Thread: Water temp near the red

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

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

Wayne

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

Thanks

Originally Posted by isuzu110

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.

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

Originally Posted by ellard

<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 ?

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

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. 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.