Always pushes out a litre of coolant????

[RichardH]

Hoping that you guys can crack this one for me, before I start dismantling the cooling system.........

4 years ago , at Le Classique, we had a slow run through the pit lanes on the way back to the compound (you remember) and a few motors got perilously close to overheating (one in front of me had a sudden misting problem in the rear window). My temp gauge was reading 130 :shocked: for about half an hour afterwards. So I decided to fit an EWP80 pump with controller as an additional coolant aid that can be left running after engine shut-down. I also took the opportunity to drill a 6mm hole through the thermostat, to allow a constant bleed of coolant. This is an additional (booster) cooling device, so the water pump is still being used.

Having fitted the EWP and controller, it does a superb job of controlling coolant temperature, however ever since then it seems to push out about a litre of coolant on every run, which is inconvenient to say the least. I have added an extra expansion tank as a temporary fix which seems to work on most occasions, but this is, I feel, fixing the symptom, rather than the cause.

Do you think this is because the coolant cannot flow around the system properly and the expansion tank is being used as an escape route? Or am I missing something more fundamental? The pressure cap has been changed for one of 21PSI, so it isnt a pressure cap problem. I cant believe that the water is expanding that much and a leak-down test has shown no head gasket problem.

What are your ideas and, maybe more importantly what do you suggest to fix this?
removal of thermostat?
removal of original water pump (and if so are blanking plates available)?

 

[Dave Bilyk]

Richard, sounds like you have some local boiling going on, do you have bleeds from the back of the heads to the expansion tank?

Dave

 

[Jim Cowden]

If you don't put a LT of water in on the next run is it correct when hot.
Trying to ascertain if it is just finding its natural level.
My set up has a tank that holds about 2lt say,when it is cold it has maybe 300-400ml in it.
But when hot it is full.

So was the pump fitted 4 years ago or just recent.
If recent maybe you do have an air pocket of air.
Is it showing hot or fluctuating on the gauge.(air pockets often make the gauge fluctuate)

You changed the cap to 21 psi ???? from what 13 15 21 psi.
If you have gone from 13 to 21 that normally will pop the tanks on the radiator in my experience especially copper brass.

Jim

 

[RichardH]

pump was fitted a year or two ago (old age/memory loss).

21PSI from 15.
New radiator last year - no probs with radiator or system other than this pushing out coolant.
I believe there is a bleed from back of heads (and radiator).

One thing I forgot to mention above is that it now runs cooler than before, so I am wondering if the pump is trying to pushing stuff around before the thermostat is fully open. Must adjust the controller setting to increase trigger temperature, but I believe the DC-EWP pulses coolant.

 

[Seymour Snerd]

In case Jim's explanation isn't correct, it seem to me the best "debugging" strategy would be to put the car back the way it was before you put in the electric pump, since at that point (I assume) your only problem was you wouid oveheat at low speeds. That means bypassing the electric pump and patching or replacing the thermostat. If you no longer have the problem then the electric pump setup is probably the cause. Also, in that regime you would determine it's normal/correct hot and cold coolant level.

One other debugging thought: temporarily put a 12v lamp (or voltmeter) across the pump that you can see while driving so you can tell whether it's pulsing or varying or whatever and correlate that behavior with temperatures, etc.

 

[Jim Cowden]

RICHARDH
One thing I forgot to mention above is that it now runs cooler than before, so I am wondering if the pump is trying to pushing stuff around before the thermostat is fully open. Must adjust the controller setting to increase trigger temperature, but I believe the DC-EWP pulses coolant.[/QUOTE]

So does it push the water out on warm up ,during the run or after the run.

Careful of that 21psi cap. If the radiator tanks are getting bloat it is to high.
I have no idea how manufacturers work out the pressure but twice in 35years I have uped the cap pressure and twice it poped the tanks.

 

[RichardH]

It seems to push it out on warm-up.

The 21psi cap was fitted on recomendation from here

i never had a problem overheating at low speeds before that "classic", but those that were there will remember a 20 minute crawl at 5mph thru the Le Mans pits.

 

[Jim Cowden]

Reduce the flow on your controller on warm up would be a start.

Jim

 

[RichardH]

Not sure how to do that. Have the davies craig EWP80 pump and controller which has a "temperature" adjustment. Would that effect flow? I assume that is how it works, but do not know in detail. Just turn the "temp" setting higher??

 

[Tim]

Where is your sender for the electric pump?

If this is just beyond the thermostat, that may be the issue.

With the 6mm hole in the thermostat your controller could be seeing hot before the thermostat is fully open starting and pumping up against a dead head so to speak. IE: 6mm hole only for circulation.

These pumps are quite powerful and could be then pumping up past the cap until the thermostat opens to allow full flow.

This could be checked by putting a pressure Gage in the return line to see peak pressure.

 

[Tim]

The sound of the electric pump pulsing could also be the pump Cavitating as it can not get full flow through the bypass hole you have drilled.

 

[Dave Bilyk]

Richard,
if this only occurs during warmup and it has the head bleeds anyway, I would tend to discount local boiling.
Is your radiator cap is sealing properly? Try your old cap or a lower pressure one.

If the cap is sealing ok, the pressure in your system must reach 21psi during warmup.
The ways I can think of that this can happen are;
The pump pressure is 21psi+ before the thermostat opens; I doubt that because others with electric pumps would get that problem too. What is the no flow pressure of this pump?

There is insufficient air in the expansion tank; but you have added another, so this is unlikely.

There is a gasket issue; but you have done a leakdown test, a good indication but not absolute proof.

There is no bypass flow, so the pump is dead headed (apart from the 6mm hole) until the thermostat opens. Can you confirm that the bypass circuit has not been eliminated?

Dave

 

[John Snook]

i never had a problem overheating at low speeds before that "classic", but those that were there will remember a 20 minute crawl at 5mph thru the Le Mans pits.

Yep, i was there and recall that agonising crawl - not only was the engine running on H for happy but the cockpit temperature was a bit warm to say the least!! My passenger and i were close to sublimating :sweatdrop: Still, the avenue of appreciative spectators was something i'll remember for a long time.

Sorry, i can't offer any advice about your water overflow, although every now and then mine used to take a small leak (100mls or so) some years ago before I stroked the engine but i never knew why. After i stroked the engine and rebuilt it with out a thermostat i haven't had a problem but I always put the fans on whenever in heavy traffic or stationary with the engine running. I have an electric pump set up ready to fit when i get the chance.

See to at LMC10 :happy:

 

[Paul Thompson 'Hooligan']

Where is the electric pump located in the system?

If at the front, near rad, then I would have thought the issue might be the restriction of the thermostat being in place.

Do they not recommend removing the stat when running electric pumps?...(although I've not seen a car with both before - norm one or t'other)

Just a thought.

 

[Gus Richmond]

RichardH,
What happens when you disconnect the waterpump (electrically) and run the engine up to temp? does it still push out the coolant?
That should give a good idea if the pump is the problem or not.
Just a thought.
Kind regards, Gus.

 

[RichardH]

Thanks folks

The Lecky pump sensor is just after the thermostat, so I will turn up the controller switch temp. If that doesnt work then I will try removing the thermostat next.

 

[RichardH]

As a final follow up, it would appear that the EWP was pressurising one half of the system, sufficiently that it was pushing water out through the overflow. EWP no removed and problem resolved