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Dan F
USA
843 Posts |
 Posted - 03/08/2010 : 00:21:02
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I haven't really had too much time to work on the P type. Engine is rebuilt and every once in a while I go out and let the engine run for 5-10 minutes. Today I let it run alittle longer than normal 10-15 minutes. Again, engine rebuilt, rad rebuilt and new water pump purchase 4 years ago and finally used. After 10-15 minutes Rad temp gage read around 85 F and engine seemed to be running hot. Antifreeze was streaming out of the rad overflow tube but I don't think the rad was overfilled - perhaps 1 inch from top when I started. Everything seemed to be running hot so I turned the engine off. Any suggestions or test I can run. Any suggestions for Rad temp gage reading when typical PA engine warmed up ?? How can I tell if the water pump is wooking ?? Any other ideas ??
Thanks,
Dan |
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Keith Wallace
United Kingdom
367 Posts |
Posted - 03/08/2010 : 08:23:43
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Hi Dan,
My PB runs at between 85-95c, but will go to boil if I leave it ticking over in the garage.
I have fitted an electric fan & thermostat to avoid this problem, but have never required the fan whilst driving.
As the hose connecting the bottom of the radiator and pump is a very tight one, I would suggest you check that water is not being restricted by a bent or twisted hose.
Hope this helps.
keith |
Edited by - Keith Wallace on 03/08/2010 08:26:48 |
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Peter Scott
United Kingdom
1240 Posts |
Posted - 03/08/2010 : 09:25:50
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Dan
I think that you are overfilling your cooling system. My PA which like yours has a pump settles at 5/8 inch from the bottom of the header tank. That's more like 2.1/2 inch from the top.
Peter |
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George Eagle
United Kingdom
3237 Posts |
Posted - 03/08/2010 : 18:04:43
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Hi Dan
I agree with Peter - it would appear you are overfilling the radiator and the water coming out of the overflow must be due to expansion?
Running the engine for 10 to 15 minutes whilst the car is static will cause the temperature to rise, I think 85 degrees is not too high after this length of time.
I run my supercharged NB with a thermostat which opens at about 80 degrees and I definately require an electric fan if stood too long in traffic. My L2, which is also supercharged, runs at about 70/75 degrees (without a thermostat) in the current warm weather, but it definately heats up quicker than the NB when stood still for a relatively short period. The engines of both cars are of the same capacity but the L rad is smaller than the NB!
I am fitting a fan to the L and I think I will also use a thermostat when the weather is cooler.
George |
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Onno
Netherlands
1044 Posts |
Posted - 03/08/2010 : 21:18:22
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Dan
you can always check the temp gauge by just putting the sender in a kettle and heating it until it boils.
In that way you know where the 100 degree mark is and know to keep slightley belowe.
Onno |
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Bruce Sutherland
United Kingdom
1564 Posts |
Posted - 04/08/2010 : 00:52:17
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In engineering terms it is generally accepted/good practice that engine water/coolant temperature should run as near as possible to 212F/100C (water boiling point) as a well-warmed engine improves combustion and raises oil temperature (which reduces oil degradation/sludge formation/caramelling – seen inside the camshaft/rocker cover - thus alleviating oil lubrication restrictions and lessening mechanical wear.
Following this logic it is advisable to fit a coolant thermostat – usually an in-line thermostat inside the top hose.
Originally most Triple-M cars were fitted with a thermosiphoning cooling system i.e. with neither a water pump nor a thermostat – doubtless for cost, and in the mid 30s, thermostats were neither well-developed nor readily available).
Thermosiphoning offered a simple system but with many compromises – slower warm up, generally lower running temperatures except in high load, hot weather, or low speed stationary traffic jam situations. The ‘sizing’ of the thermosiphoning cooling system was almost certainly designed by development trial-and-error to meet the worst case engine heat output/road speed/gear conditions.
The net result being that at most ‘normal’(UK) driving and northern European conditions the engine temperature would be less than optimal.
The fitment of water pumps to the higher-powered (supercharged) vehicle variants increased the water flow velocity through the engine and radiator to improve cooling.
BUT the physics of heat exchange is primarily influenced by temperature difference between the hot fluid (engine water/coolant) and the cold fluid (air through the radiator), HENCE BOTH increasing the water/coolant temperature with a thermostat AND a pump to increase water/coolant velocity aid heat rejection performance from the radiator.
Low speed/city traffic/idling conditions mean minimal airflow through the radiator, hence the need for forced convection with the aid of a fan.
Good water-side heat transfer requires clean/no rust/no sludge deposits both inside the engine and inside the radiator – plain water coolant cannot recommended as this leads to much corrosion/rust/sludge.
Similarly the air passageways through the radiator should be clean – no flies/road debris/oil/etc.
In summary improve:
1. Water-side conditions by raising the temperature with a thermostat and water velocity/flow rate with a pump.
2. Radiator airflow – for low road speeds/idle add a fan.
3. Cleanliness.
Bruce. (PB0564) |
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Peter Scott
United Kingdom
1240 Posts |
Posted - 04/08/2010 : 09:46:45
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quote:
Originally posted by Bruce Sutherland
In engineering terms it is generally accepted/good practice that engine water/coolant temperature should run as near as possible to 212F/100C (water boiling point) as a well-warmed engine improves combustion and raises oil temperature (which reduces oil degradation/sludge formation/caramelling – seen inside the camshaft/rocker cover - thus alleviating oil lubrication restrictions and lessening mechanical wear.
Following this logic it is advisable to fit a coolant thermostat – usually an in-line thermostat inside the top hose.
Originally most Triple-M cars were fitted with a thermosiphoning cooling system i.e. with neither a water pump nor a thermostat – doubtless for cost, and in the mid 30s, thermostats were neither well-developed nor readily available).
Thermosiphoning offered a simple system but with many compromises – slower warm up, generally lower running temperatures except in high load, hot weather, or low speed stationary traffic jam situations. The ‘sizing’ of the thermosiphoning cooling system was almost certainly designed by development trial-and-error to meet the worst case engine heat output/road speed/gear conditions.
The net result being that at most ‘normal’(UK) driving and northern European conditions the engine temperature would be less than optimal.
The fitment of water pumps to the higher-powered (supercharged) vehicle variants increased the water flow velocity through the engine and radiator to improve cooling.
BUT the physics of heat exchange is primarily influenced by temperature difference between the hot fluid (engine water/coolant) and the cold fluid (air through the radiator), HENCE BOTH increasing the water/coolant temperature with a thermostat AND a pump to increase water/coolant velocity aid heat rejection performance from the radiator.
Low speed/city traffic/idling conditions mean minimal airflow through the radiator, hence the need for forced convection with the aid of a fan.
Good water-side heat transfer requires clean/no rust/no sludge deposits both inside the engine and inside the radiator – plain water coolant cannot recommended as this leads to much corrosion/rust/sludge.
Similarly the air passageways through the radiator should be clean – no flies/road debris/oil/etc.
In summary improve:
1. Water-side conditions by raising the temperature with a thermostat and water velocity/flow rate with a pump.
2. Radiator airflow – for low road speeds/idle add a fan.
3. Cleanliness.
Bruce. (PB0564)
Well that's the 'Rolls Royce' answer. The alternative is fill it up to say 3/4 inch above the bottom of the header tank and 'just drive it'. My guess is that it will be fine. Perhaps not RR super efficient but lots of fun. 
Peter |
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DavidK
United Kingdom
14 Posts |
Posted - 04/08/2010 : 09:53:01
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Hi Dan,
All the above expert technical advice is true, but if I understand correctly your engine is newly rebuilt and has not been "run-in" on the road?
If so I would expect a rebuilt engine to be "tight" and consequently run hot, especially if static, until it has been run in.
David Kenny
PA2038 |
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Chris Bucknell
Australia
107 Posts |
Posted - 04/08/2010 : 10:23:50
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Hi Dan,
My thoughts are as follows. Please bear in mind that I am in Australia so we don't get sub freezing conditions but do get some quite hot ones. My experience is based on observations from supercharged cars which of course are going to have more overheating issues.
1. I also agree, check the operating of your temperature gauge. The kettle test is easy enough if you can find a kettle to keep the boil out near the car or just pop down to the chemist and get a thermometer.
2. I agree with previous people I think you are over filling the coolant. Just put a catch can under the outlet for the overflow. Then take the car to near boiling and stop. Let car cool and that is the level you should normally fill to.
3. Buy yourself one of those infrared hand-held temperature gauges that you can get quite cheaply now. They are invaluable for diagnosing many things including 1. water temperature, sump temperature, tyre temperature, exhaust temperature (ie one cylinder not firing or too lean a mixture) etc. Use this to check the water temperature in the radiator.
4. Checking that the water pump is working is very easy. Take outlet pipe off and turn on car. Very messy but really only way I can think of.
5. In my experience the engine oil temperature is a significant contributor to water temperature. You must get the oil to an operating temperature before you can diagnose the cooling issue. Oil temperature is very strongly affected by air flow over the sump. If you stop the air flowing over the sump the oil temperature will climb almost immediately and soon thereafter the water temp will climb. The flip side of this is that a lot of the cooling of the car occurs not only due to the flow of air through the radiator when moving but also the flow of air across the sump. That is why the fins are there. What oil temperature were you at when the 85 deg C was reached in water temp?
6. You really need to drive the car to see if you have an overheating problem. Do that after you have fixed the level issue to avoid well meaning locals flagging you down every so often to tell you that you have sprung a leak. Avoid hills and long climbs and avoid long stops and traffic. Take it on a cruise not a heavy run. Choose a cool day ie below 25 deg C. If it cruises OK ie with temp less than 95 deg C then I don't think you have an issue. Try a bit more load ie take it up a shortish hill and see what happens.
7. One possible cause of overheating maybe a lean mixture. You can put on dyno or maybe get a colourtune to diagnose that. Exhaust temperature is best indicator of that. Again grab your infrared temperature gun and check the exhaust temp where it comes out of the head. Alternatively you can usually tell if something is not right here, just by feel, assuming you know what it was like when mixture was OK. If the car is running lean the exhaust will get hot very quickly from start up.
8. If you have a definite over heating issue after all this then come back to the group. I have tried pretty much everything in terms of improving cooling on our cars.
In closing I was surprised by the efficiency of thermosyphon system even here in Australia last year when a pretty standard P-Type went on our big "Kimber Run" (>100km). The temperature on the day was 42 deg C. Yes it was a stinker. That P-Type (not mine) ran like a charm and outshone many of the more modern MG's.
Let us know how you go.
Chris |
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Brian Kelly
USA
526 Posts |
Posted - 04/08/2010 : 19:03:36
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Dan,
I found the best remedy for these symptoms is the following.
In the early morning of a warm day, less humidity the better, after checking ALL fluid levels and leaving the radiator cap OFF, start the engine and under idling conditions bring the engine and radiator coolant up to operating temperature.
Then, and here's the technical side of the equation, carefully drop two of the following tablets in to the coolant via the radiator aperture. Re-install the radiator cap immediately.
Drive the car 25 miles ensuring you have selected the full range of the gears and during which time monitor the temp readings of the coolant and oil
If this didn't cure the problem I would be most surprised.
http://www.chemicalland21.com/lifescience/phar/ACETYLSALICYLIC%20ACID.htm
Failing this, call us in the morning we're here to care for you and your car.
Enjoy!
Brian.
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Edited by - Brian Kelly on 04/08/2010 19:12:17 |
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Bruce Sutherland
United Kingdom
1564 Posts |
Posted - 05/08/2010 : 09:59:52
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Hi Chris,
Your experience with the effectiveness of thermosyphon cooling systems in the Australian heat is entirely consistent with my original comments……..”thermosyphoning systems ‘sizing’ ……. to meet the worst case engine heat output/road speed/gear conditions.”
However I suspect your Kimber Run did not involve much low speed or idle running conditions where the themosyphoning system, with low air velocity through the radiator, is at a disadvantage.
Air temperature in the lower 40 degrees C was often a design target for ‘air-temperature-to-boil’ (ATB’) for UK car manufacturers in the 1960’-70’s, hence a likely cause for the marginal cooling on the more modern MG’s to which you refer.
Bruce. (PB0564) |
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Dan F
USA
843 Posts |
Posted - 05/08/2010 : 12:11:19
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Guys:
Thanks for all the help. Does anyone have a lead on company and model for the thermostat ?? Also, I have not hooked up my oil temp gage yet. I assume that I'll need to have a hole drill in the sump for the bulb of the gage. Is this correct. As far as the other comments go, I may have some time this weekend to try some of the recommendations and get back with some answers.
Thanks,
Dan |
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Terry Andrews
United Kingdom
546 Posts |
Posted - 05/08/2010 : 13:08:50
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Dan
Look up thermostats on the search function to get the info.
Terry |
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Brian Kelly
USA
526 Posts |
Posted - 05/08/2010 : 15:11:10
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Dan,
Restoration Supply Company, CA. stock an inline thermostat that fits perfectly in the top hose.
1-1/2" dia. 2-1/8" long. Item # ACC 038.
http://www.restorationstuff.com/
The Temp. gauge bulb fits directly into the off side of the sump. There is a brass plug already installed at this location.
Brian. |
Edited by - Brian Kelly on 05/08/2010 15:17:15 |
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Brian Kelly
USA
526 Posts |
Posted - 05/08/2010 : 15:53:26
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Correction to the above statement.
The bulb connection is Female. You would require a BSP male/male connector. I'm not sure of the BSP size.
Brian. |
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Dan F
USA
843 Posts |
Posted - 08/08/2010 : 22:05:42
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Thanks guys for all the advice. Lots to pursue but after a little work this weekend, it appears like I had too much antifreeze in the radiator. I do want to try a therm, fan and some of the other suggestions but overfill was definitely a factor. Now having clutch problems. See new post.
Thanks,
Dan |
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