G300 Thermostat
Engine temp seems a little on the low side - reading just under the 80 degree mark on the dashboard gauge. Of course it could be the gauge that's wrong rather than the thermostat but thought that for a few pounds I would change out the thermostat to be sure.
But I think the one from MB costs about £33 rather than other makes available on-line.
Anyone any recommendations on alternatives?
I think that you broadly get what you pay for with these items. There are reports that cheap ones distort after a while and then don't close properly.
I think that officially, the M103 engine on G300E has a 92 C rated one, but the 87 C are more common and usual fitment on other M103 applications. I fitted the 87C version (£20-something from MB) and it works fine.
Well for £5 you can buy a digital laser thermometer and test the system at various places before replacing the thermostat. And you can balance the radiators in your house when you have finished :)
Good idea - couldn't find one for £5 but £7.50 including delivery is still worthwhile.
Will also now be able to have central heating running at peak performance next winter.
The man Arnie knows his onions!
M103.987 300GE 92deg A102 200 19 15 @ £27.42 + VAT from MB Germany
M103.94X and M103,98X 87deg A110 200 05 15 @ £25.40 + VAT from MBUK
Basically the M103 runs a 87deg stat same as the M110 280 engines unless its in a G then its a 92deg
Gav
Thanks Gav (and Arnie).
Waiting on arrival of digital laser thermometer - but hard to believe that it's running at 92deg so could be stuck fully open. If so, will be on again to order.
Mark
The M103 engine in the G is de-tuned from the car versions and with the higher capacity cooling system of the G, it would tend to run cooler, hence the higher temperature, 92C, thermostat to help keep more heat in the engine. The idea is to improve thermal efficiency and also help prevent engine oil sludge, but with modern synthetic oils, you could use the 87C thermostat, if you wished.
Is there any downside to using a 92deg thermostat instead of an 87deg one?
On the.contrary, it should be a 92 C thermostat, just saying that if you can't get one, an 87 C will do.
So, I came to replace the thermostat today (having purchased the correct MB 92 degree version for peace of mind) but a couple of questions for those that know so much more than I.
1/ The replacement has a small breather valve hole and I understand why that's there but the existing thermostat has no breather valve hole and the thermostat housing on my G is almost on a horizontal plane so can't see how the breather valve is going to work anyway. Does that matter?
2/ I can't get the old thermostat out of the housing. How much brute force is OK to use or is there a special knack that should be employed to get the old one out?
Tips, tricks and other suggestions welcomed, as always.
Mark
Not exactly the same but I guess the principal is there ?
https://www.youtube.com/watch?v=DlfMOrVlKZM
Neil.
With the top of the housing removed, you will see the thermostat with a black ring around it. This is the o-ring seal. With a small screwdriver, placed under this black ring, gently lever it up and out. this will release the thermostat unit and you'll then be able to remove it easily. Replace the new one with a new o-ring.
The the tiny air hole allows air to pass more easily to the to of the housing, where the air-bleed screw is located.
Thanks Arnie,
Will give that a go - so has the existing rubber O ring effectively welded the thermostat in place (because at the moment it really doesn't want to move)?
And once the new thermostat is installed and everything reconnected should I bleed any air out using the top nut? Because at the moment that doesn't want to shift either.
I'm wary of using too much force in case something buckles.
Yes, remove the rubber o-ring first and the thermostat will then come out. Not really necessary to bleed air from top screw. Earlier, plastic housings did not have the screw.
Yes, remove the rubber o-ring first and the thermostat will then come out. Not really necessary to bleed air from top screw. Earlier, plastic housings did not have the screw.
It is worth changing the earlier plastic housing for a metal one because the plastic ones tend to crack around the outlet pipe over time. They usually let go when the engine is hot with quite dramatic results !
Mine doesn't have a plastic housing. Aluminium, I think, which is why I was worried about applying too much force. Mind you that would apply to plastic too I guess.
Hard to imagine them fitting one in plastic anyway - given the temperatures very close by.
Arnie - many thanks. Job now done. As you said - simples, and there is a definite satisfaction in completing these easy jobs yourself and in the process learning more about our Gs.
Interesting to see that the thermostat I was replacing was rated at only 71 degrees so will be interesting to see difference in engine running/performance from here on.
It's also a good way of being able to check out condition of parts that otherwise would remain out of sight/out of mind. For instance I had to remove door cards to replace the outside window scrapers and was very pleased to note the excellent condition of internals of the doors. No rust whatsoever.
Just been on a decent trip - engine seems happier running at higher temperature (but could well be just my imagination).
Nope ! not your imagination buddy. You SORTED it. Well done.
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You're right - of course.
For the sake of an extra £20 I'm better off getting an official MB one for the added peace of mind.
Sometimes it just needs someone else to say what I was already thinking really.