Water temp near the red

[86mud]

Hi all

After 3 months owning my 1998 130 HCPU I decided to take time off work to change the coolant as I had no idea what or how old the current stuff was.

So after purchasing a new thermostat, temp sender, demin water, Nulon Long Life Coolant and Nulon Radiator Flush, I hooked into it...

Put the Flush liquid in via the expansion tank and drove around for 30mins as per instructions, then removed hoses, drained and flushed out block and radiator system with clean water, changed thermostat and temp sender, connected everthing, then filled up with new coolant via the expansion tank...exactly 11.5 litres.

Had a shower and drove to work....now after a few kms from leaving home the temp gauge began to climb and sat about 6mm from the red! Previously the temp gauge sat just above the C....

First of all I thought it was a dud thermostat, but the top and bottom radiator hoses felt firm when squeezed so the thermostat must be opening and letting the coolant flow around. There are no leaks from anywhere.

Electrical fault with the temp gauge maybe? Any other ideas?

Thanks
Andrew

[Psimpson7]

Is it bled correctly?

[one_iota]

It sounds like an airlock. Making sure that the system is fully charged with coolant can be tricky as I found out when same thing happened on my 300Tdi Disco.

[86mud]

Thanks for the replies...

The book says 11.5 litres and after poruing this in, the coolant rested half way up the expansion tank as per the book...

When I filled the coolant via the expansion tank, i had removed the two brass plugs - one from the top of the radiator and the other from the top of the thermostat housing and waited until new coolant flowed out of them before I screwed the brass plugs back in...

Unless there is an air lock in the block?

Is there a secret to bleeding?

Cheers
Andrew

[Dagsey]

Hi Andrew, I had exactly this problem on my 300 Tdi Disco 1. Having flushed the system with my garden hose, replaced thermostat and all the hoses bar the heater hoses (this was in preparation for a trip up north to Exmouth and Karijini recently) I refilled everything with coolant and set off. All was well until we hit the freeway when exactly as you described, temp gauge reached for the sky. Well long story short, my heater matrix was blocked with crud from years gone by so, as the coolant refilled there was an airlock across the top of the block causing the problem. I disconnected the heater hoses, blasted them out with a pressure washer (kindly supplied by the radiator specialist in Carnarvon; thanks guys, you saved my holiday), refilled the system and bingo, all was well. Maybe this is your problem too. Does your heater blow hot air? If not, almost certainly that's the cause, mine now blows air just bearable heat wise on full fan, before it was just warm. Remember to open the heater fully onto hot when you blow it out with the water. Finally I refilled the system very slowly via the thermostat housing using the small radiator overflow pipe to bleed the top of the rad. This led to the coolant tank being overfilled but, when all was full and sealed I just syphoned the excess coolant out of the tank with a squeezy bottle and tube.

My main problem was the addition of a roof tent for the trip acting like a parachute which is why the temp gauge was fine 'til we got out of town and hit the 110km speed limit, the extra drag then caused the motor to overheat. Hope this is of some use.

Dags

[86mud]

Thanks Dags

I have been running around for the past fews with the heater lever on heat, but have not felt any hot air coming into the cabin.

Today I disconnected the heater hoses and flushed the heater core with fresh water. There didn't seem to be any blockages, as water flowed freely in and out of the unit.

I might try tonight and disconnect one heater hose and blow through it making sure the water flows properly.

Cheers
Andrew

[PAT303]

Before you go any further do the job properly.Remove the rad and get it rodded,It is long past due and refit and take it back to a rad shop,just fill it with water and drive it straight there and just them to flush it and refill with coolant.Your rad will need to be rodded or by now it could have started to rot and need a re-core,don't do the cooling half-ar%ed,it's right or wrong,no inbetween. Pat

[86mud]

Radiator was removed and cleaned recently, but was installed with original coolant - just topped with demin water, thus reducing the glycol capacity dramatically, which is why I have been busting to find time to change the coolant.

In the 3 months I have had the vehicle the temp gauge has never moved from just above the C. I have taken it for a very quick 1900 Kms round trip recently (Brisbane-Emerald-Brisbane) with no over heating issues.

I will try and bleed the system tonight before I leave work by removing the heater hose at the back of the block and seeing what comes out.

Cheers
Andrew

[lambrover]

when bleeding the cooling system have the engine running and the heater on and then let it run up to operating temp( thermostat opened).

[rick130]

Don't trust the OE temp gauge, they are notorious for false readings as the instrument earth isn't the best.

If the gauge moves when turning lights or wipers on, it's a crook earth.

Hook up a mechanical gauge or one of the combination engine monitor units.
If going mechanical, a standard 1/8-27 NPTF VDO thermowell screws straight into the hole where the OE sender goes, then screw in the feeler bulb.

[camel_landy]

Don't trust the OE temp gauge, they are notorious for false readings as the instrument earth isn't the best.

If the gauge moves when turning lights or wipers on, it's a crook earth.

Hook up a mechanical gauge or one of the combination engine monitor units.
If going mechanical, a standard 1/8-27 NPTF VDO thermowell screws straight into the hole where the OE sender goes, then screw in the feeler bulb.

+1...

I replaced 2x head gaskets, rad, thermostat, sender, etc... before I worked that one out!!!

BTW - I used a laser thermometer to confirm mine.

M

[86mud]

Well, this morning I decided to wake the neighbours up early and cranked up the 300 TDi to inspect this airlock.

While the engine was running, I disconnected the heater hose from the back of the block and let the coolant run out for a second or two....there were no noticable air pockets. I also loosened the brass plug on top of the thermostat housing and the radiator for a few seconds.

Tighten everything up again and then drove to work. The temp gauge wasn't as bad as yesterday afternoon, but it is still just sitting over halfway. I parked the car at work and checked everything under the bonnet. Pressure was good as usual and no water leaks anywhere.

One thing that surprises me about the 300 TDi is how cool the motor is after it has been running. My old V8 rangie was a very hot motor compared to this one.

Will try a bit more bleeding tonight.

Cheers
Andrew

[ellard]

Hi there Andrew

When I first got my 130 - 300tdi Dual Cab, I had simualr issues and worked through it to resonlve problem.

After speaking to a good friend of mine in Adelaide (Land Rover Mechanic) he surgested blocking the radiator by pass..............my first question what the bl---dy hell is he talking about....

Well for those whom dont know, the radiator is split into two - water in the top through the top half of the core (L to R), then through the bottom half (R - L). Betwwen these to galleries, and you can see from the top by removing the plastic bung theres is a bypass hole about the size of a 10 cent piece......

As to why there is a by pass - I have my own opinions but......

Well I have blocked it (soldiered it up) - had the radiator cleaned and now can cruse all day in the hash summer heat of outback SA (45 plus) .......with the A/C on at 120.....ish.

All the best

Wayne

[isuzu110]

Wayne

I've heard of this mythical bypass hole before. Tell me, how do you access it to solder it up ?

Thanks

[rick130]

Wayne

I've heard of this mythical bypass hole before. Tell me, how do you access it to solder it up ?

Thanks


You have to drop (unsweat) the radiator header tank.

[ellard]

Hi there

You can visually see the hole - drian the water in the radiator and take out the plastic bung and you will see it....

I removed the radiator and took it to our local Natrad place in Pt Augusta - they cleaned it and soldered up the by-pass............and only cost around the $100......so good valve for money in my opinion....


You have to drop (unsweat) the radiator header tank.

You are correct....

A question for the forum - whats is it there for?

Wayne

[rick130]

<snip>
A question for the forum - whats is it there for?

Wayne

It'd be a bleed so you don't get an airlock, the same reason as the bleeds that come off the top of the other header tank and the t/stat housing, but why so bloody big ?

[PAT303]

Thermal shock,same reason you drill a hole in the thermostat.It stops cold spots in the coolant so it heats through more evenly and doesn't let colder coolant cycle through.You can just fit a twin pass aftermarket rad for about $800 or just patch them up.I would still have a small 1/4'' hole though. Pat

[mike_k]

Andrew,

I had this overheating issue with my 130 300 Tdi as well - temp fine until installing reconditioned radiator, new coolant etc.

Eventually traced the overheating to the viscous fan unit.

Apparently the Defender needs the fan to work hardest at higher speeds due to low airflow through the radiator the faster it goes. :eek: The aircond condensor in front of the rad does not help either.

My viscous fan was cactus resulting in overheating at high speed or climbing hills.

May not be your problem but worth checking!

Cheers,

Mike.

[malsgoing130]

had the same problem as Mike on my 300Tdi 130, new viscous fan unit and all seems to be OK.
Mal