KiwiTDI
Active Member
Hi, I’ve had the ‘96 300tdi nearly 10 years now and its over heated a few times during that time, shortly after buying it I did a poor belt, expansion tank and hose replacement job and did not properly refill it hence no heater (my fault) and a really bad overheating incident followed, then that was followed by a sticky thermostat and a few more instances of overheating and coolant loss…..and a week ago the (dayco) serpentine belt broke 20 mins from home, the belt only lasted 10 years and 40k km ….poor eh 
I drove back slowly with no power steering and no obvious over heating BUT later noticed a bit of coolant around the expansion tank BUT I did not check the coolant level after fitting the new belt.
20 mins into the next outing it suddenly went from temp ok (but no heater which I just thought odd) to the temp gauge off the scale, it got home without overheating after waiting for it to cool a bit and then a coolant top up, but coolant was now bubbling fast out of the expansion tank filler cap leaving a trail of water on the road, before settling down to normal (but no heater). Once home, when the engine was started from cold with the expansion cap off I could feel the pressure build up in the tank after a few seconds so I started the HG job. I drained the block first.
I can’t see anything obvious wrong with the HG, and heads with valves cost over $1200 in NZ, I don’t like the idea of getting a specialist to “plane” it flat given that compromises the rocker shaft bearing alignment. I have not investigated where I could get the head tested or how much that would cost.
The HG failed before I bought the car at 200k km (a used head was dealer fitted) it’s done 360k now.
I’m thinking of just replacing the gasket and crossing my fingers, maybe try to diy pressure test the head first in case its cracked rather than the HG failed. If it’s warped it might straighten out when torqued up, well some people think so anyway
Lots of pics attached, anybody see anything that would indicate why the HG failed?
I drove back slowly with no power steering and no obvious over heating BUT later noticed a bit of coolant around the expansion tank BUT I did not check the coolant level after fitting the new belt.20 mins into the next outing it suddenly went from temp ok (but no heater which I just thought odd) to the temp gauge off the scale, it got home without overheating after waiting for it to cool a bit and then a coolant top up, but coolant was now bubbling fast out of the expansion tank filler cap leaving a trail of water on the road, before settling down to normal (but no heater). Once home, when the engine was started from cold with the expansion cap off I could feel the pressure build up in the tank after a few seconds so I started the HG job. I drained the block first.
I can’t see anything obvious wrong with the HG, and heads with valves cost over $1200 in NZ, I don’t like the idea of getting a specialist to “plane” it flat given that compromises the rocker shaft bearing alignment. I have not investigated where I could get the head tested or how much that would cost.
The HG failed before I bought the car at 200k km (a used head was dealer fitted) it’s done 360k now.
I’m thinking of just replacing the gasket and crossing my fingers, maybe try to diy pressure test the head first in case its cracked rather than the HG failed. If it’s warped it might straighten out when torqued up, well some people think so anyway
Lots of pics attached, anybody see anything that would indicate why the HG failed?
