Choking engine Silver Shadow

Pinewood

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Dear all.

I hope you can assist with a non Mercedes problem.

I have recently bought a beautiful 1974 Silver Shadow 1. It had not run for almost two years, although it was stored in a good dry garage. I had an MOT and it passed without a problem. Last week I drove it home (about 50 miles). On the way it started to choke a little and stalled easily at traffic lights. It seemed to struggle and would not gain power. I gave it to a great mechanic who said it was not running on all cylinders, he put in new points and set the timing, he got all cylinders running. I then took it for another run of about 150 miles. After about 130 miles, it started to choke again and lost power, I managed to get home.

On Saturday morning my mechanic looked over it again and spent 3 hours cleaning the carburettors and set it up perfectly (apparently the needles were stuck as the fuel had turned to jelly). He said it sounded great and his electronic machinery found no faults ( he said "take it home and see how it goes").

Saturday teatime I drove home (50 miles), on the way through town it cut out at traffic lights and, then started to choke and struggle as I drove along country lanes. It had more power than before (last week), but still struggled to drive.

Once home I looked inside the bonnet-hood, I noticed that some pipes appeared frozen (white ice on the outside). I turned the air conditioning on and the ice defrosted in seconds. Can anyone help and give me advice, on what it may be or how I can fix it? My mechanic will not be available until next Friday evening.

Kindest
Pinewood
 

brandwooddixon

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CL500 Bluefficency 2012
What state are the plugs in when it starts to fail?

Check that the choke isn't still on. I don't know whether it is manual or automatic but worth checking.

The anti-stall valve in the carburettor could be sticking. Does the car still stall if it's placed into nuetral when you stop?

Worth checking the the fuel filters in case there has been fuel tank corrosion.

Another point, aren't RR's from this period designed to run on 5 star leaded? If so what fuel are you using?
 

television

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Interesting that I was the deputy technical secretary of the RROC for a time back in 1980.

I would go to halfords and get a set of 4 high voltage testers from Halfords, and I think you will find that most of the troubles are distributor/rotor arm problems.

The ignition coils can fail as they warm up,if the car start well from cold, and the problems start later then check the output from the coils,, the plug testers will also confirm this
 

Number_Cruncher

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1995 W124 E300D TE
How do these cars deal with warm air / cold air intake? Is there a thermostatic valve? A bi-metal strip? A termAC valve and vacuum actuator?

It sounds to me like the carburettors are icing.
 

wireman

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nice 201 2.5D 1993 & very nice 129 SL500 1994
You may have a choke problem.

Unlike any other SU carburettor equiped engine I have ever dealt with the choke on your shad is a butterfly inside the air inlet assembly bolted onto the air side of both carbs, there is a latching lever arrangement on the side of this unit which is supposed to set the choke onto the correct position for starting. Normal SU's use their sliding jet to provide cold start enrichment, this feature is not used on the roller engine.
The position in which the lever sets is determined by a mechanical temperature sensor which if cold allows a lot of choke and less if its not so cold.
The choke is engaged by pressing the throttle pedal once before the car is started.
Don't use the throttle whilst starting the engine this can make the choke disengage prematurely.

I belive that the levers and links on your engine may be sticky or come adrift allowing the butterfly to flop closed whilst the engine is running.

If the fat air hose from the air filter is removed you can see the butterfly, and if the engine is cold enough when the throttle is pressed you should see it move towards closed and latch in this position when the throttle is released, examine the linkages and look for loose or detached parts in the bits that connect to the choke actuation system.
You are looking for the bit that lifts the choke levers as the throttle is pressed, its a long time since I dealt with one but I seem to remember the temperature capsule or the rod that comes out of it can get stuck, or the cam and lever on the throttle spindle becomes missaligned and make the choke engage when it should not. All the choke stuff is on top of the carbs and easy to access.

Do beware of running the engine whilst over choked, this will wash the oil off the bores and kill your engine a bit, a lot if you insist on doing it.

PS if you ever change your spark plugs it is much easier to access them from the other side of the car (ie do the LH bank from the RH side), just lie on top of the engine and work down into the slim gap between engine and wing, mind your knee does not dent the ali wings. Mine used to miss at random untill I installed NGK plugs.

I never had any petrol problems my 1976 car had valve gear suited to unleaded petrol.

Are the frosted pipes around the front/LH side? if so they may just be aircon and of no concern, follow them and if they go to the bulk head or the large round pump on the engines top they are A/C.

Does your car have points or electronic ignition? the earlier type of electronic module inside the distributor was a known weak point, its power transistor blows up. I believe (but ain't certain) that electronic came with the 6.75L engine, the 6.25L had points.

Since you are a new owner beware of the left hand wheel nuts, they are left hand thread and being bronze can be damaged by excessive torque whilst over tightening them in an attempt to remove them. There is an arrow stamped into the nuts flats to show the direction.

In the Pre VW/BMW days RR service was not expensive, might I respectfully suggest that you see what they offer today. There is a thriving DIY bit among the RR enthusiasts register.

Do enjoy the car.
 
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djb

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Dear all.

I hope you can assist with a non Mercedes problem.

I have recently bought a beautiful 1974 Silver Shadow 1. It had not run for almost two years, although it was stored in a good dry garage. I had an MOT and it passed without a problem. Last week I drove it home (about 50 miles). On the way it started to choke a little and stalled easily at traffic lights. It seemed to struggle and would not gain power. I gave it to a great mechanic who said it was not running on all cylinders, he put in new points and set the timing, he got all cylinders running. I then took it for another run of about 150 miles. After about 130 miles, it started to choke again and lost power, I managed to get home.

On Saturday morning my mechanic looked over it again and spent 3 hours cleaning the carburettors and set it up perfectly (apparently the needles were stuck as the fuel had turned to jelly). He said it sounded great and his electronic machinery found no faults ( he said "take it home and see how it goes").

Saturday teatime I drove home (50 miles), on the way through town it cut out at traffic lights and, then started to choke and struggle as I drove along country lanes. It had more power than before (last week), but still struggled to drive.

Once home I looked inside the bonnet-hood, I noticed that some pipes appeared frozen (white ice on the outside). I turned the air conditioning on and the ice defrosted in seconds. Can anyone help and give me advice, on what it may be or how I can fix it? My mechanic will not be available until next Friday evening.

Kindest
Pinewood


Jus to add to the excellent other posts, when I was somewhat younger, my father had a Shadow. The float chambers had a nasty habit of sticking on the bolt,causing the carbs to flood & dump petrol on the street.


One other thing, the damper pots in the carbs need regular topping up, although the lack of topping up leads to leaness & flat spots.

As others have said, dont worry about the frost on the plumbing to the aircon, its compressor had little regulation compaired to today. keep an eye on the header tank to the rad, we had a couple fitted. I wonder if she is still on the road EMH 398 J ??
 
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Pinewood

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What state are the plugs in when it starts to fail?

Check that the choke isn't still on. I don't know whether it is manual or automatic but worth checking.

The anti-stall valve in the carburettor could be sticking. Does the car still stall if it's placed into nuetral when you stop?

Worth checking the the fuel filters in case there has been fuel tank corrosion.

Another point, aren't RR's from this period designed to run on 5 star leaded? If so what fuel are you using?

Dear brandwooddixon

I will check all that you say and thank you for your prompt reply. I have been putting in the expensive high octane unleaded...(only put £100 in so far as I have only had the car for nearly two weeks).

Kindest
Pinewood
 
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Pinewood

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Interesting that I was the deputy technical secretary of the RROC for a time back in 1980.

I would go to halfords and get a set of 4 high voltage testers from Halfords, and I think you will find that most of the troubles are distributor/rotor arm problems.

The ignition coils can fail as they warm up,if the car start well from cold, and the problems start later then check the output from the coils,, the plug testers will also confirm this

Thank you Television, you may be right.

When I bought the car (nearly two weeks ago, from a chap who is 78 years old), he gave me two new pieces of exhaust and a distributor cap and fuel filter. I have put on one piece of exhaust but not the fuel filter or distributor cap. Maybe he had bought them knowing they were at fault (the exhaust was!).

Today I spoke with a mechanic who said the engine seems as if it is becoming starved of fuel when hot. Tonight when I got home, I put on the ignition but could not hear the fuel pump (under the car under the drivers seat), when I switched the car on I could not hear it because of the sound of the engine.

Is the fuel pump supposed to click with just the ignition switched on?

Kindest
Pinewood
 
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Pinewood

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How do these cars deal with warm air / cold air intake? Is there a thermostatic valve? A bi-metal strip? A termAC valve and vacuum actuator?

It sounds to me like the carburettors are icing.

Dear Number_Cruncher,

It appears the ice was normal (I only mentioned it in passing), the carburettors are certainly not icing. It could be the fuel pump or what Television suggests.

Kindest
Pinewood
 
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Pinewood

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You may have a choke problem.

Unlike any other SU carburettor equiped engine I have ever dealt with the choke on your shad is a butterfly inside the air inlet assembly bolted onto the air side of both carbs, there is a latching lever arrangement on the side of this unit which is supposed to set the choke onto the correct position for starting. Normal SU's use their sliding jet to provide cold start enrichment, this feature is not used on the roller engine.
The position in which the lever sets is determined by a mechanical temperature sensor which if cold allows a lot of choke and less if its not so cold.
The choke is engaged by pressing the throttle pedal once before the car is started.
Don't use the throttle whilst starting the engine this can make the choke disengage prematurely.

I belive that the levers and links on your engine may be sticky or come adrift allowing the butterfly to flop closed whilst the engine is running.

If the fat air hose from the air filter is removed you can see the butterfly, and if the engine is cold enough when the throttle is pressed you should see it move towards closed and latch in this position when the throttle is released, examine the linkages and look for loose or detached parts in the bits that connect to the choke actuation system.
You are looking for the bit that lifts the choke levers as the throttle is pressed, its a long time since I dealt with one but I seem to remember the temperature capsule or the rod that comes out of it can get stuck, or the cam and lever on the throttle spindle becomes missaligned and make the choke engage when it should not. All the choke stuff is on top of the carbs and easy to access.

Do beware of running the engine whilst over choked, this will wash the oil off the bores and kill your engine a bit, a lot if you insist on doing it.

PS if you ever change your spark plugs it is much easier to access them from the other side of the car (ie do the LH bank from the RH side), just lie on top of the engine and work down into the slim gap between engine and wing, mind your knee does not dent the ali wings. Mine used to miss at random untill I installed NGK plugs.

I never had any petrol problems my 1976 car had valve gear suited to unleaded petrol.

Are the frosted pipes around the front/LH side? if so they may just be aircon and of no concern, follow them and if they go to the bulk head or the large round pump on the engines top they are A/C.

Does your car have points or electronic ignition? the earlier type of electronic module inside the distributor was a known weak point, its power transistor blows up. I believe (but ain't certain) that electronic came with the 6.75L engine, the 6.25L had points.

Since you are a new owner beware of the left hand wheel nuts, they are left hand thread and being bronze can be damaged by excessive torque whilst over tightening them in an attempt to remove them. There is an arrow stamped into the nuts flats to show the direction.

In the Pre VW/BMW days RR service was not expensive, might I respectfully suggest that you see what they offer today. There is a thriving DIY bit among the RR enthusiasts register.

Do enjoy the car.

Dear wireman

I read with interest all that you kindly wrote and will look into all that you suggest.

It has points, and thank you for the plug tips.

Kindest
Pinewood
 

television

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Thank you Television, you may be right.

When I bought the car (nearly two weeks ago, from a chap who is 78 years old), he gave me two new pieces of exhaust and a distributor cap and fuel filter. I have put on one piece of exhaust but not the fuel filter or distributor cap. Maybe he had bought them knowing they were at fault (the exhaust was!).

Today I spoke with a mechanic who said the engine seems as if it is becoming starved of fuel when hot. Tonight when I got home, I put on the ignition but could not hear the fuel pump (under the car under the drivers seat), when I switched the car on I could not hear it because of the sound of the engine.

Is the fuel pump supposed to click with just the ignition switched on?

Kindest
Pinewood

From memory I think that the fuel pumps are the Lucas type with the built in pressure cut off, that cut when the float chamber is full, and all so simple.

When you turn on the pump will run till the float chamber is full,then cut
 
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Pinewood

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Dear Malcolm

I did look and try to hear the fuel pump late last night, but heard nothing, so as you say the float chambers may be full. It looks very clean and quite new, however, I will try to take it off this morning and get it looked at.

Tonight I will put on a new distributor cap and rotor as you suggest.

Kindest
Pinewood
 

R W

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2001 E320cdi/ Sclass 2012 350cdi
How do these cars deal with warm air / cold air intake? Is there a thermostatic valve? A bi-metal strip? A termAC valve and vacuum actuator?

It sounds to me like the carburettors are icing.

I would tend to agree with Number Cruncher. Many years ago I had a very similar fault with a Granada. It would drive perfect for 20miles or even 200 miles then it would start missfiring as though it was choked. If I stopped the engine for a few mins it would again drive for 20 or 200 miles. I tried all sorts of things to cure it.Eventually when it choked up one day I quickly removed the air filter & sure enough the air intake was covered in ice. When the engine was stopped the ice melted in seconds & was able to run perfect again.The problem was the air intake was not diverting hot air from the exhaust & causing the icing up.
 

television

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How do these cars deal with warm air / cold air intake? Is there a thermostatic valve? A bi-metal strip? A termAC valve and vacuum actuator?

It sounds to me like the carburettors are icing.

I would tend to agree with Number Cruncher. Many years ago I had a very similar fault with a Granada. It would drive perfect for 20miles or even 200 miles then it would start missfiring as though it was choked. If I stopped the engine for a few mins it would again drive for 20 or 200 miles. I tried all sorts of things to cure it.Eventually when it choked up one day I quickly removed the air filter & sure enough the air intake was covered in ice. When the engine was stopped the ice melted in seconds & was able to run perfect again.The problem was the air intake was not diverting hot air from the exhaust & causing the icing up.

The Granada's of years ago had terrible auto chokes,,and I have converted at least ten cars to a manual. I cannot remember the choke fitted on this car, but is there not a starting carburetor on this one
 

R W

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Malcolm.
I agree,the choke systems were very unreliable & best converted to manual, but this one worked perfect. It was the build up of ice around the carb air intake that caused the choking effect. Within seconds of stopping the engine the ice would be melted & the engine would run perfect for a few miles or a few hundred miles till it iced up again.
 

wireman

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Having read more of what others have contributed there is the possibility of fuel starvation, the SU fuel pump has points which can and do get dirty resulting in intermittent operation, your pump is a tandem job with two pumps on one body so there is twice the chance of failiure and the possibility of one half working but unable to deliver the required fuel quantity. Within the base assembly of tandem pumps there is a strainer and a diaphragm pressure stabiliser along with the two non return valves for each pump (thats 4 valves) all of which may be showing signs of age. The points are often the cause of erratic operation and are readily available, the same parts being common to most of austin/morris cars from 1930's through to the seventies.

On switch on the fuel pumps should tick once or twice untill the pressure has built up, it was common on morris minors, jags and minis to have to hit the fuel pump occasionaly to get the car to start.

There is also a filter before the pump which could have found all the residue that a 2 year layup might generate with the same starvation results.
The pre filter may have a water trap which once full of water will allow drops of water to get into the carbs with some horrid missfiring or stalling being the result.

And the needle valve in the SU float chamber lid which can accumalate debris leaving one carb dry or partialy so causing one bank of the engine to run weak, this usualy only occurs if a lot of debris (I once found bits of rag) gets delivered as far as the carbs. The worst of the SU needle valve is a tendency to leak and overfill/overflow the float chambers.

If you are intending to work on the car a wholesome spanner set will be required there are BSF & UNF fixings on the mechanical bits along with BA and metric on the electricals.
 
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Pinewood

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Having read more of what others have contributed there is the possibility of fuel starvation, the SU fuel pump has points which can and do get dirty resulting in intermittent operation, your pump is a tandem job with two pumps on one body so there is twice the chance of failiure and the possibility of one half working but unable to deliver the required fuel quantity. Within the base assembly of tandem pumps there is a strainer and a diaphragm pressure stabiliser along with the two non return valves for each pump (thats 4 valves) all of which may be showing signs of age. The points are often the cause of erratic operation and are readily available, the same parts being common to most of austin/morris cars from 1930's through to the seventies.

On switch on the fuel pumps should tick once or twice untill the pressure has built up, it was common on morris minors, jags and minis to have to hit the fuel pump occasionaly to get the car to start.

There is also a filter before the pump which could have found all the residue that a 2 year layup might generate with the same starvation results.
The pre filter may have a water trap which once full of water will allow drops of water to get into the carbs with some horrid missfiring or stalling being the result.

And the needle valve in the SU float chamber lid which can accumalate debris leaving one carb dry or partialy so causing one bank of the engine to run weak, this usualy only occurs if a lot of debris (I once found bits of rag) gets delivered as far as the carbs. The worst of the SU needle valve is a tendency to leak and overfill/overflow the float chambers.

If you are intending to work on the car a wholesome spanner set will be required there are BSF & UNF fixings on the mechanical bits along with BA and metric on the electricals.

Dear wireman Television and all other posts, I think I may have found the problem...

...early this morning I crawled under the car and removed the rear fuel filter, as I did so (and not being a mechanic), I noticed that the flow indicators on the filter housing were fitted the wrong way round, i.e. from the tank it went into the 'out' and the 'in' was attached to the pipe running to the fuel pump.

I have not put it back on as yet (also I need to attach the fuel pump which I had tested today and works perfectly with good suction and flow), but something tells me if it was placed on the wrong way round it would starve the fuel pump of fuel and inturn the carburettors.....am I right (I hope so)?

Kindest
Pinewood
 

television

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While the pump is off lower the pump head into a bowl of diesel and run the pump backwards and see how much crud comes out
 

stivesvelo

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Blocked carbs

Hi Pinewood,

The green jelly in the carbs sounds like it could be a problem similar to one with the carbs on my Laverda SFC1000 motorcycle, which had been laid up (3 Del Orto carbs).

The green jelly is what you get when you leave unleaded petrol standing & is often a problem on bikes as we don't always use them in the winter. You can get a stabiliser to put in the petrol to prevent this if you are going to leave it standing.

I had started servicing it 4 years ago, but in the meantime got distracted with other things & it stayed on the bench. The carbs had been drained but I mustn't have run them dry because I found the same green jelly in one of the float bowls when I came to starting it again, the real problem being jelly in the jets & fine passageways in the carbs. I stripped & blew them out with carb cleaner & have it running again, ticks over etc. & seems erratic but I won't know without giving it a run as it probably just needs an 'Italian tune up' (a good thrash).

From talking to various people the solution offered by many is to have them ultrasonically cleaned & replace seals, o rings etc. to get them right.

Hope it's something simpler.

Rob
 
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Daimler picks Magna unit to make SLS AMG body

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http://www.autoshortnews.com/daimler-picks-magna-unit-sls-amg-body/

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