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Brian Vogel
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Username: guyslp

Post Number: 293
Registered: 6-2009
Posted on Friday, 15 March, 2013 - 07:06 am:   Edit PostDelete PostView Post/Check IP

Work is beginning again in earnest with "revival from the dead" of LRK37110, my 1979 U.S. spec Silver Wraith II.

Yesterday was a very good day in the garage in the grand scheme of things. After getting everything back together from the fan disintegration disaster the car fired right up and ran as well or better than it had seemed to before that incident. I still have several things going on that I'd appreciate having guidance of the "what to look at/do first" category.

I will note that the car has multiple holes in various exhaust pipes just in case this could play into any of the issues.

When the car starts the idle is really rough for a few seconds and then it adjusts itself to normal. In the past, and this was how yesterday was different, the car would stall out almost immediately when the choke was deactivated (or at least I think that's what's happening). Yesterday one could hear a slight change in idle speed, but she kept on going. The car is always sitting still in park throughout.

The exhaust is *very* pungently aromatic, but not with a strong gasoline smell like unburned fuel. I'm not burning oil based on the absence of the typical "blue smoke" indicators.

After allowing her to idle for about 20 minutes, enough to get the temperature gauge to jump up from dead cold to the lower end of the white normal band, I revved up the engine to a bit above idle speed to see the former loud squeal that occurred then had gone away. At the moment it has. As soon as you take your foot off the pedal to allow the car to settle back to idle, it always slows to below its former idle speed and stalls out.

I know that any number of factors could be involved, but hope that someone in the cohort may have experienced this constellation of symptoms before and may have insight into what to look at and in what order.

Brian
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Jeff Young
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Username: jeyjey

Post Number: 125
Registered: 10-2010
Posted on Friday, 15 March, 2013 - 07:45 am:   Edit PostDelete PostView Post/Check IP

The first thing I'd do is check the timing.

Next I'd do a rough carb balance check by pulling up the pistons one at a time with the dampers to make sure they both cause the idle to drop.

Mostly because those things are easy than that they're likely to be what's wrong.

I'd also disconnect the intake air temp switch for the weakener and short out the connector (which will turn off the weakener) to see if that changes the behaviour of returning to idle after some throttle.

Let me be clear, though, that I'm no expert here.

Cheers,
Jeff.
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David Gore
Moderator
Username: david_gore

Post Number: 1249
Registered: 4-2003
Posted on Friday, 15 March, 2013 - 08:09 am:   Edit PostDelete PostView Post/Check IP

Brian,

The joys of resuscitating early emission-controlled engines........ unfortunately, I do not have specific experience with the R-R emission control system but the following comments might be relevant.

First point, the squeal you referred to - is this from fan belts that have hardened with age or a slack adjustment setting? Do you have idler pulleys anywhere in the belt drive which could have "dry" bearings? Have had squeal problems over the years in various vehicles from all of these causes.

At first consideration, the problems you describe are symptomatic of problems associated with the fuel and/or emission control system. Given the history of the car, it might be worthwhile to strip the systems down, bench test the components and overhaul/replace as appropriate before going down the "experimenting with adjustments" path.

The rough idle on first start-up could simply be a case of lazy collapsed hydraulic lifters that take a little time to "pump up" and provide the valve openings needed for the engine to run smoothly. It could also be related to reduced fuel flow from the fuel pumps increasing the time for the carburettor chambers to fill with fuel before and after the start-up affecting the fuel/air ratio.

I have never been one to worry about exhaust smell - as we all know, fuel is a blend of organic compounds that the refiner varies during the year to suit prevailing local weather conditions. As a consequence, I would expect the smell to vary over time depending on the fuel composition. In making these comments, I am assuming the car is running on fresh fuel and not old fuel. If it is old fuel, I would not be surprised by unusual exhaust odour.

The shut-down when returning to idle when hot suggests a lag in the supply of fuel/air mixture to the engine. This can be either a carburettor problem, an emission control problem or both. I am presuming you have or will be doing a carburettor/fuel pump overhaul as part of your restoration and I would do this first and test the engine before attacking the emission control system.

Good luck and I look forward to your progress reports - your experience will add to our knowledge and assist others who also have to go down this path in the future.
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Brian Vogel
Prolific User
Username: guyslp

Post Number: 294
Registered: 6-2009
Posted on Friday, 15 March, 2013 - 09:44 am:   Edit PostDelete PostView Post/Check IP

David Gore wrote:
The joys of resuscitating early emission-controlled engines........ unfortunately, I do not have specific experience with the R-R emission control system but the following comments might be relevant.

First point, the squeal you referred to - is this from fan belts that have hardened with age or a slack adjustment setting? Do you have idler pulleys anywhere in the belt drive which could have "dry" bearings? Have had squeal problems over the years in various vehicles from all of these causes.


I shall have to check all these things, but unless it recurs again I suspect that some previous "technician" induced the squeal by not tightening down the fastener that held the original viscous fan clutch on to its pedestal. When I first acquired the car it wasn't doing the squeal, then it kicked in, then we had "the incident with the fan," and now it appears to be gone again. I have to get it to come back again (and I hope I don't) before I can proceed with further diagnosis.

As it so happens, I just had the bearings fail on an idler pulley on my Jag. It made noise at virtually all engine speeds, though.

At first consideration, the problems you describe are symptomatic of problems associated with the fuel and/or emission control system. Given the history of the car, it might be worthwhile to strip the systems down, bench test the components and overhaul/replace as appropriate before going down the "experimenting with adjustments" path.

I may do this, but sometimes some "simple adjustments" and their effects can serve as powerful indicators of where a given problem might lie. That's what I was thinking about and the sort of situation that Mr. Young's post appears to be describing.

I hate tearing things down, particularly when I'm not intimately familiar with them, as a first course of action since this tends to introduce multiple variables, all of which I'm not adept at solving for.

The rough idle on first start-up could simply be a case of lazy collapsed hydraulic lifters that take a little time to "pump up" and provide the valve openings needed for the engine to run smoothly. It could also be related to reduced fuel flow from the fuel pumps increasing the time for the carburettor chambers to fill with fuel before and after the start-up affecting the fuel/air ratio.

Just FYI, this car uses the Pierburg rotary vane fuel pump with a fuel return circuit from the carbs. This is, of course, substantially different from the SU pump setup. Another area, along with the pollution control stuff, that's virgin territory for me.

I have never been one to worry about exhaust smell - as we all know, fuel is a blend of organic compounds that the refiner varies during the year to suit prevailing local weather conditions. As a consequence, I would expect the smell to vary over time depending on the fuel composition. In making these comments, I am assuming the car is running on fresh fuel and not old fuel. If it is old fuel, I would not be surprised by unusual exhaust odour.

The fuel has now aged since last run in October, but it was brand new then. There has also not been any significant change in scent now as compared to when she was first being fired up, though the intensity may be somewhat reduced.

I drained the fuel tank before starting to work on the car in earnest. Various yard equipment ran perfectly well on the fuel that had been in the car and was probably at least five years old.

The shut-down when returning to idle when hot suggests a lag in the supply of fuel/air mixture to the engine. This can be either a carburettor problem, an emission control problem or both. I am presuming you have or will be doing a carburettor/fuel pump overhaul as part of your restoration and I would do this first and test the engine before attacking the emission control system.

I think the fuel pump is fine, actually, but have grave reservations about the carbs. I've bought a copy of SU Carburetters Tuning Tips & Techniques which I guess I really should dig in to and digest. This will be my first time ripping apart the carbs, but the more I've learned about them the less intimidating that prospect has become.

I will, of course, continue posting both questions and findings as the work continues. I try, when I can, to post solutions to my own questions when I find the answers via my own explorations. I've frequently found myself irked when people post questions, followed later by an "everything's OK now" message, but with no explanation of how everything became OK. It reminds me of the cartoon shown on this webpage.

Brian
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Geoff Wootton
Prolific User
Username: dounraey

Post Number: 123
Registered: 5-2012
Posted on Friday, 15 March, 2013 - 02:56 pm:   Edit PostDelete PostView Post/Check IP

Hi Brian

Overhauling the carbs is an easy and enjoyable job. I really like the way the carbs, central plenum and air intake ducts can be lifted from the inlet manifold as one unit. Makes life so easy.

But here's a thing; when I'd relocated the refurbished unit back on the intake manifold, the coupling link that connects the two throttle levers was touching the inlet manifold. If I had tightened the central bolt the inlet manifold would have acted as a throttle stop; clearly something was wrong. The answer was the small nut and bolt securing the coupling rod to the manifold lever had a cam action and needed to be set so that the coupling rod cleared the intake manifold. This was not at all obvious; we're talking clearances of max 1/16". I suspect that the series 2 has a different linkage, but it is worth knowing about such hidden delights. There was nothing in the manual documenting this.

Geoff.
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Brian Vogel
Prolific User
Username: guyslp

Post Number: 296
Registered: 6-2009
Posted on Saturday, 16 March, 2013 - 03:03 am:   Edit PostDelete PostView Post/Check IP

Geoff,

Thanks for the words of encouragement from the voice of experience. I will have to take very careful documentary photos of how things are arranged before I take stuff apart.

One thing that's really frustrating about this car is that while for virtually all of its life it was serviced by a Rolls-Royce dealer or specialty shop well-versed in the marque, it's also clear that "some idiot" worked on it in its later days, too.

Nothing but that could explain cutting the main wire (and a big, fat one, too) that connects the ammeter shunt to the rest of the car, thus killing any number of functions. There was also one weird fuse replacement on the fuel pump fuse (I can't recall now the details, but just finding this) when putting in the actual fuse that should be there works fine. I also now firmly believe, but can never prove, that someone once removed the fan and fan clutch from its pedestal by removing the hex cap screw that holds same on, then never correctly tightened things down when putting it back on.

The car is very largely "unmolested" but the few molestations I've found are very peculiar ones.

This makes it a bit more difficult to know whether what's currently there is correct or not. The same has been true on multiple occasions on my Shadow II as well. That car's even weirder because it is a RHD-to-LHD conversion.

Brian
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Jeff Young
Prolific User
Username: jeyjey

Post Number: 126
Registered: 10-2010
Posted on Saturday, 16 March, 2013 - 03:18 am:   Edit PostDelete PostView Post/Check IP

That ammeter shunt appears to be a favorite of bodgers the world over. A 50-amp blade fuse had been spliced in to replace mine.

Interestingly, the ammeter appeared to still work. Perhaps a blade fuse provides just enough resistance to mimic the shunt?
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Geoff Wootton
Prolific User
Username: dounraey

Post Number: 124
Registered: 5-2012
Posted on Saturday, 16 March, 2013 - 04:04 am:   Edit PostDelete PostView Post/Check IP

I think they are refered to as "vandals" on this forum. On my car the worst find was a bent spare wheel tray which someone had obviously used as a jacking point. Also a cinched wheel cover where they had being pulling at it with a long blade screwdriver. I recently changed all the tires on my car and opted to remove the wheels myself and take them two at a time to the tire retailer. The thought of them using a high powered impact wrench on left hand threaded, brass wheel lug nuts was too much to contemplate. Not to mention jacking points.
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Brian Vogel
Prolific User
Username: guyslp

Post Number: 297
Registered: 6-2009
Posted on Saturday, 16 March, 2013 - 04:25 am:   Edit PostDelete PostView Post/Check IP

Geoff,

I am blessed with a local tire shop that will actually listen to you when you bring an "odd car" to them. They have always hand tightened the lug nuts with a torque wrench, to the correct spec, once being made aware of the significant difference in materials. They also paid attention to my warnings, and the labels, that I've put on the little center cap under the hubcap on each wheel that has left-hand threads.

I have, repeatedly, urged people to go out and buy a roll of the neon green masking tape for "hard to cling to" surfaces and make labels for the wheels that have left-hand threading. It was so seldom used (and really has no good reason for having been used) that no one should be expected to expect it. I even sometimes forget until I try the first lug nut and the light bulb above my head switches on.

Brian
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Mark Herbstreit
Prolific User
Username: mark_herbstreit

Post Number: 101
Registered: 5-2005
Posted on Saturday, 16 March, 2013 - 10:50 pm:   Edit PostDelete PostView Post/Check IP

The best advice I ever got with respect to wheel nuts was that the RR on hubcaps actually means "Remove to the Rear". You can't go wrong. Also a rag threaded through one hubcap vent and out the next avoids damage by levering. Grab each end of the rag and a swift yank gets them off. An added bonus is you "catch" the hubcap before it hits the ground.

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