Td5 Defender 90 technical questions

Can someone explain to me, what the air, which is taken into the engine from the air inlet in the drivers side wing vent or, the snorkel, does? I believe that it is used in the fuel system, and not for cooling. Am I correct?

And secondly, does the air that comes through this part of the system, have any impact on the cooling of the engine?

I have had a few overheating issues recently, which I thought had been corrected. However, today towing a small horse trailer, with one small pony in it, the outward trip, about one and one half hours was fine, but on the return journey, which followed after four hours parked up, the temp. gauge rose into the red and stayed in this zone, until I started to reduce the engine revs as I drove down hill.

Can anyone suggest what could cause this? I have a new radiator and the cooling system has recently been flushed.

Hi mate, the air intake is for the engine to breath, turbo diesels take in a massive amount of air so filters should always be replaced.

It has nothing to do with cooling the engine, td5's like all modern engines are water cooled.

Your thermostat may be stuck or sticky, and need renewing, did you have you rad disconected before the engine flush? If not, it will likely to be full of rusty gunky flaky water. Same with the water pump.

Also, have you checked coolant height in expansion tank, and that it is the correct strength? The other side of the wing is the ducting for the heater, so also nothing to do with keeping engine cool.

Hi Alan,

Stupid question, did it suddenly jump into the red?
Only reason I ask, mine did this when I first got it, it was a bad earth. turn the lights on and the temp gauge jumped in to the red.

Have you checked your fluid levels?

Were you towing and labouring the engine ?

Cheers

Gottschalk said:

Also, have you checked coolant height in expansion tank, and that it is the correct strength? The other side of the wing is the ducting for the heater, so also nothing to do with keeping engine cool.

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Thanks for your reply Gottschalk. The radiator was renewed and the system was flushed out very well. The thermostat was replaced last month. The only things that I need to ensure is that the air filter is okay, but it has only done a few hounded miles, over approximately 6 - 8 months. And, I have no idea what the concentration of the coolant is.

Would a weak coolant mixture have an impact upon the cooling? I had always thought that the additive was antifreeze.

neilly said:

Hi Alan,

Stupid question, did it suddenly jump into the red?
Only reason I ask, mine did this when I first got it, it was a bad earth. turn the lights on and the temp gauge jumped in to the red.

Have you checked your fluid levels?

Were you towing and labouring the engine ?

Cheers

Click to expand...

Hello Neilly. No stupid questions at all. I didn't notice the jump into the red. But I had been keeping an eye on it on the outward journey when it was fine. After that, and on the return journey, I had relaxed my attention and did'nt notice the jump.

Fluid levels are all fine. But, I didn't mix the coolant which was done by the garage when a leek in the system was repaired. I have just asked Gottschalk if a weak mixture would effect the cooling.

Yes, the engine was labouring, but not excessively, when going up gradients. I always drive very steadily when towing with the horse trailer. My max speed, on dual carriageway, would be around 50 - 60 kph maximum.

Thanks for your kind response, as ever. I am going to have a look at the coolant mixture tomorrow.

Hi Alan,

The other thing I would check is that there is not an airlock, Have you checked the fluid level in the top bleeding hole at the front of the engine. Maybe worth running it down to the garage that did the leak work and asking them to rebleed. My Td5 disco took 3 goes and heat cycles to bleed it 100%.

Cheers

Have the cooling fan checked,it may be turning but not fully engauged.

Alan Crossley said:

Thanks for your reply Gottschalk. The radiator was renewed and the system was flushed out very well. The thermostat was replaced last month. The only things that I need to ensure is that the air filter is okay, but it has only done a few hounded miles, over approximately 6 - 8 months. And, I have no idea what the concentration of the coolant is.

Would a weak coolant mixture have an impact upon the cooling? I had always thought that the additive was antifreeze.

Click to expand...

Hi bud! The mix wont effect the cooling per say, but in time it will.

When I did mine I did half and half, 50% water, 50% oats antifreeze.

The antifreeze stops the water turning rusty and crappy as it has inhibitors in it, and ideally should be renewed every 3 years on the td5.

When I asked about the engine flush, did you disconnect the rad and remove the water pump beforehand? If not, its is very likely that one or other or both of these items will have been filled with the gunky old water (with the associated deposits ie rust flakes, thick sludge) and therefore your cooling will be effected.

If these were removed before the enginr flush the I'm not to sure. I drive with a ton chipper on the back with a triple axle and big wire cables etc for winching trees over etc etc around some of the hilliest/steepest roads in mid wales and I have yet to have any overheating problems. ( touch wood). The air filter element is very cheap and I replace mine every 3 thou, its more for economy than anything else though!

Good luck!

Gottschalk said:

Hi bud! The mix wont effect the cooling per say, but in time it will.

When I did mine I did half and half, 50% water, 50% oats antifreeze.

The antifreeze stops the water turning rusty and crappy as it has inhibitors in it, and ideally should be renewed every 3 years on the td5.

When I asked about the engine flush, did you disconnect the rad and remove the water pump beforehand? If not, its is very likely that one or other or both of these items will have been filled with the gunky old water (with the associated deposits ie rust flakes, thick sludge) and therefore your cooling will be effected.

If these were removed before the enginr flush the I'm not to sure. I drive with a ton chipper on the back with a triple axle and big wire cables etc for winching trees over etc etc around some of the hilliest/steepest roads in mid wales and I have yet to have any overheating problems. ( touch wood). The air filter element is very cheap and I replace mine every 3 thou, its more for economy than anything else though!

Good luck!

Click to expand...

Good morning Gottschalk, and thank you for your help. My local mechanic was responsible for the work done on my defender, so I can't honestly confirm precisely what he did. He's old style mechanic and normally very thorough.

Would you think that another flush might be a reasonable precaution? I might get him to do that and make sure that the antifreeze is the correct mix.

Really appreciate your help.