Coolant level changing

[adamnreeves]

RV8 4.6, 2350miles

Installed an electric water pump about 2 weeks ago. All the hose clips have been triple checked after some miles. Also check for leaks and tight as a drum. My header/expansion tank is alloy so I cannot see the level. I have noticed a bit of coolant around the cap and can hear it hiss after I have turned the car off, but its always hissed like this. Checked the coolant after it cooled down after installing the pump and the level was just under half way up the tank so I topped up to half way. Next time I ran the car coolant leaked out of the cap everywhere. I let it cool down to a sensible temperature (40c) and the level was 3/4! so I removed some. Ran some 100 miles or so and engine been off for about 2 days. Checked the coolant tonight (15c) and it was at the bottom of the tank. turned my electric pump on and the coolant moved up to the half way mark again. I have removed plugs 1, 7 and 8, electrode/anode light grey. The ceramic part of the electrode (?) on 7,8 is every so slightly different shade of grey and I mean slight, only just about detectable by my acute vision, seems little bit pink which is the colour of my coolant, this could be my imagination or just a different shade of grey which can look slightly pink to me sometimes. Engine has run hotter than I like sometimes but we are talking no more than 96c.

Oh. I've checked the oil cap and no mayonaise. I've checked the oil level and this is still the same as it has been for 1000miles.

I've started the engine up tonight and some condensation was evident on the exhaust this dryed after a few minutes and remained dry whilst it was idling away. Probably normal, never paid too much attention before. I let it run up to 89c when the fan kicks it and turned engine off. Shall let it cool down and check the water again.

Don't really want to strip the heads off due to paranoia !

I haven't noticed any degradation in performance or drive-ability.

Oh, I forgot to mention that car has no heater so the outlet from the inlet manifold is piped into the header tank. So when the thermostat is closed then coolant is pumped into the header tank. Probably not ideal and I am hoping this is the problem.

[Darkspeed]

When the coolant pump is running the level in the expansion/header tank should go down not up as the tank should be fed onto the pump suction which should also be the lowest part of the system to provide the highest static head to the pump.

Sounds like you have the header tank in a +ve pressure location rather than the correct -ve pressure.

Andrew

[adamnreeves]

Pump is lowest part of the system and the header tank is highest but with stat closed water is pumped from the inlet manifold directly into the tank. Know what you saying plumbing not my forte. But maybe the shear flow of over 4litres a second causes it but when I turned pump off with no engine start the level remained half way, strange, what's filled the void!

[seight]

Shouldn't the heater hose go to the bottom hose (i.e into pump) along with the feed from the bottom of the header tank ? Meaning that anything avoiding the thermostat just goes back into the engine - helping with warm up.
Mike

[adamnreeves]

Righly or wrongly when I installed i plumbed the bottom hose and this into the bottom corner of the tank thinking it's the same deal

[Darkspeed]

The only +ve feed into a header tank should be a 3mm bore air pipe from the highest point of the system to clear air locks the only other connection should be to the pump suction and it should be the closest connection to the pump suction.

The manifold outlet is on the pump outlet - you should place a restrictor in this pipework and route it to the pump suction but not closer than the expansion and not into the expansion pipework.

Andrew

[adamnreeves]

I have three hoses plumbed into the header tank. 8mm over flow from top of rad into the top of the header tank. 19mm Hose from the bottom of the tank which is T'd into the 32mm bottom hose. 19mm Hose from inlet manifold into the side near the bottom of the header tank.

I guess in the meantime I could just blank off the feed from the inlet manifold to see if this helps.

The only +ve feed into a header tank should be a 3mm bore air pipe from the highest point of the system to clear air locks the only other connection should be to the pump suction and it should be the closest connection to the pump suction.

The manifold outlet is on the pump outlet - you should place a restrictor in this pipework and route it to the pump suction but not closer than the expansion and not into the expansion pipework.

Andrew

[seight]

Hi Adam,
Would there still be another way out of the manifold other than through the thermostat if you block that off? Obviously you need somewhere for the water to go when the stat is closed and your pump is running.
My ex-hotwire manifold has thermostat (of course), a 19mm outlet next to the stat and a bleed which will be T'd into the bleed from the rad and go up to the header. The 19mm from next to the stat will go to the bottom hose - i.e. into the pump.
I'm pretty sure, as per Andrew's post that it should work.
Mike

[adamnreeves]

Yeah, there's a 10mm outlet at the top that I have blanked off at the moment but been told that this should be T'd into the radiator overflow to the header tank. My stat has a bleed hole at the top but I am using a JED thermostat cover which covers this up. I'll have to consider re-routing the 19mm as detailed by Andrew.

Thanks for all the advice guys. Looks like I do not have a leaking block.

Hi Adam,
Would there still be another way out of the manifold other than through the thermostat if you block that off? Obviously you need somewhere for the water to go when the stat is closed and your pump is running.
My ex-hotwire manifold has thermostat (of course), a 19mm outlet next to the stat and a bleed which will be T'd into the bleed from the rad and go up to the header. The 19mm from next to the stat will go to the bottom hose - i.e. into the pump.
I'm pretty sure, as per Andrew's post that it should work.
Mike

[seight]

You worry too much


and stay up too late


Mike

[adamnreeves]

Yeah you right on the Worry thing.

My sleep patterns all over the place due to work

I checked my coolant level this morning and its half-way again. Failing to understand how it can change from just wet on the bottom of the header tank to half full and back again in a closed system when the coolant was the same temperature. I estimate the deviance is about 500mls.

You worry too much


and stay up too late


Mike

[DaveEFI]

I checked my coolant level this morning and its half-way again. Failing to understand how it can change from just wet on the bottom of the header tank to half full and back again in a closed system when the coolant was the same temperature. I estimate the deviance is about 500mls.

Are you certain it's not just an airlock? Bad enough on a factory designed system - let alone a one off.

Try parking on a hill etc so the header tank is as high as possible relative to everything else. Start the engine from cold and allow to warm up with the filler cap off. Top up and squeeze the top hose to 'burp' the system as Ramon would say.

[SuperV8]

What inlet manifold are you using?

As mentioned above the small outlet on the top right of the manilofd needs to be plumbed into the small vent pipe which must run up hill to the top of the expansion tank. This needs to vent higher than the coolant level. This is only to vent air no coolant flows through the vent pipe.

The expansion/header tank does not have coolant flow through it, it is just there to allow the coolant to expand as it warms. The coolant level should be higher than the highest point of the engine/rad.

What are you using for a thermosat bypass when the thermostat is closed? There still needs to be coolant flow around the engine when the thermostat's closed.

Tom.

[adamnreeves]

*EDITTED NEWS* As I am working from home today. I took out the bolt that I jubileed clipped into a piece of silicon hose to block this outlet to double check the measurement, its 8mm. When I took the bolt out I hear a rush of air and a bit of coolant come out then sloshed back and then more came out. Put bolt back in and check the coolant level in the tank, yep its dropped to where it was the other day. Result, I think this is the solution to all my problems now *

Thanks for clarification of the purpose of this small outlet. I have this blocked off, this might be my problem leading to trapped air, I'll plumb that in PDQ. The only by-pass I will have is the 19mm outlet to the lower right of the thermostat cover which is used to go to the heater matrix in the standard car. This is what I have plumbed into the bottom of the header tank.

Manifold I am using the the standard Rover one use for injection and rectangular plenum chamber, believe it was off a TVR.

Similar to this minus the attachment on the left.




Found the picture of mine on the car

What inlet manifold are you using?

As mentioned above the small outlet on the top right of the manilofd needs to be plumbed into the small vent pipe which must run up hill to the top of the expansion tank. This needs to vent higher than the coolant level. This is only to vent air no coolant flows through the vent pipe.

The expansion/header tank does not have coolant flow through it, it is just there to allow the coolant to expand as it warms. The coolant level should be higher than the highest point of the engine/rad.

What are you using for a thermosat bypass when the thermostat is closed? There still needs to be coolant flow around the engine when the thermostat's closed.

Tom.

[ramon alban]

I have noticed a bit of coolant around the cap and can hear it hiss after I have turned the car off, but its always hissed like this. Checked the coolant after it cooled down after installing the pump and the level was just under half way up the tank so I topped up to half way. Next time I ran the car coolant leaked out of the cap everywhere.

That is not right Adam, the cap should seal totally and no fluid escape via it, only through the pressure release part to the overflow tube and only then to atmosphere.

If it as I suspect, from your described symptoms, as a result, I would expect you have low cooling system pressure allowing the water nearest the exhaust valves/manifolds to boil much too early in the heating process when it should not, generating steam which pushes out the air in the expansion tank followed by a glob of fluid. Steam does that because it loves expanding, but the system wont allow the pressure to build up, hence the lost fluid.

Expressed another way - Its double jeopardy I'm afraid. ie, Boiling point too low because of low pressure AND cap unable to retain fluid under pressure.

Then when the system cools down the internal vacuum sucks back the available fluid (if any), followed by as much air as it can get, but sadly with not enough fluid available you now have a goodly dollop of air inside the cooling system.

Now it can never function as required so you experience all all the classic symptoms of air locks, variable cooling, uncontrollable burps, overheating and, eventually, collateral damage to the heads and head gaskets.

Lets hope its not too late.