Thread: 300TDI coolant loss

Do you have a more accurate temp gauge installed than the standard one?
This is probably the most vital piece of extra kit next to an EGT gauge.

That is, do you know for sure that the engine isn't running at 100°C or more. The std gauge won't tell you this.

eg. viscous fan hub may not be working, engine heating up, excess pressure build up coolant needs to go somewhere.

Also are you sure you've done a good system bleed.
Blknight had a great writeup on how to do it properly and easily.
I've bled other cars in my non professional role as 'family car repairer' but the 300 tdi is another world.
I had trouble with mine for a short while losing coolant late last year, and it turned out that I was bleeding the system 'incorrectly'.
blknights method with the inverted bottle fixed me up good and proper too!

I do have an EGT gauge, but still running the standard engine temp gauge. Is swapping to a VDO gauge and sender the usual practice.. my other gauges are VDO just because they look similar to standard ones.

Out of curiosity where is the "vent" in the cooling system if you do get too hot.

I have never had what I believe is high EGT's (only time I have seen over 500 degrees is towing a car trailer up hills, and I shifted down gears and slowed down when it got over 550). But I guess it could have still overheated the engine a bit without that gauge moving much.

I am reasonably confident on the bleeding.. my heater works which I think is the most likely place to have air trapped, but I will double check that guide.

Originally Posted by AK83

Do you have a more accurate temp gauge installed than the standard one?
This is probably the most vital piece of extra kit next to an EGT gauge.

That is, do you know for sure that the engine isn't running at 100°C or more. The std gauge won't tell you this.

eg. viscous fan hub may not be working, engine heating up, excess pressure build up coolant needs to go somewhere.

Also are you sure you've done a good system bleed.
Blknight had a great writeup on how to do it properly and easily.
I've bled other cars in my non professional role as 'family car repairer' but the 300 tdi is another world.
I had trouble with mine for a short while losing coolant late last year, and it turned out that I was bleeding the system 'incorrectly'.
blknights method with the inverted bottle fixed me up good and proper too!

Originally Posted by mattims

t.

I have never had what I believe is high EGT's (only time I have seen over 500 degrees is towing a car trailer up hills, and I shifted down gears and slowed down when it got over 550). But I guess it could have still overheated the engine a bit without that gauge moving much.

I wouldn't be too worried about 550˚. That's nothing. 720˚ would be the absolute maximum, and you would not want it to sustain anything like that, but I regularly see 650˚ on mine when it's climbing long hills loaded.

Originally Posted by AK83

Do you have a more accurate temp gauge installed than the standard one?
This is probably the most vital piece of extra kit next to an EGT gauge.

That is, do you know for sure that the engine isn't running at 100°C or more. The std gauge won't tell you this.

eg. viscous fan hub may not be working, engine heating up, excess pressure build up coolant needs to go somewhere.

Also are you sure you've done a good system bleed.
Blknight had a great writeup on how to do it properly and easily.
I've bled other cars in my non professional role as 'family car repairer' but the 300 tdi is another world.
I had trouble with mine for a short while losing coolant late last year, and it turned out that I was bleeding the system 'incorrectly'.
blknights method with the inverted bottle fixed me up good and proper too!

Failure to bleed properly cost me a head gasket. I thought I knew how, but I didn't. Dave's method is great. The hardest bit is finding a bottle that stands up in the neck of the coolant bottle!

when was the radiator last cleaned/rodded out and has the viscous unit been replaced, also check the plastic ejector Y piece hasnt split.

As long as the temp probe is somewhere like the EGR plate, 550°C sounds nice and cold!
if the probe is located downstream of the turbo, 550°C could be at the high end.

Bleeder plug is the large(usually plastic, sometimes fitted with brass) nut on top of the thermostat housing.

After reading blknight's tute, the issue is that the bleeder nut is higher than the actual remote reservoir tank level.
So the problem is that you can't bleed it well enough if you don't extend the level of the reservoir tank level.

Like John said, use a bottle upside down in the filler neck and fill it all the way up.

Venting as I'm now understanding it is the small 3 way plastic sputnik looking doodad at the empty space between reservoir, radiator and thermostat housing.
I broke mine recently and replaced with a std t-piece(just to keep me going).
Bad!
This sputnik looking doodad is apparently where excess air is channelled into the reservoir tank to be vented(I guess) via the cap.

I think the seam in the reservoir tank is the 'normal' level, but on my last bleed(fixing up my sputnik) I filled it right to the top of the reservoir and it has yet to settle any lower.

I once had a very slight coolant loss(evaporation ??)
my Tdi basically runs at 83°C irrespective of ambient temp.
This one time tho, went camping so loaded to the hilt, with food and kids.
Gravel mountain road, closed the windows air con on.
Almost immediately coolant temp started climbing fast. both AC fans also running(viscous fan hub "may" have been not working properly tho) .. but in no time, coolant temps were up in the low 100s.
Max I saw was 105°C.. I understand that it's technically within specs .. but I'm basically a chicken.
AC off, windows down dusty kids and food
I cycled it as I could trying to keep from not going too far past 100°C.
No amount of changing down, going faster, tolling in neutral would allow me to keep the AC going and keep it under 100°C.

45mins later, I idled it for about 30sec, when we got to the other side of the hills, but that was from about 90-ish when we finally pulled up.
Didn't touch the car for a good few hours, so after it cooled, remove cap, no pressure at all and the reservoir was dry.
I filled it to that seam point and it took about 600ml(drink bottle).

No leaks, no steam, no drips, weeps or nothing. Just evaporated.

ps. I did eventually remember to change the viscous fan hub(thanks Roverlord ) but that was later in the year, temps weren't in the mid to high 30's.
I have run the AC just to see how it runs. So far I haven't seen above about mid 90's on the digital gauge(VDO sender). So I'm hoping that the camp trip experience was the fan hub, and not normal every day operation!

What bugs me(and every other landrover owner) is, with all that histrionics of heating up(never really overheated as such) is that the stupid dash gauge never moved past it's normal 'just below half way' mark!

yeah EGT probe is in the EGR blanking plate location. I had always intended to tweak the fuel pump to push it a little more since it only reaches 550 when I really try, but I have just always wanted to resolve other minor issues before make them worse by tweaking the pump.

interesting ... my plastic y join "sputnik" thing was cable tied together when I got the car, but I couldn't see any trace of leaking.

At one of it's services somewhere since I have had it, it has been replaced with a brass t junction. I don't know when.

I wonder if that is a problem.

You're probably already doing it, but check when system is hot and under pressure (don't risk opening anything). It was the only time I was able to find one particular leak, no green stains to indicate.

Check your reservoir cap. It has 'in' and 'out' valves for pressure management. They can corrode, fall apart and leak lots. Even if not malfunctioning now, but old, changing is a good preventative measure.

Trouble with writing responses is you lose sight of the main thread. If you have changed the water pump then discount the recommendation to check the weep hole located in the underbody of the pump.