SLROC Forum

A month ago I put 5Lt of coolant into my 300 Tdi as it was (very) low and over-heating. At the time I thought the problem was the washer on the fill-plug which was badly perished, so I replaced it. Used it a few times since but no long runs bar the GRR weekend before last and a few round trips to Stirling.

Tonight its overheating again and again needed almost 5lts of coolant.

Engine is running fine, no over-pressure so the head gasket seems OK. Checked the washer on the rad fill plug, that's fine too. No obvious leaks or drips, pipework not perished.

Any suggestions on how to trace what must be quite a small leak - I'm thinking maybe a pinhole in the rad ??  ...or do I just heave in a bottle or two of rad-weld and see if it cures itself ? 

could be the heater matrix or associated connections, worth a thorough check, Check the floor matting etc for A/F contamination. (if your socks go green that might be a clue)

I hope its not the heater... :-(

Hi Gene,
             I would check for the P gasket leaking. If you look at the passenger side of the engine block towards the front where the allow housing meets the cast iron block, look for dried antifreeze marks on the block. The P gasket seals the main waterway from the block to the allow housing at the front where the water pump sits.
Failing that, I've used a corrosion inhibitor that turns the coolant luminous green( Scania truck additive), this is ideal for making leaks obvious and easy to see especially when pressure testing the system.

Cheers,
           Stevie.

Hi Gene

We've got a cooling system pressure tester at work that you can borrow.  You put an adaptor on the neck of the filler bottle and pump up the system to pressurise it and look for leaks.  I'll look at it and see if there's an adaptor to suit

Duncan

Dont use rad weld ever! Blocks heater matrixes

Vac tester is a good idea

That's great Duncan. I'll bring it round one day next week....up in Wick tonight.

No problem Gene

Is yours the older header tank with a pressure cap, or the disco type header tank with a screwcap

Screw cap type Thanks.

Did this a while back to search for much the same thing:

http://slroc2.co.uk/forum/index.php?topic=9062.msg53683#msg53683

Neat bit of work !  Lets see how I get on with Duncans kit next week !.

5 minutes with the pressure tester gave the answer, after we re-topped up the system with water - pinhole leak in the radiator....

New Rad ordered.

Thanks again Duncan !

Glad you found it Gene.

New Rad ordered Tuesday afternoon, arrived this morning 10 am ( Thursday ), that's pretty good for out here, I was not expecting to see it before Friday at the earliest.  Well done LR Direct.

Fitted it tonight, seems OK, hopefully that's that issue sorted.