Thread: 300TDI - blown head gasket or radiator?

Originally Posted by Binca

.... Took it for a test drive. It did a lot better. Made it a lot further up the hill than previously. But then it suddenly had the same issue. Temp suddenly went up, but as soon as we slowed down and turned around it cooled down again. ....

Dash temp gauge is not trustworthy!

On mine, it sits just under the halfway point at normal operating temps.
Normal operating temps for me are 81-83 degrees.
Up to that point it seems to work fine.
eg. if my digital gauge reads 55, the needle has risen to just above the low mark. at 60 degrees it's a bit higher .. etc.

But when my engine got hotter than normal on a hot day and reached 94-95, the dash gauge still didn't move even a millimeter above the normal(81-83) just under halfway point.

That is to say, if my dash gauge were to read past the normal half way point, I'd estimate that the coolant temp would have to be way above 100 degrees! Way too hot for my liking.

So if your gauge is rising past normal(eg. half way mark), then the two possible reasons are:
1/. your engine may be excessively hot(most likely situation)
2/. your dash temp gauge may be working as any normal car would(what you're hoping is happening).

Other things to factor in are, do you have aircon? and was the aircon on/off.
is it auto/manual?(ie. what gear used to do the climb?)

As you replaced the rad, and if you have A/C, was the A/C condenser clean(or cleaned). This is usually done with a garden hose only(not high pressure) from behind the condenser flushing out any possible crud between the fins.

If you do get a new temp gauge, also look at an EGT(exhaust temp gauge) too. They're also known as a pyrometer.

Originally Posted by Binca

Thanks for the advice everyone! I really appreciate it. We replaced the radiator yesterday with one from TRS. Bled the cooling system. Took it for a test drive. It did a lot better. Made it a lot further up the hill than previously. But then it suddenly had the same issue. Temp suddenly went up, but as soon as we slowed down and turned around it cooled down again. We are currently only using the original dash temp gauge, but looking into a new one. When we had a feel though a couple of the hoses were very hot for such a short drive, most noticeably the hose going from thermostat to radiator. Perhaps that is normal though? Like I said I am pretty new to all this so I'm not sure what normal should feel like!

I am wondering if perhaps we just didn't bleed the cooling system correctly. Any thoughts there? Husband says he has never bled a cooling system before, but I'm hoping my friend might be able to show us sometime to make sure we aren't doing something stupid!

Bleed the cooling system as I stated in the previous post,but, I forgot to say the heater should be on full, so make sure that is done.
Bleeding the cooling system is about purging any air that gets trapped in the system, air will not dissipate heat and it reduces the amount of water available to do so.
The system of bleeding I have described works well for me and it is the Land Rover workshop way.
If you can get your cooling system checked for combustion gasses at a competent mechanics shop or somewhere like NatRad it will confirm whether you have a blown head gasket or not, Regards Frank.

P.S. Quote: "Bled the cooling system. Took it for a test drive."
Did you bleed as in my post and leave overnight before test driving.

the top hose from the thermostat to the radiator is going to get hot first as this is the outlet from the engine.
Hot water out the top hose of engine, cold in the bottom.

I would validate the gauge reading before spending more money. It's definitely possible your gauge is playing up. You could try a mechanical gauge or as a temporary check a bolt on sensor or handheld infrared gadget just to get a rough idea for a start.

Don't swap the gauge for another one on the same wiring - a fault with the current one could be electrical so you'd see the same problem with another identical dash gauge - that's why a mechanical one would be ideal.

Thanks I will look into a new guage - I'll do some googling when I get home from work tonight.

I'll also look for somewhere local to get the test done for combustion gasses. Then I'll go from there.

Another thing I should look at doing (but not so urgent) is to replace the old black expansion tank with one of those new clear(ish) ones. Probably not relevant right now but it's something I thought of the other day.

Thanks for the help everyone!

Have a look here ENGINE WATCHDOG Audible Engine Overheating Alarm, Gauge & Sensor I have a TM1 in my work ute, and a TM2 in the Disco. Both are good and really easy to fit.

Thanks again for the help everyone, I really appreciate it. My husband might be getting frustrated with landrover but I am enjoying learning a lot, so I'll take the positive out of my non functional vehicle. :P

This weekend's developments: bought a combustion gas test kit. Did combustion gas test. Liquid didn't go green as such but maybe took on the slightest minty tinge. I want to redo the test though in case it was the light. Certainly didn't go green like it should if combustion gas is present though.

Then when we turned on the engine today the expansion tank cap started leaking coolant everywhere. And it was done up pretty tight. So need new cap. Will replace entire expansion tank too because it is one of the old black ones and I have the money so I might as well. So that's this week's plan: new expansion tank and cap!

That is a sure sign of a head gasket issue. You can drive these vehicles without a cap attached until they get hot without that kind of water loss...

Jc