Flushing the cooling system

[chrishewett]

I have an electric fan which had a kenlowe switch in the top hose. I was not happy with this arrangement and when I was at classic le Mans the switch failed so I bypassed it. I then fitted one of cliveyboys thermostat housings. With this you can fit any standard switch. I fitted an 82degree switch, same as the thermostat. Since then the engine has run cooler and only gets up to 85 ( but no higher) when driving hard. This is, of course, the reading given by my dash temp gauge.
All in all I would recommend the housing as the best method of controlling the fan operating temp. An added advantage is that it has a filler cap at the highest point so some time I may change the rad.
Chris

[oldokie]

Boy, just when you think you've seen everything a Volvo goes by with a NRA sticker on the bumper!! Never heard of an Elan running too cool! But,back to Robbie's problem, is the rad properly shrouded? All the air coming in the nose must go thru the rad, not just over the rack,etc. I also had to make 2"X3" oval holes in my inner fenders (screened) to let the rotation of front wheels draw the hot air out of the engine bay. BTW, I'm not running an electric fan, just a nylon flex-fan( Cortina GT).

[msd1107]

There are three aspects to the cooling problem.

First is the water pump. This results in low flow at low rpm and excessive power consumption at high rpm.

Some Lotus owners have bypassed (or removed) the stock water pump and replaced it with a Davies Craig electric water pump. This pump runs only as fast as is necessary to maintain an appropriate water temperature. In idling conditions, it runs fast enough to ensure sufficient water circulation. At higher rpm, it runs only as fast as necessary to maintain the water temperature, saving power.

Second is the radiator fan. Of course the engine driven fan has already been removed, since it suffers from the same limitations as the water pump. In addition, it loads the water pump bearing, not a consideration once you switch to the electric water pump.

Use a temperature controlled variable speed radiator fan. It doesn't run until radiator temperatures reach a certain level, then runs fast enough to reject enough heat to maintain the radiator temperature in a constrained temperature band.

Third is proper ratiator ducting, both intake and exhaust. Make sure intake air is not leaking around the sides or top or bottom of the radiator, so all air is forced through the radiator core. Then make sure air that has passed through the radiator can escape, which is a weak point on the Elan. Oldokie reiterated what the Workshop Manual states on pages K9-11. If anyone needs to see these pages, I could scan them and post them as JPEGs. Finally, some people allow the bonnet to move proud of the body by modifying the bonnet catch. This allows hot underhood pressurized air to bleed somewhat along the new side and back gap of the bonnet. Or you could adapt something like the FHC exhaust grills to the bonnet.

The stock radiator is well oversized for normal needs. Incorporating these modifications will insure that low speed cooling is adequate.

David
1968 36/7988

[Robbie693]

Well I flushed the cooling system this weekend, why do I always manage to turn things into a crisis?

It went something like this:

Drained the system, disconnected the hoses and flushed backwards and forwards with the hosepipe.

Filled up with water and the flushing agent, ran the engine as per instructions. The 'stat opens and, what's that floating in the rad?

Fished out a 1" curved strip of RTV which looks about the radius of the thermostat housing.

More engine running and scum rising to the surface. Switch off.

Drain the system and flush again, refill with water and run back up to temperature. (with hindsight I think I should have let the engine cool down before putting cold water in - is this really bad?)

More scum rises in the rad which I'm doing my best to fish out.

My Dad comes over and says "maybe we should test the water temp to see if the gauge is correct, I've got a tester". Ok cool.

Hmm batteries are dead in the meter. Dad goes off in the house and comes back with a medical thermometer - "lets try this, it goes up to 110deg so it should be fine.."

Sticks thermometer in neck of the rad, pulls it out - "err, the end fell off..."

What!? So where's the end?

"In the rad"

and the mercury?

"In the rad"

You're *%$?&^*ing joking!!!??

"No...."

Great, this is all I need. Tried to pick out the glass shards with tweezers but one piece disappears into the rad somewhere. Dad suggests sucking the mercury out with a syringe - no chance.

By this time the bloke next door has come out to have a look, so I've got one eye on what I'm doing and the other on my 'helpers' who are holding/dropping tools much too close to my paintwork for comfort.

So off comes the bonnet and the radiator for a very thorough flush forwards, backwards, upside down, everyway till I see tiny specs of mercury in the pool of water. Re-assemble, one more flush with the hose and fill with antifreeze and fire it up.

Pheeew.

Finally, Dad finds another meter with a digital themometer probe (why not that one in the first place?)

Checking the water at the neck of the rad shows the car's gauge to be 8-10deg out (on the high side) which ties up with the temp the fan cuts in at.

Sorry, I got the temps wrong in a previous post - the fan cuts in at an indicated 100-105deg or so and cuts out at just over 90deg. I also found out I have a 74deg thermostat.

So it looks like the gauge is out, can these be recalibrated?

[hatman]

Told you it was a straightforward job!

[richardcox_lotus]

Well done Robbie !

On the basis of that episode, I think I'll wait a while before doing mine..........

Try this other post re gauge repair/calibration:

http://www.lotuselan.net/forums/viewtopic.php?t=11903

Rgds

Richard

[Robbie693]

Thanks Richard.

It would have been a simple job if we hadn't been stupid enough to stick the thermometer in there. Must have been a crack in it so I guess it was better to have broke in my rad than in someone's mouth...