Thread: 300TDI overheating issue?

Head gasket

Just deal with it
Its a 300tdi - one of the simpest motors in the world to wrench on

They do this at the most inopportune time - it’s their thang

Steve


Ps thank me later after
That is after you chase thermostats, heater cores and a myriad of bull**** possibilities
Then just change out the HG and fix it

Just be aware that when the water gets pumped out (for whatever reason) the temp will rise. When there is no longer coolant around the temperature sensor the gauge will start to fall giving a false indication it is cooling down. If you must drive it, let it cool down and top up the coolant.

Originally Posted by roverrescue

Head gasket

Just deal with it
Its a 300tdi - one of the simpest motors in the world to wrench on

They do this at the most inopportune time - it’s their thang

Steve


Ps thank me later after
That is after you chase thermostats, heater cores and a myriad of bull**** possibilities
Then just change out the HG and fix it

See im not sure if it is the HG because the coolant level isn't changing (i.e being eaten by the motor).. Or is this just how the 300 works?

Originally Posted by pop058

Just be aware that when the water gets pumped out (for whatever reason) the temp will rise. When there is no longer coolant around the temperature sensor the gauge will start to fall giving a false indication it is cooling down. If you must drive it, let it cool down and top up the coolant.

Yeah have been told about that

I would not rely solely on the expansion tank level , I had a coolant leak a while back that made me very glad I had the low coolant sensor fitted in the top of the radiator.
Let the pressure drop & check coolant level at the radiator plug in the top tank , mine had significant loss that did not show in the expansion tank .
If you don't have a low coolant alarm , I strongly recommend you get one .
Things can go wrong very quickly if you lose coolant in a 300TDI

Find a mechanic with one of those gas sensor in coolant things. Basically tells you if you have exhaust gas in coolant. Or check for bubbling in your expansion tank when idling.

Before I changed my head my gauge went up and down a few times in highway with camping loads. Usually by the time those gauges moves it’s already overheated. But basically kept going for months. Not saying you should do this. When I finally changed head I overhauled the whole cooling system. New radiator core, new hoses, tank, thermostat, thermo housing... everything. The radiator was about 70% blocked. Thermostat almost corroded solid in housing. Still, it never really got too hot. And when i pulled head off, still looked like gasket would have been ok.

Very easy job to do though. Could pull it off and fix it up in a weekend quite comfortably. Took me about 3 hours to get head off and radiator out etc. took me about 5 weeks to put it back though because as I mentioned i did not want to put unknown condition parts back in with a brand new turner head so basically put back a whole new cooling system (bar ghe block).

Originally Posted by Fausto79

Find a mechanic with one of those gas sensor in coolant things. Basically tells you if you have exhaust gas in coolant. Or check for bubbling in your expansion tank when idling.

Before I changed my head my gauge went up and down a few times in highway with camping loads. Usually by the time those gauges moves it’s already overheated. But basically kept going for months. Not saying you should do this. When I finally changed head I overhauled the whole cooling system. New radiator core, new hoses, tank, thermostat, thermo housing... everything. The radiator was about 70% blocked. Thermostat almost corroded solid in housing. Still, it never really got too hot. And when i pulled head off, still looked like gasket would have been ok.

Very easy job to do though. Could pull it off and fix it up in a weekend quite comfortably. Took me about 3 hours to get head off and radiator out etc. took me about 5 weeks to put it back though because as I mentioned i did not want to put unknown condition parts back in with a brand new turner head so basically put back a whole new cooling system (bar ghe block).

Might start looking at pricing for parts then! Turner heads seem to be the cheapest at the moment coming in at just under $900 (not including shipping). If I did end up going down the same path as you and the others... I might need some help! Only really started doing maintenance on my own vehicle recently and that sounds like a awful lot of work for a noobie!!

I wouldn't condemn the HG so quickly!

I've had some heating up issues over the past couple of summers too(D1 auto).
If I followed the easiest advice given by most that it's the HG, I'd have wasted $'s on all the necessary parts, and have had the same issue pop up again every other summer.

My issue is related to A/C more than anything else.
Fans all work, radiator seems serviceable(although I have had a new rad waiting to be installed for a couple of years now!) .. but somehow my heating up issue never felt like a radiator or HG problem.

Flushed coolant system(helped a little), changed viscous(no change, but mine was definitely shot).
I eventually pulled my front grille, and it completely stopped heating up on the highway(with A/C on).


Does yours overheat only at highway speeds? does it also overheat around town, or just sitting idling?
A/C on? off?

Are there any coolant leaks, be especially mindful of the P gasket basically behind the back of the alternator!
Are the front carpets wet?(when they should be dry). If you smell coolant in the interior you may have a small leak in the heater core. If this is so, it's not hard to bypass it, but a PITA to remove heater core and replace.

If there are 101% definitely no coolant leaks AND these parts haven't been been replaced/repaired/renewed the order I'd look at is:
viscous fan hub
radiator
thermostat.

Note that when I changed my thermostat, my easiest choice for replacement was from my local Auto parts store(easy walking distance), and I ordered a Tridon branded thermostat.
I order a fair few parts from these guys. Anyhow, I took a lot of time to test them, and found the Waxstat to be working, the eye opener during this testing was how much different the Tridon operated compared to the Waxstat in terms of the size of the opening.

When the Waxstat thermo opened, the gap in the valve was hardly more than a mm or two, and that was in the very high 80's temp range.
The Tridon started to open a bit earlier(more like 82°c or so) but when in the high 80's, it's opening was about 10mm or so.. maybe 8mm, but a majorly much larger opening.
The Waxstat could be made to open up 'fully'(to what seemed like about 8mm gap) but only if it were placed in the pot of boiling water.

I'd recommend they you do more testing to determine when it overheats, what are the ambients at the time, and a priority is to get yourself a separate coolant temp gauge(should cost about $100ish to do one effectively).
I found what works for me is a VDO sender in the top bung(bleeder) on the thermostat housing back to a digital readout.