T-stat change advice - PeachParts Mercedes-Benz Forum

BodhiBenz1987 · #1 02-12-2010, 02:09 PM

OK guys, the snow is clearing from the garage roof and I'm ready to put the 300D back in it and get back to work. It's drooling coolant from the t-stat housing, enough to make a mess I'd rather not have on the garage floor, so I want to change the gasket. My original plan was to drain all the coolant and replace it, but given the weather and a concurrent storm of other problems, I'd rather save that for a month or so and just do the t-stat gasket. Any reason not to do it that way? I.e., is it necessary or recommended to drain the block before doing the t-stat? Or can I just put on goggles, remove the housing, replace the gasket, put the t-stat back in and start it up?
The coolant does need to be changed -- it's about four years old -- but is and has always been the correct coolant.

jt20 · #2 02-12-2010, 02:37 PM

no need to drain the block if you are confident about the coolant.

top it off after you are done since you will lose quit a bit. (remove the cap and replace it so as to create a vacuum - you will loose less coolant.)

Change coolant when you are ready.

rrgrassi · #3 02-12-2010, 05:20 PM

Quote:

Originally Posted by jt20

no need to drain the block if you are confident about the coolant.

top it off after you are done since you will lose quit a bit. (remove the cap and replace it so as to create a vacuum - you will loose less coolant.)

Change coolant when you are ready.

How would that work? The t-stat housing is the mixing area for lower and upper radiator hose. All vacuum created would seem to be lost, especially since there is a bypass area as well.

jt20 · #4 02-12-2010, 06:04 PM

it certainly won't suspend all the coolant...

but it will definitely slow things down. There are some resistors in that 'bypass' such as the aux pump and heater core.

more so, trapping the coolant in the reservoir is what I am getting at. All the stuff in the head is going to glug out since the hole is perpendicular to the water level.

The vacuum in the reservoir will not be 'lost'... but it certainly won't 'remain' either.

jkubica · #5 02-12-2010, 06:16 PM

Quote:

Originally Posted by BodhiBenz1987

OK guys, the snow is clearing from the garage roof and I'm ready to put the 300D back in it and get back to work. It's drooling coolant from the t-stat housing, enough to make a mess I'd rather not have on the garage floor, so I want to change the gasket. My original plan was to drain all the coolant and replace it, but given the weather and a concurrent storm of other problems, I'd rather save that for a month or so and just do the t-stat gasket. Any reason not to do it that way? I.e., is it necessary or recommended to drain the block before doing the t-stat? Or can I just put on goggles, remove the housing, replace the gasket, put the t-stat back in and start it up?
The coolant does need to be changed -- it's about four years old -- but is and has always been the correct coolant.

Hi
I'm not sure about '87 300d. but with my '85 300td, I just put a tub under the radiator and unscrewed the plug - caught 95% of the coolant that came out.

Seems unusual that the gasket would fail by itself. You may find some corrosion in the housing.

Good Luck,
Joseph

BodhiBenz1987 · #6 02-12-2010, 07:01 PM

Quote:

Originally Posted by jkubica

Hi
I'm not sure about '87 300d. but with my '85 300td, I just put a tub under the radiator and unscrewed the plug - caught 95% of the coolant that came out.

Seems unusual that the gasket would fail by itself. You may find some corrosion in the housing.

Good Luck,
Joseph

Yeah it struck me as weird also ... could also be the housing itself is a little warped or something. I hope it's not a corrosion problem. I really don't need any more worrisome news right now!

Right now I'm back in holding pattern because my dad left the snowblower in Bodhi's spot in the garage, and I can't push it out. Icetastic.

layback40 · #7 02-12-2010, 07:57 PM

If the coolant is 4 years old, its in need of changing. Leaking from a gasket around an alloy component is a sign of the anti corrosion additives in the coolant are spent. Re-using coolant that age is an unwise idea. Could cost you a lot more down the track in corrosion probs, head gasket, radiator etc.

BodhiBenz1987 · #8 02-12-2010, 08:10 PM

Quote:

Originally Posted by layback40

If the coolant is 4 years old, its in need of changing. Leaking from a gasket around an alloy component is a sign of the anti corrosion additives in the coolant are spent. Re-using coolant that age is an unwise idea. Could cost you a lot more down the track in corrosion probs, head gasket, radiator etc.

That was my thought, although I'm talking about three or four weeks ... until temperatures break freezing and a bit of the ice melts. Then again, maybe it's not worth making the mess twice. I do have the coolant on hand. Sadly, I don't think I'll be driving this car much before spring anyway ... too many little things to do and too frickin' cold. But I've got my Under Armour on and going to see how far I can get tonight.

layback40 · #9 02-12-2010, 09:06 PM

This is a bit cheap & nasty!
you could try to just tighten the bolts that hold the housing on and have the radiator cap just on the first notch so no pressure.
If the leak isnt too bad, it may last till things warm up, you must be due for some global warming soon!!!

BodhiBenz1987 · #10 02-12-2010, 10:02 PM

Quote:

Originally Posted by layback40

This is a bit cheap & nasty!
you could try to just tighten the bolts that hold the housing on and have the radiator cap just on the first notch so no pressure.
If the leak isnt too bad, it may last till things warm up, you must be due for some global warming soon!!!

It's not real bad in terms of coolant loss (not noticeable). It's bad in terms of messing the garage floor after sitting for a month.

As said, this puppy isn't going anywhere just yet anyway ... I'm working on flex discs.

Junkman · #11 02-12-2010, 10:11 PM

Quote:

Originally Posted by BodhiBenz1987

As said, this puppy isn't going anywhere just yet anyway ... I'm working on flex discs.

Then put some cardboard under it to protect the floor until you can drain & refill. Only rig if it is a doesn't matter, is an improvement or you need to be on the road. Otherwise, you're only making more work.

jt20 · #12 02-12-2010, 10:12 PM

Quote:

Originally Posted by Junkman

Then put some cardboard under it to protect the floor until you can drain & refill. Only rig if it is a doesn't matter, is an improvement or you need to be on the road. Otherwise, you're only making more work.

yeah... why fix twice?

additionally though, I had a leaking t-stat seal... it was cracked and flattened. A new fixed it right up, the housings are not sufficiently machined to create a perfect seal.

the 617 and 60x have similar t-stat arrangements.

BodhiBenz1987 · #13 02-13-2010, 12:10 AM

Yeah, I think I got a little over-optimistic earlier today and was hoping to have the car back on the road soon. It may take me two weeks to do the bleeping flex discs ... I don't know why simple jobs are always so hard for me. (well, aside from it being 18 degrees out, windy and wet, and not having the right tools)