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  #1  
Old 12-19-2003, 11:26 PM
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Question Which thermostat should I be looking for?

Hello!

This has partially been covered in other topics, but I figured I'd start something fresh for this question. Sorry for the seeming to repeat myself at times...

In another thread, I was told that I should be looking for either a Behr or a Whaler thermostat. Then, in another thread, I read that there were problems with Behr thermostats that made them not open until after 100 centigrade. On reading this, I figured that I should look for a Whaler thermostat...problem is I couldn't find one. The dealer was out of stock and every parts store I checked (McParts as well as a couple of halfway-decent shops) only had Stant or Beck/Arnley thermostats. One shop mentioned a thermostat that he had that came from some company in France, but I don't remember the company name.

On here as well as on the Ford site, I've heard so many horror stories about people replacing thermostats with ones that proved not to work (usually sticking closed) that I'm being careful (okay, "over-cautious" ) with this...I'd like to get this taken care of before I leave (given what happened today, I'm not leaving tomorrow like I had planned), but if I can't get something "decent", I guess I'll just live with an open thermostat and the lowered heater output.

Also, what's the thermostat supposed to open at? www.partsamerica.com has two thermostats listed; one that opens at 180F and another that opens at 195F...or is their listing an anomoly?

Any thoughts would be appreciated...thanks in advance!
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2001 VW Jetta TDI, 5 speed, daily driver
1991 Ford F-350, work in progress
1984 Ford F-250 4x4, 6.9l turbo diesel, 5 speed manual
Previous oilburners: 1980 IH Scout, 1984 E-350, 1985 M-B 300D, 1979 M-B 300SD, 1983 M-B 300D
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  #2  
Old 12-19-2003, 11:44 PM
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Tim, what is wrong with your current thermostat ? You took it out to do the flush,, right ? Put it back in and go see your father....

These are not one opening thermostats... like you usually see... they open and close two different holes... at different temperatures.... if you really really need more info I will post it... but you really should just go and enjoy your xmass vacation.. did you get all the papers done and turned in ?
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  #3  
Old 12-20-2003, 12:02 AM
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Yes, papers are finally turned in.

However, I wound up spending all day today flushing the cooling system on a friend's '84 300D. I was going to do mine right afterwards, but in the middle of doing my friend's car, the weather turned real bad real quick... At least I got my oil changed

As to the thermostat that I've currently got, it's stuck open. Unless I let the car sit idling with the a/c running for about 10 minutes (after driivng around), the temperature won't get up above 60C (and it takes a good 15 minutes to get there from a cold start). I'm 99% sure that it's the thermostat and not the sending unit simply 'cause the heater stopped blowing as hot as it used to. In addition, the expansion cap doesn't feel as warm as it typically did in the past. Both of these events occured simultaneously, and occured very suddenly.

Actually, it was the realization that the thermostat was stuck open that prodded me into taking a close look at the cooling system and realizing that it's mainly got water in it (and I don't want to know how much rust)...

BTW, the thermostat by itself won't stop me from leaving; I can live with reduced heater output...as long as the engine isn't overheating. However, I'd still like to get it done...after the fiasco today, I'm likely going to leave a day late as it is...

Last edited by The Warden; 12-20-2003 at 12:09 AM.
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  #4  
Old 12-20-2003, 12:21 AM
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Tim, why don't you pull the thermo out and stick it into water with a thermometer in it ? That is the classic way of testing it... and might tell you something else was causing the symptoms you describe...
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  #5  
Old 12-20-2003, 11:03 AM
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I think you are over-thinking this one. I removed a Behr and installed a Wahler, both were marked 87*C. I then tried a Beck/Arnley "french" t-stat marked 80*C all in an attempt to get the gauge to read cooler, it is always at a needle-width below 100*C.... The result is, tada! Nothing! The temp is exactly the same, maybe a needle width cooler, but nowhere near 80*C, winter, summer, hills, traffic, highway, etc. Seems the guage isn't as accurate at it should be. The moral of the story is that a thermostat either works or it doesn't and it really doesn't matter who made the bloody thing. Install a new t-stat, burp the system, keep an eye on the gauges and drive happy. RT
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  #6  
Old 12-20-2003, 01:56 PM
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Well, actually it DOES matter who made the thermostat -- I played this game with my Audi Fox. Took forever to find one that fit properly (finally ended up at a part store that knew what there were doing). Quality of the NAPA and whatever other store I tried was fine, but the design was wrong. The NAPA had a bypass hole in it and no back "flap" to close the buypass system off, so it ran cold when the weather was cool and overheated once the outside temp came up.

The other one had a back flap too small, so it still overheated easily.

Behr and Whaler are the OEM suppliers, so you know they will fit correctly. Get is from FASTLANE or an independent MB shop, they will have the correct ones.

Peter
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  #7  
Old 12-20-2003, 09:38 PM
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Peter, I would have ordered it from Fastlane, except that I'm planning (hoping) to leave tomorrow, and by the time I realized that i needed to replace it, it was too late to order it and get it on time.

BTW, I just confirmed that the thermostat's bad. I think it started cracking open at 110F, and it's definitely open (not all the way, but it's open) at 135F. It's supposed to open at 80C, which according to a conversion table should be 176F. So, thus ends the debate as to whether the thermostat's really what's wrong.

BTW, it's a good thing I'm flushing this sytem out; it's really horrible...pure rusty water, and getting everything nice and clean's gonna be a PITA...but I'm workin' on it

Last edited by The Warden; 12-20-2003 at 10:28 PM.
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  #8  
Old 12-20-2003, 11:52 PM
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Peter,
I'm not recommending installing the wrong thermostat, as it seems you were provided with during your Audi debacle. Indeed if I found the "aftermarket" thermostat to be different in any way to the correct OEM then I wouldn't install it. The fact is I could take the Behr, Wahler and "frenchie", Dremel off their respective manufacturers marks and you would be hard pressed to tell them apart. They also ran identically in my car with the exception of "frenchie" that ran a needle-width cooler as expected since it was a 80*C and not an 87*C like the others. RT
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03' Volkswagen Jetta TDI blue/black, 93K
93' Chevrolet C2500HD ExCab 6.5TD, Two-tone blue, 252K
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  #9  
Old 12-21-2003, 11:59 AM
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Behr, Wahler, and European aftermarkets will probably be fine. I'd be more concerned about the chain store thermostats. Usually don't have the correct bleed valve, and if they do sometimes it's in backwards. They can also have the wrong amount of travel for the back flap, and you won't be able to tell by looking.

Nothing against aftermarket parts, sometimes they are better, but American manufacture aftermarket thermostats for European cars can be a problem.

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #10  
Old 12-22-2003, 08:42 AM
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I'd like to try a new thermostat in the 1984 300SD. It has the tendency to run a hair below 100C - but there are times when I look down at higher speed on the Interstate and see it at 85C or so, then it moves back up.

Radiator exterior looks clean and so did coolant during a recent flush and renewal.

Also considering the possibility of the water pump having problems, but usually you get a leak failure rather than a pump vane breaking off.

When I procure the Behr on FastLane, I see it comes with the sealing ring.

Do I need to buy the Thermostat Housing Gasket? It says its for the housing to head junction.

Ken300D
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  #11  
Old 12-22-2003, 08:52 AM
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Only if it is leaking.. it has nothing to do with changing out the thermostat...
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  #12  
Old 12-27-2003, 07:59 PM
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Performed the thermostat change today - replaced a "MotorRad" brand with Behr. Successfully completed the required breaking of a housing bolt. Able to get housing bolt out by removing housing and grinding down remaining bolt, then gripping with a vise. (Could not get a grip on it while in the car.) Also got by without needing another housing-to-head gasket because the gasket stuck entirely to the head.

Temperature reading has changed from just a hair under 100C to somewhere in the range of 85-90C.

Housing had no corrosion at all, interior of the head that I could see also looked good.

ANTI-SEIZE.

Ken300D
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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles
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