not so much. (DeliveryValve, for example, runs VO in a 617; he's a heretic just begging for punishment.)

Somewhere there's the thread with the 10 (or 11 or 13) most common problems in the W123's. I think the "high temp" might be on there.

DeliveryValve's point about part quality is valid, however (even from a heretic). Some non-OE parts are great; others aren't even close.

Guess again,
I specialize on FJ40's, probably changed the most in those, mostly 71-78... Worked at a European shop for 3 years in there, did a lot of BMW's (almost all older models), worked on a lot of heavy equipment for 5 years, then just about anything for 6 years. Mostly older stuff, oem, aftermarket, American, Japanese, probably some Mexican junk in there. Always worked on Toyotas in-between and I guess that's why they stuck.

Anyways, that's why the title of this entire thread is "Bad new t-stat, how common?" and why I just said, I'd be boiling the new ones for this Mercedes- it seems this particular design may be an issue.

So, yes, boil your t-stats... On your mecredes Diesels. If you want to do it to everything else; go for it. I won't be wasting my time.

__________________
Jake, 15 years working on Toyota's for a living, self employed now- Landcruiser restorations.
1985 W123 300D CA emissions, 225K miles; deleted cat/oxidizer, all EGR removed
1997 Supercharged 4runner desert buggy
1993 Cummins D250 ~250hp 650 ft lbs, keeping it mild
1978 Honda CVCC Civic, the tiny collectable
1994 F350 4x4 crew (soon to receive the cummins)
2003 Tacoma DC, the wifes/camping
1983 John Deere 310C (Backhoe, for work)

I don't see how I'm approaching anything wrong, read post above. I was pretty clear I would be boiling my Mercedes t-stats. I fail to see how using OEM coolant, Distilled water, OEM parts and boiling/testing new parts before installing is "approaching this wrong". I had one bad t-stat and said I would be boiling and testing the replacement, I don't think I'll be learning, re-learning and re-re learning anything here, fool me once- well you obviously know.

Thanks for the input though!

From above, for reference and clarity:

__________________
Jake, 15 years working on Toyota's for a living, self employed now- Landcruiser restorations.
1985 W123 300D CA emissions, 225K miles; deleted cat/oxidizer, all EGR removed
1997 Supercharged 4runner desert buggy
1993 Cummins D250 ~250hp 650 ft lbs, keeping it mild
1978 Honda CVCC Civic, the tiny collectable
1994 F350 4x4 crew (soon to receive the cummins)
2003 Tacoma DC, the wifes/camping
1983 John Deere 310C (Backhoe, for work)

Attempted wit. Didn't work. I've also been through the "you're not doing it my way...therefore it's wrong" cycle. No offense intended.

Sorry, I've been on lots of forums, and since TangoFox I've been feeling the new guy defense coming on. When all the guys with thousands of posts start questioning your every act I guess I read things the wrong way. I'll shut up until Wednesday when I can actually provide some hard data on here...

__________________
Jake, 15 years working on Toyota's for a living, self employed now- Landcruiser restorations.
1985 W123 300D CA emissions, 225K miles; deleted cat/oxidizer, all EGR removed
1997 Supercharged 4runner desert buggy
1993 Cummins D250 ~250hp 650 ft lbs, keeping it mild
1978 Honda CVCC Civic, the tiny collectable
1994 F350 4x4 crew (soon to receive the cummins)
2003 Tacoma DC, the wifes/camping
1983 John Deere 310C (Backhoe, for work)

Well, after all this, I guess I got lucky? I dunno, but the car with the 80 degree T-stat runs at 80 degrees like the needle is nailed to the gauge, confirmed with an IR gauge at the temp sender on the head...



I did boil the t-stat first, very slowly on a propane camping stove. Here is the tool that I used, it has been calibrated with a scientific grade mercury thermometer and is always dead on:



The new(er) Behr t-stat starts to open at 77.6 C, fully open at 84-85. I wanted to at leats boil the 70 degree t-stat but it didn't show up yet... If I was to run a 70 degree t-stat it would be solely to have a lower starting temp IF the car runs hot in stop and go traffic. I won't know until June.

I don't know what to say from here, has anyone else tested a t-stat that makes their car run at 85-90? This is purely speculation but maybe some t-stats are opening at higher temps than others. I'm certainly not seeing it being fully opened at 94, I do think that would be too high...

__________________
Jake, 15 years working on Toyota's for a living, self employed now- Landcruiser restorations.
1985 W123 300D CA emissions, 225K miles; deleted cat/oxidizer, all EGR removed
1997 Supercharged 4runner desert buggy
1993 Cummins D250 ~250hp 650 ft lbs, keeping it mild
1978 Honda CVCC Civic, the tiny collectable
1994 F350 4x4 crew (soon to receive the cummins)
2003 Tacoma DC, the wifes/camping
1983 John Deere 310C (Backhoe, for work)

The SD runs at 92C-102C. depending strictly on whim. At the present time, I haven't any correlation to ambient temperature, speed, or load.

I can tell you, with certainty, that the engine couldn't care less. At the present time, it's squeezing out 31 mpg in mixed driving. The hotter you run an engine, the better the fuel economy.............less heat of combustion taken away by the coolant.

Right up until that point where the oil can't lubricate anymore or aluminum parts expand and friction causes inefficiency, haha. But you're way way far from that and these cars have external oil to air coolers.

I thought my 26-28 mpg was good, 31, damn. I can't complain though, I'm amazed how much power this car makes and I don't wussy foot it often.

__________________
Jake, 15 years working on Toyota's for a living, self employed now- Landcruiser restorations.
1985 W123 300D CA emissions, 225K miles; deleted cat/oxidizer, all EGR removed
1997 Supercharged 4runner desert buggy
1993 Cummins D250 ~250hp 650 ft lbs, keeping it mild
1978 Honda CVCC Civic, the tiny collectable
1994 F350 4x4 crew (soon to receive the cummins)
2003 Tacoma DC, the wifes/camping
1983 John Deere 310C (Backhoe, for work)

I'm quite sure you could run the 617 at 110C. all day long and it wouldn't care. The synthetic oil has no issues at that temp. and the pistons don't have any clearance issues at that temp.

It's taken me nearly five years to get the 617 up to that level. When I bought it it was doing about 24-25. A change in driving habits also contributes to the figure. I don't drive it over 62mph unless I'm in the left lane doing a pass............then it goes 65 mph...........not more.

I read on another forum long ago (specifics are fuzzy) about waterless/pressureless (run the special coolant with a hole in the pressure cap) coolant running at temps in the 250-265º F for extended lengths with no adverse effects. This was an offroading forum, with some FJ40 owners reporting results. I've wondered about that occasionally since theses diesels will run better at somewhat hotter temps, just the pressurized cooling system can't handle the extra pressure, so then the problems escalate quickly at the elevated temps.

__________________
1985 300D-189k The 'UD', Ivory and Pinkamino
1979 300D-211k Dark Gray, Parchment
A 1980 Harley-~166k and
A 1994 Ford diesel pickup-349k and
A 1990 gasser Volvo wagon-145k

Waterless coolant, 375 degree boiling point. I've run it in high performance 4 stroke motorcycles with really good results. Jay leno runs it in all of his cars, haha: Evans HDTC waterless coolant for heavy duty applications

These engines are both similar metals, cylinder head to block, which would make a great candidate for running hot like that. I wouldn't do it on an aluminum head/cast block or even an all aluminum engine due to the higher expansion rates of aluminum...

__________________
Jake, 15 years working on Toyota's for a living, self employed now- Landcruiser restorations.
1985 W123 300D CA emissions, 225K miles; deleted cat/oxidizer, all EGR removed
1997 Supercharged 4runner desert buggy
1993 Cummins D250 ~250hp 650 ft lbs, keeping it mild
1978 Honda CVCC Civic, the tiny collectable
1994 F350 4x4 crew (soon to receive the cummins)
2003 Tacoma DC, the wifes/camping
1983 John Deere 310C (Backhoe, for work)