Bleeding radiator

[allen l]

Installed a Radtech this morning, a new expansion bottle cap and a new thermostat and I've got some problems, trying to bleed the system. I tried to jack up the car as high as possible, but somehow, only the upper side of the radiator gets warm. The underside of it and the cooling hose there stays cold and temperatures went well up over 100 degrees celcius.
I hear different stories from different people who tell me to remove the expansion bottle cap or to keep the cap on it, so that there is some pressure in the system.
I've only got some experience in bleeding the system of a BMW, but the work on the Caterham seems to be a pain in the ....

Anyone know the correct way to bleed the system?

[mickrick]

I'd have the cap off.
I'm currently doing a coolant change on two 2000hp V16's which take two days to get the air out!

[mickrick]

Forgot to mention, give the hoses a good squeeze to help belch out any air, and keep topping it up with the mix, as the air burps out, and the level drops.
Don't blip the throttle, as it'll just belch the coolant to out at you! Just let it idle.

[allen l]

Thanks Mick, I'll give it a go on Friday or Saturday again. Hopefully with good results.

[mickrick]

Forgot to mention, make sure your heater valve is fully open.

[allen l]

Thanks Mick! Think the only two things I did wrong, was to keep the expansion bottle cap on and to give it some revs when I got impatient after half an hour of fiddling. The idea of having to bleed the system for over two days is shocking. Good luck if you have to do that more than once a year.

[Incorrigible]

I'm assuming you know there's water in the rad ? the bleed nut at the top is undone/checked/repeat

Also that your thermostat is working ?

You can get hot spots if the air bleed from the head is blocked (1/4" hose to the top of the expansion bottle (you had to modify old school Jenveys to include this but that's another story))

[allen l]

Hi, Yup. I've read the bleed nut at the top of the radiator had to be higher than my heater unit, and that I had to bleed the cooling system there. I hope the thermostat is working as it is new. It's not opening at the moment I think, because of an air lock?

[Incorrigible]

If there is an air lock, it's unlikely to be at the 'stat, however if the engine is getting red hot and the rad is not, then I would suspect that the 'stat is not letting water through

Al tough if you're running the engine with the car at an angle even the tiniest amount of air in the top of the rad will make it very hard work for the water pump to get coolant up there. Run it with water actually trickling out of the top rad bleed to make sure

you say the temp is getting hot, this could be a dodgy gauge (they all do that sir) the gauge can be reading 100 but the actual temperature is about 80 (before the 'stat is meant to open)

[allen l]

Which, in that case, will lead to an interesting question for myself: ignoring the gauge with the risk of killing the cilinder head or gasket, or relying on the gauge so I'll never get the bloody thing fixed.

[Incorrigible]

borrow an ir pyrometer, or get some of those temperature strips from Demon thieves

[allen l]

Good one. Have an ir-thingy.

[Jack_and_MLE]

When I did mine, I had some air trapped in the top of radiator so with engine running( expansion bottle cap on) I un screws the top bleeding screw an waited until I had clear fluid (no air bubbles) going through then re tighten.

I then let the engine run with the expansion bottle cap off for a good 10 minutes (waited for the fan to turn on then off then on , then off) for the water to push through all the possible trap air in the circuit (heater valve on full open).

No problem of air trapped since I done it like that.

Hopes that helps

Jack

[allen l]

Thanks. Hopefully I can post some good results coming Friday or Saturday.

[mickrick]

Got my two cooling systems filled and bled today. Took 120 ltrs each.
Good luck with your second atempt.

Edited by mickrick on Wednesday 24th February 21:13

[allen l]

Well, have been busy for over an hour or so. Discovered that I can't jack the car up as high as I want. Totally fed up with it, so after a quick call with the Caterham dealership over here, I have now decided to see how it will be, driving without the heater. If I don't like it, I can at least drive the car to them, so they can get the fron sky high to bleed the system with the heater.
At the moment I'm just totally annoyed as I haven't been driving the bloody thing for too long!

[allen l]

Well, last update:

Disconnected the heater, everything seemed fine. Jumped in the car for a short spin and after a while I gave it some beans. After that problems again. Everything seemed fine as long as I didn't really rev it up, so I drove home slowly. Checked everything again, and for the first time we checked the waterpump. We discovered there was no stream of coolant coming in the coolant reservoir. Bingo!

Have to see how I get my car to Lotus in Amsterdam, so they can change that for me. Glad I found the problem, as I really need a good day of driving and a trackday!

[Steve-B]

Guys this is dead-nuts simple

1) go to hire shop, rent engine crane for one day
2) put blocks behind rear wheels, attach crane to engine
3) hoist front of car
4) open bleed screw slightly on rad*
5) leave car running (no beans!) until no air

This has worked for me every time, in UK and Oz without fail. I also have a new bleed connector near heater that helps check during the year.

• I have also taken cap off of expansion cap on overflow tank and blown into it, helps push fluid through engine provided you keep topping up tank.

Don't screw around with ramps, no way high enough

[allen l]

I now know it was as easy as I thought it should be. It just didn't help, that I could never have thought the water pump died within 20,000 miles.

[Yellow 7]

Here's how to do it;-)
http://picasaweb.google.com/lh/photo/iROPZW4LMfGht...