Thread: HELP My 300TDI is killing me

Hi dero,

Sorry to hear your woes.

What sort of temperature are you seeing?

How is it being measured? Standard LR gauge, block or head temp, aftermarket coolant gauge?

When you say it's pressurising, is it pumping coolant out the expansion tank?

Has it being over heating from straight away when the moter was rebuilt? Or was it OK for a while?

When the head was removed for subsequent rebuilds/ head replacement was the head gasket OK? It sounds like head gasket, but seems unlikely with all the rebuilds/heads it's had.

Is the heater blocked off?

Tony

Head temp 85 to 90 , coolant steady on 1/2 std gauge , runs fine .
I keep bleeding the air out until I can get it looked at , slowly gets worse with time .
occasionally I have been caught out , going good then , cooked motor .
use of the car has not changed since I got it , work , fun , towing , mostly open road with a little town work .
Never had a problem before , 750,000 km .

Starts off filling the expansion tank , not blowing out unless catastrophe .
At the moment , average is 100 km bleed in the morning , no loss of coolant .
Hoping to drive it to Perth when they open again .

Heater has been bypassed for a long time .

Mechanics suspicions , possible HG failure & once an intermittently faulty thermostat not opening [ one in 10 ]
Seems like head gasket failure , but why ?

85-90 isn't overheating.

Or are you saying it slowly builds up air in the cooling system, and then has a catastrophic overheat?

Does it lose coolant?

It should self blend air from the system through a small hose coming out of the thermostat housing, one out of the top of the radiator, through the "3 way ejector" and into the expansion tank.

I believe the "3 way ejector" is a one way valve, but I i have heard of them being swapped for a brass T piece.

20241231_173353.jpg

Tony

Originally Posted by dero

Heater has been bypassed for a long time .

Bypassed or blocked off?

I believe is necessary to have coolant flowing, so you need a hose from the motor outlet looped back to the inlet, not just blocked off.

I don't know what happens if it's blocked off.

Tony

Originally Posted by dero

Mechanics suspicions , possible HG failure & once an intermittently faulty thermostat not opening [ one in 10 ]
Seems like head gasket failure , but why ?

My young fella's D1, we bought with a blown HG, then he did a heater hose and HG, then another HG.

The machine shop that machined the head suggested injectors, they were leaking badly and terrible spray patterns.

We replaced them and it's been good so far, touch wood.

Tony