Bleedin' radiator! HELP/discuss pls......

[ROD]

Just a filling point,or a filler with cap and do away with rad cap?
 had a re think ..how about ..putting a zero cap on the rad,and fitting a t piece with tallish neck,into the top hose(highest point on system),with a overflow tube on the side ala a normal rad set up,with a rad cap (7 lb) on this. Then run a hose from the overflow tube to the expansion bottle,as I am now ?..this would ensure that when I fill the system it has plenty of water,straight into the top hose(highest point).

[hunter]

A filler with a cap,and fit a higher pressure cap on the rad.
This is what they use in reliant race cars,If you look at the rear of the cyl head you will see what they call a swirl pot.the rad in this car is at a very low point.

Bleedin' radiator! HELP/discuss pls......

[ROD]

Thats quite an extreme set up,and  mustve taken a while to suss out!..........
 have just spoken to Fifer re the problem. He reckons that my rad being slightly lower than 'normal' isnt too much of an issue. A filler neck in the top hose would give more fluid in the system,but there wouldnt be an area in the system for expansion(ie the rad top tank would be full). this in itself would cause probs as there would be lots more water that would have to expand somewhere,and would require a very large catch bottle. Overall he reckons there wouldnt be an advantage to my suggestion.Also with the hot temps we are getting at the moment ,any system that isnt quite perfect will have water expanding and coming out the rad overflow....So my plan is to renew  the thermostat and rad cap just as a precaution ,and fit an even larger expansion bottle! I really dont know what other improvements can be achieved at this late stage.I may also fit a aly shield a couple of inches deep round the rad to channel air into the rad core.

[hunter]

Not extreme Rod,Pretty simple really,
A lot of motorcycles run fillers with pressure caps high above the rad.

[fifer]

As long as the top of the rad is slightly higher than the thermostat then that will leave enough room for the thermostat to open and let the hot water out into the rad .
The normal procedure with some of the Reliant rads is to only fill up to the top of the fins when engine is cold and the thermostat is shut .
This allows for expansion and , normally , no/or little water was expelled from the rad overflow which normally dumped on the ground .
By the very nature of this setup there will be no water in the top hose till the thermostat opens .
The expanded water from the thermostat will rise up the thermostat housing , travel along the hose , and drop into the top of the radiator which is filled with air above the water level at the top of the internal rad fins .
The hot water falls/is sucked down through the radiator by the water pump 
When the engine cools down and the thermostat close , then the rad top hose will be empty .

However , I would try ;
leave the rad cap off ,
fill the new top up coolant in through your " T " setup on the hose to the rear of the engine till the rad was filled up to the bottom of the neck of the rad cap tunnel   ,
replace the 7lb rad cap ,
continue filling till hose full .

Fit your larger expansion / overflow ,
slowly run the engine up to temperature , and the excess should be expelled into the overflow bottle { and , depending on size of overflow bottle , might overflow that } .
With the engine running and up to temperature , the hose from the water pump to the rear of the head should be evenly hot along its length and the same temperature as the other top hoses .
If not ,then you will probably have an airlock which is often removed by doing the following .
While the engine is running and up to temperature , place the hose from the water pump to the rear of the head between the palms of both hands and squeeze the hose to restrict the flow for a good few seconds ; release quickly and then squeeze again . Do this a few times and you should be able to feel the water pulsing through the hose as you release the squeeze and the hose will get hotter .

When the engine is fully cooled down , then you can remove the rad cap and that should be the level to aim for in the rad ?
.



 
 

[ROD]

Pete.................I thought you told me that it didnt matter too much if the rad was a bit lower? my rad is LOWER than the thermostat housing.The centre of the top house outlet is 3" lower than the centre of the thermostat housing outlet.ie the top hose goes UPHILL toward the thermostat outlet.
  Theres got to be a reason the water is p****ng out the rad cap . I realise it is expansion,but my thinking is that a' normal ' reliant doesnt do this?
 I have far more air rushing past the rad to keep it cool.
 Im wondering if I should fit a sealed system? ie zero rad cap on Rad, and expansion bottle with 7lb rad cap? Fit the bottle so that its top is level with the highest point of my system,ie the thermostat housing?
 What about fitting a much larger fan,or maybe another fan to the front of the rad?
 

[tbone]

Pete.................I thought you told me that it didnt matter too much if the rad was a bit lower? my rad is LOWER than the thermostat housing.The centre of the top house outlet is 3" lower than the centre of the thermostat housing outlet.ie the top hose goes UPHILL toward the thermostat outlet.
  Theres got to be a reason the water is p****ng out the rad cap . I realise it is expansion,but my thinking is that a' normal ' reliant doesnt do this?
 I have far more air rushing past the rad to keep it cool.
 Im wondering if I should fit a sealed system? ie zero rad cap on Rad, and expansion bottle with 7lb rad cap? Fit the bottle so that its top is level with the highest point of my system,ie the thermostat housing?
 What about fitting a much larger fan,or maybe another fan to the front of the rad?
 

It wont matter, the water flows out the stat into the rad so is effectively going downhill with your setup.
Your right, water heats up and it expands, as it does so it increases pressure in the system. The only escape for the pressure is via the rad cap into the expansion bottle.
It sounds as tho the system is working correctly except the water is leaking past the cap instead of going into the bottle. Why???
A faulty seal on the rad cap?
A faulty valve on the rad cap?
Too small an overflow tube into the bottle?
Too much pressure in the entire system?

The first 2 are easy to check....fit a new cap
Assuming the rad is stock reliant then the overflow pipe would be the right size for the intended setup.
Increase the boiling point of the coolant, by adding anti freeze it only expands and pressurizes as it heats.

[ROD]

Just waiting for Halfrauds to open to get new cap and thermostat. What I cant suss out is why so much water is expanding! As I said before if this happened on a reliant,it would lose all its fluid in next to no time!Hoping it is the cap! Should know by midday after I fit a new one and blast it up and down the bypass!

[tbone]

I just popped back to edit my post..... .......by adding........

Faulty thermostat would cause back pressure in the system.

[ROD]

OK Thanks everyone for your input,its very much appreciated,I shall report back later today on my findings after testing!

[Olds]

At the start of this thread you mentioned that the overflow pipe has a tight 90 degree bend. Is it possible that the pipe is kinked or is kinking when it gets hot restricting the flow to the bottle?

[ROD]

No I checked that! But Im wondering whether cos its stainless braided covered hose,it may be collapsing inside.Doubtful,but I'll check.I now have a straighter hose with only a gentle curve to the new bottle.

[ROD]

Couldnt get a thermostat or a cap anywhere round here. Checked stat seems to be opening ok. Put it all back together with 25/75 a/freeze in system,and fired it up.Filled it at 2 points..rad cap and t piece I have in the pump to rear of block hose. Left it running for a bit,until fan came on.
 Now heres the thing........As said before the rad is lower than the stat housing. I accept the argument that it wont matter as the top hose is running toward the rad,and the water flows that way any way,..BUT....I removed the rad cap and it being LOWER than the stat,and also lower than the pipe from pump to rear of block,the water drained out of the higher part of the system (ie the rear pipe) through the rad filler neck.So now there is some,but very little water in the rear part,and also to gain a air gap in the rad header tank ,more fluid needs to come out. It seems to  me that this water would splurge out ,whether the stat was open or not,cos the rad cap is lower than the rear pipe.Therefore ,surely it does matter if the rad is lower? OR should I have a pressurised system as I mentioned before?
 
 BTW ,have given ourselves until Weds to solve this,or I will cancel our trip(no pressure there then guys!! )

[ROD]

A test drive........after a short 50/60 mph blast and short stop in traffic queue,the temp guage went sky high. Had to stop to let cool down. Nothing out of rad cap or into bottle as far as I can see.Think its time it and me parted company !

[hunter]

Sounds like an air lock Rod.