TomGaval Posted August 25, 2014 Share Posted August 25, 2014 I recently purchased my second Caterham, after 14 years with a RoverK series. With the help of Blatchat I thought I knew all the subtleties of the coolant system pretty well. This new car is a big hp 2.3L Cossie Duratec, and I'm finding that I've got a lot to learn on this one now. I've recently noticed that the expansion tank was filled to the correct min/max level sitting in my garage. After starting up and driving it a 100 yards to load it in the trailer for a trip to the track, upon unloading I've noticed twice now that the level in the tank is down significantly. There are no wet spots on the garage or trailer floors and I don't see any evidence of a leak. I started the car yesterday outside the garage, and ran it up to temp. Coolant level was stable. Thinking like a K series owner, assuming that there might be a air bubble, I let it cool down, massaged the hoses ala the Carmichael technique, opened the top bolt on the radiator and was able to add a small amount of coolant to top off the radiator. Now this morning when I looked at the expansion tank it was down about a half inch below the Min. line. So what to do? Is there a different procedure for filling a Duratec? Tom Link to comment Share on other sites More sharing options...
Pendennis Posted August 25, 2014 Share Posted August 25, 2014 No Tom, you still need to purge the air free from the system, natural venting over a couple of nights is a good method. What does the car rev to and is it a standard CC set up? Link to comment Share on other sites More sharing options...
TomGaval Posted August 25, 2014 Author Share Posted August 25, 2014 Definitely not the standard Caterham spec. This one has a billet Crank, 13:1 compression ratio, the Cosworth Roller barrels, hot cams and is putting out 309hp at the crank. Sadev sequential with Geartronix Flappy paddle set up. I think the rev limiter is set to 8K. Haven't been much above 7200 yet as I've only had it on track 3 times and still getting use to it. Way quicker than my 195bhp Rover k S3. Tom Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 25, 2014 Member Share Posted August 25, 2014 What's the relative height of the radiator port where you're filling, the highest point of the circuit, any bleeding point and the expansion tank? Did you raise the rear when you first filled it? I can't see the difference between what you've observed with the trailer and starting it closer to home except: * One came after the another * There will have been some shaking in the trailer. Jonathan PS: Quoting TomGaval: Way quicker than my 195bhp Rover k S3.... that will be mostly due to the improved cooling system... :-) Link to comment Share on other sites More sharing options...
Dr Slotter Posted August 25, 2014 Share Posted August 25, 2014 A few thoughts from me and others here. Link to comment Share on other sites More sharing options...
TomGaval Posted August 25, 2014 Author Share Posted August 25, 2014 I just purchased the car from one of the guys I track with, so I haven't done any of the maintenance on it yet. He had the car serviced just prior to my buying it. So don't know if the rear was raised to fill it. The bleed bolt and top of the radiator are slightly higher than the bottom of the expansion tank. I'll open up the bleed bolt and start up the car and see if air or coolant come out. Anything else I should try? Thanks for the help. Tom Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 25, 2014 Member Share Posted August 25, 2014 If you're having problems (some 7s do, some 7s don't) I'd recommend fitting a bleed t-piece at the top of the circuit (typically in a heater hose) and jacking the rear as high as possible when filling and bleeding. Jonathan Link to comment Share on other sites More sharing options...
Pendennis Posted August 25, 2014 Share Posted August 25, 2014 Does it utilise a water rail and catch tank? Link to comment Share on other sites More sharing options...
TomGaval Posted August 25, 2014 Author Share Posted August 25, 2014 No water rail. Looks like a big hose under the Intake to the rad. Round standard expansion tank up front. No heater or bleed tee. I'll try the rear jacking. I'm use to the K series and raising the front. Tom Link to comment Share on other sites More sharing options...
Pendennis Posted August 25, 2014 Share Posted August 25, 2014 If tank is in front of engine jacking rear is of no use 😬 Is header tank water level below top of head? Link to comment Share on other sites More sharing options...
TomGaval Posted August 25, 2014 Author Share Posted August 25, 2014 Yes the header tank level is below the head. and thanks for the clarification on the jacking up the rear. Didn't make any sense to me. See I have learned something after all theses years. Just added a little more to the rad. Going out to start it up and will report back shortly. Keep the suggestions coming! Tom Link to comment Share on other sites More sharing options...
Dr Slotter Posted August 25, 2014 Share Posted August 25, 2014 The point of jacking up the rear is to get the coolant that gets trapped at the bottom of the circuit (like in a u-bend) into another part of the circuit were it doesn't get trapped. Which is useful for doing a fluid change. You would also jack the rear to get a particularly stubborn airlock out via the heater bypass circuit. Edit - merged posts a JK's post crossed my addtional reply. Edited by - Dr Slotter on 25 Aug 2014 18:42:15 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 25, 2014 Member Share Posted August 25, 2014 Quoting Dr Slotter: The point of jacking up the rear is to get the coolant that gets trapped at the bottom of the circuit (like in a u-bend) into another part of the circuit were it doesn't get trapped.Agreed, but isn't that "air"? And my best guess is that the difference between cars with a problem and cars without is the existence of a trap like that somewhere. But there is a theory in a recent thread that attributes the difference to the operator rather than the machine. Jonathan Link to comment Share on other sites More sharing options...
Dr Slotter Posted August 25, 2014 Share Posted August 25, 2014 Merged posts. Edited by - Dr Slotter on 25 Aug 2014 18:42:31 Link to comment Share on other sites More sharing options...
Pendennis Posted August 25, 2014 Share Posted August 25, 2014 You will not be able to purge air out of head if tank is below it Without engine running, remove nose cone, unbolt and raise header tank, fill it halfway, you need to vent for a while maybe an hour, initially remove top rad plug, but when water comes out the rad is vented. Leave header tank cap off whilst tank is highest point of coolant circuit, occasionally squeeze top hose to rad, should be job done. Then reinstate tank but ultimately you should be looking at relocating tank to highest point of scuttle bulkhead. If tank is below head your never vent the air free from the engine, that's a carp design Link to comment Share on other sites More sharing options...
TomGaval Posted August 25, 2014 Author Share Posted August 25, 2014 Thanks Jonathan. Make sense. Not much room up front as that is where the pneumatic controls for the paddle shifter is located. I'll see what can be worked out. Noticed that my Fan comes on at 190F but does not seem to slow the advance of the temp. On track there is no issue as it's getting plenty of fresh air, but at idle seems to need more help. Maybe a better shroud around the fan as there is about a 3/4 inch gap from the radiator? Thanks a lot for the help guys! Tom Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 25, 2014 Member Share Posted August 25, 2014 *arrowup*Have you checked which way it's blowing... ? Jonathan Link to comment Share on other sites More sharing options...
TomGaval Posted August 25, 2014 Author Share Posted August 25, 2014 yep, it's sucking. 😬 You guys are awesome!!! I unbolted the expansion tank, and placed it on top of the front mounted dry sump tank. Started it up and after a minute or two, saw and heard a Gulp, and a gush of coolant and air emptied into the expansion tank and at the same time it sucked out a huge portion of the coolant from the tank. Still enough in there to cover the hose/bottom as I had it tilted so that it pretty much emptied right into the hose. I turned off the engine, filled the tank a little more and PRESTO!!! Fan kicks on at 190F, Temp stays pretty stable and top hose is now nice and warm. 😬 😬 😬 Makes my L7C dues well worth it!!! Thanks all. Tom Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 30, 2014 Member Share Posted August 30, 2014 Quoting Pendennis: Without engine running, remove nose cone, unbolt and raise header tank, fill it halfway, you need to vent for a while maybe an hour, initially remove top rad plug, but when water comes out the rad is vented. Leave header tank cap off whilst tank is highest point of coolant circuit, occasionally squeeze top hose to rad, should be job done. Then reinstate tank but ultimately you should be looking at relocating tank to highest point of scuttle bulkhead.That trick with the expansion tank is clever. If you have to do this a lot you might be able to use something like a bike quick-release skewer to hold the tank in place... Jonathan Link to comment Share on other sites More sharing options...
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