300tdi Overheating - again!!!!

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Mr_V

Mr_V

Active Member
Posts
351
Location
Boston, South Lincs
I have had overheating issues with my Disco 300tdi for some time, and just when i think it's all sorted, it kicks in again.

I have replaced:
Core plug
Top Hose
Water Pump
Thermostat
Radiator

I have flushed, flushed and flushed again.
I can't find any leaks now (core plug resolved that problem) but still seem to lose water. Oil level is normal and no creamy muckmuck, so (hopefully) no BHG.
When flushing and refilling, everything is fine. I always top up the expansion bottle to level then put the cap on and top up from the top of the thermostat housing. I can drive for miles with no issues. Cabin heater heats up as expected and temperature settles in the middle of the guage.

I then stop the engine, go in a shop (3 minutes) Get back in, and drive off. The heater is now cold and after some time, the temperature goes up. When looking under the bonnet, the expansion bottle is boiling over, the top hose is cold, bottom hose hot, and the radiator, petty cold, but is warm at the bottom where the bottom hose connects.

I have no more hair to pull out. Any one with expert knowledge can give me a few pointers. Could it be the thermostat again? And what does that round plastic bit do that splits the small hoses from the bottom of the expansion bottle? and does it fail?
 
Airlock? I think you are supposed to fill up though the thermostat housing. Then top up the expansion tank.Pour the coolant in slowly.
 
Mr_V said:
I always top up the expansion bottle to level then put the cap on and top up from the top of the thermostat housing.
Click to expand...

Umm.....:confused::confused::confused:

Not sure if I do mine wrong! But I take the 2 plugs out (Radiator and Thermo housing) and fill the expansion tank up with water/antifreez.

Then when it fills and starts to leak out of the Radiatior (Lowest) hole I put the Plug into it and tighten it up.

I check that there is still fluid in the expansion tank and top it up if required, then wipe it clean!

Then I get my handy assistant to seal the top with his/her mouth and blow into the tank forcing the liquid into the pipes and thermo housing. When it gets to the top and starts to leak out I put that plug in and seal it. It helps to masage/squeez the top radiator pipe in and out as you do it!

Then when its sealed I get the assistant to brake the seal and breath as normal! Whilst I flick the engine over for a second or 2.

Like I say it may be wrong but I have never had an air trap since I have done it this way on any car I have had!

It is also the similar way to which you would bleed a home central heating system so makes sence to me!
 
sounds very similar to my problems which was solved by getting the head done AGAIN 2nd time in 10months been runing for 18 months now with no probs
 
dont no ithis helps but i went through exact same thing even changad gasket water pmp thermostat ended up swapping engine ,i had changd the rad for a second hnd one(scrapyard)and still had the problem,i decided to start again and got a brand new rad and its run perfect ever since,i had flushed water through both other rads and seemed fine,i see you have changed yours but is it new,or recon?if so sorry mate,iknow how you feel!!
 
Mr_V said:
I have had overheating issues with my Disco 300tdi for some time, and just when i think it's all sorted, it kicks in again.

I have replaced:
Core plug
Top Hose
Water Pump
Thermostat
Radiator
Click to expand...

When you changed the water pump did you change the gasket? It doesn't come with the water pump... if not check there, get it warm, then get some one to rev it and have a look behind the water pump with a torch for gasket fail.... common problem
 
Last edited:
hi MR V,
its been a whilst since ive been on here, but i had exactly the same fault.
i spent days,weeks,months, money etc trying to sort.
i asked on here too for pointers but with no joy.

i did eventually sort it. i found the heater matrix behind the dash had a very small leak.

not big enough to be noticed but enough that when you were once blowing warm air then park up and then come back and bee cold so you had to blead again.

from what i remember was reason able to do but dash had to come out to get to. parts wasn't too much either from what i remember. but has been 12 months plus.

hope this helps sort your fault...... the other thing with mine was localy no overheating, but on a run and giving it a bit of welly the temp needle came close to red but never over heated.

you 'll have to let me know how you get on
thanks mark
 
Thanks for the suggestions. I'll replace the one way valve and see where we go from there. I am so preying its not the head gasket. i have the mot due in feb, and may be tempted to not mot and tax it until it's done, which could end up being the middle of summer....Having no warm garage to do the work in...
 
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