Seems to be a new version of these miraculous insta-service-decoke devices every decade or so.

Forget what the last one was but the blurb was seriously impressive, allegedly something developed for Canadian armed forces, good press reports from usually reliable magazines and one of the local guys got the kit. The big red beast wasn't running too well at the time a years or so later so I was tempted. Called the man to get an emphatic "Hell, no. We gave that up after it killed two engines. Should have known better."

Stripped of the blurb its just a hi-tech version of the old tip water in the carb trick described by Marshall8hp. I suspect that a modern engine ECU won't let the motor keep running it you induce enough water to be useful by simply feeding some in. So needs to talk to the ECU so as not to drown the engine.

I doubt if a modern vehicle kept in good running order builds up enough carbon to make much difference of itself so even if it does no harm its unlikely to do much good. But if Joe and Joanna Q Public have spent £100 or whatever they will convince themselves.

Browns Gas is amusing. Lots of internet puff from folk who don't understand the thermodynamics or appreciate the difference between temperature and energy. Yes Browns Gas does burn hotter but its a low energy flame so you can't do much real heating with it. Unless you have a small part carefully insulated from it surroundings the heat flows away faster than it comes in. Nice for jewellery tho'

Clive

Looks great.
I have an LED bulb in my standard light which is getting towards OK (ish) but your set up is so much better.

Ordered 2 pairs for mine this morning. Figured I'd get in first before the rush!

Discovered that I didn't use enough Martrim stickum stuffum when I did my headlining as its sagging at t'back over the load space. All off and re-do I guess.

Clive

According to this link https://garagewire.co.uk/news/company/osram/osram-canbus-control-unit-resolves-led-bulb-error-messages/ Osram reckon that CanBus and related systems need to see about 1/4 of the current drawn by the proper bulb to stop warnings being triggered.

Which was about what I did for my reversing light LEDs

No great point in exact calculations but if considering headlamps a 48 W bulb draws 4 amps at 12 volts and a 60 W 5 amps. So a parallel resistor drawing around 1 1/2 amps should do the deed. That will be nearly 20 W of heat to get rid of in the resistor. I'd probably go for an 8.2 Ω metal cased wire wound resistor in either 25 watt or 50 watt size. The 25 watt one is smaller but will get rather hotter as having less surface to get rid of the heat. Looking at the fins on my, still unfitted, LED headlamp bulbs they look about right for getting rid of something around 15 - 20 watts in the hot engine compartment. My bulbs claim to use 30 W of power and to work on both 12 and 24 volt systems so the LED driver will be something a bit more sophisticated than a simple dropping resistor. Presumably producing less waste heat.

Its probably good enough to say that reversing lights, stop - tail and flasher bulbs draw 2 amps so the parallel resistor will need to draw around 0.5 amps. Theoretically 24 Ω, 22 or 27 Ω should do. It will need to dissipate 6 W, a 10 w metal cased wire wound will be up to the job.

Osram do their own range of CanBus warning defeat controllers which look just like ordinary metal clad resistors to me. The specified power dissipation isn't vastly out of line with my estimates but it wants more than a quick glance at the data sheet to sort it all out link to the basic data is here https://www.osram.com/ecat/LED%20CANBUS%20CONTROL%20UNIT-LED%20signal%20and%20interior%20lamps-Truck%20lighting-Automotive/com/en/GPS01_2810559/ . The Retrofit Application Overview download shows whats what in relation to the car itself. One to print out and study if really interested, less than screen study friendly. The Exchange overview is basically a list of bulb types.

Interestingly Osram now claim to have TuV approval for their Nightbreaker LED low beam headlamp bulb. Is this the start of proper official recognition?

Clive

Current needed to trigger the build failure warning system depends on how the system works. As I understand it the way P38 electronic control gubbins is fairly close to the CanBus standards. Although, like everything else, the actual magic smoke control is done rather differently from the modern way.

As I understand it CanBus and related, pre Can Bus, systems have three ways of doing the bulb monitoring.

1) Low level pulses to determine if a bulb is actually fitted during the power-up self test on a modern car before everything comes on line and the car can be started. Fortunately doesn't appear to be done on the P38. Things that do tend to need proper CanBus bypass doobies. Although its still a good idea to wait until the self test lights have gone out before starting up.

2) Low current detection circuits to determine if there is an operational bulb. Generally these need to see the something around the impedance of a cold bulb before the drive transistor can turn on. Easily done. From memory the headlamp drive transistors in the BECM have the necessary monitor ability implemented in the device itself hence 4 terminals rather than the usual 3. Osram suggest that a current of around 1/4 the normal, i.e. hot, draw of an operating bulb will suffice. I suspect this is what the P38 uses. Simple, effective and good enough for its purpose.

Pretty sure thats how I worked out the the parallel resistors for the LEDs I put in my reversing lights about 6 years back. Now up to two young active glow worms per light level rather from the standard one geriatric and seriously undernourished glow worm. Better than nowt I guess.

3) Operating current monitoring. The electronics continuously measures the actual current draw of the bulb or illuminator and flags up anything outside that specified for that particular vehicle. We certainly haven't got that although the transistor drive light controls are quite capable of implementing it. In Europe driven by TuV (German) homologation requirements, with a bit of deliberately malicious input from the French, which essentially demand that a modern car has a Car Configuration File of all specification and approved part fitment details hidden in its electronic brain. Anything not on the internal approved list is verboten for that vehicle. So switching stuff from a different specification version becomes a nightmare.

And you thought BECM issues were bad!

Its all getting rather worrying. My second bike is a Yamaha GTS (the funny front end one) and the fraternity are getting reports of German inspection failures when using a 120-70 front tyre instead of the standard 110-70 despite it being an approved alternative fitment because it doesn't actually appear on the original homologation data supplied by Yamaha. It is said the machines are over 10 years old getting the changes approved requires the whole homologation process to be re-run by Yamaha. Which isn't going to happen. Apparently, in Germany at least, the powers exist to invalidate insurance, ban the use of and possibly confiscate anything that doesn't exactly comply with the on file paperwork.

Regrettably pragmatism is out of favour these days.

Clive

Been at the "OK, sort of" level for the past year or so.

But I'm thinking I may have under estimated the effect of tyre wear, and age as they are over 10 years old. Been getting the odd kick of anti-lock in the damp this year and Mr MoT man agrees with me that the tyres are coming up to their sell by date so this months pension will have to stretch to four new booties.

Currently researching to decide on a good 16" fit for road use. Local tyre man wants to sell me some Yokohama boots in a slightly off beat size and minimalistic tread pattern. Which isn't going to happen however good he thinks they are. Right now I'm tending towards Michelin Latitude Cross or Goodyear Wrangler as the tread patterns look effective without being off-road aggressive.

Amused to see that both Michelin and Goodyear have a C wet grip rating but the Goodyear claims to be specially developed to be good in the wet. O-Kay! Looking at the pictures the tread pattern on Mr Goodyears offering looks to be "bog standard for the last 40 odd years ever since they figured out snipes". Cynical moi asks "So where did all the development effort go.". Which may be good thing given how much a P38 doesn't have connecting the round rubbery bits to the car.

Asymmetric tread patterns always seem to me an invitation to the sort of issues that eventually lead to the death wobble.

Fundamentally modern tyre designs expect to see strut, or even wishbone, front set ups with the wheels moving in vertical arc controlled by relatively short links. Our rigid axles holding the wheels mutually upright put a rather different set of forces on the tyres under bump or roll which a tyre expressly designed to handle the (slightly) opposite and arcuate motion of independent front suspension may not cope with well.

We shall soon see.

Clive

Another vote for starting at the top and working down.

First time I used axle stands under the chassis to support the car whilst playing with the blocks. Made for a slow job, especially as I only have one high lift jack. But easier on the nerves. Got reasons for not trusting jacks! Second time round I used a friends short "between the wheels" hydraulic lift. When the third time comes round I now have similar lift of my own.

I reckon it equally important to have a nicely set out "form" to note down the values on so you can keep track of what you are doing. Write them all down as you go. Then file for future reference. Being Captain Anal or Inspector Meticulous tends to be something of a chore but when it pays off it pays off big.

Not a bad idea to do a dummy run through first and see what Nano says it has then come back for a proper go. If the values for the proper go are significantly different than they were for the run through could be a poor connection or a sensor getting to the end of its life. If either a sensor or connection is unreliable you will get nowhere fast. We have to accept that our cars are getting old and things are as likely to age out as wear out. Objectively 20+ years is a decent run for almost anything really.

Naturally make sure the battery is up to snuff and well charged too.

Clive

When I fitted the Hankook battery the strap profile needed a bit of manipulation so the front bolt would drop straight through the hole and tighten up without hanging on the side.

Maybe 1/4 to 1/2 hole diameter short as was.

Soft alloy jaw covers in the vice and a gentle tweak spread it just fine. Not forgetting to grease the spreading side jaw first so things would side apart easily without ripping the paint off!

Clive

If you don't have soft jaw covers extruded alloy angle 1/8" or so thick works well or split, hammer and bed an off cut of copper pipe. Fibre jaws are expensive and a bit to soft for many automotive jobs. The standard hatched grippy type are for bodge jobs. One day I shall buy a stash of those lethally strong button magnets off E-Bay an machine up a few sets with useful grooves and pockets like what the CNC guys use.

Standard M8 is 1.25 mm pitch.

If its coarser it ought to be 5/16 UNC which is 18 TPI, equivalent to 1.41 mm pitch. If so the nut should be nominal 1/2" A/F.

There is a non-preferred coarser metric 8mm x 1.5 mm pitch floating around. I defy any normal person to tell the difference between that and UNC with components of normal production tolerances. Originally adopted for sensors, banjo unions and similar duties its creeping into a lot of unexpected places. I'd have thought the Rover V8 too old to have that oddity inflicted on it but the Thor rejig was done under BMW ownership and they use some non preferred strangers.

Often wondered how the normal guy in the garage manages without sets of thread gauges, a micrometer or vernier and some sort of reference book. For standard stuff the Zeus book is compact and handy, I have about 5 scattered around but when it comes to potential oddballs like that you need something more comprehensive. My go to is a listing from Andy Pugh that covers pretty much all the common sizes, along with a range of oddities folk dealing with really old stuff may encounter, arranged in size order. Dimensions in both imperial and metric. Mine is 6 A4 pages in Excel spreadsheet format. PM me if you want it. I really need to update it with some of the becoming less oddball things like M8 x 1.5.

Clive

That particular issue, albeit in a more minor way, fell off mine when I bled the brakes after changing the rear flexi hoses.

My normal procedure has aways been to wait until the lights are out before moving off but sometime I get impatient. I want to think that the lights were taking longer to go off during the 6 or 12 months of run up to the burst hose. If so it probably had started loosing pressure a bit faster than it should. Remembering that the last bleed was maybe 6 years previous when I changed all the calipers.

Doesn't help that, even pre COVID, mine might stand for a fortnight or more between outings.

Clive

I've always done mine with the car up on four strong axle stands. Easy to get at calipers and the job can be done in a single sequence.

Modulator bleed screws are a bit tricky to get at. I have a brake line type spanner, 6 point ring minus one side, that is a decent shape for access. Williams brand that I've had for maybe 30 years so current version may be different. No need for great torque so heating and bending the shank to adjust a spanner shape will be OK.

As its a two person job I reckon the most useful accessory is a pair of task list sheet sets with each part of the job listed in sequence and a box to be ticked when each part has been done. One sheet for each participant. Use the classic instruction, read back, execute , check off sequence.

If you've not done the job before and are trying to work off the listing in RAVE its very easy to get mixed up, loose your place, or work at cross purposes. Got my version of the sheets as a pdf on the computer "somewhere" so PM me if you think a copy may help.

Despite the number of steps involved brake bleeding on a P38 is an easy "painting by numbers" job. Unless there is an underlying fault it just works! Unlike certain lesser vehicles where brake bleeding can be equivalent to hoisting a banner invitation of the "Gremlin Party Here Today. Free Entry. Free Beer." variety.

Clive

Worrying comment in this months Car Mechanics magazine concerning LED headlights and the MOT test.

Start Quote

"There have been a few revisions made to the MOT inspection manual in January.Problem was , current MOT testers weren't informed in the usuals way (by notification) of these updates . Since the last update in 2019 there are over 50 revisions to take on board.

Section 4 of the manual is lamps, reflectors and electrical equipment- its fair to say this gets a lot of attention. One of the added checks now required on each MOT is

Compliance with requirements

Existing halogen headlamp units should not be converted to be used with high intensity discharge (HID) or light emitting diode (LED) bulbs. If such a conversion has been done you must fail the headlamp.

The tester did, of course, check on conversions to HID before but the new added text is about fitment of LED bulbs into a halogen housing. As far as I'm aware this revision is for the headlamp bulb itself and won't affect any white LED sidelight bulb fitted to a car. However I'm unsure as to insurance companies views on fitting LED sidelights."

End Quote

More bloody stupid rules for the sake of rules. Beam pattern is what matters not technical details of the source. Typical shutting the stable door after the horse has bolted. Plenty of decent LED units that give the right beam pattern around now. Bad ones were an automatic fail before anyway.

Looks as if I ever get round to fitting the pair of LED headlamp bulbs I got a while back I shall have to invest in a beam setter, or, more likely "Clives cheap field expedient equivalent", so I can do swopsies before the MOT.

Clive

I like the 16" 5 spoke Lightings on mine but there doesn't seem to be an 18" equivalent. Which is getting in the way of my plans to try Vredesteins. I'm unconvinced by Grabbers in any shape or form despite mine being very good when new.

I know there is similar 18" wheel used on the D2 but that has a large flute down the middle of the spokes instead of the small subtle depression the Lightnings have. A bit too new money brash for my tastes.

Comets just seem flat and most of the other styles try too hard at the "look how stylish / cool I am" thing.

Clive

Never noticed that so I had to go and look!

My Bristol 603 is the same. Allegedly Anthony Crook, long time head honcho of Bristol cars, said that the accelerator pedal should be lower than the brake pedal at full depression to ensure that brake and accelerator cannot be pressed simultaneously. Clearly not a desirable under emergency braking when you have a honking great V8 shoving you along. Bristol footwells are quite cramped due to the engine sitting so far back so its quite feasible to imagine folks with larger feet being able to hit both. Same applies I suppose to driving a Range Rover in wellies.

Of course Mr Crook was well known for both holding strong opinions and complete indifference to the feelings of folk having different views. Hafta say there is a certain charm to the superficially illogical scattering of the 603 electrical controls with different shape knobs so you know by feel which one you have grabbed. The P38 centre console windows, door et al switches look neat but I've been known to minor profanity on hitting the wrong one.

Google pulls up several sources of tyre size - rim size data.

This is the one I used https://www.tyresizecalculator.com/charts/tire-width-for-a-wheel-rim-size-chart as its nice simple list. Hafta assume its right.

Clive

7J rims are supposed to be for 205 or 215 tyres, max 225, so the 235 is oversize on those too. Has to be a reason for the specifications.

Oversize puts more curve into the sidewall which will alter the stiffness and damping. Most likely in yaw or sideslip as when you run along the size of a lorry rut.

Given the known issues of a P38 on inadequate tyres, like the "death wobble" I don't fancy experimenting. I wonder if there is any tyre size link with the death wobble? I can see mine trying that sort of trick in a few thousand more miles.

Probably doesn't help that modern tyres are designed for independent front suspension systems.

Clive

The road manners of mine are definitely not what they should be, especially when well loaded, and have been dropping off over the last couple or three thousand miles. Bump steer and tilt steer effects plus general skittishness. ABS cutting in when it shouldn't too.

I figure the 9 year old Gabber HTS tyres are past their sell by date with around 4.5 mm of tread left despite having covered less than 30,000 miles.

Time for new Vredesteins I thought but they don't do the 255/65 R16 size called for in the book. 235/70 R16 they do do but RAVE says 255/65 are the size despite being 8J rims which, officially, should carry 225 or 235 although a maximum of 245 is permitted. 255 should go on 9J.

Presumably there is a reason why the official fitment is oversize.

Do I go for 235/70 R16 Quatrac 5 as per the Vredestien list, find some 18" wheels so I can use 255/55 Pros or settle for something different.

Gonna be a pain binning the unused spare but I don't trust the Grabbers any more.

Clive

Best to get the slip rings really clean whilst you are in there too.

One gotcha issue with brushes is making sure you get the right composition. Hardness varies considerably between apparently same size brushes initially depending on the voltage and current involved. Wrong composition can either wear the slip rings (or commutator if its a motor or old school dynamo) or jam up in carriers. I've seen some where a DIY fix using "some brushes he had lying around" worked fine for a while then jammed up in the carrier. With witness marks to prove it. Then there was the guy who filed down some oversize ones, but not square.

Yet another reason why I tend to steer clear of real economy range replacements.

The only really nasty gotcha with aged alternators is a poor joint between slip rings and coils. The back joint is usually well buried and a total PIA to deal with. Fortunately its not common but something folk forget to check on an iffy alternator as it should be done at operating current. Had to fix one on a BMW flat twin alternator once. Idiot Germans bolted a near standard car alternator onto the end of the crank so the shaft was different. No exchanges, new price sky high and the local rebuilder wouldn't touch it "they don't come apart mate". Really. Hold my beer!

Clive

Its had a cheapy replacement screen job.

Went to a local independent supplier when my original screen had to be changed due to stone damage as the insurance company I was then with worked on the find your on supplier and we will pay basis. Not the best idea in the world as the "We're super good and know everything technicians" struggled and clearly didn't know what they were doing. Came that close to chucking them off the job halfway through but paying for two screens rather than just the excess on insurance was gonna be painful.

Put the impulse down to standard Clive being unreasonable and sucked it up.

But it never seemed dry inside afterwards.

Three years down the line a stone chip straight in front of me killed that one and Direct Line set everything bar the date up with National Windscreens. The technician knew what he was doing, had the proper gear and put the screen in in a quarter the time. Very uncomplimentary about the previous fitting job. But a lot more polite than I was when I saw how badly it had been done. I'm surprised it didn't fall out! So little sealant so badly applied.

Apparently crap screen change jobs aren't that uncommon on a P38. The National technician said screen changes are actually quick and easy if you have the gear and do it by the book. But if you are short on gear and scratch around bodging it takes longer and rarely lasts. Just like every job on P38 I guess.

Clive

If mine is anything to go by you have about 3 years before it dies.

I'm down to 2 maybe 3 segments about half the time but about 1 in 5 starts, if its not that damp chill cold, they all come up and wave "Hi, I'm still here."

Then go away on the next start. Even if it was an "go to .." morning run and next start to come home was midday or early afternoon so its actually warmer.

Not to mention the occasional few minute to half hour appearance mid drive once the car is nice'n toasty inside.

Frustration may be good for the soul but not blood pressure or vocabulary.

Clive

Thanks for the zebra strip link.

Mine has just decided to go from very occasionally not all there to almost nowt. So its got to be done now rather than waiting for summer.

I expect the zebra will turn up same day as the snow!

Clive