| Author | Message | ||
     PETER DIXON Frequent User Username: petenlinid Post Number: 16 Registered: 8-2003 |
I have read volumes within the Technical Forum on overheating problems. So vast is the information available that it has served only to confuse my meagre diagnostic capabilities. I was hoping someone could please give me a simple checklist to go through with a view to my detecting the fault in my cooling system. The vehicle is a 1980 Shadow2. It had a major engine overhaul by Chellingworths WA less than 40,000k ago so I assume that the water ports in the engine itself should be OK. I have had the header tank modified to take a standard radiator cap and I have already replaced the thermostat with a genuine part. The bottom hose has been removed and no evidence of gunk etc. flowed forth. Since replacing the thermostat I have not had the opportunity to test the system at the 40C temperatures that we sometimes have in Mildura. Last year on one occassion it truly gushed. The symptoms are that when the ambient temperature exceeds about 30C, with the aircon operating, the temperature reads slightly high and will run all day like that. I dread to think of the possibilites of driving on a hot day in Melbourne traffic. On parking, leaving the engine running for a few minutes then turning it off, pressure builds and coolant pumps out of the radiator overflow. Any thoughts and advice would be appreciated. Peter | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 315 Registered: 9-2004 |
With the engine hot on switching off with what you describe as happening re a gusher, i would suggest that the localising engine heat within the heads or rad. This can in my expierence be caused by circulation probs, first the waterways within the head choked or the rad cores parshully blocked. In my opinion you should have some thermo syphon effect within the system when turning off with the hot engine with the thermostat working correctly. There are many more problems that could cause the overheating but check the flow rate of the rad and block first. Reverse flush etc. Does the electric fan opperate ok. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 576 Registered: 4-2003 |
A curious modification indeed. Why did you replace the radiator cap type, what pressure cap do you now use, and what did you do with the steam valve ? | ||
| John Dare Grand Master Username: jgdare Post Number: 185 Registered: 12-2004 |
Hello Peter. I am concerned that you continue to experience cooling system problems. Whatever the reason/s, it will NOT be as a result of your modified radiator header tank (with the correct pressure cap) since that particular modification has been performed both here and the USA on countless occasions. When are you next coming to Melbourne? (send priv. e' mail) | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 578 Registered: 4-2003 |
John, Can we record that instant elimination of cause as your first cast-iron guarantee at last ? Good luck. | ||
| John Dare Grand Master Username: jgdare Post Number: 186 Registered: 12-2004 |
ABSOLUTELY, as I would not expect that you would be aware of the circumstances and this particular car, whereas I am. I do not understand the implication that I have neglected to previously provide "guarantees", so perhaps I could be reminded of the "question(s)issue" to which you allude. Irrespective of that, I will certainly provide this guarantee (that the cause is NOT the header tank modif.) but rather than a "cast-iron" g/tee (too "flakey") perhaps I could offer an ALUMINIUM one, since that would seem to perhaps be more appropriate. | ||
| Mark Anson Frequent User Username: bentleybloke Post Number: 30 Registered: 11-2004 |
Hi Peter, Have you tried driving the car with the thermostat removed? I had a Ford that had a similar fault. It turned out that the thermostat was sticking and not opening fully. This caused the engine to heat up too quickly and caused ketteling or gushing from the header tank/rad cap. Some BMW's suffer from the water pump impeller becoming loose, this allows the fan belt/pulley to rotate OK but the pump blades inside hardly turn. Just a thought. Try the thermostat first it costs nothing to rule this out. Cheers Mark. | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 317 Registered: 9-2004 |
Mark you are correct on the BMW water pump impellers comming loose but all the ones i have done are plastic the shadows are steel. Regarding the removal of the thermostat and running without im not happy with that,Peter has had a new fitted to try and correct the prob it could be faulty as you say,far better to test the unit off the car to the opening temp with hot water and thermometor. Im just thinking if the temp gauge is showing cooler than the engine realy is. ie the correcting resisters for the gauge reading being faulty. What pressure rad cap are you useing? | ||
| Gabriël Viljoen Prolific User Username: gabriel Post Number: 31 Registered: 3-2004 |
The previous owner of my Silver Shadow removed the termostat. I could not understand why the car was running so hot. Eventually I devided to take it to a mechanic. On replacing the termostat, he noted that there were no termostat fitted. According to him the water takes the easier route which is through the engine and not through the radiator. Thus, the car heats up and that was the reason why my car was running that hot. After fitting the termostat, the car runs at a normal temperature. I would suggest you checking the termostat as a starting point. Gabriel | ||
| Patrick McGlashan Unregistered guest Posted From: 69.107.3.24 |
Have you checked the fan clutch? Try to turn the fan with your hand. You should feel a slight resistance, this indicates the clutch is working properly. If the fan turns freely then it's not doing its job of pulling air through the radiator core while the engine is running. (Message approved by david_gore) | ||
| PETER DIXON Frequent User Username: petenlinid Post Number: 17 Registered: 8-2003 |
Many thanks to all. I am still working on the problem and will advise when its fixed. Cheers Peter | ||
| Mark Anson Prolific User Username: bentleybloke Post Number: 41 Registered: 11-2004 |
Gabriël Viljoen wrote:....Eventually I devided to take it to a mechanic. On replacing the termostat, he noted that there were no termostat fitted. According to him the water takes the easier route which is through the engine and not through the radiator. Thus, the car heats up and that was the reason why my car was running that hot. After fitting the termostat, the car runs at a normal temperature. Mmmmmm how does that work? Surly a thermostat is supposed to open and let the water circulate. My point was if the thermostat is staying closed the water will only circulate around the engine, after all this is what its designed to do, its job is to get the water hot quickly so the choke does not have to be on for long. The symptoms were....."engine over heats and the extreme boiling water pushes out of the header tank". This is one of the classic signs of faulty thermostat. If you let the water flow freely i.e remove the thermostat, have a look into the header tank with the engine running (FROM COLD!!!!) what do you see??? A fast flowing stream of water going past the radiator cap hole as the pump circulates the water around the radiator and block. I should know...I have been a mechanic for over 22 years now. If anything, the car will run cooler (depending on the size of the thermostat hole). If the engine still overheated with the thermostat removed then the problem is elsewhere. We ALWAYS did this check before removing a customers cylinder head. Its hard to get £300 off them for a head gasket they did not need after missing a £4 faulty thermostat! Cheers Mark  | ||
| PETER DIXON Frequent User Username: petenlinid Post Number: 29 Registered: 8-2003 |
At long last I have been able to remove the radiator ready for transportation to the radiator man. This is my first attempt at actually doing any work on the car, something I have to date avoided. To a Ford/Chrysler /Holden person even this was a daunting task. Can't believe it was so easy. What I would like to know is while I have the radiator out and can see all theses interesting bits and pieces is there anything else I can should/could/can do or check before I put it back particularly in relation to the fans. Cheers Peter | ||
| PETER DIXON Frequent User Username: petenlinid Post Number: 30 Registered: 8-2003 |
Can someone please tell me, apart from somewhere to fit the coolant temperature sensor, radiator cap and pressure relief valve what is the purpose of the separate header tank on top of the radiator in the SS2. Cheers Peter | ||
| PETER DIXON Frequent User Username: petenlinid Post Number: 31 Registered: 8-2003 |
G'day all, For what its worth, my radiator man advises me the radiator core is about 50% blocked and whilst apart from a couple of obvious minor weeps its appearance overall was good (to me that is) it will have to be replaced at a cost of only $611.25A. He is of the opinion that it is the original radiator/core which makes it 25 years old. As the car spent most of its life in the heat of Western Australia I would suggest that is testament of a fine piece of cooling equipment. The type of blockage I would think would account for the old girl cruising at relatively normal temperatures and only disgorging her coolant when she comes to rest. Cheers Peter SRH 40250 | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 730 Registered: 4-2003 |
Provided it has not been committed yet, may I suggest that you consider the following core: NATRA radiators (Australian Made), D-Type (DFX) louvred fins. Maybe you have already chosen this one. It has a greatly increased heat transfer cooefficient than the original. RT. | ||
| PETER DIXON Frequent User Username: petenlinid Post Number: 32 Registered: 8-2003 |
Thanks for that Richard, wish I had posted first and acted later. The radiator is completed and ready for collection. I didn't know there was a difference in cores. I will ask the rad man what he has sold me though. Regards Peter | ||
| PETER DIXON Frequent User Username: petenlinid Post Number: 33 Registered: 8-2003 |
Sorry to repeat my question of the 1/5 but I really would like to know the answer. I know its probably pretty obvious to most but: Can someone please tell me, apart from somewhere to fit the coolant temperature sensor, radiator cap and pressure relief valves what is the purpose of the separate header tank on top of the radiator in the SS2. Cheers Peter | ||
| Robert Wort Grand Master Username: robert_wort Post Number: 200 Registered: 12-2004 |
Hi Peter, Sorry no one has answered you yet. I'm not absolutely certain, but it probably doubles as an expansion tank to keep air out of the main cooling system. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 734 Registered: 4-2003 |
A header tank is separated from the main coolant circuit flow. Regardless of the configuration (see below), the header has several important functions: 1. It ensures that the active cooling circuit has absolutely no air, or steam in the case of pressurised headers (stops hots spots, foaming etc) 2. Increases the overall coolant capacity so the active cooling circuit itself may have the smallest possible capacity (faster warm-up) without too little reserve. In other words, the designers may take advantage of the smallest possible cooling system circuit volume, yet bolster it with capacity in the header so not to lose the benefits and protection of a larger capacity. 3. Allows the coolant to expand and contract without overflow and without relying on a cushion of air in the radiator to act as an accumulator. Configurations In some applications it is at coolant pressure (pressurised header), with the pressure cap or steam valve on the header leading to the final overflow hose (Silver Shadow and 20,000-series Spirit onwards). In others (early Spirit) it is at atmospheric pressure (unpressurised header) after the radiator pressure cap and is fed by the radiator overflow hose after the pressure valve. In that case there is a simple final overflow hose at the top of the header tank. On some other applications, the header is semi-pressurised. There is a pressure cap on both the header and the radiator, with the radiator overflow after the pressure valve feeding the header tank. The header tank pressure cap leads to the final overflow hose. In that case the pressure ratings of the caps are usually either the same or the one on the radiator is rated at a lower pressure. Disadvantages of Unpressurised or Semi-pressurised Systems The system must be filled first through the radiator, then the header, and the system must then be bled. It is more time consuming and less idiot proof than filling a pressurised system. A system leaking slowly may not safely be driven any distance at all. As the coolant volume increases with temperature, or even with engine speed, there is no accumulator to reduce the pressure. The radiator cap valve must open and vent to the header. When the speed drops, the return valve will not allow fluid back until there is a vacuum. It is not good for a motor to run much below the pressure rating of the cap, and it is unwise to rely on the pressure cap as a control valve in this manner. These systems give very poor pressure stability. The entire system sealing relys on the secondary seal of the radiator pressure cap. This is poor practice. Advantages of Pressurised Headers The air in the header tank acts as an accumulator. Correctly filled, there is no movement of air or liquid past any control valves as in the other systems. The main cooling circuit pressure remains more constant. Pressurised systems reduce the possibility of system vacuums when cooled down. Water pumps and heater matrices do not like vacuums. Filling pressurised headers is a simple fill-in operation and normally self-bleeding as you fill. Under conditions of mild overheating, a pressurised header will deal with the steam as it is generated (collect it and usually condense it immediately) whilst the others will not (damaging steam can remain in the main circuit until it cools). The secondary seal of the pressure cap does not hold system pressure. It is purely to make sure that overflow goes down the hose and not onto the chassis. These are all sound reasons why pressurised headers are the preferred industry standard. The advantages of the others are that they are cheap and can be tacked on to a car without a header very simply. RT. | ||
| Bill Coburn Grand Master Username: bill_coburn Post Number: 405 Registered: 4-2003 |
Peter/ Sorry also. Robert is quite right. There are three problems with cooling an engine, corrosion which causes blockages leaks and hotspots, loss of fluid, and aeration. Air is a good insulator which ain't good to get heat away from a hot valve seat. The impeller in the pump moves the coolant by centifugal force and fires it up to the top of the radiator where it falls down the cooling tubes which have air rushing through them. If there is an air space at the top of the radiator the upcoming coolant is going to spray out the top hose mix with air and carry it down the radiator to be pumped through the block. The solution is to fill the cooling system ie the block, pump, radiator core and top and bottom tanks right to the very top ie no air and then just to make sure put a small tank full of coolant on top of the whole system to allow the water in the engine to expand into it when it is hot and suck some back when it cools down. And that is why the header tank is there. Which raises the question of changing coolant which you do once a year after a really good flushing and change the hoses and thermostat every other year!!! After you drain flush drain and refill run the engine until it is at full temperature (the top hose will be very hot). Let it cool overnight. Top up the next morning and check it after each cool down for the next few times. The object is to ensure that all air is out of the system. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 736 Registered: 4-2003 |
ps I forgot to mention that a semi-pressurised header (ie two pressure caps in the cooling system) largely overcomes the pressure stability problems of an unpressurised header, and has the very slight advantage that cold-starting coolant pressure builds faster than in a pressurised system. In the past I have coverted semi-pressurised systems to pressurised simply by replacing the radiator cap by a plain one or by removing its valve. That is an improvement, but only goes part-way. A proper pressurised header system like on a 20,000+ SZ will take full advantage by employing a bypass coolant flow through the jeader at all times when the thermostat is open. That allows gases to escape as coolant passes through the header. RT. | ||
| PETER DIXON Frequent User Username: petenlinid Post Number: 34 Registered: 8-2003 |
Gentlemen, what else can I say. I asked and you answered. Thank you very much. Peter | ||
| Miguel A. Garcia Experienced User Username: magarcia Post Number: 33 Registered: 3-2005 |
About overheating, today was the first warm day in spanish spring, with a tem that was in 30 Cent degrees. I was having lunch in Segovia (a very nice town in Spain) and coming back home after lunch, the temperature of the coolant was quite up, till the ending of the continous band of the coolant clock. I am afraid that in the warmer summer, with temops over 45 degrees, will not be able to use SRH3430 by the overheating. I have changed the full coolant, cleaned the full circuit, changed the thermostat and renew with fresh coolant. The coolant colur does not change (as does in John Aravanis matter). having in mind that obviusly an electric fan in the front the radiator pushing air (between the grill and the radiator there is a free size of 9 cm depth and 0,35 width and 0,40 high (more or less), having in mind as i was saying that it will not be too hortodox addon, i was wander if it will be effective. I have seen in JC witney site some universal electric fans with thermostat that could fit in my SRH3430. Has anyone any experience adding this kind of elements in s Shadow I? mine, as i have said in other posts is a 1968 spacimen. Thank you for the time. | ||
| John Aravanis Experienced User Username: krug300 Post Number: 20 Registered: 2-2005 |
Miguel, check if your viscous coupling is operating properly. I presume though, that your overheating was present while driving at speed. I went through the same story last year, problem was solved ONLY when I removed the radiator (very simple and reasonable-110 euros for labor and cleaning) and had it taken apart and cleaned. Everything is normal now, it seems that by design, these radiators and fans can handle any ambient temperature. I would not install an electric fan, because if your radiator is clogged you are indirectly dealing with the cause of your problem. Plus the fact that you are spoiling with the car's originality. Speaking of originality, I had a classic style (ebonite/tar) battery manufactured just for the sake of having everything as close as to original as possible and albeit the fact that the battery is out of sight. In any case, if you have money to spend, order a reconditioned radiator (300-400 euros exchange) or do it like I did. I am sure that there are still many radiator shops in Spain that still deal with "classic" radiators. | ||
| Miguel A. Garcia Experienced User Username: magarcia Post Number: 34 Registered: 3-2005 |
Thank you John, I think, (not sure still, i have to see the workshop book) that my shadow I has not viscous coupling. Yes, the overheating happens in high speed only or when the car is stopped in a high traffic condition for a while. I will order a work for the radiator. Yes, here are many good workshop specialist in radiators where i think it will not be aproblem to clean and/or repair it. I upload a pic of today in from of a 1100 A.C. romanic style church. Thank you very much  | ||
| Miguel A. Garcia Experienced User Username: magarcia Post Number: 35 Registered: 3-2005 |
HI again. From the Workshop manual: "cars prior to Serial 6300: five blades 45,72 Cm fan. cars from Serial 6300: seven blades viscous drive coupling..." so is confirmed, My SRH3430 has not viscous coupling... Thanks again |
