KV6 Stat replacement - fuel rail(s) removal

[SD1too]

Originally Posted by Rover600

... given the array of universal joints, extensions and spanners which were required to remove them - I can see it being slightly easier if the rails were not in the way but not by much.

You're right John! As I said earlier, I normally remove the fuel rail first but yesterday on another car I refitted the inlet manifolds and fuel rail as a complete assembly. On the right-hand bank, the fuel rail damper just about prevents the use of any socket and driver. I did eventually manage to apply the specified torque using 1/4 in. drive extensions and a universal joint but it was a precarious arrangement that I wouldn't rush to repeat.
Removing the fuel rail before the manifolds enables the torque setting to be observed upon reassembly which is important for the manifold gaskets' elastomer strip.

Originally Posted by Rover600

V is filled with about a quarter of an inch of coolant although no obvious leak apart from some white "salt" staining around the seam of the stat. However, I'll be swapping the lot now I'm this far in.

The "salt" is antifreeze residue where the spray from the 'O' ring below has been projected upwards and hit the housing at it's widest point, the seam. This was (and still is, sometimes) misdiagnosed as a cracked housing.

I'd urge you to resist the temptation to "swap the lot". It's not necessary and if they are original MGR parts they're best kept rather than risk an imperfect fit from aftermarket replacement parts.

Originally Posted by Rover600

I'll investigate further later but the pipes showed no signs of budging so I think I may have to break them out of the block in pieces.

Place a stubby, wide bladed screwdriver (or equivalent) underneath the curved pipe mounting flange.
Carefully lever upwards whilst simultaneously lifting by hand under the curved pipe. Withdraw the curved pipe.
Next manoeuvre out the thermostat housing and straight pipe as a jointed assembly.

Originally Posted by Rover600

It is begging for some sort of metal pipe or spigot and silicone hose conversion - daft unnecessary design in the first place really.

I beg to differ John! The plastic components actually work satisfactorily. The problem is that no-one was aware of the function of the serrated clips on the straight pipe and so didn't position them properly which causes the coolant leakage. MG Rover does mention them in the service procedure but in a very vague manner which doesn't sufficiently emphasise their importance and that is the problem, not the physical parts themselves!

Simon

[Rover600]

The pipes are out, sort of.
The elbow and stat housing are both cracked off where they enter the block, which looks to be exceptionally badly corroded.
The straight pipe removed complete and the bore for that one looks pretty good. There isn’t much salvageable from that lot I suspect.


I think they have been cracked for some time and this is where they have been leaking looking at the residue and staining.
Now to try and dig out the remnants from the block without damaging the bores of the holes any further.

I don’t think the issue was the plastic clips in this case, which were installed with the ratchet mechanism at the top.
I have no idea what the correct orientation is, or why that would matter, but that is how they were and I believe this is all original.


We might have to agree to disagree on the suitability of the pipes.
They seem to be quite a common issue on these engines.

I’ve almost never seen a simple rubber hose and spring or band clamp on a spigot leak or fail.
Hoses perish and split occasionally yes, but usually not for many decades. Usually the issue is they are sealed so well after 20 years you struggle to get them apart!

The L series used plastic stats, which also suffered a lot of failures, but they were relatively easily accessible.

Perhaps I’m missing something but I can’t see the advantage of this complex, and presumably expensive arrangement over a straightforward and well proven hose and spigot!
It certainly wouldn’t be the first time Rover (or any manufacturer for that matter) made a questionable design choice which has later had to be rectified either by them or a third party.

[SD1too]

Originally Posted by Rover600

I don’t think the issue was the plastic clips in this case, which were installed with the ratchet mechanism at the top.

Hi John,

The position of the ratchet mechanism actually doesn't matter but having it at the top provides easy access for a tool to tighten the jaws.

For information, the way these serrated clips work is as follows. The channels in the straight pipe are wider than the clips. This enables the clips initially to be slid inboard so that the pipe has some horizontal movement to facilitate insertion between the water pump inlet and the 'stat housing.

Once the 'stat housing and straight pipe are fitted to the engine, the clips are slid outwards in their wide grooves so that they make contact with the water pump and 'stat housings. The serrated jaws are then tightened so that the clips grip the straight pipe's channel. This operation tensions the assembly so that there can be no horizontal movement when the engine is running and vibrating. My practical tests have proved that it's this movement that causes the 'O' rings to flatten and the coolant to leak.

You've reported that both the elbow pipe and 'stat housing are cracked where they enter the block. This is typically due to rough handling or inexperience (I damaged my curved pipe the first time I attempted to remove it) so I doubt that they are the original parts.

Originally Posted by Rover600

We might have to agree to disagree on the suitability of the pipes.
They seem to be quite a common issue on these engines.

They are a common issue, yes, but now that I have discovered the reason and publicised it, slowly people are setting the serrated clips correctly and the number of KV6s with coolant leaks into the 'V' is decreasing.

Simon

[Matt_75]

Originally Posted by Rover600

That's interesting, I've got slightly distracted chasing down this coolant leak, but still debating whether to pull the engine and box out or not.
Did he happens to mention what he did with the A/C? That's really the only thing that is putting me off. It is fully gassed and working flawlessly so I'd rather not pull it apart if possible.

That's where his situation differed from yours. When he got the car the AC wasn't working and he replaced the condenser as part of the repairs, so no gas removal was necessary, just a refill after the job was done.

[Rover600]

Thanks Simon,

Now you have explained and I have had a chance to take a good look a the pipes and I can see that the clips are there to prevent lateral movement. They were both fully "outboard" of the pipe if that makes sense.

Originally Posted by SD1too

You've reported that both the elbow pipe and 'stat housing are cracked where they enter the block. This is typically due to rough handling or inexperience (I damaged my curved pipe the first time I attempted to remove it) so I doubt that they are the original parts.

They are a common issue, yes, but now that I have discovered the reason and publicised it, slowly people are setting the serrated clips correctly and the number of KV6s with coolant leaks into the 'V' is decreasing. [IMG]file:///C:/Users/MonkeH/AppData/Local/Temp/msohtmlclip1/01/clip_image001.gif[/IMG]

Simon

I can say with (almost!) certainty that these are the original MGR parts and haven't been removed since it left the factory. There is no evidence any of this has been taken apart or disturbed before.

The bottom of the elbow and the stat house both sheared off in the block at the thinnest part (the land for the O ring).
The remains of the plastic are very crumbly so I suspect this is just age and heat cycling that has caused this particular failure.
It isn't uncommon to see on plastic end caps on radiators which shouldn’t get subjected to the same temperatures, so I can't say I'm too surprised. OAT can be hard on plastics too.

Two of the bores (stat and waterpump housing) have cleaned up fine, the one for the elbow had a lot of bad corrosion and I've managed to clean it up reasonably smooth by hand but still some light pitting is evident.
I don't want to oversize the bore or get into remachining it so hopefully it will be good enough to seal, but only time will tell.

Removing the plastic remnants was a bit tricky as the corrosion had locked them solid.
A technique that others in the same situation might find useful that worked well for me - heat up the end of an old screwdriver and use it to carefully melt through the ring of plastic to release the tension.
It can then be folded in on itself and carefully removed without putting any extra scores or scratches into the aluminium by chiselling away at it.

I still get the impression this was very much an engineering solution in search of a problem.
I can see that damage could be done by incorrectly replacing the parts, but of course the originals wouldn’t have been replaced if they hadn’t failed in the first place, so there is an inherent issue here.
I know a lot of the BMWs suffer similar problems with plastic degradation and having to be regularly replaced.
A traditional stat housing or hose arrangement absolutely wouldn’t have any of these issues, that’s guaranteed.

If I had more time (and inclination) I would be very tempted to investigate a way of modifying it and making some sort of conversion kit.
Nothing easy immediately springs to mind but I’m sure something could be developed to eliminate this issue entirely.

For me that’s it for a bit as I’ve got some other commitments for a couple of weeks, but when I’m back to it I will continue my voyage of discovery and get the cambelt cover off and check out the waterpump as well.

There was a lot of staining down the front of the engine, but I think it’s just from where it has drained out of the V, rather than the pump itself.

One good thing is the more bits I remove, the more access there is – the engine bay is looking roomier already!

[Rover600]

Originally Posted by Matt_75

That's where his situation differed from yours. When he got the car the AC wasn't working and he replaced the condenser as part of the repairs, so no gas removal was necessary, just a refill after the job was done.

That makes sense, I’d be very tempted to do the same – but with the cost and effort of recharging the system I’m not sure it offsets the hassle.

I’ll see how much room I would have to wiggle out the AC pump, but by the time I’ve got everything else stripped down I’m not sure it’s worth it – I might just struggle on with it in situ.


At least with the manifolds off I can get to the plugs easily now!