Coolant Thermostat question
 

I just drained my coolant and put a new thermostat (old one was broken).

Prior to the thermostat breaking and the new coolant, the car would run at about 85-90 (closer to 85). Now it runs closer to 95.

I used MB coolant with r/o water. I got about 1.75 gallons out of the system and when adding back in I used about 3/4 gal of cooland and about 4/5 gallon of water.

The thermostat is a MB unit part number 110-200-05-15

Is it typical to see a 10 degree diff in operating temp from a thermostat?

I know it's not a problem with the car because during the week the thermostat was broken, it had a hard time getting above 80 degrees at cruise.

Thanks

On my 123, I replaced the thermostat because the old one was sticking open, no heat in the winter. The new one had a 82 degree rating, meaning it STARTED opening at 82, so my car ran about 85 to 90 in cruise, and up to 95 sitting in traffic. If your old one had failed, or was old/weak and opened early, yes you can get a 10 degree change.

I think I was not clear.

Prior to the old one breaking (about a week ago) it ran at a constant 85-90. When it broke, it would baely get to 90, now with the new one I'm running about 95.

This is on the 190 BTW.

Thanks

What is the temperature rating of the new thermostat?
A thermostat will start to open 3-5 deg before it's rated temperature and be about half open at the rated temperature.

No idea. how do I find out? I looked at it and did not see anything.

Should run 80 to 90 deg C, might be a faulty new thermostat - it happens. Ensure your coolant water ratio is not more than 50:50.

It's usually stamped into the flat part of the thermostat or the bypass valve at the bottom. It might be on the box of the new one.

It came in a bag and I don't see anything on it. I'll have to pull the unit and see if I can find a stamp. What a PIA lol

Same thing happened to me, before it was fixed it never even got close to 90 now in traffic 95.

I see a pattern here
 

I replaced my water pump and thermostat last weekend and the car is also running ~5-10 degrees warmer than before the work.

Don't pull the 'stat. Check with the seller first to see if the temp rating is listed in the parts book. Or maybe someone here can do that cross reference.

I just checked with a parts house. You *should* have an 87 C t-stat.
I have bought new t-stats that did not open according to their rating.
If you pull the t-stat, check it with a thermometer in a pan of water heated until it boils.

Make sure that there is no air in the watercourse.