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flushing the block


bob dunn

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my car is running very hot even with recored rad ,no thermostat ,50/50 coolant and water.so do you flush the block or do you take of the water pump to get the silt out of the block. how do you empty the systemjust draining only gets1/2 a gallon.??? car is 75 1300 spit

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There is a block drain plug towards the back of the block on the carb/exhaust side.  Remove this - if your block is silted up, then nothing will come out (or a trickle).  Water should flow freely when this plug is removed.

To fully drain down the system, take the radiator cap off and disconnect the bottom hose at the radiator, and also remove the block drain plug.  

There are some proprietary engine descaler products out there (like the stuff you use on your kettle/steam-iron, but on steroids).  I cannot remember the name of the one I used last time, but boy it did the job :-).  It consisted of two bottles, one to shift the sludge, and one to dissolve the harder stuff.  A full descale took about an hour with several cycles of running the engine up to temperature and then letting it idle for 15 minutes with each of the compounds added to the coolant in turn, with several complete flushes interspersed.

However, before you start flushing the block, check the obvious:  is there anything stopping the air getting to the radiator (like a large number plate?  :-/)
Also, do you have the radiator side panels in place (part numbers 16 and 17 in this diagram:   http://www.canleyclassics.com/catalog.asp?category=200208041050123385868557 )?  These are needed to make sure that any cooling air that makes it past your number plate actually goes through the radiator instead of spilling around the edges.

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Have a good poke about in the block drain hole with a stiff piece of solid conductor wire. If coolant doesn't run out initially, having a good poke about will release an alarming amount of rusty flakes of crud- you'll be amazed at the amount of rubbish that comes out of that little hole ;D Then back flush with a hose pipe and repeat the exercise until it runs clean.

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after cleaning my system out numerous times, fitting the side boards, running no thermostat etc, i still had a temp reading at 3/4 way up the guage. perplexed, i stuck a temp probe hooked into a multimeter into the top hose, went out for a burn and my water never went past 79.9C. obviously i have a dodgy guage, but at least i can rest assured its not overheating. my system is totally standard, no re-cored rad, no electric fan, not even any coolant, just water.

one thing i wondered though - is it possible to have the guage reverse wired so it sends the needle the wrong way or something ? i ask because numerous people have told me if you switch the blower on, the temp should go down - however on mine the temp goes up with the blower on. the reverse of what i've been told should happen. coupled with the fact that if my guage was reading right instead of 3/4 it might only be at about 1/4 (not sure where 80C is relevant to the guage) it gives me the impression my guage is just reading backwards.

possible ?

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bob - really ? well perhaps mine is normal then. though when i brought this problem up before it was suggested i needed a new guage. im on a mk3 though, might be different ? seems a bit bizarre that they would have the operating temp half way round the guage, making the first half of the guage pointless ?

charlie - i shall get on the case. havn't got any in the garage, and its just not one of those things i remember to do. topping up the oil more often than the petrol takes up my 'remembering to do stuff' allocation.

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new voltage reg fitted gauges now ok, took out plug in block and got a big flow of green coolant  fitted new plug with a tap from spare engine .spare seized engine has saved weeks and euros (pounds) .total mileage 210. two tyres turned on rims because they were running backwards, it made traffic islands easy. also moved the front number plate down of the bumper, for better flow .

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