coolant leak problem

[verdav]

Can anyone advise please,

Having dreamt for years of owning a Land Rover, I finally managed to put aside enough money and buy one. I did this last month and purchased 1998 300 Tdi discovery LHD in Malaga, ( I live in Madrid ).

The vehicle managed the 380 miles from Malaga without a hitch. The next day we made a family trip to the Gredos and another 200 miles again with no apparent problems.......until we got home and the wife said, ‘ooh what’s all that water under the car.’ At first I thought it was the AC, and left it at that while I returned back to work in the UK. A week later and upon inspection I found the coolant reservoir / expansion tank to be empty. When I filled the reservoir water leaked out, the water leaking (apparently) from the back of the engine (hard against the bulk head) and in the region where the cylinder head joins the engine block. It’s very hard to get a clear view, but the water does not appear to be leaking from the two hoses that travel to the heater matrix and there is visible ‘rusty’ residue on the block, (there’s a small lip) in the region of the cylinder head gasket.

Now here’s the rub.....the engine runs fine. There is no evidence of emulsification, oil in the water. There is no smoke from the exhaust, apart from the odd black puff if you put your foot down, (this is a relatively small amount, which I assume to be normal).

One other tell tale sign.... on the RHS of the engine there is what I assume to be a drain plug and above the plug there is, what I can best describe as a ‘pressed seal’ about 1 inch dia. Here you can also see evidence of water having once leaked from a hairline crack, as there is a rusty residue. However this is now completely dry.

Can anyone please advise? Though I have a mechanical engineering background I have very little automotive experience. I can’t help feeling that the leak is from the cylinder head gasket, but it seems extremely odd that it should be from the water jacket. I don’t want to take the head off unnecessarily; if it is just a leak from the water jacket should I try a product like ‘Kamilex’? Any feedback would be greatly appreciated. Thanks

Edited June 10, 2008 by BogMonster
Naughty word!

[BogMonster]

Welcome

The "pressed seal" is called a core plug and if you have a leaking one then there is a good chance this is the source of your problem. It is basically a metal plug pressed into the engine block or head and is normally in coolant galleries. I don't know off the top of my head whether there is a core plug at the back of the engine or not but there may well be. If they are rotted through on an engine that age it probably means it has not had the correct antifreeze mix put in it at some point so you may be best to replace all of the core plugs, and refill with the correct antifreeze mix which will provide the right anti corrosion protection. It is possible that if the engine has been overheated due to the other leaking core plug at some point, then it might have damaged the head gasket to produce the leak you can see, or in the worst case warped the head, but I would expect other signs of distress in that case.

You might get away with Radweld or something similar but I expect you would only be delaying the inevitable if the core plugs are that bad.

[verdav]

Welcome

The "pressed seal" is called a core plug and if you have a leaking one then there is a good chance this is the source of your problem. It is basically a metal plug pressed into the engine block or head and is normally in coolant galleries. I don't know off the top of my head whether there is a core plug at the back of the engine or not but there may well be. If they are rotted through on an engine that age it probably means it has not had the correct antifreeze mix put in it at some point so you may be best to replace all of the core plugs, and refill with the correct antifreeze mix which will provide the right anti corrosion protection. It is possible that if the engine has been overheated due to the other leaking core plug at some point, then it might have damaged the head gasket to produce the leak you can see, or in the worst case warped the head, but I would expect other signs of distress in that case.

You might get away with Radweld or something similar but I expect you would only be delaying the inevitable if the core plugs are that bad.

Thanks for this reply, with this useful information. Indeed it is looking like a new head gasket and replacement core plugs. Though if there is one at the back, I assume it will be engine out. Once again thanks for your help.

[SteveRK]

picture of 300tdi head below shows a core plug at the back - part no. shown also

[verdav]

Well thanks Steve, as this drawing appears to indicate the problem. The likely failure of the plug explaining the amount of water leaking. Extremely relieved to see it's, (obviously), in the cylinder head......so it's just the head off. Will fly back at this weekend and takle the problem, and will report back next week.

Cheers!

Dave

[BogMonster]

I should change all the other core plugs while you are at it or at least in the very near future as they are probably all in the same state if a previous owner has not had the right antifreeze mix in it. You certainly need to change the one you said had shown signs of previous leaking as it will probably do so again once the cooling system comes up to operating pressure with the engine hot.

[JimAttrill]

The block has 5 core plugs, 3 on the LHS looking from the rear, and one (unfortunately) right at the back. There is another at the back but that is for the camshaft and is not in coolant.

I have known people with Series LRs to make a hole in the bulkhead to change the rear one, I don't suppose that is possible in the Disco.