Lotus Elan

Have I got an air lock?

PostPost by: William2 » Wed Jan 20, 2021 2:08 pm

Having recently drained my antifreeze by removing the rad drain plug and both the heater hoses and I also had the thermostat housing removed to fit a new thermostat, I then followed the advice and thoroughly flushed out the heater, the head and the rad with a garden hose. I then used compressed air to clear out all the water remaining.
As I still had the thermostat housing removed, I refilled with new 50/50 mix of antifreeze by pouring it in the thermostat housing first and then added more via the rad filler cap till both were full up. I noticed that to refill the system used up 8 pints yet the manual shows the capacity (inc. heater) to be 14 pints.
I then ran the engine for about 10 minutes with the rad cap off all the time and gradually added a little more antifreeze as the level went down but it was only about 1/2 pint. All the time I had left the heater valve open and when the engine warmed up I ran the heater blower fan and the air coming from the ducts was nice and warm.
My aluminium rad installation does have the filler at a lower level to the thermostat housing. I noted that the temp gauge to slowly go up to about 80 degrees C.
I suppose my question is, how do I know if the system is fully purged of any air locks, particularly because the refill process used 8 only pints and should I have ran the engine with the rad cap on instead of me leaving it off?
If there are any airlocks, will they eventually go?
Any help gratefully appreciated.
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PostPost by: mbell » Wed Jan 20, 2021 7:38 pm

Did you remeove the block drain plug? If not you may not have drain all the coolant, so require less to fill it up.

If level is steady and stays high, I'd just take it on a drive and give it some revs, as that should remove any remaining air. Then just keep an eye on the level/temp for a while.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: alan.barker » Thu Jan 21, 2021 7:30 am

Do you have an Overflow/Recuperator Bottle to neck of Filler on the Rad.
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PostPost by: richardcox_lotus » Thu Jan 21, 2021 7:58 am

Did you raise the car so the filler neck was above the level of the thermostat ? That’s what helps me purge any air when refilling on a stock setup.

And yes, lots of coolant can remain in the head.

Thanks
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PostPost by: William2 » Thu Jan 21, 2021 9:20 am

In answer to the questions, I tried to remove the brass cylinder block drain plug but it was stuck fast. Remaining water in the block would explain the reduced refill amount. Yes I do have a recuperator bottle. I did try jacking up the front of the car but not until I had filled the system up. Thanks for all your advice.
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PostPost by: bdea » Fri Jan 22, 2021 7:05 pm

In addition to all the comments to resolve williams2 questions... I wonder if anyone has observed these problems?

Overnight the Top Radiator hose becomes flaccid and soft when squeezing it, like coolant has left and air has replaced the coolant overnight ? I can pinch the inner walls of the hose so they touch each other. Is there Air in my system too? Where is the air coming from, if the coolant over flow hose is submerged?

My setup:

Overnight and after everything has cooled down,the overflow bottle level has dropped about 1/2", which was normal.

All the air was purged out of the system, front nose was raised, top hose was disconnected, coolant was poured in and radiator was topped off. Radiator cap is functional. Top radiator is semi hard. This is not a closed system.

When everything is hot and running for some time ...30 miles or so, the top radiator hose is hot and turgid. Coolant bottle level is about 1/2" higher.

Many Thanks, Brad
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PostPost by: mbell » Fri Jan 22, 2021 8:16 pm

My money would be on you expansion setup allowing the system to suck air back in when cooling. It could be bad radiator cap, air leak on hose to expansion tank, water level too l low in expansion tank letting air get sucked back in.
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PostPost by: bdea » Sat Jan 23, 2021 3:40 pm

mbell: thanks for your ideas.

The expansion tank always full and tube end is submerged with no leaks. Again this not a closed sealed system. Tube enters cap with a clearance of twice the diameter.

Any more thoughts? :shock: :shock:
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PostPost by: alan.barker » Sat Jan 23, 2021 4:10 pm

On my Sprint the tube touches the bottom of Overflow/Recouperator Bottle. Bottom of Tube cut at 45` so it can suck back as cooling.
Is your Rad Cap the correct depth.
Measure between Cap Seals and measure between sealing surfaces in Rad Neck.
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PostPost by: USA64 » Sat Jan 23, 2021 4:15 pm

I'm not sure I see the problem. Are you over heating? You say the heater works, and the overflow works. Yes there is air in the system. You stated the radiator is below the thermostat but as long as there is water going in at the bottom and out at the top it's OK. The system IS sealed when operating and the fluids expand with the heat. Your cap is a pressure cap so what ever pressure it is set at is what stiffens the radiator hose when hot but not when cold. At the set pressure point fluid is vented to the overflow and then returns as the pressure drops during cooling.
We are supposed to be having fun, are we not?
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PostPost by: bdea » Sun Jan 24, 2021 1:00 am

Setup similar to the above notations.

No overheating. Everything works, just thought it odd to have a soft hose even when cold compared to semi hard when I fill the radiator hose upon initial fill up... Must be the Magic Replacement Air in the system! :mrgreen:

Radiator cap is correct and seals at radiator neck-
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PostPost by: oldelanman » Sun Jan 24, 2021 10:24 am

bdea wrote:Radiator cap is correct and seals at radiator neck-
Stant Lev-R-Vent , 7 psi, Model 328


Are you sure that type of cap suits the Elan ?
The cap needs to incorperate a recovery valve to draw coolant back in as the system cools down .. does your cap have that?
Radiator cap 001.jpg and
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PostPost by: alan.barker » Sun Jan 24, 2021 10:40 am

Yes it must have a recovery Valve but also a rubber Seal at the top, not just Brass to seal the Top :shock: That is Rubber Seals for the Top surface of Rad Neck and also the bottom surface/ledge.
Alan
sorry Roger that's the wrong Cap for me.
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PostPost by: oldelanman » Sun Jan 24, 2021 11:33 am

alan.barker wrote:Yes it must have a recovery Valve but also a rubber Seal at the top, not just Brass to seal the Top :shock: That is Rubber Seals for the Top surface of Rad Neck and also the bottom surface/ledge.
Alan
sorry Roger that's the wrong Cap for me.

Quite right Alan.
The brass seal type does work fine if it's not damaged and the rad neck is perfectly flat but a rubber seal is no doubt superior. I was just trying to point out what the recovery valve looks like.

Is this one better ? :wink:

PXL_20210124_112223991.MP.jpg and
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PostPost by: alan.barker » Sun Jan 24, 2021 11:52 am

Yes that's better.
Sorry for being a bit of an Anorak :mrgreen:
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