300tdi running hot

Rorie · Mar 2, 2019

300tdi, sat for 2 years. I’ve been running it for 30 mins each night this week. I noticed the temp gauge in the cab was sitting about 3/4 the way up.

I went to locate the thermostat and noticed these two sets of connectors. Should they be connected to anything?

Is the thermometer inside this bit of pipe?

neilly · Mar 2, 2019

@Rorie
Do you have the RAVE workshop manual?

May be worth you reading that or even the Haynes manual.

Cheers

Rorie · Mar 2, 2019

Thanks!
So ultimate question then, should the water temp sensors be connected to something or is that an option on the different cars?
Where does the gauge in my car get it’s reading from? Is that more oil temperature rather than coolant?

Rorie · Mar 2, 2019

Hmm. I just took the thero out and it doesn’t work when put in hot water. New one required.

However, I don’t think water has gone through there in a long time! Water in the header tank, but the pipes were bone dry and burn looking!!

How would I test my water pump?

Water came out the rad and engine. Rad water was brown! Engine water was clear.

Al2O3 · Mar 2, 2019

Where has it been sat for two years? If it hasn't had decent antifreeze in it it may have frozen, burst a core plug which has then allowed the coolant to run out. The whole system should be full of water. That section is not dry because the pump isn't pumping water through it. Your pump might still be carped though.

Rorie · Mar 2, 2019

Rad was full. Brown water came out.
Engine had water that came out clear.
Header tank also had water though.

Flushed through everything. I’m hoping the coolant level has just been too low and the thermostat being gubbed has resulted in the over heating.

But, why would the header tank have fluid if the thermostat bend is empty? Should the header not ensure the system has water?

I’m going to replace the thermostat and fill up. Is there a way to test if the pump works and system is ok? Or is it just a case of monitoring the engine temp?

Al2O3 · Mar 2, 2019

The 300Tdi water system is a little peculiar. In your first picture that black plastic plug, seen between the jubilee clips and the yellow dipstick handle, is that last point you should fill the system up from. You can fill the system (or you think you have) then take that plug out, and it's amazing how much more fluid you can get in.

Rorie · Mar 2, 2019

Al2O3 said:
The 300Tdi water system is a little peculiar. In your first picture that black plastic plug, seen between the jubilee clips and the yellow dipstick handle, is that last point you should fill the system up from. You can fill the system (or you think you have) then take that plug out, and it's amazing how much more fluid you can get in.

Yeh I have watched a few videos on YouTube so think I understand the draining, flushing and filling.... but not quite how it all works!

If my thermostat was broken, would that stop coolant getting to the u-bend in my last photo? And also explain the engine overheating... or at least getting hot when idling?

Al2O3 · Mar 2, 2019

Rorie said:
Yeh I have watched a few videos on YouTube so think I understand the draining, flushing and filling.... but not quite how it all works!

If my thermostat was broken, would that stop coolant getting to the u-bend in my last photo? And also explain the engine overheating... or at least getting hot when idling?

No, that U bend should be full of coolant at all times, it just won't be flowing if the stat is shut. There's a rabbit off there, I reckon.
You need to find the connectors that fit on your temperature switch as shown in the pic neilly posted for you. Otherwise, we don't know where your temp gauge is getting it's information from.

Rorie · Mar 2, 2019

So where do those sensors feed the info to? What are they for? By the image I can see they are water temp switches, but what does that mean / what do they do?

jamesmartin · Mar 2, 2019

Rorie said:
300tdi, sat for 2 years. I’ve been running it for 30 mins each night this week. I noticed the temp gauge in the cab was sitting about 3/4 the way up.

I went to locate the thermostat and noticed these two sets of connectors. Should they be connected to anything?

Is the thermometer inside this bit of pipe?

View attachment 171351

no not connected unless you have air con, the temp sensor is the blue wire on the left behind the thin hose, check top hose gets hot and rad cores does all over

tottot · Mar 3, 2019

Best thing is to fit an aftermarket cappilary temp gauge. Getting the original system to work right when doing an engine swap is a common problem.

Rorie · Mar 3, 2019

Great thanks folks.
Got a long journey on Saturday. I’ll have time to change the thermostat over but not sure about the water pump. So, what’s your thoughts on what has actually gone wrong?
Just not enough fluid in the sysstem? And the thermo being stuck closes? Or is there a high chance the pump is gone too?
Guessing I know, but just from experience?

tottot · Mar 3, 2019

As James says it is very important that the top hose gets hot and the rad gets warm all over. 300's do not like low coolant,same for most engines but the high position of the water pump does not help.
Heater working is good,not working an early sign of problems.Do as AI203 say's and fill through the plug.
Run for a bit with plug out to clear any air left.
I would change the pump before going a long way. [ they do not like doing nothing for years as seals go hard]

Al2O3 · Mar 3, 2019

Rorie said:
Great thanks folks.
Got a long journey on Saturday. I’ll have time to change the thermostat over but not sure about the water pump. So, what’s your thoughts on what has actually gone wrong?
Just not enough fluid in the sysstem? And the thermo being stuck closes? Or is there a high chance the pump is gone too?
Guessing I know, but just from experience?

Have you tried filling it up yet, to see if it's leaking out anywhere?

Your radiator sounds like it needs a good flush out. You might find it leaks after that though

. Do have another vehicle you can use for your long journey? Like tottot said, I'd be getting it all sorted before relying on it for such a trip. I would get the hose out and flush everything thoroughly, heater matrix, radiator, engine. Put new stat in and fill it up with water. Take it for a run for an hour (go around in a circuit not far from home!) Then check it thoroughly for leaks. Try to check all of the core plugs, which isn't that easy. If temp looks good and the system indicates it's working properly, top hose hot etc Then you have the choice of draining it and filling it properly with antifreeze or doing that but changing the water pump while you're on. Personally I'd be tempted to replace the pump and the rad depending on what I found.

300tdi running hot

Rorie

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Al2O3

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