upper radiator hose

[turboedbug]

The upper radiator hose that tee's off and goes to the expansion tank ball. Does that have some sort of plug in the end or check valve? Mine has something in the end of that hose

[theman53]

restrictor

[turboedbug]

Yup u are correct finally found a post talking about it. Mine was clogged....its gone now

[ORCoaster]

OK, why would they do that?  Any insight from theman53 would be appreciated.  My MK1 just flows like crazy back into the reserve tank.  Getting it to generate back pressure would do what for the cooling system?  I am lacking comprehension on this one.

[TylerDurden]

The small hose is just to bleed out air, and not divert much coolant away from the radiator.

[libbydiesel]

I agree.  Any coolant flowing from that small hose will bypass the radiator and so reduce the effectiveness of the cooling system.  Limiting the flow is wise.  15 years ago I had the restrictor clog on a mk2 and it made for some odd cooling temperature behavior.  I kept the restrictor, but added an inline metal mesh fuel filter before it to catch anything that might clog the restrictor.  After having the filter in place for a while it was remarkable how much crud it caught despite having fresh coolant; rust flakes, bits of silicone sealant, etc...

[ORCoaster]

I agree there is a ton of gunk in the cooling system.  You have to wonder why manufacturers don't include something comparable to an oil filter on the cooling side.  That tiny inline filter I think you are talking about Libby is only a couple inches long and about an inch round isn't it?  I would think something more along the line of a 3 inch by 1.5 from a small gas engine or lawnmower would do the job.  There's an engine mod I don't see, cooling system filter.  Maybe the cleaning interval would be too short for most people to deal with.  It would have to be a cleanable filter like that wire mesh thing to be reusable.

[libbydiesel]

It was like this:



I ran it for approx. 4 years that way before selling the car.  It never actually plugged up but did show quite a bit of crud by the end of that time.  Whenever I'd pop the hood for someone who knew cars they would always ask why I had a fuel filter in by coolant hose.

[ORCoaster]

Why that isn't even the cool Chrome and glass one I had in mind.  More like the mower version.  I think I might find my old one I had on the Ford gasline and see what I collect in the next several weeks.  Just for crud fun.

[air-cooled or diesel]

and not divert much coolant away from the radiator.

I agree.  Any coolant flowing from that small hose will bypass the radiator and so reduce the effectiveness of the cooling system.

i havent seen an older mk1 or a restricted small by-pass with a ball or such; but on my 2 mk2's the upper radiator hose with the small by-pass to reservoir, is post radiator, the coolant doesnt by-pass the radiator, its at the top of the cooling system and is over-flow for the reservoir and flow, maybe also for air so it burps out and doesnt flow (air) to head, and back thru system. but on mine the by-pass to reservoir is post radiator.

After having the filter in place for a while it was remarkable how much crud it caught despite having fresh coolant; rust flakes, bits of silicone sealant, etc...

I agree there is a ton of gunk in the cooling system.

a lot of scale and other gunk are fairly normal for a cooling system, seems a lot to us, but its normal, as long as its not too much; and you can have funny cooling problems, and cannt find what it is, or fix one part, it works for a while, and cooling problems again.
as far as a filter, the water pump has almost no type of flow for a filter, its an impeller at the bottom of water jacket, run by a v-belt, pushing water/coolant up thru rad down jacket, back to pump, not much real pressure by design, flow is what you want, the pressure is from the rad/res cap &water heating up, the pressure is mainly to increase coolant boiling point, not for flow characteristics. and the system at no point maybe other then a radiator hose or 2; a short lower hose and the upper rad hose, is sealed at any point, water is going all places, controlled to go down the head and jacket, and thru heater core, etc and flow.

[libbydiesel]

but on my 2 mk2's the upper radiator hose with the small by-pass to reservoir, is post radiator, the coolant doesnt by-pass the radiator, its at the top of the cooling system and is over-flow for the reservoir and flow, maybe also for air so it burps out and doesnt flow (air) to head, and back thru system. but on mine the by-pass to reservoir is post radiator.

Your post sounds like you are thinking the entire system flows backwards.  Air cannot flow 'into the head'.  The only way coolant flows into the head is from the block.  Both ports at the head flow OUT.   The top of the radiator is HOT, the bottom is COLD.  The top is also the high pressure side of the radiator and the bottom is the low pressure side.  Any coolant going from the top of the radiator to the expansion tank does not pass through the radiator and is not cooled.  It returns back to the engine uncooled into the center port (heater return) of the water pump.  The heater return is unregulated by the thermostat so limiting the flow of uncooled coolant on that circuit is very wise.

[air-cooled or diesel]

thats got to be my bad;; i ve got to check 1 of my manuals shows a fairly good pic of coolant flow, iirc, have to look in it.
for 1 thing the older mk1's didnt they have a manual flow cut-off from vent panel? it is inbetween head and heater core, dont remember the old vent set-up; then again an a/c older mk1's are rarer, later came 5th gear or E gear, and a/c was more common. i was going to say as far as a filter in cooling sys, if you rigged up a fancy (some kind of) flow filter; (i wouldnt know how it would be possible to full flow it); unless you did some extra fancy unnecessary plumbing. but a filter you can drop or unscrew, and clean-out or change out. but in the most part i ve heard this is unnecessary, and a filter will slowly cause more of a restriction, maybe from 1st start-up and on. the scale & debris and gunk that gets around system much is normal, flush when doing wp. the uum, by-pass line to reservoir is a very good tool for flow, as system stays air free and flow has a run-off route, at the top of sys, i wouldnt worry about the by-pass to res. its constant but not much; look at the size of upper and lower rad hoses and the by-pass is quite small. the heater core is quite a bit more than by-pass,

[libbydiesel]

The filter works to keep the bypass restriction from being clogged by a single piece of debris.  It doesn't really matter if it is a restriction.  The bypass line is only there to bleed air.  You just don't want it to plug completely. 

Heater circuit is more flow than the bypass line, but it is closed when the heater temp is switched to cold and when it is open (switched to hot) the ambient temp is usually cold and the coolant is cooled by the heater core/fan blowing the heat into the cabin.

[air-cooled or diesel]

Heater circuit is more flow than the bypass line, but it is closed when the heater temp is switched to cold and when it is open (switched to hot) the ambient temp is usually cold and the coolant is cooled by the heater core/fan blowing the heat into the cabin.

i know the older mk1s the heater core flow was controlled by the vent cold/heat setting; this they did away, i have no idea when, i forget my lost 84 if it had this or the cold/hot controlled vent doors, but my 86 the heater core always gets coolant flow but the vent door of course can bypass the core. what i was asking as far as this old shut off heater water flow feature is in these models does the vent cold/hot slider control vent doors also? or does outside vent air flow thru a cold not flowing heater core? and to vents?

[ORCoaster]

In the older MK1 I have there are no doors that change the flow of air.  It is the second choice you noted.  Heater core is not getting hot water in it so air just comes on in from outside.  What ever temp is outside soon becomes temp inside.  If you want a bit warmer then bump the temperature slider to the red zone.  But you can't make it cooler unless you have A/C. Or a wet towel.