Thermostat part number

[hands_aus]

I decided to replace my cooling system thermostat because the engine didn't warm up completely the other day after driving it about 15 miles. (It was a 7C winter morning here)

Are the 79 C thermostats still available?

The Kit part number on the K&K site is 110 200 05 15. This includes the seal.

I would like to confirm that number is for a 79C thermostat.

The reason I am doing this is that the local MB parts people supplied a thermostat marked 002 203 76 75 ...87C in a packet showing  A 110 200 05 15 on the outside.

thanks

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[Naj ✝︎]

Bob,

quote:I would like to confirm that number is for a 79C thermostat.

The reason I am doing this is that the local MB parts people supplied a thermostat marked 002 203 76 75 ...87C in a packet showing A 110 200 05 15 on the outside

I make both 002 203 7675 and 110 200 0515 as 87 degree t/stats.

If you want a 79 degree t/stat, go for 100 200 0715. Same as a truck t/stat 616 200 0215 but the price is X3.

naj

65 230SL
68 280SL

[hands_aus]

Naj,
They checked their computer listing and it showed the 87c Thermostat for each 113 model. This is in Australia. I wonder if there was a different temp thermostat for the USA and Europe because of the climate differences?
I asked after the 79C because I remembered reading about the different temperature thermostats and it was stated that 79C was the correct one for our cars.

I will remove my existing thermostat and compare it to the one supplied before doing anything else.
I sprayed the bolts with penetrating oil earlier tonight.

thanks

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[rwmastel]

When I bought a thermostat 3 years ago (?), I believe there were 3 different temps available.  Sorry, I can't recall what they are, but please keep asking around until you get all the info.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[Naj ✝︎]

Bob,
My parts cd is showing the 87 Degree t/stat for both 250 and 280 SLs.
The part # for the 79 degree t/stat is from a different source

naj

65 230SL
68 280SL

[bpossel]

The information below is from other posts...
I tried the 87c thermo, and this was too warm for my climate in Memphis.  I am currently using the 75c.  This is what the dealer had a number for at the time.  Works good for me.  The dealer didnt have a listing for the 79c when I was in the market.  Good Luck!
----------------------------------------------

Available thermos for 113 are from 71,79,and 87C
These are Start to open specs.

MB Part Numbers are:
79 degree = 100-200-0715
75 degree = 116-200-0015

In tropical climate , the 71C [ 160F] is best.
In normal temperate climates ,the 79C [175] is OK , specially w a/c
and cooler climates 87C [ 189F ] is fine ..
Both A/C and auto trans tend to increase the thermal load ....
Some owner that live in 4 Season climates actually change thermo w/season [ winter /summer]change....


bpossel
Memphis, TN.
1971 280SL
1997 E320

[hands_aus]

Guys, thanks for all the feed back and info

I am definitely in a moderate climate. Min 4C, Max 39-42C (maybe one week a year)

Is there a trick to removing the bolts in the thermostat housing?
The front bolt under the injection pump lines (it has a hex head with a large slot) looks to be almost inaccessible.

Also is there supposed to be a gasket between the two housings? Or does it seal using the new O-ring that comes with the thermostat?

I looked at the SLS site and it doesn't show a replacement gasket but it does show a 79degreeC thermostat and a 83degreeC thermostat.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[bpossel]

Hey Bob,

No gasket, just use the o-ring that comes with the new thermo.  If the bolts have'nt been off in awhile, they can be a challenge!

The bolt that is under the injection lines that has the slot in it, can be started using a good screwdriver (clean edge, not rounded).  You need to get a good grip in the slot so that you dont ruin the slot edge and loose the grip.  I think I used a screw driver with a good pair of piers to assist in the initial few turns.  I then used a wrench.  Next time I will use the new ratchet box wrenches that I rec'd for Fathers Day.  These new wrenches are really cool!!!

Also, not sure if this was a good thing to do...  but before I re-installed the bolts, I smeared a bit of anti-seize paste on the threads.  Dont forget to "burp" the system and get all of the air out.  With air in the system, the engine can overheat.  I usually park my car on an incline, front higher than the back.  After replacing the fluid, start the engine and look inside the over flow tank.  When the car reaches the point that the thermo opens (ie 79c), you will see a big bubble, burp, and the air is then out of the system.  I also made the mistake once to change the fluid when it was hot.  It is better to change it when the car is cold.

Another thing to remember is to ensure that the thermo is positioned the correct way.  The small "floating bearing" on top of the thermo needs to be positioned at the highest point.  Usually positioned towards the front of the car.  This is how the thermo releases the extra air in the system.  The air escapes from the highest point...

Bob

bpossel
Memphis, TN.
1971 280SL
1997 E320

[hands_aus]

Hey Bob,
Thanks for your advice.

I was thinking I might give the bolts a gentle tap to break the tension before trying to undo them. I have already sprayed them with penetrating oil.

Also while I have some of the fluid drained I think I will look at the air slide valve in the injection pump and re-oil it. This has been added to my 12 monthly maintenance schedule.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[hands_aus]

I decided to replace my thermostat..the engine has not been reaching working temperature of 180F. It is winter here.
To do this I removed the housing from the side of the head because the injection lines covered 2 of the bolts and the metal line from the front of the thermostat housing (early 250SL) covered the other 2 bolts. Very bad design.
It was held on by two nuts/washers that I had been spraying with penetrating oil.
I drainded the fluid, removed the hoses, then the housing.
In trying to remove the cover I broke 2 of the 4 bolts.
This morning I took it to an engineering workshop to have the bolts removed and threads re-tapped. Also they will remove the hollow bolt that holds on the metal tube that supplies hot water to the inlet manifold.
The metal tube should be replaced (AUD $50.00), and the hollow bolt (AUD $11.00) plus the other bolts and copper washers. I intend using hi-tensile hex-key head bolts for the cover.
I hope to have it back Wednesday and maybe I will find time to install it before the weekend.
I wish I had more garage space for a workshop.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[hands_aus]

I took the housing to an engineering workshop and the guy removed the broken bolts and cleaned the threads for me….$50.00 cash in hand.

He said if I was planning to keep the car for another 38 years the existing metal line would do the job.

I bought some ‘never seize’ and 4 new 6x25mm hex head stainless/S bolts and spring washers.
Of course the aluminium crush washers on the banjo fitting / heater line to the inlet manifold are now replaced with genuine replacement Copper washers $2.00 each.

When I re-installed the housing to the head I 'smeared' on some water based lube onto the by-pass hose, this made it a lot easier than when pulling apart.

I flushed the system with the garden hose. No muck came out so I was pleased about that.

After checking all the clamps I started to add coolant into the LHS hose of the heater to the head.
It went well with the coolant coming out of the top heater line and the top of the injection pump. I then re-connected those lines too and filled the reserve tank to the top and put the cap on.

My local mechanic told me that when the system is full, any air in there will be displaced when the thermostat open and any excess water will be blown out the overflow of the expansion tank

I started the car and let it warm up at idle. The temperature is now stable at 180F.
At this point it seems to be water tight and the expansion tank level is about 40mm below the cap.
I think now the temperature will be more stable and the Injection Pump Thermostat will operate more consistently at proper temperaure. I oiled the Air Slide Valve while there was no coolant in the car, I am doing this every 12 months.

Thanks for your advice and the part numbers were really helpful too.

I am gradually becoming a shade tree mechanic.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[n/a]

Bob,

You mentioned about not using the gasket when replacing your thermostat. I am wondering what the thermostat housing gasket is for? Are you reusing the old one?

Louis 70 280sl red auto

[Ben]

There is always a gasket between the thermostat housing and the head, there is only a rubber ring between the two halves of the thrmostat cover where the 4 Allen bolts are.

This is a worthwhile job and its interesting to note the point Bob makes, if you have a 'stat that opens early the coolant will tend to be always a bit cooler, and therefore the slide valve in the warm running device may not actually close fully, affecting your mixture !

I had this problem, and came to realise that when testing the car whilst stationary, the car would heat up the 'stat would open, the valve would shut off after a few minutes but actually open again slightly once I started to drive !

Regards,
Ben in Ireland.
'64 230SL 4sp.

[hands_aus]

Hey Louis,
I bought a new MB housing to head gasket $3.50 and used that on top of the existng one which looked like thin black paper.  It worked.

Hey Ben,
I think the temperature changes when the thermostat open because there is so much cold water in the radiator. This would make the Inj Pump thermo temporarily open again.
If you are driving you probably wouldn't notice much difference but if you were stationary you might notice a change in rpms.
This could be why MB recommends driving off slowly straight away.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[n/a]

My car is currently running without a thermostat. It is summer here and the temperature is usually between 70-90F. My mechanic believes it is OK to run without the thermostat since I need all the cooling anyway and the engine will warm up in no time. I will have the thermostat re-installed when fall comes around.

Louis 70 280sl red auto

[Naj ✝︎]

quote:My mechanic believes it is OK to run without the thermostat

That was the logic used in equatorial Africa, but you do want that engine to warm up to optimum temperature asap .
The increase in flow rate between no t/stat and open t/stat is marginal.

Just my $0.02.

naj

65 230SL
68 280SL

[rwmastel]

quote:Originally posted by ll2002

My mechanic believes it is OK to run without the thermostat since I need all the cooling anyway and the engine will warm up in no time.

Louis,

Sorry to say your mechanic is wrong.     I started searching through posts but there are too many on this topic for this time of night!  I'm heading to bed, but others can speak on the necessity of having a thermostat installed, having it installed right side up, the way it opens in two stages, etc.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[pagodino]

Don't use 87°C Thermostat at all, it is a error in the MB part-list. The 83°C is the winter termostat, 79° is the best joice. I'used the 87° and my new gasget blows for overheating an an to high pressure (water came out off the expantion-tank).
If I heard in the German forum (www.pagodentreff.de) this wasn't the only case!
In the last time I saw many mistakes in the recent MB list (230 Sl Clutch), be carefull!
The 230 SL cooling-system is limited an if you had to change the radiator you can let it modify by yuor craftsman. The old type net hav 1.5 cm distance wich make 42 single tubes, the new ones had a distance of 1 cm wich mekes 60, a 20% more radiator-superfy.
Also a Oilcooler is a good job for this engine.

Saluti from Italy Pagodino


Pagodino

[n/a]

I am going to order the 79c and have it put in at my next oil change. Thank you for all the inputs.

Louis 70 280sl red auto