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Disco 4.0 V8 overheating issue - help please!


plasticbadger

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Hi all, I’m hoping someone can help with suggestions on a problem we’re having on my wife’s Disco. It’s a late Disco 2 4.0 V8 Thor, auto, with the secondary air system etc. Basically last of the Rover V8s.

It’s done just over 100k and for the last couple of years I’ve been chasing some water leaks here and there, however I’ve always kept it regularly topped up with proper coolant. A couple of weeks ago it seemed to suddenly use a lot of water, plus coughed and spluttered a few times. I topped it up, ran it locally for a few days and all seemed good. Then it overheated on my wife, about 10-15 miles up the motorway for us. I came and picked it up, refilled the coolant, drove it home gently no problems. I stripped all the hoses off it, flushed the cooling system, refitted everything and checked it was water tight. The next day I took it to work, it overheated again, 5 miles onto the motorway. So I delivered it to the local Land Rover specialist and left it!

The garage had it for six days, replaced the radiator, replaced the thermostat, replaced the water pump, replaced all the nasty hose clips with jubilee clips. They say they pressure tested it and sniff tested it, all good, no issues. I picked it up (getting over £500 poorer in the process) and hey presto it overheated about 5 miles onto the motorway.

Now its back at the garage, again they pressure tested it, sniff tested it, ran it locally, ran it on idle for hours, no problems. They replaced the viscous coupling. Then THEY took it on the motorway, a couple miles of going fast (real fast) and it overheated.

So what do you guys reckon? Head gaskets? Block? If so why doesn’t show on a pressure test or sniff test? Why does it only die on the motorway?

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Internal engine temperatures when idling for hours and going down the motorway are completely different, EGTs will be hundreds of degrees different.

My money is on it being as simple as headgaskets, 100K is about right.

Whip them off and change the cam while you are in there.

now come the doom-mongers to say your block is scrap, but honestly, it is unlikely :)

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Have any of the hoses been replaced?

BTW if you're doing head gaskets -  go for rubber rocker cover gaskets and a set of ARP head studs. Exhaust studs + brass nuts are nice too - the ones which are 3/8" UNC into the head but then 3/8" UNF on the nuts.

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I'm getting a lot of suggestions that it's liner related from friends, so I'm at a bit of a loss!

Work done so far is:

radiator replaced, water pump replaced, viscous fan hub replaced, thermostat replaced, top hose assembly replaced, most of the spring clips of hoses changed for jubilee clips, head tank cap replaced.

I've not used the truck since picking it up from the garage, their conclusion being 'engine internal issue' but not what or where without stripping the engine down. My concern is if I pour loads of time and money into doing the head gaskets only to find it's a liner and the problem still exists... 

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Have you got any evidence of liner issues? Or is it just pub-talk?

Liner issues are rare, much rarer than the internet (or the pub) suggests.

If you can do the job yourself, you can change the gaskets in a day if you don't come against any problems.

if it was any other vehicle, with similar symptoms, you would just say 'yes, head gasket(s) has(ve) gone' and swap them.

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2 hours ago, plasticbadger said:

I'm getting a lot of suggestions that it's liner related from friends, so I'm at a bit of a loss!

It's a 4.0, if you have a flat tyre everyone will tell you it's because of a slipped liner :lol: had that with my 4.6's and the Freelanders, when you pick a lump with known issues everyone can't wait to tell you it's f***ed, or that it will explode any minute and kill many innocent kittens. So far they have all turned out to be 100% wrong, so ignore them and be methodical. If memory serves, a slipped liner would steam-clean the bore/piston so you can look for that with a spark plug spanner and a torch.

If you've got doubts, Banda engineering in Portsmouth are your guys, they know their stuff and are embarrassingly cheap for engine work. If you're likely to have to pull the lump anyway, pull it out and give it to them for a coat of looking at. By way of example, they have charged mates in the region of £40 to test TDi heads, charged me all of £40 to remove and helicoil a snapped inlet manifold stud from my 4.6 (without removing the heads!).

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What size tyres are you using?  I met a guy in the US who has one of these on bigger tyres, which means the transmission's torque converter doesn't lock up until high speed.  What I learnt from him is that BMW, as owner of LR at the time, decided that the ZF4HP24 didn't need a fluid cooler and deleted it.  That surprised me and it still seems like lunacy.  So, check you have an oil cooler for the transmission, as the torque converter would be dumping all that heat into the back of the engine.

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I've seen those - a long conventional block with transverse cooling tubes and vertical fins, much like a  2" high radiator, and very different to the Series vehicles and the RRC/Discovery 1 "bog brush".  This chap is sure his US spec D2 doesn't have one because of BMW cost cuts (they may have been knobbling the brand too, given how they didn't plan to hold onto LR for long and didn't bring about any improvements).

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3 hours ago, FridgeFreezer said:

Or maybe, just maybe, they didn't really need them and he's knobbed his truck up by fitting bigger tyres than it was designed for? :ph34r:

That's what he suggested, but a DII on 235/85s shouldn't really be struggling, given that it never tows.  Removing the transmission cooler from an automatic, if they did do that, is pretty damned stupid - these are meant to be hard working and adaptable vehicles used in far harsher conditions that that one is.

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20 hours ago, Snagger said:

That's what he suggested, but a DII on 235/85s shouldn't really be struggling, given that it never tows.  Removing the transmission cooler from an automatic, if they did do that, is pretty damned stupid - these are meant to be hard working and adaptable vehicles used in far harsher conditions that that one is.

One guy's truck overheats and it's evidence that LR knobbed the entire fleet? It's not like they spend so many millions flying trucks around the world to test exactly this sort of thing... :rolleyes:

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On 27/06/2018 at 4:44 PM, FridgeFreezer said:

One guy's truck overheats and it's evidence that LR knobbed the entire fleet? It's not like they spend so many millions flying trucks around the world to test exactly this sort of thing... :rolleyes:

In that case, why did the smaller V8s need oil coolers for the ZF?

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4 minutes ago, Snagger said:

In that case, why did the smaller V8s need oil coolers for the ZF?

That's a different ZF box isn't it? 4HP22 vs 4HP24? Maybe the 24 can lock-up more often / sooner (in conjunction with the bigger lumps) and therefore not heat the oil up as much. You're second guessing millions of pounds of R&D by teams of specialist engineers, and there's two possibilities - they're all wrong, or you're wrong.

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Ah, like our discussion where I thought that LR's decision to use viscous fans must be because they were superior to electric, but you disagreed?  Seems you disagree with anything I say just for the sake of it, John. 

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15 minutes ago, Snagger said:

Ah, like our discussion where I thought that LR's decision to use viscous fans must be because they were superior to electric, but you disagreed?  Seems you disagree with anything I say just for the sake of it, John. 

Are you referring to the discussion where you claimed categorically that an electric fan could not possibly cool an engine that previously had a viscous? :lol:

They use what works for least cost/effort, if the engine is longitudinal it's cheap and easy to design in a viscous. If the thing needs an oil cooler, they fit one, if it doesn't, they don't. My point was one guy's toasted transmission doesn't prove a major car manufacturer wrong.

There's a reason I have temperature-sensitive labels scattered around my trucks - it shows me if something is getting too hot. So far, nothing ever has, yet people on forums with no evidence whatsoever will advocate the cost & complication of fitting oil & transmission coolers to things which do not need them.

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Back to the original posted and query,  do you have oversize tyres for the reasons I asked?  That friend in the US has replaced his cooling system and got nowhere, though he didn't suffer coolant losses as far as I know.  The only non-standard thing about the vehicle mechanically was the tyre size, but they weren't enormous, and I understood it to be similar conditions that give him trouble, with lower speed driving not creating such high temperatures.

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On 22/06/2018 at 3:13 PM, Snagger said:

What size tyres are you using?  I met a guy in the US who has one of these on bigger tyres, which means the transmission's torque converter doesn't lock up until high speed.  What I learnt from him is that BMW, as owner of LR at the time, decided that the ZF4HP24 didn't need a fluid cooler and deleted it.  That surprised me and it still seems like lunacy.  So, check you have an oil cooler for the transmission, as the torque converter would be dumping all that heat into the back of the engine.

My 2001 V8 auto has a autobox cooler as standard. Aswell as a cooler for the ACE system. So 4 coolers in total with the aircon and engine rad. 

To the original question 

Mine over heated while towing and I couldn't understand it. Got recovered home and couldn't find anything wrong with it. So i took it out and it was fine for 15 miles or so. Then it threw the belt off turned out one of the idlers had seized throwing the belt off. So it must have been effecting the viscous fan or water pump turning. Changed all the idlers tensioner and water pump while it was all apart. Not problem since touch wood.

Looking at the state of my aircon rad i think it would benefit from having that taken out. 

 

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Well, I hope the information that I was given about the transmission cooler being deleted was erroneous.  As I said, I found it surprising, but the fellow who told me this was certain and seems to know his car pretty well; he has 2 D1s, 2 D2s, a RRC, a 109 and a D4 as well as a garage we'd all love to have, including a lift that he had the Discovery up on.

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  • 3 weeks later...

Sorry, not been on for a couple of weeks, so thought I'd update.

The truck is mechanically 100% standard, running the factory 18" alloys. It does have a transmission cooler.

After the work done by the garage over two sessions (new rad, flushed coolant system, new thermostat, new viscous coupling, new expansion bottle cap) it was still running on idle fine, but overheating as soon as it was at speed/load. I took it home and it overheated twice in the 25 miles - not ideal. I've had suggests of head gaskets, block porous, slipped liners, etc. Sadly with an impending house move I don't have the time or money to pull it apart and start looking inside, plus Mrs PB was starting to get fed up with driving the non-AC equipped Land Cruiser everyday.

So I ran the Irontite system through it. I thought i'd done a terrible thing, as the D2 cooling system is hard to drain fully between stages and I ended up with loads of sludge in the system, so I left it sat for 2 weeks, then thought sod it, I'll buy a banger, but before I do I'll take it out and kill it to prove a point. I drove it Winchester and back not taking it easy (officer). No issues.

Now, 4 days into daily use again all seems good. I'll properly flush the cooling system in a week and strip it down at some point, but a good temporary fix has been had. Plus I can go to 7S this weekend in the Land Cruiser without worrying about using it when I'm back 😉  

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Excellent!  Could have been silted up and corroded engine passageways, but I have doubts about the new rad being clean inside.  It's definitely a new rad, not a second hand one they painted and charged you new for?

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Unlikely but the fans on the right way isn't it?... 300 tdi and serp v8 fans look the same but spin opposite ways I think. I remember someone with a 50th having issues.

 

why not get some heads and rebuild and then do a straight swap. They aren't dear and I'm sure you would sell them if it comes to the worst.

 

will.

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I recently found a problem with my Td5 where the small line from the left top of the radiator to the reservoir was clogged up and not allowing the air to bleed out the radiator. I unclogged it and it returned to it's old self after a few incidences of overheating.

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