Lotus Elan and Lotus Elan Plus 2 Forums

Having a bit of bother with our hillclimb +2 in that we seem to keep getting air locks in the cooling. Seems to be the rad is lower than the top hose so filling is not working. Considering fitting an in-line filler and overflow (pic below if it has loaded?), rather than a full swirl pot in the top hose line. will then blank off the original rad filler. don't want to change from the standard rad, as it seems to work fine for what we want. Just keep having issues with air in the system. I like to see the water move in the rad when squeezing the hoses. Have seen a few swirl pots fitted to modified systems but not a standard rad. Any input would be welcome.

http://www.coolexperts.co.uk/product/th ... mbination/

Probably a bit more expensive that the suggestion but probably a better solution. I have one (from the original supplier) and radiator with filler neck removed. Never have problems bleeding it.

Otherwise a lot of people bleed the cars with the front raised and rear on ground so that the radiator is higher relative to the top hose.

I have the one from coolexperts - works quite well.

Thanks for that. Think I'll get one organised. Only about twenty quid, so worth a go I think. Not that we are doing much competition at the moment, but might as well be ready. Cheers, Rob

I have never had an air problem in my +2, even though the radiator cap appears to be slightly lower than the hose.

Are you sure there is not something else going on? Odd leak, head gasket, bad cap.

A lot of cars where filling the cooling system without air locks developing is difficult have an air bleeder valve installed near the thermostat housing so you can open the valve whilst filling to let the air out and close it off again once it's filled. You might be able to install one on your car somewhere.

The other thing to do of course is to measure how much coolant goes into the system when correctly filled and use this figure when refilling to establish whether air locks have developed and an incorrect amount of coolant poured in.

See link below for bleeder valve example:

https://www.ebay.com.au/itm/KILKENNY-BL ... ctupt=true

What we and no doubt a few others will have found, is that if we fill the thing through the thermostat housing and top hose, the system thinks the radiator is too full and blows the water from the overflow till it levels in the rad at about 10mm from the filler neck. No more comes out of the overflow at this point but anything higher than the rad has no coolant in it. We don't have issues with overheating, just the fact that the level is always low in the top of the motor. Hopefully this filler with the other one blanked off or with a 25-30lb cap on will sort the problem. We'll see once it's fitted? Will post the results either way. Thanks to everyone for the input.

jasper2347 wrote: Hopefully this filler with the other one blanked off or with a 25-30lb cap on will sort the problem. We'll see once it's fitted? Will post the results either way. Thanks to everyone for the input.

Why would you want a cap with that kind of rating?? You're risking a steam explosion!!

Honestly, I do not think this is true

Have a large enough recovery tank and you will have no problems

Fill it cold, cap it as it starts to expand, keep the recovery tank 1/4 full when cold, the system will be full.

10mm below the filler neck means there are no empty cooling passages in the engine.

Let's get i the wayback machine. May of 1984. I had bought my +2 in April . Drove it to work, springtime cool weather. Went on a camping trip with some friends Memorial day weekend[last weekend in May] Drove 3 hours north on a sunny 80 degree day. Got of the highway and stopped at a rest area off the exit ramp.

Coolant on the ground. Oh crap! no steam, no continuing leaks. Temp gauge hit maybe 105C

It didn't boil.
It didn't overheat.

The coolant volume that I had diligently made sure was correct at 55 degrees F had expanded beyond the capacity of my 1 pint recovery tank when I stopped moving after creating a bunch of horsepower[AKA heat] on the highway.

IT is my thinking that when doing a a hillclimb, you create a bunch of heat your engine gets hotter than it normally does, and you burp some coolant out. If you had a 1 quart recovery tank and tight hoses, this won't happen

jasper2347 wrote:What we and no doubt a few others will have found, is that if we fill the thing through the thermostat housing and top hose, the system thinks the radiator is too full and blows the water from the overflow till it levels in the rad at about 10mm from the filler neck. No more comes out of the overflow at this point but anything higher than the rad has no coolant in it. We don't have issues with overheating, just the fact that the level is always low in the top of the motor. Hopefully this filler with the other one blanked off or with a 25-30lb cap on will sort the problem. We'll see once it's fitted? Will post the results either way. Thanks to everyone for the input.

Do you have a recovery bottle and the correct (two way) radiator cap fitted ?
If so the system should bleed itself with a couple of heat/cool cycles, you should not be losing any coolant. Don't be tempted to remove the radiator cap until the engine has completely cooled or it will not suck the coolant back from the recovery bottle as it cools.

Not on a +2 but fitted this with a standard radiator and works well.

Jasper

I have had a cooling tube made up which looks like the one shown (many thanks Axminster Panels). I have not yet tested it so I may wrong with my comment below...but here goes:

- I think this will do the job quite well (assuming the radiator is lower than the filler). A swirl pot for a mid engined car with a front radiator makes sense, the 26R slab tank just seems to add extra weight and clutter and from what I could read, a tube/pipe creates less hydrodynamic problems than other shapes.

- As mentioned by Roger and Gus, the recuperation bottle is essential (as mentioned in a post a decade or so ago, cap valves are reversible).

- High capacity caps is not necessarily a good idea...as it helps to keep an eye on what is happening before it goes pop.

I'd second the idea of a bleed valve on the heater pipe (Caterham's do this I believe).

Andrew

The 26R style tank is very interesting. It has a straight through pipe but with rather large holes in it. The box surrounds the holy part. I think what is going on is the water flows almost unimpeded with low turbulence through the pipe, and any air then gets trapped in the box. The exiting water is then even smoother and unaerated for the rad. I could be wrong. I'm just imagining what must be happening in there. And of course it does provide a high fill point.

John

Frogelan wrote:- High capacity caps is not necessarily a good idea...as it helps to keep an eye on what is happening before it goes pop.

I agree but the in this case the high pressure cap is for the radiator and there is a second standard pressure cap fitted at the new filler point. The high pressure cap is just a quick easy way to seal the traitor filler.

This is to avoid having to modify the radiator or have duel expansion bottles.

mbell wrote:

Frogelan wrote:- High capacity caps is not necessarily a good idea...as it helps to keep an eye on what is happening before it goes pop.

I agree but the in this case the high pressure cap is for the radiator and there is a second standard pressure cap fitted at the new filler point. The high pressure cap is just a quick easy way to seal the traitor filler.

This is to avoid having to modify the radiator or have duel expansion bottles.

I did the same but was even lazier and did it in reverse so I wouldn't have to move the recovery bottle.