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Message |
    
PETER DIXON
Frequent User
Username: petenlinid
Post Number: 11
Registered: 8-2003
| | Posted on Saturday, 06 March, 2004 - 18:07: |    |
I know that the information I need has been previously addressed in the forum but I can't find it. I have had a overheating problem. It occurred on a day of 42-44 deg with a rather splendid display of steaming gurgling iridescent green stuff. Needless to say this happened in front of the local shopping centre which is my usual place for overt posturing and generally showing off to mere mortals fact that "I" own a RR. Having recently changed the coolant and even at the time of overheating it was perfectly clean and there was no evidence of radiator glugg. I have since then changed the thermostat. The old thermostat was clearly overdue for replacement some of the plugs were in really poor condition though not actually corroded through were heading in that direction. As far as I could tell when testing it, it was opening about 2/3 of what it should have. The inside of the thermostat housing etc was as new with no discolouration whatsoever A test drive with the ambient temperature being 33 deg. had the gauge showing about 2/3 of the way up the white normal zone but it didn't actually overheat, even when I stopped and left the engine running in drive, not very scientific I know but its all I have. I know there is a procedure for testing the temperature in case the gauge is out, I would appreciate any advice on this. I have the appropriate temperature testing equipment. Any other options and advice would be truly welcome.
Thanks in anticipation
Peter
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PETER DIXON
Frequent User
Username: petenlinid
Post Number: 12
Registered: 8-2003
| | Posted on Saturday, 06 March, 2004 - 19:01: | |
Sorry folks, should have said. The vehicle refered to in my previous post is a 1980 SS2
Cheers
Peter |
Martin Taylor
Frequent User
Username: martin_taylor
Post Number: 15
Registered: 11-2003
| | Posted on Saturday, 06 March, 2004 - 21:17: | |
Peter do you have access to a pressure tester? If not one can be made from a foot pump and some hose and T sections.
Pressurise the cooling system and see that the first thing that lets pressure go is the steam valve, pressurise until fluid comes out the overflow hose from the header tank (don't go above 15psi) this checks everything up to the header tank itself. The drain hose connects to a drain around the filler neck and to the exhaust from the steam valve, if you are getting low pressure leaks from this area block the drain from the filler neck and repressurise, if fluid escapes from the drain hose it is coming via the steam valve, if it comes out around the filler cap you need a tank cap and or seal.
Most coolant problems are caused by the system not holding correct pressure, especially if it lets go right after you stop the engine.
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PETER DIXON
Frequent User
Username: petenlinid
Post Number: 13
Registered: 8-2003
| | Posted on Sunday, 07 March, 2004 - 17:52: | |
Many thanks for that Martin, but I have had my header tank modified to take an ordinary radiator cap.(gasp' shock "horrorror" from the purists) As a consequence of course I never normally raise the bonnet in public. On this occasion however I just couldn't help myself and all the coolant was blowing from the radiator cap pressure release pipe as far as I could tell.
Cheers
Peter
SRH40250 |
David Gore
Moderator
Username: david_gore
Post Number: 220
Registered: 4-2003
| | Posted on Sunday, 07 March, 2004 - 18:39: | |
Peter,
I would replace the cap if you haven't already done so and see if the problem reoccurs; if it does then more detective work will be required.
When you replaced the thermostat, did you remove the drain plugs from the cylinder heads and flush the engine before refilling with coolant? It is possible you have disturbed some "crud" during the draining/refilling process and this is lodged somewhere in the system causing an air lock; this air pocket will be compressed to system working pressure as the coolant expands during engine operation and when the engine is switched off, the water temperature rises further and the pressure increases until the pressure cap setting is reached and the cap vents the excess pressure to atmosphere. The pocket of compressed air then acts as a pump by expanding and pushing an eqivalent volume of fluid through the system until the air pressure drops below the cap relief pressure. It is possible the fluid quantity you observed escaping is a consequence of this problem.
If not, you will need to do a compression test on each cylinder to see if there is a possible blown head gasket/cracked or corroded head allowing compression pressure into the cooling circuit. This may be confirmed by removing the lead from the coil to the distributor to stop the engine starting, installing the pressure cap and cranking the engine on the starter motor for about two minutes and immediately cracking the pressure cap open whilst listening for the sound of escaping pressurised air from inside the radiator. This is not fool-proof as it depends on the extent of compression leakage past the head gasket but can confirm low compression readings resulting from a blown gasket. |
Phil Sproston
Unregistered guest
Posted From: 203.109.249.138
| | Posted on Wednesday, 10 March, 2004 - 19:32: | |
Peter
On your SS2 you should have a fan on the front of the radiator which is connected to the air comditioner. Firstly, is there one on the car and, secondly, is it working? The engine should be spotlessly clean because heat doesn't transfer through grease efficiently and I haven't found, on all the cars that I've worked on, a car that doesn't need some sort of clean, from a quick spray to a complete degrease. Also you could try checking if the viscous coupling is working correctly. It may sound silly but has the radiator been checked for flow rate?
Phil Sproston
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John Dare
Unregistered guest
Posted From: 144.138.194.13
| | Posted on Wednesday, 10 March, 2004 - 21:32: | |
Peter, I dont think you have mentioned to readers that your engine was (as I recall?) fully re-built by a authorised R-R agent in fairly recent times. Consequently, I would assume that the block is internally "clean" or at least cleaner than normal. Cant imagine therefore, that your apparent overheating is being caused by anything really serious. Have you discussed with Bob C? If anyone will work it out, he will. |
PETER DIXON
Frequent User
Username: petenlinid
Post Number: 14
Registered: 8-2003
| | Posted on Thursday, 11 March, 2004 - 17:56: | |
Many thanks David, Martin, Phil and my reluctant "e-mail" friend and mentor John Dare. My apology for a slow response, I have been away. John is correct the engine was completely rebuilt about 30.000 ago by a company of considerable standing within the RR industry. Prior to I departing I drove the lovely lady for an hour or so. The temperature on the gauge was a little over mid way of the centre point. When I stopped there was no apparent upsurge of pressure or temperature rise at all. I guess I will have to wait for another 42-44 degree day to really test things out. I will in the mean time take a look at those items suggested.
Peter
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