Thermostat on E300TD?

[DrNick]

The temperature gauge on my '99 E300TD always reads low, at about 60 degrees. The max I've ever seen is 75 degrees!
It warms up to 60 very quickly, within a couple of miles, and then sits there. The fans are not on so its not that. Could be the gauge I suppose, but I was thinking it was most likely to be a thermostat opening early.

Being new to Mercs and there being no Haynes manuals available, does anyone know how easy it is to change the thermostat, where is it, and (if I need to bleed the system) is there a bleed point I should know about. Or indeed, am I barking up the wrong tree completely?

Many thanks

 

[25 Ttriumph]

See my post on Thermostat replacement.
I changed mine, needed a Torx socket to remove the housing, other than that, job was easy if a little fiddly on the E320.
Temp now 87 as it should be, but can take a while to get there, there is a full blown bypass on the E320, don't loose it when you take the housing off, there's lots of places for it to fall.
Stealership cost was £33 for the complete housing and sensor as well as rubber seal. Strangely they didn't have one on the shelf and said Merc Uk only had 1! "they're still to new to need changing yet"
Keith

 

[Motard]

I was having exactly the same problems with my 250TD so today I changed the thermostat...end of problems.

Cost me €17.50 (£12ish) and was a ten minute job. If it is time for a coolant change drain it from your bottom radiator hose, there will drain plug on the side of the engine, 17mm socket I think.
Disconnect any hoses that restrict access then remove the thermostat cover!
When I go to the Parts dept in the local stealers they give me a print out of the exploded view showing the part in question, if yours won't do that they may let you take a look.

Bob

 

[Ian B Walker]

Really pleased that you have your problem sorted Bob, temp now up to spec?

 

[mark.t]

temp e300td

mine runs about 78 to 82 and i have warm air ina couple of miles is this ok

thanks mark

 

[Dieselman]

mine runs about 78 to 82 and i have warm air ina couple of miles is this ok

thanks mark

Ditto. It goes up when using air-con or when driving hard.

 

[Dieselman]

The temperature gauge on my '99 E300TD always reads low, at about 60 degrees. The max I've ever seen is 75 degrees!
It warms up to 60 very quickly, within a couple of miles, and then sits there. The fans are not on so its not that. Could be the gauge I suppose, but I was thinking it was most likely to be a thermostat opening early.

Being new to Mercs and there being no Haynes manuals available, does anyone know how easy it is to change the thermostat, where is it, and (if I need to bleed the system) is there a bleed point I should know about. Or indeed, am I barking up the wrong tree completely?

Many thanks

This does sound low.

The stat housing is low on the drvers side of the engine, on the return hose. Easy job just need suitable Torx socket.

There is a drain tap on the bottom of the rad and a block drain under no6 exhaust manifold.

When draining and refilling ensure the heater is set to hot. Fill slowly, squeezing the bottom hose then run the engine at idle with the filler cap off. This does take some time.

 

[DrNick]

This does sound low.

The stat housing is low on the drvers side of the engine, on the return hose. Easy job just need suitable Torx socket.

There is a drain tap on the bottom of the rad and a block drain under no6 exhaust manifold.

When draining and refilling ensure the heater is set to hot. Fill slowly, squeezing the bottom hose then run the engine at idle with the filler cap off. This does take some time.

Many thanks for your succint reply! I'll let you know how I get on.

Nick

 

[Motard]

Sorry to hijack in on your post Dr. Nick but it is relevant and I think within the new guidelines for forum use.
Since changing my thermostat the temp is OK and back to what it should be but there is something odd.
I don't use this car very often and I note that when I switch on after it has been stood for a couple of days there is a gurgling/rush of water somewhere behind the dash. Clearly this is something to do with the heater but it isn't normal that is for sure. Any ideas anyone?

Bob

 

[Dieselman]

Sorry to hijack in on your post Dr. Nick but it is relevant and I think within the new guidelines for forum use.
Since changing my thermostat the temp is OK and back to what it should be but there is something odd.
I don't use this car very often and I note that when I switch on after it has been stood for a couple of days there is a gurgling/rush of water somewhere behind the dash. Clearly this is something to do with the heater but it isn't normal that is for sure. Any ideas anyone?

Bob

Bob

You've got trapped air. But then we knew that all along. Oops not very PC!

 

[Motard]

Bob

You've got trapped air. But then we knew that all along. Oops not very PC!

Gonna report you for not being PC!!!! First tell me how to fix it though if it needs to be fixed

 

[Ian B Walker]

Bob, let your engine tick over, open the header tank (remove the rad cap) turn the heaters on full (both sides) squeeze the top hose repeatedly and keep topping up the expansion/ header tank. You will be amazed at how much you can squeeze in.

 

[Motard]

Thanks Ian, I will try it tomorrow. If it works I will come over and help you screed your car roof.:bannana:


Bob

 

[DrNick]

Sorry to hijack in on your post Dr. Nick but it is relevant and I think within the new guidelines for forum use.
Since changing my thermostat the temp is OK and back to what it should be but there is something odd.
I don't use this car very often and I note that when I switch on after it has been stood for a couple of days there is a gurgling/rush of water somewhere behind the dash. Clearly this is something to do with the heater but it isn't normal that is for sure. Any ideas anyone?

Bob

How did changing the thermostat affect fuel economy. Mines in the low thirtys mpg at the mo at a constant 70mph or so. I was expecting a bit more!

Nick

 

[Ian B Walker]

Changing the thermostat to one which works properly will allow the engine to reach optimal operating temperature. Thereby allowing the fuel to be burnt at a constant rate, at the right temperature making your engine more efficient. Hense better fuel economy.

 

[Motard]

How did changing the thermostat affect fuel economy. Mines in the low thirtys mpg at the mo at a constant 70mph or so. I was expecting a bit more!

Nick

Haven't used the thing enough to find out yet Nick. Going away this coming weekend so maybe I will give it a run.
Ian has explained exactly what I was told about economy.

Bob