Just back from the menders and....

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Against all the odds - logged onto the difflock forum (wash my mouth out :eek:), which hosts the Northern Ireland Land Rover Club forums.
One 2.25 series diesel head on it's way tomorrow.
I'm crossing everything that it's not cracked/warped.
:D
 
The head arrived - joy of joys, no signs of cracking. It's more modern that the one fitted too - all metric studs, and it even has the more recent parallel wired glow plugs. There's a slight dip between the inlet and exhaust valves, whereas mine was completely flat. I would almost say the head may never have been off before - the metal is really fresh and shiny under the gasket.
Now I need to consult the oracle(s): Is the valve gear the same? - should I just use the rockers etc. that came with it? I think so.
And one other question. The series cast iron thermostat housing is still bolted in place. The long bolts into the head look like a prime candidate for shearing. Any tips apart from releasing oil to get them out?
 
a bit of luck it seems then ,push rods etc is all the same just bolt it all up ,give the bolts a good tap with a hammer to shock the threads as well as working back and forth with spanner along with penertrating fluid ,they are prone to shear
 
jamesmartin said:
a bit of luck it seems then ,push rods etc is all the same just bolt it all up ,give the bolts a good tap with a hammer to shock the threads as well as working back and forth with spanner along with penertrating fluid ,they are prone to shear
Click to expand...

how about running a tape down the threaded hole and blowing out with a air gun before fitting the head with new bolts
 
I will rig up something that hammers the bolt heads and turns at the same time - impact wrench with an insert the right length to give a bit of hammering at the same time. If I use a lightish hammer I might get away with it.
I'll find out tomorrow. There's a lot of cleaning to do as well. The head was black with accumulated oil/dirt on the outside, in the way that series heads can be. I couldn't wait earlier and started before getting the "old clothes" on. Mrs not impressed!:director:
 
zeaphod said:
I will rig up something that hammers the bolt heads and turns at the same time - impact wrench with an insert the right length to give a bit of hammering at the same time. If I use a lightish hammer I might get away with it.
I'll find out tomorrow. There's a lot of cleaning to do as well. The head was black with accumulated oil/dirt on the outside, in the way that series heads can be. I couldn't wait earlier and started before getting the "old clothes" on. Mrs not impressed!:director:
Click to expand...

do that and you stand a good chance of either breaking a bolt or striping threads. Nothing better than a good cleaning
 
The thermostat housing bolts all came out like wee lambs! I put about 15mls of releasing oil into the housing, which was then able to get at the threads. I could then see the coating on the threads when they came out. The head has now been given a scrub and looks good. It's been painted black at the factory, whereas the old series head was light blue.
I'm considering fitting new valves as I'm in "the area". Do you think it's worth the bother just to get rid of some wear marks on the existing valves and rockers? I know I'll have to lap the new valves in, which I haven't done before, but it doesn't appear to be difficult.
This would mean using the rockers off the other head though, which are unmarked.
Your opinions and experience welcome as ever.
 
Lapping valves is a fairly trivial operation - not hard at all to do. if the valves are good and don;t have knife edges (overground or overcut) then i'm not sure I'd replace them unless they needed replacing (pitted, warped or bent - look at the contact patch on the valve seat to be sure).

Definitely replace the seals if you've got it apart - if you can get the later type Viton seals as used on the 2.5 engines they're worth having, too.

Definitely worth grinding them in if you're there - not to mention cleaning the valves and the exhaust runners in the head that are no doubt carboned--up. Definitely give the valve guides an inspection while you're there - if the head is in good nick odds are they are too - but if not then a valve job might be in order.

ajr
 
Thanks for the advice guys. The valve heads look very fresh and there's not even much coking, but the valve stem contact points with the rockers and the matching rockers points show quite a bit of wear - about a 1mm dip in the valve top. The rockers and valve tops of the older head are much less worn, so I thought I may have to replace the valves. I'll post a piccy later. It's a bit odd. The new head is in really excellent shape, but somehow the valve/rocker contact points are very worn. The PO said he only ever used it around the yard, but before that - anything is possible.
 
A few pictures - I know you all like the pictures!
The new series head:
newhead.jpg
And the valve tops:
valvetops.jpg
The hot spots had been put in with roller pins:
hotspot.jpg
The valves all came out easily. Both valve flanges and seats look OK. However, I'm not happy with having to grind 1mm off the tops of most of them, so new valves will be ordered today. The valve guides were good as new.
The old valve seals were hardened like bakelite, certainly weren't sealing much!
 
Thor1950 said:
how many miles and what type of oil and weight did you use. what was your running oil psi
Click to expand...

Did you mean to post on this thread?
If so, the answer is "I don't know" As I said, the previous life of the head is a bit of an unknowable thing. Running on low oil/oil pressure would explain it. The old oil on the head was black as soot.
I'll be using the rocker assembly from the existing head, as the rockers from the "new" one are as worn as the valve tops.
 
Last edited:
zeaphod said:
A few pictures - I know you all like the pictures!
The new series head:
View attachment 52929
And the valve tops:
View attachment 52930
The hot spots had been put in with roller pins:
View attachment 52931
The valves all came out easily. Both valve flanges and seats look OK. However, I'm not happy with having to grind 1mm off the tops of most of them, so new valves will be ordered today. The valve guides were good as new.
The old valve seals were hardened like bakelite, certainly weren't sealing much!
Click to expand...

looks like a decent head ,but valve stem mushrooming is one of the reasons for fitting caps ,though it does normally take many years ,hotspots are supposed to be held with roll pins or at least held so they dont turn by roll pin head gasket holds them in
 
Thanks James, a mine of information as ever. I had looked at valve caps, but the depth/severity of wear on the tops made me decide on new valves. I'm looking forward to my first taste of valve grinding when the new valves arrive next week. This more recent head has really shown just how far gone the old one was. It's really just fit for use as a large door stop.... (thinks, might paint it and use it a a large door stop if the missus allows)
 
Quick update. Ordered parts. The SIII and defender parts manual agreed on the part numbers for the valves and collets, so I was confident.
That's was...After lapping in the valves, it appears that the valves and collets are different from the older type - they have smaller collets. This means the valves sit deeper in the valve spring cup, with less spring pressure, and not enough valve top sticking out to make contact with the tappet. These later valves and collets have three grooves where they contact, whereas the older type have one. AAAAARRRRRRRGGGHHHHHHH! :violent:
New valve springs and cups ordered. Lets hope it all fits.
 
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