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Post by redherring on Aug 25, 2012 14:51:40 GMT
Hello everyone,you have been good enough to help me before,and would be grateful for your input with an ongoing problem. I Have a 72 P5B which i have spent nearly three years restoring to something approaching top condition. All areas which could affect everyday reliability have been attended to,not least of which is a brand new 4.6 V8. This was undoubtedly a mistake,but whats done is done. Amongst the endless new parts are; Large capacity rad,water pump,hoses,conversion to elec fuel pump,kenlowe fan. The car (sorry,that should be Percy) runs beautifully but i'm unable to have complete confidence in him as every time he stands in traffic for more than 5-10 mins he edges ever closer to the red (even with fan running). This eventually leads to petrol starvation and he breaks down. The thermostat was removed but makes no difference other than now running too cool whilst moving. I can only assume that the larger engine and modern petrol are causing excess heat. Anyone have any ideas? Any success with totally different rads or fans,or any experience with the option of wrapping exhaust manifolds in heat soak material? I am a mechanic,and i amazingly still have some money left to spend on him! He now looks magnificent after a toal strip down and respray,but i am not enjoying him as i should as in the back of my mind i am always dreading a queue around the next corner. Cheers,Tim H
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Post by johnwp5bcoupe on Aug 25, 2012 16:19:07 GMT
This will be a better place for help Tim as most guys run a 3.5 On a personal note last weekend it was baking hot stuck in traffic for 5 miles and I had no overheating problems! I am sure someone here will be able to help Good Luck I hope you sort it.
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Post by felixlighter on Aug 25, 2012 19:15:38 GMT
Kenlowe fan fitted , what size and what temperature is the stat set to? A quality good sized fan should remove enough heat at low engine speeds with the car stationary, I have two 8 inch fans at the top of the rad and struggle in hot weather but two 8 inch fans don't make a 16 inch fan, so size is important. Are you positive that the air bleed hose from the highest point of the cooling system is not blocked?that is the small hose from the inlet manifold to the rad. Are you running engine management or carbs? weak mixture will increase combustion temperatures, anyway never mind the negatives with overheating, what is it like to drive with a more power full engine? worth the effort? how about some pictures of your conversion and work repairing so far, I'm sure we'd like to see them.
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Post by Smallfry on Aug 25, 2012 21:30:21 GMT
What size fan/s do you have, and is it fitted in front of, or behind the radiator ?
Does the engine run at normal temperature while the car is moving ?
Where is the fuel pump situated ? What make and type is it ?
I assume you are running on the standard twin SU setup, with standard exhaust manifolds ?
Does the fuel system have a flow and return........i.e. standard ?
I have done quite a few V8 conversions to the old series Land Rovers, and have used the standard Land Rover rad along with an electric fan, and these rads are WAY smaller than the standard P5B type, and had no problems. The engines would get warmer of course when sitting in traffic, but did not overheat, or stall.
I dont think your problem is overheating as such, but more to do with the fuel system.............routing of components and pipes etc. Modern fuels ARE more prone to vapourisation, so you have to be careful with this. Some heat resistant pipe covering can help.
What will not help is setting the mixture too weak in an attempt to get more fuel economy. DONT do it, the engine will idle better, and run smoother, and it doesnt actually make much difference.
I am also of the opinion that Kenlowe and pacet fans are not powerful enough either, or the thermostat positioning and operation very good. Do they still use that silly probe that fits into the top hose ? I always use production car fans from a scrapyard and modify them to suit...............but I dont think that this is the root cause of your problem, especially with a bigger rad !
As the previous poster stated, CHECK the top air bleed hose on the inlet manifold if you have the standard carb set up !
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Post by redherring on Aug 26, 2012 8:33:55 GMT
Thankyou all for your replies so far. The pipe you mention is new,and yes i have checked both rad and manifold are clear. The kenlowe fan is on the front of the rad,not sure what temp its set to but i adjusted it to come on when gauge was just passing the middle. As with quite a few of the new parts i have fitted,i was disappointed with the quality of its manufacture,and suspect i shall end up doing as one of you suggested and put a different,more robust model from a scrapper on (perhaps on the engine side?).The facet type pump is in the engine bay,but i intend to move it to the back during the winter. Although it is fuel vapourisation that is causing him to break down,there is no doubt in my mind that Percy is definitely running too hot. I have just had the finishing touch of the white pin-stripe added,and if i say so myself he looks good,will try to get some photos on soon.The 4.6 engine now runs well,but i bitterly regret not taking time to overhaul old one,to the point that i may at some time source an old engine to recondition & fit. Afraid i couldn't recommend the company i bought the engine off,had several problems which came down to shoddy preparation/attention to detail. Thanks again,Tim H.
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Post by eightofthem (Andy) on Aug 26, 2012 9:01:09 GMT
Check the timing as well.
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Post by lagain on Aug 26, 2012 20:49:14 GMT
Is the radiator new ? I would suspect that the water is not going around fast enough and that there may be sediment somewhere. My Stag always ran hot until it had to have some engine work done on it and they back flushed the engine and recored the radiator. After that it ran cool. It helps to put the heater on hot, but you will need to open the windows !
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Post by redherring on Aug 27, 2012 7:45:16 GMT
Thanks for your interest,lagain,rad is new larger capacity (the extension piece promptly leaked and i had to get a local rad company to repair- i've seen better workmanship,have to say). Engine's new,hoses new,etc,etc. Hard to see where any sediment or blockage could come from.
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Post by allanthomas1 on Aug 27, 2012 17:26:34 GMT
I have been considering using waterless coolant, Evans supply it in this country, sounds really good, the boiling point is a lot higher than normal water and antifreeze mix might be worth a try. It is used in racing cars, classic cars, aeroplanes and commercial vehicles.
Just go on search and type in Evans waterless coolant, might be worth a contacting them.
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Post by redherring on Aug 29, 2012 15:17:45 GMT
Thankyou for that,may look it up online. Thanks to you all for your suggestions,i think this winter i shall move the pump to the back,perhaps install a separate temp gauge and larger elec fan.
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