Overheating at 70 mph

[jnoshea]

Hi guys,

My 300Tdi has recently started to overheat at sustained speeds of 70 mph...and only then :? .  I can drive around town all day, stuck in traffic, climb rocky mountains at low revs and whatever and the temp gauge stays fixed at just below the middle.  But get it up to 70 mph on the motorway and it strats to get much hotter.  I can keep the engine temp at normal by keeping the cab heaters on full but this is not very comfortable.  Any ideas what could be wrong?

The Disco is a standard 1995 ES with Aircon and viscous fan.

[evang]

Check the lower radiator vains both sides. Last year I had a 90TD that done the same thing and it turned out to be the lower half of the radiator, the cooling vains between the water ways had rotted and knacked, due possibly road salt etc . The rad did not leak. The rad looked o.k till it was given a good looking at and was not blocked.

Therefore the 90TD rad did not have enough cooling capacity on long journeys at 70mph!!!!.

The local Landrover shop man pointed me in this direction and said this is becoming more common on LR's

Changed the rad every thing was o.k

Cheers

[hobbit]

Same here, the fins for cooling just dissolved on mine, but no leaks.
Once I fitted a new one, one third on the gauge always.  Checked it with a mechanical temperature gauge as well just in case the sender/disco gauge was faulty

I think Paddocks are still doing replacement ones for around 105+vat, but Mansfield Radiators may be worth a call, they had one is stock for me and it was cheaper than Paddocks

They even modified one of the fittings to take a mechanical temp gauge fitting

[Skywalker]

I had a similar problem recently with my Defender TD5, as said above turned out to be the lower half of the radiator (particularly the back of) ................  

Powerwashing the bottom of the radiator, front and back did solve the problem (short term) :oops:

After  a bit of mud pluggin you think a powerwash will sort it ...   :shock:  ....  believe me.......... it don't come close .............  Im gonna have to spend quite a bit of time on the radiator I believe    :roll:

Dave

[hobbit]

One thing which is handy to carry is one of the pump up water sprays cans, used for weeding, low pressure washing and can be done before leaving site. Followed by a garden hose wash through after you get back

ALso back washing it helps too

Bit awkward with the cowling on though

[spy]

I have had this problem twice on my series 3 (not 70 mph tho :D).  1st time I took the radiator off, flushed it and the rest of the cooling system.  I also found an unbeliveble amount of mud that wasnt visible.  Was fine for ages then started again overheating on the motorway.  2nd time it was the water pump.  

Gotta be one of the two!  Fingers crossed for mud in radiator....

[Bill jones]

As most of the others have sugested start with the radiator. I had the same problem with wrotten fins, fitted a new radiator and no more over heating at higher speeds.

[ChrisW]

Are you using any water at all?
Whats the back of the front cover look like behind the water pump? Are there any traces of water running out and down?
Didn't your cylinder head go recently? Sounds uncannily similar to my experiences  

I'm still on the original radiator but you probably need to spend a good couple of hours hosing through the radiator from the engine compartment to the front of the car - you'll be surprised just how much comes out  

The P gasket on the back of the water pump had gone on mine - water tracks on the block behind the water pump are the tell tale signs, fortunately on a 300 it's a seperate component to the rest of the timing cover so isn't so much of a major job, still a PITA tho  :roll:
If it has gone you need one of the 'uprated' gaskets made of metal.

The above seems to have cured the problem for me for the time being although a new radiator will be on the cards at some point, after 10 years or so they tend to clog up inside and lose a fair bit of their efficiency.

[jnoshea]

Thanks for the tips.  I'm not loosing any water from the system and I've never really given the radiator a good hosing from the engine side out, only the other way and the air-con exchanger is in the way then, so I'll start by giving it a good clean.  At a little over 100 quid I'm really hoping I don't need to get a new radiator 'cos I've spent out on the car recently with the turbo, head gasket and clutch  

[simdeb]

Had same prob with my disco , but untill i removed the rad found no vines left in the bottom part that you can not see , fitted new rad and electric fan been loads better since

simon