TD5 head - different solution

[Coolvirgo54]

At about 100k and 2006 my 2002 Xtreme( I purchased it new) with 15P engine started seeping coolant between the block and head on exhaust side. I had heard this was common, if not inevitable, and that one possible cause was plastic dowels. After a bit of thought I tensioned the head stretch bolts another 90degrees. This solved the problem. The engine has now done over 300k, and for over 200k has had around 200hp at the flywheel and boost up to 26psi. (With tune, 4x bigger intercooler etc.) Still has original head gasket. It's just possible LR under-specced the original head tension. Those long head bolts would easily take an additional 90 degrees without a problem. The other possibility is the starting head tension was too low before the angular tension procedure started.

[Tins]

That is interesting indeed. Not sure the plastic dowel problem was a thing with 15P engines, thought it was only a certain build window of 10P ( happy to be corrected on this ). Still, good result imo.

[shack]

Yes, interesting for sure.

I have a TD5 in a disco that was overheated, another head, new bolts (genuine) and head gasket etc fitted, always in a hurry and I did NOT use the correct assembly lube, the bolts all started grabbing really badly part way through, but like an idiot I soldiered on.

It now uses the slightest amount of coolant, I can't find where it's going, therefore I know where it's going.

It's done maybe 10k km since I did it.

The last head we replaced was on 7.6L diesel, we used ARP assembly lube, I've never had head bolts go up so smoothly. And they go pretty tight as well.

I have been thinking of lazy ways around the issue with the TD5, from trying to retorque all the current the bolts (bad idea - TTY) to pulling one out, replacing with a new and doing a full retorque procedure on them one at a time, so NM first, then the angle.

I was recently talking to a guy who works on "proper" size machinery in the mining industry, he says they have a chart for the rebuild jobs they do specifying tightening torque based on the assembly lube used, this surprised me at first, but of course when you think about it it makes sense.

Too me it just shows how important the lube is, it's critical.

Even with the run of the mill work we do, the difference in the clamping force between a non lubed thread (grease or neversieze) is quite surprising.

And no, I don't think the lubed bolts rattle loose easier, they need to undo much further before the clamping force reduces and makes them loose.