| Author | Message | ||||
     Mujahid Khan Experienced User Username: anjumkha Post Number: 7 Registered: 12-2003 |
1977 SSII Problem: Coolant Dumping from the steam valve outlet. The steam valve and the gasket are new. Thermostat is out to help in diagnosis The radiator cap is a bit chipped. However I put a new gasket on the top so no liquid comes out of the cap, but coolant emanates from the overflow tube. I saw a hole under the cap which is connected to the outlet tube. I was able to blow through the tube into the hole. What is the purpose of this hole? What is a foolproof way to ascertain that it is not a blown head gasket? Regards M Khan | ||||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 565 Registered: 9-2004 |
My thoughts on this is before you do any testing you must always have a correct and fully working thermostat in the system. If still a problem then procceed with the testing of many possible causes starting with a leak down test fist. Some possible other causes that spring to mind. Viscous faulty, fan not working at the correct speed or not at all. Incorrect belt tension. Rad blocked. Cracked or corroded head. head gasket. Incorrect ign timming to name just some. | ||||
| bob uk Unregistered guest Posted From: 80.3.64.11 |
The purpose of the holes connected to the overflow is to stop overfilling. This means that if the cap is not sealing properly then coolant will leak form the overflow. The cap gasket will seal small chips in the cap face but there are limits. The cap could be refaced in a lathe leaving a nice lip. AS Pat said the themostat must be refitted. The themostat is a service item like spark plugs so fit a new one. £20 max. Without a stat the by pass will be open and this can cause overheating because instead of all the coolant going to the rad some of the coolant will go though the bypass and back around the engine. Best way to check for overheating is check the coolant for exhaust gases using a chemical dye that changes colour when it detects exhaust gases. Your local garage will have this equipment. The test takes 30 seconds and takes all the guess work out. Also if a cooling system is being pumped up by the cylinders try this -- . release the pressure in the system. put the cap on then start the engine immediately pinch the top hose between finger and thumb. if the system is being pumped up then quite quickly before the heat expansion of the coolant pressurisers the hoses you will feel the hose go hard You at the back stop sniggering . (Message approved by david_gore) | ||||
| Mujahid Khan Experienced User Username: anjumkha Post Number: 8 Registered: 12-2003 |
Bob: Nice to hear from you. You are right, the cap is not sealing properly. Although I fited a new gasket and tried to dress a few chips on the lips with JB weld, but the coolant still escapes. I also blocked the vent hole in the header tank. Tommorow I will order a cap. I have heard that folks have converted the header tank to a simpler conventional system. What is the procedure? Thanks fro the help M Khan | ||||
| Glenn Amer Experienced User Username: recordo Post Number: 17 Registered: 4-2005 |
My new thermostat a month ago cost over AU$200. Thanks Bentley of Sydney... I baulked two years ago when they were $97. How much higher can they go? | ||||
| Larry Halpert Prolific User Username: larry_halpert Post Number: 88 Registered: 9-2003 |
Eventually someone will figure out what aftermarket thermostat will fit and work with these cars. These can't be 100% unique only to these cars. This is something we are just told, but some other thermostat must have the same diameter, opening temperature, and mechanism. Larry | ||||
| Bill Coburn Moderator Username: bill_coburn Post Number: 648 Registered: 4-2003 |
well Larry let us know when you find it. All other thermostats in my experience simply open and close - one way passage. The RR one not only opens to let the coolant through to the radiator it closes off the by-pass. That is why you must never run these engines without a thermostat as too much will go through the by-pass and not enough through the radiator core and the engine she will hot up mate!! The six cylinder engines did this by closing a gate at the side of the thermostat. The main valve in these units moved upward. The later Vee Eights the valve opened downward until the base jammed onto the by pass inlet and closed it off. | ||||
| Glenn Amer Experienced User Username: recordo Post Number: 18 Registered: 4-2005 |
Bill, your comments have explained a lot to me. When I took out the old thermostat, I was horrified to find it had been wired open with copper wire. No wonder the temperature was all over the place! Now with the new thermostat the car runs cooler and the temperature is always steady. | ||||
| Bill Coburn Moderator Username: bill_coburn Post Number: 649 Registered: 4-2003 |
Glen You should not be too horrified. At least the 'wirer' understood to need to close off the by-pass. These units are not fail-safe and if they fail to open you have to do something. Several times on trips with owners who had not changed the thermostat for years and it stayed shut the emergency action was to lever it open with a screw driver and jam a small rock in it! As with your wiring, that blocked off the bypass but opened the flow to the radiator. Drastic problems breed novel solutions! | ||||
| Mujahid Khan Experienced User Username: anjumkha Post Number: 12 Registered: 12-2003 |
Bill: I am trying to understand the by-pass thing. Can you explain where is the by-pass and what is the significance of the by-pass? Is it the small dia hose that connects from the water pump to the header tank? Best regards M Khan | ||||
| David Gore Moderator Username: david_gore Post Number: 578 Registered: 4-2003 |
The attached Adobe PDF files show the Shadow II bypass connection - hope this helps.
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| Bill Coburn Moderator Username: bill_coburn Post Number: 650 Registered: 4-2003 |
Well Mujahid, David has given you the diagram. The object is to restrict circulation of the coolant to the engine until it warms up A cool running engine is not only very inefficient but also promotes a high wear rate. So when the thermostat is shut the coolant simply goes round and round the engine block using the by pass until it gets so hot the thermostat opens closes off the bypass and the pump then forces the coolant up through the open thermostat into the large top hose and into the radiator it then goes down the radiator core cooling, out the bottom hose and back to the pump. The smaller hose from the header tank to the pump is the means to get the coolant from the filler into the engine. The only other connection the header tanks has with the system is the little hose on the front of the tank which is intended to bleed off air/steam from the top radiator tank. | ||||
| bob uk Unregistered guest Posted From: 80.3.64.11 |
The design of the cooling system of the Rolls-Royce V8 is absolutely first class. The header tank and steam valve are particularly clever and I would not recommend modifications to any part of the system. Modifing the system to use cheaper parts will always end up more expensive than servicing the exsiting design. Remember before the car was released for saleto the public in 1965 that RR spent many 10000000s miles thrashing the engine around to make sure it does not over heat and the heating and ventilation system worked well. My car is a 1974 and RR had much Shadow experience before they put my car together so I loathe to alter anything without very good cause because I know that the car worked good before so repair propely and it will work good again. I am sure that I paid less than £20 for a stat and gasket 2 years ago from Bently Crewe via my local man. The cap not sealing is a common problem and if the cap cannot be repaired then just fit a new one. (Message approved by david_gore) | ||||
| David Gore Moderator Username: david_gore Post Number: 581 Registered: 4-2003 |
Hi Bob, Unfortunately, it appears R-R did not think it necessary to send a Shadow prototype "Down-Under" to see how it performed in a hot climate - the South of France which I presume would have been used for testing cannot properly replicate a typical Australian summer's day on the coastal fringe in the lower half of the continent let alone in the Inland or tropics given the heat load coming from the engine and air conditioning system especially in city traffic conditions. Overheating in summer can be a problem in our part of the world due to the high ambient temperatures and the high back pressures encountered when trying to drag [by the fan] or force [by external electric fans] sufficient air through the A/C condensor and radiator core. There is insufficient clearance around the engine and ancillaries to allow the volume of cooling air required to exit the engine bay easily. For this reason, higher flow rate fans [with higher power absorbtion from the engine] may be fitted to overcome the back pressure to allow the required mass of air for absorbing the condensor/radiator heat rejection to flow [this is a consequence of the fact that heat absorbtion is proportional to the air mass not volume - as the air temperature increases, the air density and thus mass will decrease as its volume increases due to expansion and accordingly the amount of heat transferred per unit volume of air decreases with increasing temperature]. Problems with the filler cap seal/steam valve are frequent enough for some owners to fit a standard radiator pressure cap assembly to eliminate embarassing "failures to proceed" in city traffic conditions. It is common for the owner to retain these items for later replacement by future owners desiring a concours "garage queen" rather than an every-day "road warrior". As far as the thermostat price goes; one of our contributors above mentions a cost of over AUD200 [GBP65] for a recent purchase. | ||||
| Mujahid Khan Experienced User Username: anjumkha Post Number: 13 Registered: 12-2003 |
Dear Bob UK: It is always nice to hear from you. my SSII gave me lot of headache with the header tank. I spent money on a steam valve, on a new rad cap and its gasket, and not to mention gallons of coolant. I finally found that the tank itself had developed stress fractures and was leaking under pressure. This was in addition to the bad cap etc. I have decided to get rid of the header tank and I have ordered an inline neck to be fitted to the upper hose >> http://static.summitracing.com/global/images/prod/large/mor-63730.jpg I will let you know once the part arrives. And yes, I will definitely have the coolant examined for compression gasses before I open the heads. M Khan | ||||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 575 Registered: 9-2004 |
Cripes, in my opionion if the header tank is shot it will leak. The coolant + air will not be seen to flow out of the overflow pipe unless the head gasket or cap etc is faulty. If it is the mod you are going to do with the pressure cap fitted to the inline neck disaster will occure without an expansion tank and proper type caps in the correct position when the going gets hot etc. Best to renew it with the original type and carry out further tests. | ||||
| Mujahid Khan Experienced User Username: anjumkha Post Number: 14 Registered: 12-2003 |
Pat: I will fit the neck with 15 psi standard cap and also attach an overflow tank. Do you think disaster will still occur? To my mind, I have converted the system to a conventional type which, RR reverted to on later models. Regards M Khan | ||||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 576 Registered: 9-2004 |
Yes disaster will occur unless the the standard type cap has a vacuum valve, there are two types of pressure caps. Also are you carrying the mod after the testing for head gaskets etc are ok. As Bob has said the original system is by far the best. Make sure your engine weep holes are not flooding when the engine is running at a hot temp when 15lb pressure is met. Reminds me to check the electric fan operation on my SS2 a i have yet to hear it run. | ||||
| Bill Coburn Moderator Username: bill_coburn Post Number: 653 Registered: 4-2003 |
Well I feel a bit timid creeping into this flood of erudition but a few sparks went off in the head by various remarks, which I will share with you lot. David got the jump on me on the Australian conditions prompted by Bill UK's remarks. York Motors - the now defunct Australian agents begged Rolls-Royce to send their trial cars here even offering to accomodate the drivers etc to save costs but the offers were not even referred to. This was a prime example of the arrogance of the old Factory that no bloody colonial is going to tell us how to build cars. The classsic case was the breaking up of Mark VI chassis frames. This was ignored when reports were sent until the late Bert Ward of York Motors devised a strengthening scheme with welded on bits which fixed the problem. As a courtesy he sent drawings of all the bits to the Factory for interest. Receipt was never acknowledged but lo when the Factory finally decided to weld their frame and throw those rivetts out you will not be suprised to hear that all of Bert Ward's modifications were included to the millimeter!!!!!!!!!!! I have no doubt Bill UK that Zillions of hours were spent testing but the best empirical data is often just around the corner. Our climate and road conditions out back make North Africa seem like Park Lane, yet these cars were pounded up and down them till they simply fell apart! It really is quite sad on reflection. Next is the cooling problem. The later Corniches did indeed have have 'conventional' two way radiator caps with an overflow bottle so putting a neck and cap on the header tank is really not too radical. I hate non-originality if I can avoid it but that is just me. But Muj as Patrick observes your scheme sounds very hazardous. In short don't do it. If this whole problem is a problem modify the header tank to take a double action cap and fit an overflow bottle. That way you have a nil loss closed system, you can see what is happening and there is an engine compartment that doesn't look like a desert conversion carried out by an Afghan camel driver!!! One other thing Bob UK if you can get thermostats for under twenty pounds I had better get you to get a dozen or so for me. This morning the local people have them for AUD167-68 including GST. Now that they have scrapped the plugs the price has come down about $40!! And if you fit a new screw cap do fit a new seal!!! There I feel better already! | ||||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 577 Registered: 9-2004 |
Ah Bill Hazardous that is the word,now Muj be sure to run the pressurized system not a sealed cooling type system. Now you are putting the pressurized cap on the neck and not the expansion tank. Do check weep holes and pump seals etc after the mod! Best of luck. | ||||
| bob uk Unregistered guest Posted From: 80.3.64.11 |
I must repeat my advice. The system fitted must be correctly repaired. Any rad shop will be able to fixed the header tank. If you start altering things and you still have problems then you will have no idea of what is wrong and what is right As Dave said Shadows down under have proved to have marginal cooling. In the UK we do not have the temperatures that they have in Oz. However doing away with the header tank is not going to improve matters. Recommended for hot climates is cooling system service and electric fan --- The modern ones are very good and at a guess three times better than the metal fan and vicious coupling. Which wear out and are differcult to check I suggest that most of the Shadows in the world have dodgy couplings with out the owner knowing. My one is dodgy. At say 60 mph the forward motion of the car is forcing loads more air through the rad than any fan could do so if the car overheats when on the move then a fan will not cure it. Also modern antifreezes have water wetters added Incidently in traffic keep back from the car in front because that car's spent heat is coming back towards your radiator. Also I read somewhere that if the bonnet is not fully closed it helps cooling. I keep my bonnet firmly latched when I am driving -- I have visions of the bonnet flying open under heavy braking (Message approved by david_gore) | ||||
| Mujahid Khan Experienced User Username: anjumkha Post Number: 15 Registered: 12-2003 |
Dear Bill, Bob and Pat: I am sure I am missing something here. From your replies it is evident the mod must not be carried out; one reason being aesthetics. What is the reason from the point of view of physics? What exactly can go wrong if you bypass the header tank and apply a 15 lbs pressure cap to an inline neck and then attach it to a reservoir, just as in any other car? Will the rad burst? Will the car loose a lot of coolant which cant be retreived once cold? Please let me know becuase this subject has started to baffle me. Mujahid | ||||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 579 Registered: 9-2004 |
Muja not useing the RR expansion tank sitting above the RR radiator can have its problems. One, the proper tests for faults cannot be carried out. Two, the filler neck of the mod will be lower than the top of the rad, so initial running will have air in the top of the rad bad news. Repair [braze] the old header tank and refit, carry out the tests already stated. Report back. |
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