OM617 without thermostat - problems?
 

Hi all,
I have an option to buy a MB diesel vehicle that was imported into N-A from the Middle East last year. THe seller tells me that he got a shop to put in anti-freeze last Fall, and they noticed that there was no thermostat in it at all, so they put one in.

I am no expert in mechanical practices in hot countries, but would think that some harm to the engine could be done by running it without a thermostat (ie. straight through). That it wouldn't allow the engine to warm up properly or evenly. There is no way to know how long the vehicle was run this way, but probably some time.

Any indications of what this may do to am OM617 engine (non-turbo)? I did notice that the engine has a small oil leak toward the front or underneath (not at the back). Upon starting cold, there is a bit of blueish-whitish smoke for a few minutes until the engine warms up. It seems to run well when it's up and going.

Thanks for your thoughts.

I don't see how it would harm anything, it isn't the same as having a stuck one that fries the engine. If it would do anything at all, it might just cause a little bit of buildup, but not anything that wouldn't burn out now with a good T-stat and a nice good run or two to clean 'er out. Mine does the same, a little bit of smoking until the temp gauge picks up off the peg, but she runs well and the mileage is where it should be. When I had first gotten this engine, I had found the T-stat was there but had grenaded making it effectively non existent, at least all the pieces stayed right in the housing for me to dump out, lol.

It needs a t-stat for normal operation. The t-stat is actually a mixing valve and without it the engine will not cool or heat correctly.

As long as it's running well now, there is no point in worrying about it. If something was going to happen it would have done it by now.

i agree.

not to worry.

but don't run that way long term.

tom w

Thanks folks, sounds like running without a thermostat for a while will likely not have caused irreparable damage to the 617 engine, and it's not something I should be overly worried about. It has a new thermostat in it now and runs well. Cheers!;)

My car ran at about 65 degrees for a couple years till I woke up and changed the thermostat. Years later, it's ok and running at 80+. I didn't see any sludge build up on the valve train or anything.

Something to think about....
 

coking...?

Most folks don't understand....
 

The Europeans especially the Germans do things a bit differently.....USA automotive engines have thermostats that restrict the flow of coolant exiting the engine......and as Forced said the thermostat in a Benz is in all reality a mixing valve that allows the engines water pump to pull from hot coolant exiting the engine, and cool coolant exiting the radiator.....the "thermostat changes the amount of coolant from each source as necessary to send 80*C coolant into the water pump.....

If you think that's interesting, check out how the fan works......

German Engineering is amazing.....

SB

5 years ago I installed a new motor in my 240D, the motor came from the dealer, for whatever reason thermostats would not open on that engine, after trying 5 different tsats I gave up, so I removed the tsat and have been driving without one ever since, no problems.
I must add that I live in Houston where summers last at least 8 moths.

Vahe
240D 77/350K

Along with the 5 different thermostats, did you burp the system? Air inside the block will definitely not open any properly functioning thermostat with these MBs.

Yes, the coolant was drained properly by removing the plug on the engine block, refilled, burped, all done by Mercedes shop, at the end the frustrated tech told me "I give up the damn tsat will not open"

Vahe
240D 77/350K

Is the water pump actually circulating the coolant, or is the impellar worn out? Has the T-Stat been tested on the stove with a pot of water?

Efficiency
 

efficiency is the normal reason for making an engine run at normal operating temp. To me, if the stat was removed, all it means is that it was not running as efficient. Another thing to consider is that temps in the middle east average upwards of 100f.

IMHO, no harm done.

:flamethro If the tech gave up like that, then you need to find a different tech. That is plain lazy (on the tech's part.)

T Stat.
 

I ran my 240D for 2 years with no tstat.....engine ran very cool and took a long time to warm up in the cold months....but summertime I could not tell a difference except a little faster warm up according to the gauge...I put one in because one is supposed to be there and I got to glass bead and paint my housing....no problems of any type noticed...