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NineCherries

Member Since: 10 Aug 2019
Location: Falkirk
Posts: 44

low coolant temp/ heat problems

I'm hoping you folks can help. I've done a bit of forum searching but i'm not finding an exact answer - similar, but i'm still not sure.

I've had my 110 for about 18 month with no real issues but last week the coolant gauge was dropping quite quickly when i stopped and the car was idling, I've never really noticed it doing that before, the temp gauge has been pretty static once up to temp. Air temp in the car was warmish, but seemed cooler than before.
as a starting point I've swapped out the thermostat for a genuine Landrover unit, but if anything i've made the problem worse.

Now it is very slow to warm up, only reaches operating temp with warm air coming through after about 8 miles of motorway driving. as soon as i slow to a 30mph road the temp needle drops then tanks to just above blue if i stop to idle. This is worse than before i swapped the thermostat out. I didn't drain the coolant down completely when i swapped the thermostat out, I just undone the hose clips and swapped the unit out quickly - lost some, yes, but the engine wasn't drained.

What do you think, airlock? faulty new thermostat?

if the coolant cap is off and the bleed screw is out completely on the top hose should coolant trickle out? it doesn't.
I don't have RAVE so i'm not sure if there is a td5 specific way to bleed the system.
Coolant is clean, no oil or exhaust gasses present (that i can detect anyway). Top hose gets warm firms up bit still can be squashed by hand, bottom rad hose stone cold (but ive read that is normal). no leaks and i rechecked the coolant level this morn, car was stone cold and i only had to put in a tiny amount. i opened the bleed screw and nothing overflowed. I squeezed the top pipe gently till the coolant started to come out and replace the bleed screw.

on a final note I'll include a few pics of the temps after I parked up. (motorway drive into work, short 30mph drive to the carpark, then I let it idle for a few mins to see what happened.

after 30mph drive

Click image to enlarge

after 4min of idle

Click image to enlarge

after 10min total of idle

Click image to enlarge

Where the needle sits when motorway driving (blue line as i couldn't take a pic with driving).

Click image to enlarge

Apologies for the long post. And thanks in advance for any nuggets of wisdom.
Tony

20th Jan 2021 9:41am

landy andy

Member Since: 15 Feb 2009
Location: Ware, Herts
Posts: 5417

2006 Defender 110 Td5 USW Zermatt Silver

All fairly normal for a Diesel engine to be honest. Try removing the fan completely and doing the same drive.

How free spinning is your fan.

20th Jan 2021 7:49pm

Leamreject

Member Since: 19 Dec 2020
Location: Middle Earth - Leamington Spa
Posts: 954

I would have to disagree that this is normal, if goes down on the move (slightly) it’s understandable but at idle it’s not right it would more likely increase.

Does it have a fixed/viscous or electric fan?

If everything else is normal and the coolant level hasn’t dropped, I would recommend a new thermostat for starters. Ride like you stole it!!
If I’m not on a bike it’s because only a 4x4 will do…
2011 2.4 Puma 90 HT

20th Jan 2021 9:03pm

Leamreject

Member Since: 19 Dec 2020
Location: Middle Earth - Leamington Spa
Posts: 954

Just thinking about it, do you know the condition of the cooling system, could you have a blockage or an air lock? I’ve also seen this type of oddball if the impeller breaks on the water pump but normally it would overheat. Ride like you stole it!!
If I’m not on a bike it’s because only a 4x4 will do…
2011 2.4 Puma 90 HT

20th Jan 2021 9:19pm

Sicastle71

Member Since: 21 Aug 2019
Location: West Lancs
Posts: 126

If the outside temp is cold diesels will struggle to get up to temp out of interest is the outside weather chilly and are you using the heater on hot. This will act as another small radiator possibly explaining the drop in temp/struggle to get up to temp.

21st Jan 2021 10:04am

excossack

Member Since: 22 Feb 2012
Location: North West
Posts: 5738

1999 Defender 110 Td5 SW Caledonian Blue

My TD5 takes a while to warm up, even worse at idle. A trip on the motorway gets it up to temp but the heat is not that warm from the vents. I feel that the temp drops off when at slower speed i.e 30mph

The flaps in the heater box have full movement and have been checked adjusted when i swapped the matrix

I am sure its not as warm as it used to be. I have changed coolant, heater matrix and thermostat.
The only thing left to change is water pump. 1999 Defender TD5 110

Regards
John M0VAZ
Econet Station 48 no clock

21st Jan 2021 10:59am

NineCherries

Member Since: 10 Aug 2019
Location: Falkirk
Posts: 44

Thank you for the replies

Something isn't working as it should as this problem has only became noticeable in the last week.

LandyAndy i'm going to try and take the fan off and see if it improves, even if only as an experiment - the fan has a little resistance when cold but move freely.

Leamreject it has the factory viscous fan, coolant level was/is fine, no oil or exhaust gases noticeable either. I did think it was a sticking thermostat so it was swapped out two days ago for a genuine landrover one, i think it has made the problem worse

an airlock is a possibility.

Any hints on shifting an airlock?

sicastle71 Understood, but only a few weeks ago we had -8c and this problem wasn't there.but yes i did have the heater on while waiting to pick up my wife after work. this week has been +2c at the coldest and my heater and engine temps are still haywire.

excossack i think i remember reading a post that you either started or contributed to regarding this sort of problem when i was searching the forum. I have double checked and adjusted the heater flap just in case something had slipped but that hasnt made a difference.

The main radiator looks to be in very good condition, still has sticky parts label on it, no leaks, fins appear clear etc
heater matrix going my the condition of the connection pipes looks healthy. I was getting acceptable heat through previously (although i was considering a diesel heater as they have came down to a very reasonable price on ebay)

I'm going to try taking the fan off and giving it a run - I assume if the engine temp is happier, and i get heat, then my viscous fan has failed.

If I still have issues, I'll swap the thermostat back to my old one, maybe i bought a dud.

possible airlock? as mentioned above, can anyone advise on getting it to move? I did undo the hoses to the matrix and it was coolant that came out so i assume no airlock there. bleed screw undone and no air, but fluid does not flow out even with the expansion bottle cap off.

water pump. - I'll keep it in mind but if everything else doesn't help ill look at changing it, i would expect it to start overheating if the pump wasn't working.

thanks for the help so far.

Tony

21st Jan 2021 12:30pm

windy81

Member Since: 14 Mar 2018
Location: North Wales
Posts: 311

thermostat needs replacing. It's stuck open.

21st Jan 2021 4:39pm

excossack

Member Since: 22 Feb 2012
Location: North West
Posts: 5738

For my issue I have changed the thermostat twice. OEM and Gen LR item and the same 1999 Defender TD5 110

Regards
John M0VAZ
Econet Station 48 no clock

21st Jan 2021 5:13pm

NineCherries

Member Since: 10 Aug 2019
Location: Falkirk
Posts: 44

Windy81, that's what i thought too, I've just replaced it with a genuine LR one and its worse. i tested the old one out of curiosity and it was appears to be working

stupidly i did not test the new one as i assumed as i'd bought a genuine part it would be good.

If I had a faulty thermostat the bottom hose from the thermostat would warm up, yeah? Its stone cold even though the top hose, bypass hose and heater hoses get warm.

I need to make a locking bar of some sort so i can get the fan undone to give that a test as i worked around it to fit the thermostat. I've got a 36mm thin spanner from my doing bits n pieces on my pedal bikes, i just need to stop it turning.

One other question.
How can i get the engine up to working temperature as at idle it cools down and driving (even in a lower gear) doesn't do it as, i'm assuming airflow is doing its job and keeping it cool..

I've read leave the car running, from cold, with the lid off the expansion bottle works, I guess because the system isn't under pressure the fluid reaches boiling point sooner??

Tony

21st Jan 2021 6:42pm

Paul1275s

Member Since: 21 Apr 2019
Location: East Sussex
Posts: 80

Mine shows exactly the same behaviour since I've had it the last two years.
Gauge never goes above about 1/3rd even when towing in the summer. I replaced the thermostat with a new one which made no difference at all, I tested the one I removed and that seemed to be working fine too! Heater is excellent as long as I am actually driving, as soon as the car sits at idle for a period of time it drops down to just above the blue and the heater gets cooler. 2003 Defender 110 TD5 SW
2003 Caterham 7
2006 Mini Cooper GP

21st Jan 2021 7:15pm

rallysteve

Member Since: 10 Feb 2014
Location: Cumbria
Posts: 2197

2002 Defender 110 Td5 DCPU Keswick Green

Have you verified that the viscous fan has not seized up and is always being driven?

Steve 02' 110 TD5 Double Cab Rebuild Thread
84' 90 3.9 V8 Caged Pickup Build Thread - Now For Sale

Mobile Diesel Heater Build Thread

21st Jan 2021 7:46pm

NineCherries

Member Since: 10 Aug 2019
Location: Falkirk
Posts: 44

That's tomorrow's job. It can be turned by hand when the engine is off. Need to make up a locking bar and remove it tomorrow to see how it acts without the fan..

Thanks.

21st Jan 2021 7:58pm

familymad

Member Since: 13 Dec 2011
Location: Bucks
Posts: 3463

2016 Defender 130 Puma 2.2 HCPU Santorini Black

Sounds normal to me. Our TD5 used to quickly loose heat (and our TDCI come to think of it) and with it the heater in the cabin. So downhill runs around ski resorts in zero to sub zero you would watch it cool off fast. The speed of the drop only beaten by my wife and kids whining

1951 80" S1 2.0
1995 110 300TDI
1995 90 300TDI

21st Jan 2021 10:15pm

windy81

Member Since: 14 Mar 2018
Location: North Wales
Posts: 311

NineCherries wrote:
Windy81, that's what i thought too, I've just replaced it with a genuine LR one and its worse. i tested the old one out of curiosity and it was appears to be working stupidly i did not test the new one as i assumed as i'd bought a genuine part it would be good.

If I had a faulty thermostat the bottom hose from the thermostat would warm up, yeah? Its stone cold even though the top hose, bypass hose and heater hoses get warm.

I need to make a locking bar of some sort so i can get the fan undone to give that a test as i worked around it to fit the thermostat. I've got a 36mm thin spanner from my doing bits n pieces on my pedal bikes, i just need to stop it turning.

One other question.
How can i get the engine up to working temperature as at idle it cools down and driving (even in a lower gear) doesn't do it as, i'm assuming airflow is doing its job and keeping it cool..

I've read leave the car running, from cold, with the lid off the expansion bottle works, I guess because the system isn't under pressure the fluid reaches boiling point sooner??

Tony

Must be your gauge then. I have heard, somewhere on these forums, that there are 2 senders you can install that fit but 1 is for another Landrover variant that will give you false temp readings.

22nd Jan 2021 1:07pm

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