Nigelbb is a new member here after being rescued from the other side but has a 2001 4.6 Vogue which he's had for some time. It's been 'maintained' by a local to him LR specialist but he was asking about an engine rebuild as it had been pressurising the cooling system. His specialist had dealt with that by adding 3, yes that's right 3, bottles of Steel Seal. Although the car ran fine (other than a knackered cam follower so it sounds a bit tappety) after driving it for a long distance and then letting it idle for 15 minutes while waiting to get on a ferry, it got a bit hotter than it should. He had taken the header tank cap off and lost quite a bit of coolant as that was forced out due to the pressure but after letting it cool a bit and topping it up, it had been fine for his journey home. I had previously asked him to check if it was combustion gases by running the car until hot, then leaving it to cool down and see the state of the hoses then. If they got hard when running but went soft again when the engine had cooled down, that meant the pressure was down to thermal expansion of the coolant, if the hoses remained hard then extra pressure was getting in there from somewhere else, most likely combustion gases. Once cold there was no pressure any longer so simply thermal expansion.

He also had an intermittent fault with the EAS but EASUnlock simply gave him a page full of errors that wouldn't clear. I went to have a look at it and we found the hoses were getting rock hard when the engine was running but my Nanocom wouldn't connect and his EASUnlock wasn't getting good idle. Thinking the OBD port could be corroded dropped the panel to find it wasn't corrosion but the pins were loose in the socket so were being pushed out as soon as you plugged anything in. Having got diagnostics to connect, found a few things that weren't as they should be. To start with, after idling for 20 minutes, it was running at a steady 107 degrees C. Now with a pressurised system that could be considered OK but there's no headroom left in case it gets too hot and the hoses were rock hard too. While it was sitting there idling, the EAS was randomly rising and falling so had a look at that too. The settings were all over the place. It looked like someone had programmed it with a bunch of random numbers, best of all was that the Motorway heights were actually higher than Standard, so rather than drop at speed it had been raising! Then I looked at the drivers side footwell and the stains from leaking coolant could clearly be seen.

Seems like a set of heater core O rings are required.

Then turned our attention to the high running temperature and with the aid of an infra red thermometer worked out that it looked like the radiator could well be clogged. Which, after 3 bottles of Steel Seal isn't really surprising. So it was arranged that Nigel would get a new radiator and an OBD port and drop the car off with me for a couple of days while he was working not far from my house. I ordered a pair of genuine LR heater core O rings and once it was at my house (and Nigel had driven off in the Ascot so he could still get to work), work commenced.

Figured the first job should be the OBD port so one that had been ordered from eBay was duly fitted. It was actually better quality than the original with plastic shields that pushed in to stop the pins from backing out as had happened on the original one. Then I moved to the other side to start on the heater core O rings. The carpet was absolutely sodden

so I put an old cloth over the carpet to try to soak some of it up (and to stop me getting soaked in OAT when leaning on it) and set about removing the panels. It soon became pretty obvious that somebody had been in there before, the holes in the side panels to give access to the ducting screws and the cut ducting poorly sealed with masking tape were the immediate giveaways. The small stalactites of, what seems to be a mixture of OAT and Steel Seal, were interesting.

The joint between heater matrix and pipes clearly showed where the leak was.....

The screw came out easier than I had anticipated and the O rings were removed. One was split but the interesting thing was that they were obviously not genuine, or not even aftermarket, heater core O rings as they seemed to be being dissolved by the OAT and were also thinner than the new ones I had to put in. The black on my fingers is from the O rings themselves.

So whoever had been in there before had obviously fitted some generic O rings that just weren't fit for the job. Cleaned everything up and fitted the new O rings. Before putting it all back together I started the engine to run it and make sure they no longer leaked. As soon as the engine was started, there was a leak. Not a big one but a steady drip, drip, drip. Slackened the screw off to see if giving the pipes a wiggle would reseat them and stop the leak but as soon as the screw was even slightly slackened, I got a jet of coolant sprayed out showing pressure in the cooling system. As I had topped up the coolant as soon as the new O rings were in I knew there was no pressure in the system and it had been running for less than 30 seconds so not even remotely warm but where was the pressure coming from? Switched it off and checked to find a solid top hose and pressure in the system. Figured that the system was so clogged with something, probably the Steel Seal, that the pressure was coming from the water pump trying to circulate it.

Decided to leave the O rings for the time being and move on to fitting the new radiator. That didn't put up too much of a fight but what was surprising was how heavy it was compared to the next one. It must have weighed at least twice as much and not only did it appear to be clogged internally, not a lot of air would have been flowing through it either......

New radiator was fitted and the system refilled with nice new OAT. Made sure there was no air left in the system and started it up. Still had a drip every couple of seconds from the heater but ignored that for the time being and concentrated on the pressurisation and temperature. After 30 minutes of running at idle the temperature was sitting at a steady 99 degrees, still higher than I would like to see, but as soon as the revs were raised it immediately dropped down to 94 degrees, far more acceptable. What was more pleasing was that although the hoses were hard due to thermal expansion, they were nowhere near as previously and after turning the engine off and slackening the header tank cap, there was only a small amount of pressure in there. So the pressure was almost certainly been the water pump trying to force the coolant through a clogged radiator. Went back to the O rings, tried reseating the pipes but still couldn't stop the drip. Dried everything off so I could see exactly were it was leaking from only to find it was coming from a tiny crack in the matrix body just behind the screw. Whoever had been there before had overtightened the screw and cracked the heater casing. Bugger......

Nigel was due to collect the car the following afternoon so next morning I leapt into mine and drove to Rimmer Bros, a one hour each way journey. Well it would be one hour each way if Lincolnshire County Council hadn't decided to dig up at least 20% of the roads I wanted to drive on. Got there, picked up a new heater matrix and headed home. Attempted to fit it and despite having seen various people say it can be done without taking the dash out, it may be that it can be but you do at least have to remove the steering column and, as Nigel was there by then, we decide to bypass it for the time being and have the dash out at a later date.

We got my blocks out and recalibrated the EAS, the settings were miles out, and it sat nice and level and would at least drop at speed now. Nigel reported that on his drive home it behaved perfectly and no longer does a little dance every so often while standing still so that was a success.

I have a theory on the sequence of events that had led up to the specialist's conclusion that it had a leaking liner. The heater matrix, or O rings or both, were leaking so allowing air into the cooling system. That meant there was an airlock in there which would expand far more than coolant so cause pressure in the system when it got hot. That fact that this pressure dissipated when the engine had cooled down again would seem to confirm that. Quite why they thought they had cured the problem with 3 bottles of Steel Seal when, if anything, it had made it worse, I have no idea. The overheat when he was waiting for the ferry would have been a combination of the high running temperature, the almost fully clogged radiator restricting coolant flow and the crud clogging the outside of the radiator meaning that there wasn't a lot of air managing to get through it either. I suspect that the still higher than I would like to see running temperature may be down to the Steel Seal restricting flow elsewhere, possibly the thermostat, so when it comes back for the new heater matrix to be fitted, I'll drain the cooling system completely and reverse flush it which should get rid of any remaining gloop that could be clogging anything else. Should be a fun way of spending a couple of days.....

Well done and a great write up.

Agree, great post and great "this you must know" story for all dedicated P38 owners.
I lived (suffered) for long time with +100 temps, loss of coolant, bla bla before I went thru the entire circuit with new and proven components. A good, in order V8 should not see more than 95-100 in the most demanding condiitons ...

As for trash in the radiator, I do this on all vehicles I own. A little fibreglass fly screen neatly applied.

Grille Mesh

(Great idea David)

Interesting/comprehensive write-up Richard; Three bottles of gloop was clearly/expectedly a mistake..

Of course "Steel Seel" have a 'money back guarantee' up to a 'maximum of three bottles' No mention of compensation for the almost inevitable gloop-blocked rad & heater matrix that might result from that though. An excellent example of the "Law Of Diminishing Returns" too.

Like your theory on air entering the system via the matrix leak too, very plausible as the system cools down

Maeshall, very practical but oh gosh, it is horrible to see :-)
You gave me an idea though, it could be mounted "temporarily" ... will look into it :-)

Tell you the truth, you don't actually see it after a day or two. Make sure if is pulled nice and tight, it fits well. You wouldn't credit how many bugs it catches on a drive. On a trip to my brother's place (600km) you need to get a broom to clean the remains off. Still, they aren't in the radiator or cooler.

Very interesting thread --- I've used my bosses defender --- that's got Steel Seal in it and everything seems ok as far as heater concerned ---- it's not like Radweld ,that stuff definitely seems to block any small capillaries like heater matrix's ----- The vogue of mine had same issue of O ring letting go --- the aquavac hoover worked overtime to suck up the coolant ---- the electrics got soaked too dried out with electrical cleaner and airline ---- took most of day just to do that --- probably worst job on a P38 for anyone not a contortionist

To add further to the background. I have been using the same garage for over four years. They are specialise in 4x4 & always have a collection of Range Rovers parked outside. I have had long chats with the mechanic who specialises in P38s. He was formerly employed by the Land Rover main agent & told me all about the many training courses he was sent on when the P38 was introduced as there were so many advanced features for the car at that time. They are OK for regular servicing & have replaced various components of the EAS over the years but I have lost faith in their competence recently.

The car had a spectacular water loss when the water pump sprung a leak & subsequently had regular overheating problems. The garage put this down to leaking a head gasket or cylinder liners as their test for combustion gas in the coolant was positive. They offered me the option of stripping down the engine to find the problem at an unknown but high cost or using Steel Seal as a last ditch emergency repair. At the time I was getting disheartened about the car & saw it as a potential money pit so opted for the cheap option. To everybody's surprise it fixed the problem & there was no more issues with overheating for over six months. They used three bottles of Steel Seal as that is the correct dosage for an engine of 4L or more. I believe that the overheating was due to a leaking head gasket or cylinder liner & that Steel Seal did fix the problem. When I got the car back after this repair I noticed that the heater operated very poorly. Some warmth did come out but not the roasting hot temperature of which it was previously capable. The garage should have by-passed the heater matrix before pouring in the Steel Seal.

Six months later I had another overheating issue but this time it wasn't so dramatic as it didn't occur until I had driven 10-15 miles & then while the red overheat light came on the needle didn't get up to more than 3/4 of the way to max. This time they put in two more bottles of Steel Seal but they also flushed out the cooling system which I think is what fixed the problem. Unfortunately as @Gilbertd (Richard) has shown the effectiveness of the cooling was still vastly reduced by a radiator that was clogged internally so the coolant flowed poorly & clogged externally so that air flow was reduced too. Now the heater matrix was horribly clogged & so the heater was hardly working at all. The needle was no longer going above normal & the overheat light wasn't illuminating but the overall efficiency of the cooling system was marginal so while driving along with air flowing through the radiator was OK sitting idling for 30 minutes was enough for it to overheat & boil over.

I'm really grateful for Richard's assistance in fixing my problems. It's unfortunate that replacing the heater matrix proved impossible in the time available but I needed to have the car back for my return to France where I now live over half the time. The car has just been re-registered & put on French plates. It didn't miss a beat in the 500 miles 10 hour journey from my house in the UK to my house in France. The heater matrix was bypassed to stop the leak & I had thought that I wouldn't miss the heater in August but found a 7am start would have been more comfortable with a bit of extra warmth.

Just to add to Richard's write up. He handed me one of the O rings which cracked & shattered in my fingers. It was the consistency of dried pasta.It was interesting to actually calibrate the EAS heights after I had read up on all the theory. Clambering under the car with the blocks then reading the Nanocom gives you a much better idea of what you are trying to achieve than just reading the instructions.

I'm looking forward to more repairs next month when I drop off the car with Richard for him to have for as long as it takes to fit the new heater matrix plus he has promised some other fixes like cruise control (to help me avoid speeding tickets) & the glove box strut (to avoidd my wife's complaints of it dropping down & hitting her knees every time she opens it😀).

In theory, Steel Seal, unlike Radweld, KSeal and the other magic potions, shouldn't clog anything as it should remain liquid unless it encounters lots of heat, the sort of heat it is going to find if combustion gases are escaping somewhere, but someone (Chris I think it was) pulled the top off a radiator and found a sort of slime clogging it. Maybe it starts to gel after time or when it has got hot a few times? Nigel asked if there was anything else worth doing while the dash is out so I figured it will be easier to replace the cruise hose (it was split at the Tee when I first saw the car so trimmed the end but blowing down it showed it was leaking somewhere else, almost certainly where it goes through the bulkhead) and it will probably be easier to refit the broken glovebox strut mount with it out. The mount had previously broken and been glued back on but that had let go and it fell out from behind the dash when I dropped the panel to get to the OBD port. While in there I'll also seal the joints in the ducting so everything from the heater actually gets to the interior of the car.

Glad to hear you made it over OK Nigel. I had a feeling you were being optimistic thinking you wouldn't need the heater, maybe you won't in France but at 7am in the UK you would no matter what time of year.

I had great success with sodium silicate (the active thing in steel seal) on my V8 - however I didn't leave it in the system, nor did I mix it with coolant. I flushed the coolant out, filled with water and some of the sodium silicate, ran it for a bit, and then flushed/refilled with coolant.

I clearly didn't do a very good job of flushing it out though, because not long after there was some gelling going on in the header tank, so it got another flush/refill. I haven't had any issues with my heater core though being less effective - and its still got the same one in it now with the diesel engine fitted.

As I understand it Sodium Silicate on it's own (or Steel Seal for that matter) should not clog things up as it only hardens on contact with air.....
but that might have been the problem due to that extra air ingress in Nigel's car ??

Not sure just what else 'Steel Seal' uses in its formula (that makes it so much more expensive...) but it seems to be a thickener of some kind (?). On their website they are certainly very critical of Sodium-Silicate-only formulations !

**_ "Steel Seal is a unique mixture of chemical compounds that have been specially blended to react under sufficient heat and pressure to create a hardened seal in the damaged area of a head gasket or block.

However there are lots of products claiming the same thing.

While there are other products that claim to repair a blown head gasket in a similar way to Steel Seal and these products are predominately comprised of little more than Sodium Silicate and dye.

Unfortunately, while using Sodium Silicate will initially seem to fix the issue, Sodium Silicate is also commonly known as ‘Liquid Glass’ or ‘Water Glass’. The reason for this is that Sodium Silicate once heated and cooled down will harden to a glass like substance. This substance cannot possibly stand up to the heat and pressure within the engine and this ‘seal’ will eventually break and the problem of the blown head gasket will return. "_**

Sounds like whatever else is in it needs flushing out if/when it has "done it's job" ?....

This _partly _answers it but not entirely !
https://mrcheckout.net/wp-content/uploads/2017/08/Steel-Seal-Info.pdf

Well it solved my problem and the engine did thousands of miles without using any more coolant or pressurising causing leaks until we took it out last year - and that was only because it was generally tired, and we did the M57 conversion etc.

So it lasted a couple of years and the engine was, to be fair, given a lot of the loud pedal and was certainly not driven lightly.

But yeah it should only harden under high temperature and exposure to air - as you'd get in the cylinders conveniently. It shouldn't harden anywhere else - but I did as I say find it accumulating a bit of gel like stuff in the header tank prior to another flushing.

Can be a problem though sourcing some of the genuine o-rings, elsewhere in the car I tried yesterday to get DHSE oil cooler o-rings (under the filter) and air con o-rings for the compressor and condenser from my main dealer and I was told all of these are now obsolete.

They are telling you lies, AC O rings are available https://parts.jaguarlandroverclassic.com/parts/index/part/id/L7.L7F.L7F01.L7F01010/brand/land-rover/ although some of the oil cooler ones are shown as NLA.

Any AC service place will have the AC O rings. Try BMW for the oil cooler ones, although buying an O ring kit from your local parts store should give you plenty to choose from.

3 bottles, wow, the rad I took out that had 2 bottles was totally sealed, so 3 it must of been super sealed ,, bit of a bugger the matrix having a crack,,,
Actually gonna start on mine tomorrow, it’s about time, been over a year since I touched it

Many thanks Gilbert, I hadn't realised we were elevated to 'Classic' now. I have ordered a set. I have had to use some generic ones for the time being but exact size matches were not available locally, and as per the theme of the OP, quality is not guaranteed. With the oil cooler I have imperial and metric sets of 0-rings but the oil cooler ones are quite a fine guage and the nearest isn't near enough. The old ones went back in with a couple of wraps of ptfe tape to bulk them out a bit. I might try a BMW source for them, But the nearest one isn't very near, more internet searching I suppose.

For the engine oil cooler I have found the BMW part No. 17228604345 size is 13.4mm x 1.78 (I think that is I.D. by thickness). And I have now ordered 10 from Latvia, supposedly genuine. If any one else wants a couple let me know. (mind you delivery to Ireland post Brexit is dire, it won't do if you are in a hurry!)

I've had a bit of spare time today and have been doing a bit of tidying up outside. The bucket I'd used to drain Nigel's coolant into was still out there and this is what I found

Seems that OAT and Steel Seal form a gel when left. The bucket has just been sitting outside, no hot sunshine even but despite it only supposed to do anything when it gets very hot, it obviously has. That's obviously why his radiator wasn't flowing too well.