3.9/4.0 V8 Transplant Cooling System

[Phill S]

Having successfully done my first engine start on my 3.9 with a lashed up cooling system, attention turns to doing it properly. I think what follows is relevant to both the 3.9 and 4.0 engines - don't know anything about the ones bigger than that.

I went for the NTC6168 radiator for the 2.5TD. It has very similar proportions to the donor Disco 1 the engine was taken from, and has the top and bottom hoses coming out pretty much square. I shan't use the built in oil cooler, doesn't make any sense to me, but will maybe use it to make hot water for the shower system, washing up etc 😉 

I bought Britpart. Don't judge me. I own a 1987 110 - I'm broke.

A number of questions I'd like to address, and of course I'd like to know how you did it. Let's start with the top and bottom hoses. Top hose is easy - same as the Disco 1. Here's the one from the donor vehicle doing its thing:

 

I will of course fit a new one, part no. PCH000050

Slightly trickier on the bottom hose:

 

I used an old Davies Craig electric pump at full power for my initial engine run up so I didn't have to worry about the PAS pump etc. Not the final solution I want, and I'm keen to use standard parts as far as I can, albeit for a non-standard installation. Anyhow, it's a right angle bend that needs to clear the steering box. I believe the water pump and position is the same for the 4.0?

So my first quest is to find the simplest solution for the bottom hose, bearing in mind the need for heater connections etc. As far as I can seeeeeee........

The Disco 2 bottom hoses might give me a solution. Item 11, part no PCH119020, coupled to straight metal pipe instead of the thermostat, will then align with item 12. This is part no PEH101620. Or should it be PEH000080? My Russian isn't good enough to tell the difference. The up and over bit is superfluous, but I understand why it's there. It has connections for the heater return and a long woggly bit to connect to the coolant reservoir. Looks promising? But relatively expensive...

A workable solution? Better ideas?

[Bowie69]

Are you using the pigs heart thermostat or one in the inlet manifold? 

[Phill S]

Ah - should have made that clearer. The thinking was to keep the D1 thermostat in it's right and proper place at the front of the inlet manifold, and use the D2 hoses 11 and 12 in the diagram to get the alignment right for the bottom hose. With the D2 thermostat absent and the height difference between the radiator outlet I'm using and the D2 one, it would need a short length of metal pipe to connect 11 and 12.

I did think about using the D2 thermostat, but if what I'm suggesting would work it looks like it would be simpler? I have a cunning plan on bypass arrangements. More on that if it's thought the bottom hose thing would work...

2 hours ago, Bowie69 said:

pigs heart thermostat

Wasn't that an old Pink Floyd album? 😉 

[Paul C]

I use ESR4223 

[Phill S]

This guy?

I think the radiator for the Defender 3.5/4.0 EFi would be ESR3685:

I decided not to go for that because (from memory) the dimensions of the core were much that same as the 2.5TD one, but it was almost twice the price. If that's the radiator you're using though, the connection for the bottom hose looks to be the same as mine (NTC6168), and assuming it's the same water pump geometry, it looks like bottom hose ESR4223 would fit. Expensive though...

Edited May 27, 2023 by Phill S

[Paul C]

Those are what I have. Though I have been thinking of cutting it to fit the p38 thermostat in the hose, I haven't done it yet though. 

[Phill S]

1 hour ago, Paul C said:

Those are what I have

Great! That looks like the way ahead then. Except, just to be sure, what about the heater return? Here's the heater return pipe I have, centre stage, as I dismantled the engine donor Disco 1:

 

And that connects into the bottom hose like so:

 

So by eyeball the ESR4223 looks about right. Any thoughts on that? Having trouble finding anything on the detail of the heater pipes on the Defender 4.0 EFi

Curious as to why you might want to fit the P38 thermostat in the hose? Is that to do with the bypass circuit? I have a cunning plan on that...

On the subject of thermostats I'm planning to run with the standard Disco 1 configuration at the front of the inlet manifold as mentioned above, but probably the 82⁰C which I'm guesstimating ought to give me a normal conditions running temperature of 88-90⁰ - although I am toying with the idea of an 80⁰ job. Planning to be driving to hot places and with an eye to potential for overheating would be good to have the additional margin. Somebody will know. Or have an opinion....

[Bowie69]

My 82C thermostat makes it run at 76C at anything over 45mph, or with the fans on.

One of the most important things to note about thermostats is that they do not determine your cooling ability one bit, fitting a low stat just means it opens up earlier and lets hot water into the radiator, it does not affect the amount of heat being generated by the V8.

Whether your vehicle overheats is entirely down to radiator and water pump, assuming you also have coolant in it.

Stick with an 88C (or was the pig's heart 92C? I forget), especially as you are using factory computer, otherwise it could throw things off.

[Paul C]

Heater pipes are plumbed the same as the Disco, just two hoses to connect.  Mine gets more complicated as the carb manifold has extra connections to confuse things.  My 3.9 did run a little hot at times which is why I bought the esr3685, I had a 4 row core fitted to a narrowed disco frame and tanks, but wasn't sure if my plumbing was allowing water to bypass the radiator or if the core was too dense to get a good airflow at low speeds. 

[FridgeFreezer]

If you can be bothered to trawl through my Ambulance build thread in the members' vehicles forum I posted pics of all the plumbing there - 4.6 into a 3.5 engine bay with original Defender V8 rad, no oil cooler. Pretty sure I used a standard top & bottom hose too.

 

[FridgeFreezer]

Photo dump of mine...

 

[ThreePointFive]

9 hours ago, FridgeFreezer said:

If you can be bothered

 

If you can be bothered!? That thread is a treasure trove of information and an asset to the forum.

[Phill S]

Wew. At a wedding yesterday - you guys have been busy!

So now:

20 hours ago, Bowie69 said:

My 82C thermostat makes it run at 76C at anything over 45mph, or with the fans on.

 

Isn't that a stuck open thermostat?

 

20 hours ago, Bowie69 said:

One of the most important things to note about thermostats is that they do not determine your cooling ability one bit

Agreed, but the thermostat will regulate the temperature within that ability. Minor digression follows. A number of years ago I bought a recon ex-army 3.5 for a price I couldn't ignore:

 

As I recall, This had a 76⁰ thermostat in it. I take it from that that the vehicle it was intended for (forward control?), was designed to function correctly with that stat, so surely the pump/radiator combo's we're talking about here should function fine with an 82⁰ job? Don't want to go cooler than that as it seems the 14CUX moves into closed-loop mode above 82⁰ and a cooler stat would mean spending more time in the enriched fuel state.

I should perhaps also clarify why I'm interested in running cooler - North Africa and the Western desert are calling. You might question my choice of the RV8, but looked after and not allowed to overheat they'll slog away all day every day. Army wouldn't have entertained them if they didn't. A long winded way of saying I'm after every scrap of margin I can find on the right side of 100⁰

Doing my homework on this before starting this thread I read this little lot:

 

Jagwit (in South Africa) in his Disco 2 found the 83⁰ PEL500110 thermostat and...

On 9/13/2011 at 10:26 AM, jagwit said:

Thought I should report back that I fitted the PEL500110 and it works a treat. Engine temp now sits at just under 90degC on my VDO gauge whereas before it was sitting just above 100degC.

 

90⁰ translates into just over half of the stat extension range which stacks up very nicely.

As before I'm sticking with the Disco 1 configuration stat at the front of the inlet manifold but the running temperatures he's coming back with sounds good to me. Happy for people to throw rocks though - I want to get it "right"

 

21 hours ago, Paul C said:

Heater pipes are plumbed the same as the Disco

Great! I'll order up the ESR4223. Thanks for that. More questions on the heater circuit later...

 

10 hours ago, FridgeFreezer said:

Photo dump of mine

Brilliant - there's lots of what I'm looking for there. I had run away with the idea that the later series engines were very different and hadn't taken the trouble to look very far in that direction....

 

19 hours ago, FridgeFreezer said:

If you can be bothered

I can be bothered - that's my job for this evening

[Bowie69]

4 hours ago, Phill S said:

Isn't that a stuck open thermostat?

No, it works fine, as did the previous 82C stats, genuine. 

A thermostat defines the running temp of the engine, to a point, if your cooling system is too small then you are going to over heat anyway. 

[FridgeFreezer]

On the stat thing - I've found with the 4.6's they heat up faster than the older system design allows for, I was seeing spikes in temperature from cold, as the coolant would be warming up faster than the stat could open so the temp gauge would ping up to the hot zone and then drop again, and then be fine for the rest of the journey.

Solution is to drill a small bypass/bleed hole in the top of the stat (or remove the jiggle pin and enlarge the hole slightly), that's smoothed the response out greatly and it now runs a little cooler than it should for the given stat.

You're right that 14CUX will likely misbehave if you mess with the stat although I don't know the exact point at which it goes closed-loop... that said, I wonder if the lambda sensors will enjoy poor quality fuel? I'm not going to say "just megasquirt it" but I would give it a thought as at least you can control what it does when (and see what it's doing), plus you can re-tune to ignore almost any sensor or other failure in the field.

[Phill S]

6 hours ago, FridgeFreezer said:

On the stat thing - I've found with the 4.6's they heat up faster than the older system design allows for, I was seeing spikes in temperature from cold, as the coolant would be warming up faster than the stat could open so the temp gauge would ping up to the hot zone and then drop again, and then be fine for the rest of the journey

Ok - going through your suggested Shed thread shortly. I understand the dynamic response but I'll be interested to see what plumbing changes you made that causes it...

 

6 hours ago, FridgeFreezer said:

I wonder if the lambda sensors will enjoy poor quality fuel?

Dunno - guess I'll find out.

 

6 hours ago, FridgeFreezer said:

I'm not going to say "just megasquirt it" but I would give it a thought as at least you can control what it does when (and see what it's doing), plus you can re-tune to ignore almost any sensor or other failure in the field.

I'm sort of wanting to look at one thing at a time. I've done some reading on Megasquirt, but I want to understand and work with the standard 14CUX before launching off into something else...

[AlWorms]

The 14CUX closed loop settings vary by software AND MAP settings.

I run the latest 3652 "Op Pride" software, but have transferred the Saudi climate coolant-temp/fueling adjustment map in, so I'm running in fully warmed up mode from 81C (and have an 82C 'stat, that runs at 82C on Rovergauge), the UK CAT map doesn't actually totally stop enrichment until 86C. That's the Map4 settings, in the MAP5 part of the EEPROM, but with the MAP5 AFR tables.

Having said that, the fuelling enrichment tapers off very fast after a cold start, and it doesn't actually run in open loop prior to that - closed loop starts much earlier, but the fuelling is still adjusted in the software up until the points mentioned above.

I have lambdas, but the cats are long gone.

There is a piston heads thread about fiddling the 14CUX. It's a bit of fun, not worth megasquirting my Disco, when the whole truck cost less than megasquirting it 😄

 

I've managed to change over to Bosch injectors, remap it to suit (mostly) AND reduce fuel usage by about 20% when driving sensibly.
 

[smallfry]

Jiggle pin and/or hole through the thermostat is a must in any case, also allows proper system filling. Fit hole at the top.

The Efi system did not have sufficient bypass flow for the thermostat to react quickly from cold start, but once opened works absolutely fine. The old carb manifold was better in this respect, which is why I believe they went to the later "Thor" setup.

As said, it will be your engine condition, radiator, fans, and water pump, which will be the factors in overheating problems, and not the thermostat (unless it has failed)

The Turbo D radiator you have is more than you will ever need. However, I do question the wisdom of buying a cheap one, as although not at all glamourous, its a critical component. Even more so given your intended destinations.

[Phill S]

8 hours ago, smallfry said:

The Efi system did not have sufficient bypass flow for the thermostat to react quickly from cold start, but once opened works absolutely fine. The old carb manifold was better in this respect, which is why I believe they went to the later "Thor" setup.

 

Ok - thanks for that summary. I'll be wanting to return to the bypass thing later

 

7 hours ago, smallfry said:

I do question the wisdom of buying a cheap one

 

So do I. As a variation on: 

On 7/10/2015 at 10:39 AM, FridgeFreezer said:

the whole ethos with the ambulance is not to get carried away trying to build it perfect 1st time but to get it up together & usable and then go out & use it to see how it goes, then make changes / improvements as we go.

 

And some discussion in this thread:

 

 

Picking out just one of the less negative responses from that:

  

On 7/19/2022 at 2:17 PM, DavidW said:

I've been running the Britpart plastic ended 19J type rad with built in oil cooler with my 3.9 v8 for a few years and it hasn't failed yet.

 

So when one turned up on ebay as having been returned to the seller - Maltings - box opened so reduced to £200, I decided to just do it. The plan is to run it around this summer, trip to southern Italy in September, and then take stock of how the complete 3.9 installation has stood up and how much irritating squeaking has been coming from the passenger seat. With plans to venture further afield next year, and also to hot places, I need to make the vehicle look less like an army truck - we'll be running close to the Syrian border in south-east Turkey if it all pans out. So this winter will see the body stripped back for painting, the front bodywork will all be coming off (again) and amongst other things, let's decide the final fit for the radiator. The current one can go back on ebay

[Phill S]

17 hours ago, AlWorms said:

The 14CUX closed loop settings vary by software AND MAP settings - etc etc

Whoa fella - I need full and unfettered access to your brain. Well, maybe not all of it.

I try to group my questions by topic because you seem to get more input from folks that way, and it's then easier for anyone in the future to find information. This forum is a massive repository of information and experience and it's a wonderful thing that people provide support and advice in the way they do.

I have been planning to start a thread on the 14CUX to try to group as much info as possible in one place. I want to "finish" this one first and there's a bit of a way to go yet and also complete the EUC searching already started, but as a control systems guy I want to understand the 14CUX as far as I can. I reckon that's about a week away so don't go anywhere! Unless somebody else wants to start that first of course. And maybe it's been done already - searches not finished yet - don't beat me up.

 So we've given thermostats, radiators and hoses a good old going over and now I'd like to pick your collective brains on the heater/bypass circuit if I could. In the Disco 1 donor I bought, the heater circuit appears to act as the bypass mechanism, meaning the heater core is getting hot coolant all the time. Frankly, I don't want it working that way. Here's the Disco pipework disappearing into the heater:

 

I managed to turn up switch valve BTR4022 which just dumps the coolant back to the pump inlet:

Pic courtesy of Britcar. https://britcar.com/product.php/83105/0/coolant_by_passive_heater_valve___v8___range_rover_classic_from_vin_ma647645_to_1994___discovery_1_1989_1998

Says it's applicable to the Disco 1, and you can see it would (probably) line up perfectly, but mine didn't have that. Not sure how it's actuated - obviously pneumatic and I don't know that I'd want that anyway. Or would I? Anybody have any suggestions for an electrically operated one? Must have been done before....

[FridgeFreezer]

1 hour ago, Phill S said:

I managed to turn up switch valve BTR4022 which just dumps the coolant back to the pump inlet:

Pic courtesy of Britcar. https://britcar.com/product.php/83105/0/coolant_by_passive_heater_valve___v8___range_rover_classic_from_vin_ma647645_to_1994___discovery_1_1989_1998

Says it's applicable to the Disco 1, and you can see it would (probably) line up perfectly, but mine didn't have that. Not sure how it's actuated - obviously pneumatic and I don't know that I'd want that anyway. Or would I? Anybody have any suggestions for an electrically operated one? Must have been done before....

@TSD has done a lot of fiddling with bypass valves and the popular wisdom seems to be they like to fail or leak - I've no idea if he found a trustworthy one in the end.

Personally I'm not a fan of plastic bits in my cooling system (EG plastic header tanks, plastic rad tanks, plastic hose bits) as when they fail they're totally un-repairable whereas a metal thing can usually be bodged up in the field. Copper stuff especially can be done with basic plumbing bits - blowlamp & solder.

[TSD]

There's a fair few solenoid operated H valves if you look around. Quality was dreadful on every aftermarket unit I looked at (I bought a few to try out for the Ibex). Ford ones seem to be comically unreliable even as gen parts, so I avoided them.

In the end I settled on a valve from a VW Phaeton, from some online breaker for £20. Design wise, it's not much different to the typical Ford Fiesta valve, but the quality of the materials seems good.

ebay says the part number was 3D0820035, but there are lots of similar units for other cars with different port positions. It think the ports were slightly larger than Defender heater, but close enough to work.

It looks very similar to this one I just found.

As built/used, it's a 3 port valve, but you can take the cap off the 4th port and use it, that's how mine is set up. Downside is that it's really only on/off, not variable.

[Phill S]

11 hours ago, FridgeFreezer said:

Personally I'm not a fan of plastic bits in my cooling system (EG plastic header tanks, plastic rad tanks, plastic hose bits) as when they fail they're totally un-repairable whereas a metal thing can usually be bodged up in the field. Copper stuff especially can be done with basic plumbing bits - blowlamp & solder.

Yup - not going to fight you on any of that, and thanks for the lead...

 

9 hours ago, TSD said:

There's a fair few solenoid operated H valves if you look around

Sure - the interest really was on whether any sort of favourite might have emerged. Will certainly look in the German direction as a starting point, there certainly seem to be a fair few of the used 3D0820035 model on ebay as a first look.

Interesting point though, were the original Land Rover ones a snap on/off job or a graduated thing using the vacuum system? I know there was all sorts of clever dickery going on with airflow mixing inside the massive Disco/RR heater unit

 

[AlWorms]

On 5/30/2023 at 4:40 AM, Phill S said:

Whoa fella - I need full and unfettered access to your brain. Well, maybe not all of it.

Deffo don't go into ALL of it. We're all pretty relaxed in here though. I'll watch for your thread. 14CUX is fun.

[Phill S]

9 hours ago, AlWorms said:

14CUX is fun

Yeah - you're not a weirdo or anything 😉   But great! Sadly I need to be away next week and it's also the time of year where the sun is shining. Living in the far west of Cornwall friends and family start asking if they might be able to stop by to say hello. For a couple of weeks. That's going to put a bit of a dent in the proceedings, but I'll get there with the 14CUX eventually.

Edited May 31, 2023 by Phill S