What do ya think? Tstat? - Page 2 - PeachParts Mercedes-Benz Forum

imagesinthewind · #16 01-15-2009, 09:15 PM

Gonna change it out tomorrow.

Along with the #2 glow plug.

imagesinthewind · #17 01-16-2009, 04:38 PM

Well maybe it wasn't the tstat.
Still has little to no reading.
And now I have a small leak at the tstat housing.
I didn't do it the completely RIGHT way, I just opened the
housing and let the coolant flow into a bus tub under the
car. I used the gasket from the other tstat as it looked
pretty good.
I took everything apart twice (once to replace and once to see if I seated
the stat wrong resulting in the leak) and used 2 gallons of coolant.
The leak is itty bitty. I may leave it for a few days.

So on the housing of my car AND the 79 there is a small squat cylinder
with a wire coming out of it. What's that?

Thanks!

jt20 · #18 01-16-2009, 04:40 PM

pretty sure thats for the egr circuit.

rrgrassi · #19 01-16-2009, 05:41 PM

That wire is the grounding switch for the HVAC blower. When the coolant temp reaches a certain level, the switch closes allowing the blower to operate.

jt20 · #20 01-16-2009, 05:48 PM

where is the temp sender for egr on this model?

rrgrassi · #21 01-16-2009, 05:52 PM

The EGR is vacuum controlled, so look for a vacuum switch. I do not see an EGR in the pic.

imagesinthewind · #22 01-16-2009, 05:59 PM

So if the temp gauge isnt moving then it's probably the sensor, right?
I don't get under cars. So how do I fix this?

I can't leave it like this right? What if the car starts to overheat and I
can't tell because of the sensor.

rrgrassi · #23 01-16-2009, 06:01 PM

Possible, or poor grounding in the cluster. Or, a bad guage as worst case.

The temp sender is on the same side of the head as the GP's

It is possible to knock the temp sender wire off...

imagesinthewind · #24 01-16-2009, 06:05 PM

chit. was hoping it would be easy. tstat replacement is easy.

Oracle12345 · #25 01-16-2009, 08:18 PM

thats the cold engine lock out in the picture. The sensor for instrument cluster is on the side of the head, 2nd sensor screwed in head,

imagesinthewind · #26 01-16-2009, 10:05 PM

anyone got photos of the location of the sensor?
I will have to do this myself and I'm highly claustrophobic.
I can't be under the car just looking for things. I need
to know what I am looking for and the area it's in.
So I can go to work right away getting it fixed.

Photos would help a lot.

rs899 · #27 01-17-2009, 06:48 AM

There is no EGR valve on a 78 or 79 300SD- that's why you don't see one

.

No need to crawl under car. The temp sensor is on the head , about even with the glow plugs right about in the middle. It has a single wire clipped to it.

300dmichael · #28 01-17-2009, 01:30 PM

In your picture of the t stat housing, I see what looks like the remnants of a paper gasket around the housing..if that is what there is ,was there a rubber gasket that fits around the t stat it self..If you are trying to seal the housing with a paper gasket and the t stat has no rubber ring on it like my picture, then the t stat will let coolant by it and the car will never warm up.

imagesinthewind · #29 01-17-2009, 01:38 PM

Quote:

Originally Posted by 300dmichael

In your picture of the t stat housing, I see what looks like the remnants of a paper gasket around the housing..if that is what there is ,was there a rubber gasket that fits around the t stat it self..If you are trying to seal the housing with a paper gasket and the t stat has no rubber ring on it like my picture, then the t stat will let coolant by it and the car will never warm up.

Thanks.
Ihave the rubber gasket around the tstat itself. It's on nice and snug and fits nice and snug into the housing. Don't know why it's leaking. Is there also
a gasket that goes around the housing? I've never seen one and changed the tstat on three MBs so far.

The photo is actually from the parts car. I just didn't feel like opening my hood (walking across all the ice in my driveway) and the parts car hood is open forever (robbed of it's latch cable).

I just wanted to know what the 'thingy' (it's an industry term) was on the housing. The wire goes down and back to something with a motor and fan.

Thanks,
Ginny
(sad and angry that the time I took to 'fix' things yesterday did NOTHING)

300dmichael · #30 01-17-2009, 02:31 PM

There is not suppose to be a paper gasket on it at all..the rubber o ring that fits on the t stat is what seals the housing together..Is the engine getting hot at all?? If you drove around for 20 minutes and brought home ,opened the hood and put your hand on the top large radiator hose,would it be hot?? If the hose is just warm,were you are not un confortable holding it.,.then there is a need for a new t stat..that hose should be HOT..that hose should be about 180 degrees hot and that is hot enough to burn you after a few seconds. but if it is just warm,then your gauge doesnt really start reading till it gets about 120 and that is what you are saying about the problem with your gauge..

I just replaced a tstat on my 83 300d and it was not stuck open,but it always ran cold..it just simple opened too soon..new t stat and everything changed..it now runs about 185..