Heater Core Corrosion problems!

[Landy Lover]

I'm looking for some assistance as to the cause of an ongoing corrosion problem to the heater core in a Discovery Tdi build date 06/1995.

We have owned the vehicle since new and had it service by the same company ever since!

The corrosion first appeared on 31/08/01 at 147,471 klm’s. It appeared to corrode from the inside out around the base of the inlet/outlet pipes, which would leak coolant into the cab area. Because of the materials the core had been made from it was decided to replace the core with a genuine part, replaced the entire coolant (Valvoline) that was said to be of a suitable standard.

At 158,970 klm’s on the 09/05/02 the core again started to leak lasting only 11,499 klm’s. The location of the leak was the same as the previous unit! We initially thought that the coolant was a possible cause, so we replaced the core again with a new genuine unit. Through discussions with other Discovery owners that weren’t having the problem, it was decided to change the coolant to a different brand (Wynn’s)!

This appeared to have fixed the problem than at 183,900 klm’s on the 30/01/03 after traveling 24,930 klm’s, the leak returned. It was decided to renew the core again! The cause of this problem still unknown. We had spoken to the LR service center (Paul Skewes) here in Newcastle but we’re unable to assist.

The vehicle has now traveled 240,846 klm’s, and the leak has returned again! This has become ridiculous, so we are asking for your assistance. There is something in the vehicle that is causing this to return. We are at a complete lose as to the cause!

[pavel]

What is the core made out of - it isn't a copper unit by any chance? The reason I ask is because this sounds like a copper pipe plumbing problem where little pieces of another metal (usually iron from an old hot water tank) get deposited along the inside of a horizonal lengths of copper pipe, Corrosion then is quite fast and results in pin-hole leaks everywhere. Is it possible that there is a similar chemical reaction between two metals in your system?? Just an idea.....

[Landy Lover]

Core is completely made from aluminium!

[Disco]

My first impression would be that the coolant is somewhat caustic and this is causing the leak at the end caps, however, if the problem is not happening to others, I'm guessing that there is perhaps 'electrolysis' occuring. I have heard that corrosion in the heat cores can also occur as a result of the coolant flowing through the core faster than normal. I believe you can get a 'restrictor' to slow the speed of the coolant through the heater core.
Hope this helps.

[pavel]

OK Landy lover, its made out of aluminum, but there still has to be a chemical reason for you going through so may heater cores. Is the cooling system being properly flushed or is something remaining in the system (perhaps some cleaning agent)? If you end up replacing the core again, find out if you can have the inside surface coated with an epoxy like is gone with gas tanks - this should stop corrosion. I keep coming back to the idea of some nasty contamination in your system. One final idea, don't laugh, but hook up a voltmeter to the core and see if there is a charge going through it somehow; if there is, ground the core unit carefully.