I have a new water temp sensor for my OM617. Looks like it takes a 19mm wrench and seems to be quite simple. It's on the block just behind the IP. Is it as straightforward as it looks? On a cold engine, how much coolant can I expect to seep out while doing the job? Are these things torqued in very tightly, it's probably the original one I'll be replacing. Any tips, suggestions appreciated for this DIY.
Thanks

It's on the head behind the IP, right?

You can do it without losing much coolant, just do it on a cold engine. Or, after the car has sat for a few minutes, take the coolant cap off and re-tighten. Then wait until it is cool. This will create a slight vacuum in the system so that when you pull the sensor, water will not spill out so fast.

maybe a cup of coolant on a cold engine without any vacuum in the system.

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It is probably original sensor. Or do these not put up too much of a fight?

I did mine hot and dumped plenty of fluid....

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It shouldn't give you any problem coming out. Just make sure you have a good wrench for the job, either a box end wrench or a socket that is deep enough to get on the body of the sensor really good. I would recommend a god straight pull with the box end wrench.

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Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!

Instead of getting antifreeze over and into every thing, why not just drain it down a bit and not spill any. There is a radiator drain plug, there is also a block drain plug and it is really easy to drain a small pail full of coolant out of the system. You can pull any hose also. I think I would tend to pull the heater hose that is connected to the electric water pump on the passenger side fender. Pretty easy to collect it there with a pan under neath.

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Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!

Installed in about 5 min. using 19mm combo wrench. About a pint of coolant escaped but was captured in a bowl and put in to expansion tank. Running temp back to about 80 to 85C under just about every driving condition! Had been running 90 to 100C after replacing water pump and thermostat. All is good again with the SD.