Hello from Dorking!

Yes, we had someone pop up a few weeks ago who was advised to replace their coolant cap before anything else. He was convinced it was fine and seemed intent in getting into in depth fault finding.  After another couple of people pointed him squarely back at the coolant cap he eventually replaced it and his problem went away.
 Other than checking for obvious leaks the cap should be the first go to every time. they wear out with age. Each time a cap releases coolant under pressure it weakesn the spring a bit more. Replace regularly and carry a spare.
 

Notanumber wrote:

Yes, we had someone pop up a few weeks ago who was advised to replace their coolant cap before anything else. He was convinced it was fine and seemed intent in getting into in depth fault finding.  After another couple of people pointed him squarely back at the coolant cap he eventually replaced it and his problem went away.
 Other than checking for obvious leaks the cap should be the first go to every time. they wear out with age. Each time a cap releases coolant under pressure it weakesn the spring a bit more. Replace regularly and carry a spare.
 

Noted with thanks! Interestingly, my  one and only week of overheating-free driving was directly preceeded by me cleaning up both the caps and making sure they both had full range of movement on the spring..
Just in the process off ordering new caps as recommended: has anyone tried the MGOC spares yellow cap from britpart  or is the general forum consensus to always go for the black Febi one installed as OEM ?

In other news, some more progress and discoveries made:

• Rear bumper, exhaust and heatshield removed, slowly recreating the monster track look from cjj's amazing engine removal write up!
   
  
• I've completely drained the cooling system again - what came out was definitely cleaner than when I did the first flush with Holt's, but surprising amount of crud was still present: both milky-sh fluid layer, but also a lot of solids: rust and sand-like grains which I expect were dissolved calcium deposits
• The car appears to have had quite a bit work done already on the cooling system: the underfloor pipes have been replaced with the stainless steel ones, and rad appears to be the uprated aluminimum one. The newest discovery is that it appears that the previous owner might have already installed a PRT ( the red-ish monstrosity in the 2nd picture) - am I correct in thinking that?
   
  
   
  
• The "PEP103230 - Pipe assembly-engine coolant" on which the engine bleed screew is located appears uprated on my car as it is a stainless steel set up, rather than rubber or black metal I saw in some of the forum pictures. Not sure if it was done as part of the Cheetah supercharger upgrade or perhaps part of previous remedial work to tackle overheating? Has anyone come across this stainless steel type for this type?
   
  
• An interesting discovery re the supercharger package - noticed that the rotrex unit appears to be cooled/lubricated(?) by engine oil (return to sump pictured) which I found strange based on what I read about the Rotrex chargers which normally use their own oil supply with different characteristics. There might be different feeds there for lubrication vs cooling as I can see the car has 2 small coolers attached to the main radiator which I took one to be standard oil cooler and the other to be for the charger - will post more when I continue disassembly
   
  
• ..and finally, the exhaust backbox, finishers and cat in all their glory. Appears to be a stainless steel set up, that someone painted black!? The Cheetah package came with two options of either the "GT SP Performance exhaust system" or "Super Sport exhaust" - based on the limited pictures I could find mine looks similar to the latter, apart from much bulkier finishers. Has anyone come across the system in my picture? If it helps, it is mated to the 4into1 manifold
   
  

A few thoughts. Stick with the accepted pressure cap, I have invested time & money with Land Rovers since I past my test & I’m now well into my seventies. Britpart have earned an interest reputation & my comments are; If it comes in a blue box it didn’t go in any LR of mine. My son isn’t quite as fussy.
That red device could well be a PRT, stick with it if it works. There has been a lot of thought gone into the supercharger conversion & if a PRT was proscribed when the job was done that’s what is required. You already knew that. It might be worth finding out about that particular item, the chances of the MGR PRT being compatible is questionable.
The bleed screw is M6 as standard. I had some development work to do & my long suffering car became the test bed. One aspect was to data log the engine temperature, you can buy a K type sensor with an M6 thread. Fitting one of these with it’s matching box of electronics will let you know the water temperature to within a few degrees & these units are less than a fiver. Bleeding process is standard although you have a display to fit.
M

Can't agree more with AP about the parts sold in a blue box

Airportable wrote:

A few thoughts. Stick with the accepted pressure cap, I have invested time & money with Land Rovers since I past my test & I’m now well into my seventies. Britpart have earned an interest reputation & my comments are; If it comes in a blue box it didn’t go in any LR of mine. My son isn’t quite as fussy.
That red device could well be a PRT, stick with it if it works. There has been a lot of thought gone into the supercharger conversion & if a PRT was proscribed when the job was done that’s what is required. You already knew that. It might be worth finding out about that particular item, the chances of the MGR PRT being compatible is questionable.
The bleed screw is M6 as standard. I had some development work to do & my long suffering car became the test bed. One aspect was to data log the engine temperature, you can buy a K type sensor with an M6 thread. Fitting one of these with it’s matching box of electronics will let you know the water temperature to within a few degrees & these units are less than a fiver. Bleeding process is standard although you have a display to fit.
M

Thanks @Airportable! I got lulled into thinking they were a viable option as they were listed on the MGOC Spares website, but when I saw your post and then checked britparts on trustadvisor..   Febi ones ordered!

I dug a bit more into the cooling set up yesterday, focusing on the rad set up and got completely bamboozled by what I found: 

Oil cooler aside, I seem to have 2 separate radiators, including one with a cap, which I have not seen on any parts diagrams or how to photos.  This half-height rad connects to what I asume might be the "coolant engine heater valve assembly" and on the left side goes back to the engine bay - I will try to trace exactly where it connects to there. Here's where the right side connects to:
 

Has anyone come across a set up like this or can shed some line on the function of this?

I’ve just spent five minutes trying to interpolate the nest of pipes at the bottom LHS of the picture, assuming it was associated with the supernumerary radiator.It’s a sunny lunchtime in a field in sunny Hertfordshire, it was only after I reached out to take a sandwich did I realise that the “pipe work” was indeed gloved fingers.
Henceforth you may have good reason to ignore whatever I write!
Firstly though do you have air con’?
M

Airportable wrote:

I’ve just spent five minutes trying to interpolate the nest of pipes at the bottom LHS of the picture, assuming it was associated with the supernumerary radiator.It’s a sunny lunchtime in a field in sunny Hertfordshire, it was only after I reached out to take a sandwich did I realise that the “pipe work” was indeed gloved fingers.
Henceforth you may have good reason to ignore whatever I write!
Firstly though do you have air con’?
M

Thanks @Airportable and hope you've had a lovely lunch! In the meantime I think I solved the mistery - appears the Turbo Technics kit comes with a basic intercooler setup! I did a full trace of the pipes coming of the smaller rad and realised that they both terminate at the metal "box" type part connecting the turbine outlet with the intake manifold. The strange contraption that the bottom/cold pipe went into appears to be an electric pump (sorry for the blurry picture from earlier - will post some cleaner pictures once I get the engine out and can show the Cheetah kit in all it's glory)

Airportable wrote:

Firstly though do you have air con’?
M

No and aparently not even an option with the Turbo Technics kit due to space, or lack thereof..

There’s much to digest with your cooling stack, especially with a car where not all of the radiator is in the breeze & thus not available to shift excess heat.
The question on air con’ was prompted by the need to shift the supplementary heat created by that & rather than have two fans, a second radiator was fitted.
So, I’m reading between the lines;
At the front is the oil cooler, is that at the top of the radiator assembly?
Behind that you have the intercooler, which had a pump in circuit. This isn’t full hight.
Behind & in the least advantageous place is the radiator & it’s single fan.
One could argue that as it’s only the bottom of the radiator on the f that does the heavy lifting, then all should be fine. However the original design didn’t get enough cooling area exposed to the air flow, was the body kit for the Cheetah better or worse.
Obviously these are rhetorical questions but it might answer why the number plate had found a new home & you’re overheating.
Off for a dog walk now, possibly more thoughts later.
M

Your engine is going to be suffering more thermal stress than that of a normal MGF it might be a good idea to fit the 2nd fan of the A/C  unit anyway either running in parrelal with the existing fan or on it's own temp sensor (cutting in at a higher temp than the normal fan) effectively giving you a  2 stage radiator fan system.
And seeing as you have all that extra hardware stuffed into that small engine bay, choking airflow and generating their own heat, you might even consider fitting extra engine bay fans like I have done on my car. They are from a quad bike and as such they are designed to deal with water and muck getting all over them. they wont really prevent over heating but that's not what I fitted them for, they are to reduce heat build up in the engine bay and thereby reducing thermal stress on hoses, wiring, electrical components, plastics etc.

 

If you do remove the head take careful note to see if they've used a head gasket shim to reduce the compression ratio.  
It's not uncommon for boosted engines to need a reduction in compression ratio to combat pre-ignition.

Sounds like a prime candidate for a fully ducted rad!

http://mgf.ultimatemg.com/group2/aerodynamics/200HPD_aeropack.htm

Whatever car I get will get one sooner or later.   

One problem which we’re unused to experiencing is the contradictions within the hole in the Red Special’s boot lid.
Until this, the hole has been an exit through which some heat escapes, our new friend encourages us to view it as a cold air intake. The dynamic within the engine space is reversed when Cobber’s fan system is considered & will have to have the polarity reversed, to have any effect here.
The void between the boot & the outer wing skin could be opened up & vents created outboard of the rear lights. Some hot air could be directed out via that route.
Just a thought. Right, this creator of hot air is off via another route.
M