Engine running hot: advice please

[Landyrover]

Greetings,

I have a 10 year old Defender with 66k miles on the clock.

I've become aware of a developing problem with the cooling and would appreciate any advice about what to do...

In the 6 years I've had the truck, the temperature gauge has always lay just below the midpoint, once its warmed up. I've never known it to deviate from this position at all. Until recently. Now I find that at speeds over 60 mph the needle slowly inches its way up until its pointing about half way between the midpoint and red. When I slow down it will eventually fall back to about the midway point.

I've checked the system and there are no leaks.

By coincidence, the heater is also playing up (although this has happened more recently). It refuses to blow air out into the cab at all. When I switch it on, there is a low rumbling noise, so something is happening. Listening with the bonnet up, it seems to be trying to suck air in via the intake on top of the left wing but there's nowt blowing through the other end.

Is it likely these two problems are related? I wondered if the intake might be blocked? And whilst the engine is running hot at over 60 mph, it isn't actually overheating (yet)? I wondered if I should flush out the system or whether the water pump might be becoming faulty?

I'm about to do a fair few miles on the motorway over the next few weeks and really don't want to breakdown!

Any pointers gratefully received.

Cheers,

Nick

[TDi90]

well, they are and arent related. if you put the heating on, then it takes heat from the engine and is a good way of getting the old temperature guage down a bit. have you checked obvoius things like coolant levels/radiator clear/leaks. otherwise, if you are worried, you could think about getting a kenlowe in there.

hope this helps

[drmike]

I can't see that a Kenlowe is the solution here. There is a certain problem that needs a remedy to restore the engine ti where it was before.

My own faviurite question is to ask if a thermostat is in there and if it's working OK.

Others I am sure will say check the radiator for 'cool' spots to see if it's clogged internally which it seems is a common problem.

Mike

[Landyrover]

Guys,

Thanks for the replies, much appreciated! :D

The thermostat has been changed, makes no difference to the symptoms. There are no leaks.

I wondered if the radiator may have some crud in it as it is a Landy that is used off the beaten track. How do I check for 'cool' spots and/or fluch out the rad?

Cheers,

Nick

[thermidorthelobster]

You could backflush the radiator.  Basically, disconnect the top and bottom hoses, then stuff a hosepipe in the bottom, and flush the water out the top (hosepipe bans notwithstanding).  Don't go crazy with it because you might break something.

I have to say, I've found in the past that if the rad is crudded up badly, it's time for a new rad pretty soon.

[bombx3]

hi ,, i had the same problem on 59k we changed the thermostat twice and was realy confused as we could not trace a fault ,so we tried another stat still wrong .So my mate who works for a motor factors said the stats are comimg from asia in a uk box and are crap so we took it out and my landy runs perfect but takes a little longer to warm up.i will be looking for one soon to put in it for the winter.I have just tested 5 stats in water and the earlist one opens is 122deg where it should open at 88deg that is what it says on the top.One of the others opens at 80deg but not properly must be bent ...i hope this helps...these were all brand new stats

[Landyrover]

Thanks guys, some more ideas there for sure!

I'll try flushing the rad before trying another thermostat. I'm also led to believe the heater matrix (if this is playing up) could also be contributing to the problem...

Nick

[beast5680]

gords has had a very similar problem on his disco and ended up changing the rad for a new one, it may be the internals of the rad have become clogged and are not letting the water flow correctly

[Landyrover]

Thanks... Checked the water level this evening and it has lost some since I drove approx 100 miles yesterday. My bro-in-law and I are going to have a good look at it tomorrow night. Thanks for all the ideas! :)

Nick

[dew1911]

Have got anything blocking the grille like spots and stuff? I know it sounds silly but in the hot weather some were having problems with air flow.

[Landyrover]

Well, have flushed out the rad - no blockages. Water loss wasn't real, wasn't topped up from thermostat change.

We have bypassed the heater matrix as there is obviously a problem with this - the motor is working but no air is being blown into the cab. It would seem that if the water flow is interupted because the matrix is blocked then the cooling efficiency of the system of a whole will deteriorate.

I will take it for a blast down the dual carriageway in the next day or two - if the temp gauge doesn't move then this will be the problem. If it does, then I guess it is time for a new rad... :(

Cheers,

Nick

[TDi90]

been down the dueal carriage way yet?

[Matt_H]

the thing that is ringing bells is the heating radiator, rather than the cooling radiator.  Can't work the fan bit out but I wonder if you could have blocked it with mud if you've been offroading, blocking that would explain a few bits.  That will loose a reasonable amount of heat (it is alwyas open even when the main rad stat is closed)

I'm not sure of the calibration of the guage but I'm guessing the rad stat may be opening a little higher than the half way you are used to.  Add on the hot weather and it's going to be sitting higher than normal.

If you take off the wing vent cover you can reach down into the air intake, there is a drain valve at the bottom - mine was totally full of clay/mud when i got the car - scooping out by hand and flushing with  water helped, but my rad wasn't blocked.

Let us know how you get on.
Matthew

[Ben]

If nothing else appears to work, then check the coolant for combustion gases. I think I tried pretty much everything going on my 90 to sort out a similar symptom (rad, stat, water pump, viscous fan, heater matrix). Nothing appeared to work, as it still overheated after a bit of pushing.

You might have to get a really good overheat going to spot the gases - it took ages to find that was the most likely problem on my 90. It got nicked before we had a chance to try it...

If this is what's happening, then it's a head off, new gasket...

As I said - if NOTHING else seems to be fixing it, then this MIGHT be something to check. The magic chemical that you put into your coolant to check for colour change isn't the cheapest thing in the world, but it's really effective to help diagnose sometimes.

Cheers

Ben

[Landyrover]

Blocked heater matrix was to blame. Diverted the plumbing so no water goes to or from the heater - problem solved! :D

Thanks for all your input guys!

Cheers,

Nick