Cooling system - How many vent pipes
Discussion
I am re-piping my cooling system on my 350se.
There are 3 vent / fill pipes going to the expansion tank, which seems over complex.
* One from the radiator
* One from the heater pipe in the Vee
* One from the Swan neck
To simplify the piping I am eliminating the Plenum intake heater (only needed in Artic conditions?)
Has anybody successfully reduced the number of vent pipes ?
David
There are 3 vent / fill pipes going to the expansion tank, which seems over complex.
* One from the radiator
* One from the heater pipe in the Vee
* One from the Swan neck
To simplify the piping I am eliminating the Plenum intake heater (only needed in Artic conditions?)
Has anybody successfully reduced the number of vent pipes ?
David
19560 said:
I think that you're going down a dangerous road. Because the top of the engine is above the top of the rad air pockets develope and these pipes try to remove them.
Agree the highest one is necessary but surely the air in the rad and heater pipe will find it's way to the Swan neck vent.
I have had the system significantly altered on my 450 to cope with Aussie summers and I understand that the number of pipes has been reduced (I haven't got the car back yet so can't really be more specific or say what it's like).
The expansion tank has been changed to a Range Rover item with a single bottom outlet and various mods to pipework and routing to improve flow. The guy I am using has worked for the last 20 years on RV8 both in UK and here now so I am hoping he knows what he is doing.
When I get it back I will try and be a bit more specific on the pipework mods.
As far as venting the top of the engine for air then I would have thought that once the system was correctly filled then as long as there is always coolant in the expansion tank and there are no other vents then unless you have a leak somewhere and air enters when the system is cooling (and contracting) I can't see how the top of the engine can get any air pockets ?
>> Edited by chunder on Wednesday 9th June 13:19
The expansion tank has been changed to a Range Rover item with a single bottom outlet and various mods to pipework and routing to improve flow. The guy I am using has worked for the last 20 years on RV8 both in UK and here now so I am hoping he knows what he is doing.
When I get it back I will try and be a bit more specific on the pipework mods.
As far as venting the top of the engine for air then I would have thought that once the system was correctly filled then as long as there is always coolant in the expansion tank and there are no other vents then unless you have a leak somewhere and air enters when the system is cooling (and contracting) I can't see how the top of the engine can get any air pockets ?
>> Edited by chunder on Wednesday 9th June 13:19
chunder said:
As far as venting the top of the engine for air then I would have thought that once the system was correctly filled then as long as there is always coolant in the expansion tank and there are no other vents then unless you have a leak somewhere and air enters when the system is cooling (and contracting) I can't see how the top of the engine can get any air pockets?
I think that you have misunderstood me. It is the pipes that tend to develop air pockets. Chunder, once you are running your car do not rely on an expansion tank level check, always check the swan neck as well. It is the swan neck where air pockets develop even with an overflowing expansion tank!
David,
to go back to your original question...
Yes, it is possible to remove the heating chamber under the plenum from the cooling circuit without any obvious problems. However, I think removing any more pipes is likely to cause problems with air-locks.
I have also routed two other pipes from the expansion tank across the top of the engine, these go to the inlet manifold and the swan neck. (most cars I look at now seem to have this done)
It is also critical that the bent hose joining the thermostat housing to the swan neck is as short as possible, making the filler cap on the swan-neck as LOW as possible, this helps prevents air from accumulating in the swan-neck..
Hope that helps,
Brian (and a Red 350i)
to go back to your original question...
Yes, it is possible to remove the heating chamber under the plenum from the cooling circuit without any obvious problems. However, I think removing any more pipes is likely to cause problems with air-locks.
I have also routed two other pipes from the expansion tank across the top of the engine, these go to the inlet manifold and the swan neck. (most cars I look at now seem to have this done)
It is also critical that the bent hose joining the thermostat housing to the swan neck is as short as possible, making the filler cap on the swan-neck as LOW as possible, this helps prevents air from accumulating in the swan-neck..
Hope that helps,
Brian (and a Red 350i)
19560 said:
As far as venting the top of the engine for air then I would have thought that once the system was correctly filled then as long as there is always coolant in the expansion tank and there are no other vents then unless you have a leak somewhere and air enters when the system is cooling (and contracting) I can't see how the top of the engine can get any air pockets?
I think that you have misunderstood me. It is the pipes that tend to develop air pockets. Chunder, once you are running your car do not rely on an expansion tank level check, always check the swan neck as well. It is the swan neck where air pockets develop even with an overflowing expansion tank!
Ok thanks, I will bear that in mind although if all connections are airtight under vacuum then in theory this shouldn't happen.
When calculations were done on the cooling system apparently it had 35% of the performance required to keep it cool whilst stationary on a 40 degree day - the mods are supposed to cope with this so once I have it back I will try and list the pipework changes etc as if it works then the same mods may be useful even for an English summer.
Chunder - The final result will be interesting - If it works for you then OK here.
During the re-pipe (old cracked hoses replaced with Silicon) I have removed the Plenum heater connections and the heater pipe vent (behind the pump) but will manully bleed at the heater end when initial filling.
Otherwise standard connections but still believe the sytems more complex than necessary.
During the re-pipe (old cracked hoses replaced with Silicon) I have removed the Plenum heater connections and the heater pipe vent (behind the pump) but will manully bleed at the heater end when initial filling.
Otherwise standard connections but still believe the sytems more complex than necessary.
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