grind or replace?

[strangy]

Hi folks, there has been a lot of discussion on TD5 heads here.
A few answers that I cant seem to find in current threads would be appreciated.
The manual states replace the head if out of limits and, it cant be machined due to the hardened surface.
I know some have ground their head and are operating successfully.

Firstly I havnt got mine off yet (tomorrows project between shifts) so do not know if it even requires a surface job. It will be pressure tested regardless. LR told me they have ground one with no idea if it is still going strong and that replacement is the only option also that the service limit was 4mm!! warpage. I have to go back and check the manual but 4mm seems way too much.

Is the hardening like a case hardening with a only a few thou depth or is it more like an induction hardened item with hardeness going deep or right through?

My reasoning is that 4 or 5 thou grind may effect a case hardened item for durability but unlikely to have any detrimental effect on a surface hardened otherwise.

For those who have ground their TD5 head (and banged their own head) have there been any recurrent problems since doing it?

How much did you take off?


Thanks in advance.

[Psimpson7]

I had 6thou taken off mine.

The head place i used was close to a LR main dealer and they seemed quite used to working on 5 cylinder heads. (If you can assume anything from that ;) )

If aything was warped by 4mm (157 thou) I would say it was absoloute scrap.

No issues on mine atall since. Done about 20k km since

IMO you cant refit them without a grind. The headgaskets run a type of wills/fire ring and dig into the soft head face a fraction. I wouldnt refit one without griding, and the most you can grind seems to be about 8 thou.

[davros]

I have heard that cracks around the valve guides are hard to find, even with pressure testing. Dunno if it's true. I got a new head :(

dave

[Blknight.aus]

IMHO like all ally heads they should be hot pressure tested not cold.

if your local tester is only doing a cold test that wont cut it.