cooling fan viscous coupling fitting

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guzet-neige84

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28
hello,i have tried to turn by hand the engine belt but it will not turn so what i gather its the cooling fan viscous coupling that has seized? ive had a look under the shroud and i see a large nut inbetween fan and engine,is this what needs to be loosened?is the coupling the fin part in the middle of the fan itself? if that is correct i have seen for sale a coupling and fan complete,is it a matter of undoing the large bolt and putting new one on?any help would be greatly appreciated so i know what to buy and do.would the nut need a special spanner and is it right or left thread?many thanks,paul
 
hello,i have tried to turn by hand the engine belt but it will not turn so what i gather its the cooling fan viscous coupling that has seized? ive had a look under the shroud and i see a large nut inbetween fan and engine,is this what needs to be loosened?is the coupling the fin part in the middle of the fan itself? if that is correct i have seen for sale a coupling and fan complete,is it a matter of undoing the large bolt and putting new one on?any help would be greatly appreciated so i know what to buy and do.would the nut need a special spanner and is it right or left thread?many thanks,paul

Undo the nut in the direction the fan spins. My diagnosis is confirmed then.
 
Hang on - "i have tried to turn by hand the engine belt"

No, you need to try to turn the fan blades! The plastic fan should turn fairly easily on the viscous hub when it's cold.

The idea is when cold that the fan blades turn slower than the engine (therby producing less cooling effect) until the engine warms, then the viscous 'thickens' to provide a more rigid association with the engine speed, providing a greater cooling effect. Simples! When the VC fails, it won't turn easily when cold, delaying the warm up.

Do a search on here for 'the rolled up newspaper test'.

If you do need to remove the fan, you need a spanner the right size for the big nut, and as Wammers says it undoes in the direction the fan turns, I've found that the best way to prevent the engine turning in sympathy is to jam a rag in between the belt and pully.

Good luck.

Alastair
 
Last edited:
Hang on - "i have tried to turn by hand the engine belt"

No, you need to try to turn the fan blades! The plastic fan should turn fairly easily on the viscous hub when it's cold.

The idea is when cold that the fan blades turn slower than the engine (therby producing less cooling effect) until the engine warms, then the viscous 'thickens' to provide a more rigid association with the engine speed, providing a greater cooling effect. Simples!When the VC fails, it won't turn easily when cold, delaying the warm up.Do a search on here for 'the rolled up newspaper test'.

If you do need to remove the fan, you need a spanner the right size for the big nut, and as Wammers says it undoes in the direction the fan turns, I've found that the best way to prevent the engine turning in sympathy is to jam a reg in between the belt and pully.

Good luck.

Alastair

A good point but he was told how to check the fan in an earlier thread. Hope he took notice, trying to turn the engine with the fanbelt is a little difficult at the best of times.:):):)
 
thanks guys...mind boggling stuff:confused: i found this morning that i could turn the fan easily enough,so will that mean coupling is ok? if so i take it lots of air in system so try to get air out,and check stat?sorry for asking these questions but i do very much appreciate all your help and want to get this fixed.
 
thanks guys...mind boggling stuff:confused: i found this morning that i could turn the fan easily enough,so will that mean coupling is ok? if so i take it lots of air in system so try to get air out,and check stat?sorry for asking these questions but i do very much appreciate all your help and want to get this fixed.

If there is air in the system it should be running hotter not cooler. Unless water is not getting to the temp sensor but this is unlikely. Check for air and the stat then, maybe Data has a point. But in all my years i have never know one to stick open or fail open. If they lose their wax they fail shut and cannot open leading to overheating never cold running. Many stats now have a bypass valve that allows some flow to prevent total loss of cooling if they fail. This bypass is closed when the stat opens to allow full flow.
 
ok,thanks.one last question...what would you recommend as the correct antifreeze for the 1996 p38?unipart universal non methanol? when you drain cooling system is there two taps near the cylinderhead to drain engine?i have an old range manual and dont know if that means for the p38 or the classic?i was going to undo the plug under radiator and then top up in the reservoir,would this be right?many thanbks,and i will get there in the end with all your help:)
 
I think there are two drain plugs? One as you mentioned in the bottom of the rad and one in the block near the turbo.
 
im not sure if its deisel or petrol but, i would try and check the earth strap, it can cause a poor signal for the temp sensor. easy check is to put a jump lead from battery earth to engine, keep it away from moving parts, if the temp reads better or more in the range you would expect then put a secondary earth on!!
 
thanks guys for your thoughts.i will look for other drain plug,and i will also try the jump lead to see if it helps sensor,i need to try all i can,so thanks for your help!!:)
 
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