TDI300 overheating and air lock woes - any advice?

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Originally Posted by Blknight.aus

IF you're lucky its just shoddy workmanship on putting the headgasket in and all you'll need is a new gasket and bolts. A blind freddy clue to this will be having a go at torquing up the head bolts to about 120nm, if you can tighten a bolt at that low a setting then it wasnt done properly the first time and somethings let go.

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Yes thanks Blknight. I thought of having a go at re-torqueing the headbolts just to see what I would find too. Its a brand new head that previous owner had put on it. I may give your tip a go tomorrow...it goes to a Landy Mech Weds.

For the T Piece bit, there seems to be good flow with the new venturi piece ...I can see quite a flow entering the exp tank when I shine a torch on the other side of tank (and see it stop when the air lock comes into play).

I really do hope it is just a dud gasket. With everything else now replaced and spanking new big core radiator, I hope I can get some confidence back in it.

Hi all. Don't mean to hijack this thread but I have just experienced something similar. 97, 300 tdi seemed to be running beautifully. Driving to town, had just entered the motor way when I noticed the temp gauge was off the scale. Pulled over just as the engine decide it had had enough. Had it towed back to my mechanic. A welsch plug had popped. Coolant totally drained. Head has been taken off and it seems the gasket had failed between pots 2 and 3.
I am really not sure if I am prepared to spend any more on this vehicle! Or should I say I am not sure that the Wife will let me!

The rub is that I had just had a new second hand short motor fitted with my new head from the original motor installed. It was done by a "professional" crowd and it was done less that 8 months ago! Can anyone suggest why this happened and do I just wear the loss as one of those Land Rover idiosyncrasies? Or is it something that was done very wrong? Any thoughts would be greatly appreciated.

Is the welch plug that failed the small ones in the head proper or in the block?
If in the second hand short then you may have some warranty to run with.
If in the head you moved from one block to the next you might be outta luck

ALL 300TDI ENGINES MUST HAVE COOLANT LEVEL ALARMS FITTED

or have deep pockets... two choices peoples




oh and JC may indeed be the "diagnosis king" but he still drinks girly fizzy pink drinks ;)

S

The plug that went was at the rear of the engine on the passenger side.

There is one towards the front and the one that went towards the rear

Perhaps have a look at the documents for the "short engine" you purchased.
If it has a warranty surely that sort of thing would be covered.
Otherwise chalk it down to experience.
Yank the head, have it surfaced, new bolts new gasket and bolt it up
and put a bloody level alarm on!!!!!

S

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Originally Posted by Blknight.aus

...but

remove the purge line valve (Part #9) and the thermostat. replace the purge valve with a simple T piece

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This purge valve has been mentioned before in other contexts. So is it a standard thing to replace it with a T, or is that just for testing? I thought as a purge valve it did have a function, or is that from mainly where its located.

Hi Spel1,
As I can understand the operation from testing and reading here..it seems to work like this: Raw flow from the high point of the thermostat housing (upstream of the stat) flows to exp tank via the Y piece device. This has an internal venturi. So, not only is vapour purged to the exp tank by this raw flow, but the low pressure zone created by the venturi will 'in theory' also suck in to the exp tank vapour that has got into the radiator top. Simple and effective maybe?..but appears to block easily on the raw flow side (as mine was found) thus then becomes useless!

At least a bigger bore 'non venturi' T Piece should keep a healthy flow from the stat housing..but little if any purging of the radiator top.
I have not changed mine to a T piece...as yet.

I also noticed there are no valves in the piece..(atleast not in the new replacement one I installed or the old one that blocked).

Thanks for the explanation, makes sense. Not sure how you could get too much of a bigger bore as the hoses from the thermostat and radiator determine the size, maybe the walls are (or can be made) thinner in brass. Mine still has the purge valve but the plastic is looking shaky. I will look for a brass T in my travels. Maybe they have them at Enzed or even at better parts shops. Simon

stumps pretty much nailed it.

Makes the coke bottle bleed a cinch when its working, pain in the butt when its not.

I've seen one installed such that when it was a little low on coolant it would draw the vapour from the top of the expansion tank air lock the thermostat ( installed with the bleeder hole at the bottom not the top) and then overheat the engine.

Fortunately it was an old cast petrol that didnt mind an overheat, it just kept muncing thermostat and water pump gaskets.

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ALL 300TDI ENGINES MUST HAVE COOLANT LEVEL ALARMS FITTED

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and put a bloody level alarm on!!!!

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X 2
saves a LOT of money