The head has been tested, and is apparently ok. Got it back today. But I do still think the head is the problem, seems unlikely to be anything else. Will rebuild when new head gasket arrives...
Did they pressure test the cylinder head with cold or hot water?
 
and in point 14 of your original post, you didn't test it with a hot engine either I suppose. Beginning to think it all will only show up when hot.
This really is a facer.:(:(:(
 
Not hot, as far as i remember (that was a month or more ago!), but I did run the engine for 10 mins while it was pressurised, expecting a rise/drop.... no change at all.

Trying to find a dimensional drawing of the head or gasket so I can get a test plate made up to pressure test myself. If anyone has one, that will save a lot of measuring! Preferably a dxf file!
 
Not hot, as far as i remember (that was a month or more ago!), but I did run the engine for 10 mins while it was pressurised, expecting a rise/drop.... no change at all.

Trying to find a dimensional drawing of the head or gasket so I can get a test plate made up to pressure test myself. If anyone has one, that will save a lot of measuring! Preferably a dxf file!

They only test the cooling side and not the combustion side, but as 60psi is 4 times the running pressure is should be enough, but if it was was done cold then there may lie your problem.
If you think logically about it the combustion is at a much higher pressure and if there was a leak the combustion side is always going to win pressure wise, so it could be some weird crack that only leaks from the high pressure side when it is hot, and as the workshop pressure test is done from the coolant side!

At two hundred quid for a new head, money and time wise it is the sensible answer.
 
Update! Last weekend I was ill, so nothing happened! Well, bought new head, gaskets, bolts etc.
This weekend I fitted the shiny new head. After fitting, bled the system, taking as much care as possible. Pressure tested for leaks - all fine. Took for run, exactly the same, overheats. Stat housing fills with air, stat does not open. Rebled, tested, no change. Rebled, no change.

Some words were said......
I'm working away during the week, so next weekend I'll isolate the heater matrix (15mm copper pipe I guess), see if that has any effect.Also hope to compression test it when hot, see if I get any clue for a cracked block. (Last test, semi warm, all looked fine)

Starting to seriously run out of options.
 
Update! Last weekend I was ill, so nothing happened! Well, bought new head, gaskets, bolts etc.
This weekend I fitted the shiny new head. After fitting, bled the system, taking as much care as possible. Pressure tested for leaks - all fine. Took for run, exactly the same, overheats. Stat housing fills with air, stat does not open. Rebled, tested, no change. Rebled, no change.

Some words were said......
I'm working away during the week, so next weekend I'll isolate the heater matrix (15mm copper pipe I guess), see if that has any effect.Also hope to compression test it when hot, see if I get any clue for a cracked block. (Last test, semi warm, all looked fine)

Starting to seriously run out of options.
How are you bleeding it? even if bled wrong it will get hot/veyr hot once then self bleed, not nice on the engine.
Where is the air coming from?
 
type 1 Bleeding - by filling to rad bleed screw overflows. Fit screw. Then continue filling until stat house bleed screw overflows. Run for a while allowing coolant to flow, as observed through expansion tank. Usually squeeze bottom rad hose a bit to help expell air to exp tank.
type 2 bleed - fill rad through bleed screw until overflows. Fit screw. Fill stat through stat bleed screw to full. Fit screw. Check levels, squeeze rad hose a bit to help shift air around. Run for a bit and watch water flows ok.

"Where is the air coming from?" Well, thats the $64,000 question!
Bleed hoses (y hose assy) all new, spigots on three ends checked, and water flows freely through it when running with exp tank cap off.
I'll keep playing until I sort it, or buy a replacement engine...

Or sell it in disgust!
 
I wonder if it has been overheated quite badly sometime in the past and you somehow have a loose or leaking liner?
 
type 1 Bleeding - by filling to rad bleed screw overflows. Fit screw. Then continue filling until stat house bleed screw overflows. Run for a while allowing coolant to flow, as observed through expansion tank. Usually squeeze bottom rad hose a bit to help expell air to exp tank.
type 2 bleed - fill rad through bleed screw until overflows. Fit screw. Fill stat through stat bleed screw to full. Fit screw. Check levels, squeeze rad hose a bit to help shift air around. Run for a bit and watch water flows ok.

"Where is the air coming from?" Well, thats the $64,000 question!
Bleed hoses (y hose assy) all new, spigots on three ends checked, and water flows freely through it when running with exp tank cap off.
I'll keep playing until I sort it, or buy a replacement engine...

Or sell it in disgust!
Mate I am feeling so sorry for you.
Could it be possible that some hose has delaminated inside?
Really scraping the bottom of the barrel for ideas now as you have done everything I can think of and prolly more. :(
 
I wonder if it has been overheated quite badly sometime in the past and you somehow have a loose or leaking liner?
I've had it 8 years, its never been overheated in that time. But cracked or damaged liner is starting to look like all thats left!
 
Mate I am feeling so sorry for you.
Could it be possible that some hose has delaminated inside?
Really scraping the bottom of the barrel for ideas now as you have done everything I can think of and prolly more. :(
Hoses have been looked at and look fine, inside and out...but they are about the only things that I've not changed! (And matrix)
 
Not hot, as far as i remember (that was a month or more ago!), but I did run the engine for 10 mins while it was pressurised, expecting a rise/drop.... no change at all.

Trying to find a dimensional drawing of the head or gasket so I can get a test plate made up to pressure test myself. If anyone has one, that will save a lot of measuring! Preferably a dxf file!

Get a gasket, scan it, use a trace function, and then, just to be safe, check a couple of dimensions.

I'm doing exactly the same with another 300 gasket currently.
 
Today I :-
1. Isolated heater matrix (15mm copper pipe) - bled etc. No change.

2. Fitted clear (ish) pipe to bleed ejector thingy (y pipe assy to expansion tank from stat and rad) - obective to see if air sneaking back from expansion tank - couldn't conclusively see anything.

3. But as it's the only place in the system where there is air, i fitted a one way valve so water/air can only go from stat to exp tank, not vice versa. Think its what LR had in the ejector assy anyway. Bled, tested, no change.

4. Fitted new hoses to heater matrix (getting desperate now). Bled, tested, no change.

5. Jacked up O/S front while bleeding (get exp tank high). No change.

I can only work on it at weekends, as I work away during the week.
Tomorrow all i can think of to try is perhaps a compression test again when hot - that might show up a cracked block....possibly.

How do you test for a cracked block?

Going to a Steam rally monday, as there should be a selection of Landys on show too, hopefully will ask a few owners for any ideas!

Will probably order any hoses that I've not yet changed, just for a laff...that'll be next weekends jobs
 
This morning i removed air filter, glow plug wiring, went for a drive, got it nice and hot.
Removed glow plugs, disconnected cut off solenoid.
Compression test on all cylinders.
cyl 1 435 psi (406 a few weeks ago)
cyl 2 424 psi (391)
cyl 3 420 psi (413)
cyl 4 431 psi (413)
all pretty good, no great differences.
I'm guessing increase over previous results due either to doing it hot, or as its a new head the valve seats are perfect.
Any, more inconclusive results really. No further forward to finding the problem. Will change bottom, top, and bypass hoses next weekend, possibly test the stat for the 3rd(?) time. Then I have nothing left to try.

Anyone want an 87 plate 90, with brand new galv chassis, new galv bulkhead, 5 new tyres, shocks, springs, all bushes, ball joints, handbrake shoes, rear shoes, diff bearings and seals, xfer box seals, filters, new head, water pump, radiator etc etc... makes me weep.
 
Remove stat and clamp bypass hose?
Mad to sell it for just an engine, though I can understand why.
 
This morning i removed air filter, glow plug wiring, went for a drive, got it nice and hot.
Removed glow plugs, disconnected cut off solenoid.
Compression test on all cylinders.
cyl 1 435 psi (406 a few weeks ago)
cyl 2 424 psi (391)
cyl 3 420 psi (413)
cyl 4 431 psi (413)
all pretty good, no great differences.
I'm guessing increase over previous results due either to doing it hot, or as its a new head the valve seats are perfect.
Any, more inconclusive results really. No further forward to finding the problem. Will change bottom, top, and bypass hoses next weekend, possibly test the stat for the 3rd(?) time. Then I have nothing left to try.

Anyone want an 87 plate 90, with brand new galv chassis, new galv bulkhead, 5 new tyres, shocks, springs, all bushes, ball joints, handbrake shoes, rear shoes, diff bearings and seals, xfer box seals, filters, new head, water pump, radiator etc etc... makes me weep.
TBH I would persist at least for a bit.
Why not simply bung some K-Seal in it and see if it makes a difference?
You say that neither the coolant nor the oil level has changed appreciably. So if there is a leak it is minimal and K-seal will fix it.
Have you really carefully examined both the coolant and the oil to see if either is contaminated with the other?
I know I may well be teaching grandma to suck eggs here.
As you have done so much to it why not simply go for a good secondhand engine or a recondtioned one from Turners or somewhere? Seems a shame to flog the truck as is.
 
One last thought for the mo.
Have you checked your header tank isn't slightly cracked?
This happens a lot on D2 TD5s and also, have you checked the cap on the top of the expansion tank is OK?
Both of these can cause overheating as if pressure drops then the coolant will boil at a lower temp.

Really do hope you get to the bottom of this.
 
One last thought for the mo.
Have you checked your header tank isn't slightly cracked?
This happens a lot on D2 TD5s and also, have you checked the cap on the top of the expansion tank is OK?
Both of these can cause overheating as if pressure drops then the coolant will boil at a lower temp.

Really do hope you get to the bottom of this.
I have pressurised the entire system a few times (15-20 psi) when checking that all is secure. Longest time i left it pressured was about 2 hours. Any probs would/should have shown then. Pressure cap seems to release at about 20psi, although it should be around 15psi.
I never let it get to 100 C, I am very cautious not to damage head (especially as its a new one). About 3/4 mark is 95C ish, if I remember from when checking that the gauge worked correctly. Normal temp is 88c.

I hope i get to the bottom of it too, I'm a logical bloke, with an engineering and problem solving background, it annoys me that I can't fathom out what is going on. Its not logical!

Next weekend I'm gonna take a long look at stat housing. Water appears to pump from there to exp tank (I can see it squirt up into tank), so why does it not purge air from stat house as it should. (Yes, new bleed hoses, plus old one was checked when it came off, and new before it went on)
 

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