PO bypassed heater control valve and always empty overflow jug?

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Jul 24, 2006
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hey man. thanks for the eyeballs and also the thoughtful response.
is it possible that i have a leak in the rear heater lines but that when the "system" (whatever that means) does not have the full amount of fluid in it - well it doesn't leak? but when it has a full amount of fluid in it it does?
maybe that makes no sense and you are saying there would have to be a different reason for there to be that much fluid on the ground.
i admit it is kind of weird. the overflow jug will hold coolant. but it does not stay there. the radiator system will take additional fluid when "burping it". and the valve to the overflow jig appears to work both ways.
is it possible the engine cooled after i burped it? it was full of coolant? then it ducked in the amount remaining in the overflow? then it puked it out overnight? but the leak is small enough to not lose all of it?
maybe? the rear heater lines are at the firewall and fairly high up. so as the system leaks down, it could drop below the level of the leaky hoses and lessen the coolant loss. when my radiator had a hairline crack in the top tank cap a similar thing happened...it wouldn't leak until i topped everything up. then i had a puddle as large as yours. over days the overflow level would drop as the system self purged onto the ground...eventually stopping once it got low enough. if i took off the cap, coolant was not all the way up.

the flow diagram (thanks @NLXTACY) shows everything on one page. however the direction of the arrows for the PHH and heater valve are backwards; if you want to check yourself, the arrow on the valve clearly points from right to left. and therefore the main heater core arrows both flow towards the motor so that's not right. but its a great picture nonetheless!

wits-end-1fz-coolant-map-jpg.1752010


remember that liquid expands when it heats up. so coolant is pumped into the overflow reservoir when you are driving, and is pulled back in as the engine cools off overnight via a siphon effect. the overflow is not under pressure. and the level in the radiator shouldn't change.

when i've filled up my system, i find that if i slowly add coolant it self burps. once i get the radiator completely filled, the extra will drain into the overflow if i pour VERY slowly. when i've done this it has been in my slightly sloped driveway so the nose is high.
 
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maybe? the rear heater lines are at the firewall and fairly high up. so as the system leaks down, it could drop below the level of the leaky hoses and lessen the coolant loss. when my radiator cap has a hairline crack, a similar thing happened...it wouldn't leak until i topped everything up. then i had a puddle as large as yours. over days the overflow level would drop as the system self purged onto the ground...eventually stopping once it got low enough. if i took off the cap, coolant was not all the way up.

the flow diagram (thanks @NLXTACY) shows everything on one page. however the direction of the arrows for the PHH and heater valve are backwards; if you want to check yourself, the arrow on the valve clearly points from right to left. and therefore the main heater core arrows both flow towards the motor so that's not right. but its a great picture nonetheless!

wits-end-1fz-coolant-map-jpg.1752010


remember that liquid expands when it heats up. so coolant is pumped into the overflow reservoir when you are driving, and is pulled back in as the engine cools off overnight via a siphon effect. the overflow is not under pressure. and the level in the radiator shouldn't change.

when i've filled up my system, i find that if i slowly add coolant it self burps. once i get the radiator completely filled, the extra will drain into the overflow if i pour VERY slowly. when i've done this it has been in my slightly sloped driveway so the nose is high.
oh. thanks for this. i didn't realize he had updated this. i used the original when i was doing the heater control valve.
i'll study up and get back. appreciate that.
by the way - maybe a dumb question - but can coolant loss like this prevent the AC air from cooling fully...?(!)
 
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oh. thanks for this. i didn't realize he had updated this. i used the original when i was doing the heater control valve.
i'll study up and get back. appreciate that.
by the way - maybe a dumb question - but can coolant loss like this prevent the AC air from cooling fully...?(!)
maybe he has updated it since the one i linked to. i dunno. i found this one in a post of his.

a mis-adjusted heater valve is a common complaint about always warm air. in the engine bay, disconnect the heater cable and manually shut the valve. with the ignition on, slide the temp to full cold, turn ignition off. re-connect heater cable, making sure to keep valve fully shut.
 
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maybe he has updated it since the one i linked to. i dunno. i found this one in a post of his.

a mis-adjusted heater valve is a common complaint about always warm air. in the engine bay, disconnect the heater cable and manually shut the valve. with the ignition on, slide the temp to full cold, turn ignition off. re-connect heater cable, making sure to keep valve fully shut.
might be the same one. i have to check. i remember really studying this one so it is good to see again.
 

FMC80

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Someone’s gonna say it. May as well be me. This is why I use Toyota Red. Easier to track down leaks. :flipoff2:

I was going to suggest the same thing @leonard_nemoy said. I’d start with the most basic and seemingly obvious thing first: overflow reservoir constantly empties? Leak check it.

Rule it out first then start eliminating all lines/connections/clamps while the engine is running. Run it up to temp first. Then scan the engine from firewall to the rad, top to bottom, and side to side. Be methodical, leaks can be tough to spot.
 
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If your rear heater lines are leaking, you're probably going to see it on the ground. One of mine had a rust hole about 1 mm across and the the coolant poured out like a tiny waterfall. It is a low point on the system.

When I bleed my coolant system, I make sure to raise the front end so the top of the radiator is exaggerated as the top of the system. It helps to burp it quicker.
 
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now that i'm not on mobile, maybe its my eyes but in your picture below, it looks like lots of old dried up coolant around the radiator cap. and that would definitely pool up on the ground like yours did. if you are certain your cap is sealing properly, then the next logical explanation could be as simple as a loose or torn hose connecting the overflow jug. you could be losing coolant externally as the reservoir fill and empties.

as others have said, clean up ALL the old coolant mess, fill up, and try again.

47808cbb-ce89-4e50-9d43-f608e10175d0-jpeg.2890924
 

Dave 2000

Not all Land Rovers are useless!
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There is a misconception when bleeding the LC 80, first and foremost the car should simply be level, second the ignition MUST be on for the heater slider to operate the heater valve, so ignition on and slide to hot, a motor operates the cable which in turn opens the valve, there is no need to have the fan blower on, now slowly fill the radiator, just chucking in a load of coolant traps air, do it slowly and as water moves around the system it will push the air out. Don't get too hung up about getting the water right to the bottom of the neck of the filler, above the core tubes is sufficient. Now with the cap off start the motor, the water pump will start to move the water around the system including the heater, just let the motor idle over keeping an eye on the water level in the radiator, keep topping it up but again not trying to get it to the bottom of the filler neck this allows air to escape, after a few minutes the level will settle, check your heater pipes for warmth, once they start to get warm the water will start expanding, as long as it is over the core tubes put the cap on. Check the expansion tank level is around mid way, this allows room for expansion and enough to be drawn back into the engine when it cools. Check the tube between the rad and expansion tank are tight or the system will not work, once the system has cycled a few times there will be no air in it. Now I would increase rpm to about 1000 and hold it for a couple of minutes, then back to idle and check the various hoses are getting warm.

Shut off the engine and leave to cool for about an hour slowly release the radiator cap and check the level, it should be at the bottom of the filler neck, if the water has gone then you have a leak, check the exhaust for water being blown out (don't confuse this with a cold engine and condensation, check under the dashboard remember the heater valve was open so water will have gone through the matrix, so you may have water on or under the carpet, and of course the pipes that run under the car but above the exhaust heat shields so out of sight.

That's about it, I seem to remember you mentioning shaving the radiator neck or something similar? Sorry I am getting tired, there must be an airtight seal at the top of the filler neck or the expansion system will not work properly, if you had to shave it then you had the wrong cap or the radiator was damaged in some way?


Regards

Dave
 
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now that i'm not on mobile, maybe its my eyes but in your picture below, it looks like lots of old dried up coolant around the radiator cap. and that would definitely pool up on the ground like yours did. if you are certain your cap is sealing properly, then the next logical explanation could be as simple as a loose or torn hose connecting the overflow jug. you could be losing coolant externally as the reservoir fill and empties.

as others have said, clean up ALL the old coolant mess, fill up, and try again.

47808cbb-ce89-4e50-9d43-f608e10175d0-jpeg.2890924
thanks. i did spill a bunch and i will run it to the power wash when i get a minute.
here is an interesting link with some nice images for anyone looking to do the bypass. not totally sure if he did the bypass but the images look super helpful.
95ECD2C2-5591-4FE1-95C8-7E17284C8DF1.jpeg
9D08707F-BD96-4A10-B7E6-2E888990FB8E.jpeg
 
Joined
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Messages
1,871
Location
tejas
There is a misconception when bleeding the LC 80, first and foremost the car should simply be level, second the ignition MUST be on for the heater slider to operate the heater valve, so ignition on and slide to hot, a motor operates the cable which in turn opens the valve, there is no need to have the fan blower on, now slowly fill the radiator, just chucking in a load of coolant traps air, do it slowly and as water moves around the system it will push the air out. Don't get too hung up about getting the water right to the bottom of the neck of the filler, above the core tubes is sufficient. Now with the cap off start the motor, the water pump will start to move the water around the system including the heater, just let the motor idle over keeping an eye on the water level in the radiator, keep topping it up but again not trying to get it to the bottom of the filler neck this allows air to escape, after a few minutes the level will settle, check your heater pipes for warmth, once they start to get warm the water will start expanding, as long as it is over the core tubes put the cap on. Check the expansion tank level is around mid way, this allows room for expansion and enough to be drawn back into the engine when it cools. Check the tube between the rad and expansion tank are tight or the system will not work, once the system has cycled a few times there will be no air in it. Now I would increase rpm to about 1000 and hold it for a couple of minutes, then back to idle and check the various hoses are getting warm.

Shut off the engine and leave to cool for about an hour slowly release the radiator cap and check the level, it should be at the bottom of the filler neck, if the water has gone then you have a leak, check the exhaust for water being blown out (don't confuse this with a cold engine and condensation, check under the dashboard remember the heater valve was open so water will have gone through the matrix, so you may have water on or under the carpet, and of course the pipes that run under the car but above the exhaust heat shields so out of sight.

That's about it, I seem to remember you mentioning shaving the radiator neck or something similar? Sorry I am getting tired, there must be an airtight seal at the top of the filler neck or the expansion system will not work properly, if you had to shave it then you had the wrong cap or the radiator was damaged in some way?


Regards

Dave
thanks for this dave. a couple comments/questions.
1. i didn't quite follow what needs to be correct on the hoses on the overflow.
2. also not totally sure which hoses should be heating up but i gather the overflow should open at about 180 degrees.
3. i don't quite follow the proper fill level exactly but on my vehicle it is always full to just at the bottom of the filler neck. what was weird is the level was not dropping when idling as i remember it. it also was not dropping when the overflow opened again as i remember it. but the radiator DID suck down about 2 ounces at a time if i filled the neck from the bottom of the neck to the top. so when i did this i filled 2 ounces at a time about ten times to put in about half a gallon over a period of time but just a little at a time. so fill two ounces. wait a minute and it would suck it down. fill 2 ounces. suck it down etc. not sure why it works like this or what this level is in relation to the cores but i would like to.
 
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My guess is the rear heater lines. There was probably a reason the previous owner deleted the heater control valve. :meh:
yeah. thanks cahill. looks like i am going back in and recapping or re-bypassing it. i save all the parts i take off so hopefully this will not be too big a deal.
i will also bring in the hard lines and find a good time to repair them.
by the way thanks to all here. the heater control valve was busted and i couldn't figure out why they would cap it instead did just replacing it. then it took me a long time to try to understand better how the system works and why the overflow would always be empty. which i guess has to do with how high the leak is in the lines and maybe something to do with it equalizing pressure. then when you fill it up and pressurize it instead of letting it out a little at a time it sort of pukes it out i guess.
 

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