TomGaval

Well, not quite. I've had the car on track 3 times so far this year and the first time out I still experienced some pressurization of the coolant in the expansion tank which resulted in some slight puking of coolant after 20 minutes at speed on track. I received some info from Cosworth USA on the engine which stated that they recommended a 21 to 25 PSI cap for the expansion tank. I was using the stock 16 psi one. So I found a 20 psi one and while I still had some pressure build up, I did not have any puking. Water temp on track running hard stayed pretty much around 210F and Oil temp around 220F. Last time out 2 weeks ago I switched to a 29 PSI cap that I found at a Range Rover dealer, and again, no puking. However, the pressure that had built up after a day on track was still there two days later while the car sat in the garage. When I went to open the cap, coolant started filling the tank rapidly and when I replaced the cap and then undid the bleed bolt on the radiator some air bled out and then the coolant dropped out of the expansion tank and started to come out of the radiator bleed hole. l just finished relocating the expansion tank from the front cruicform up onto the highest point on the scuttle/bulkhead. It definitely self bleeds now, and I have another track day scheduled for this coming Thursday to test it again. The only other step left if this doesn't work is to switch to an electric water pump system as recommended by SBD. While it could still be a head gasket, my mechanic still doesn't think so based on the lack of oil/coolant contamination and the fact that it's only high rpm related. I'll update again after Thursday's track workout. Tom

Noted. Thanks Simon!

6speedmanual, as a result of your comment, I did another test of the coolant for the presence ofexhaust gases. I used a new kit with fresh fluid and after letting the car warm up to 195F and reving it to 5000 rpm a few times, I conducted the test as per the instructions and the results were again negative. So hopefully the head gasket is not the issue. I did notice today that the coolant level which started just below the min line on the bottle really does not leave much coolant in the tank. The bottom hose is covered but the far side and middle are barely covered at that starting point. That leads me to believe Pendennis's conclusion that the fluid sloshing in the tank could cause air to introduced into the system. However, while letting the coolant warm up before testing, with the cap removed, the level of fluid in the tank did rise to just ove the Max line on the tank, which was about an inch or more above where it started. Temp here in Philly was 70F yesterday, 55F today and we are expecting 1-3 inches of Snow tomorrow. That's probably it for the garage other than Shovelling. Tom

Just checked out the routing of the hoses. 1) The rear outlet appears to be the standard one with the large hose exiting on the left and running below the Roller Barrels and into the top left of the Radiator. 2) The bleed hose originates from the right side of the rear outlet and runs to the top of the expansion tank. It is a 1/4 inch ID hose. 3) The lower hose on the bottom of the expansion tank feeds into a tee that comes off the thermostat housing the other side of the tee connects to a hose that I added in place of some blanking plugs and replicates the heater hose. (no heater) and connects on the right side of the rear water outlet on the head. 4) Yes the OE bypass hose is connected as stated. 5) I eyeballed the level of the tank bottom hose outlet vs the height of the rear water outlet on the head and it is close but appears that the bottom hose is slightly below the level of the water outlet on the head. Not much but a litlle. 6) I've measured and it looks like I have room for a small expansion tank on the left side of the bulkhead. I'll start looking for one that fits now. I will also look into the smaller pulley for the water pump. Thanks Guys! Tom

Ok, it warmed up enough for me to venture back out into the garage for a few minutes. Car was idle since last trackday. I opened the bleed bolt on top of the radiator and no coolant came out so again, obviously airlocked again. Unbolted the expansion tank and put it up on top of the dry sump tank and opened the cap. Coolant/air sputtered out for a bit. Replaced bolt, and started car with the expansion tank open and held on top of the dry sump tank. Watched air bubbles rise into the expansion tank for a full 5 minutes before stopping. Radiator got progressively warm and at 195F the Fan kicked on. Temp gauge dropped to 185-190F and radiator cooled off so that it was actually cool on top and on the front. Hot air was being pulled out the back. The top right where the top hose entered was hot and the Bottom left where the bottom hose exited was hot as well. Does that sound right? I thought it would have been a bit cooler at the bottom. No more bubbles rose, and after a full 30 minutes idling, the water temp was 200F and the oil temp was 175F. When I revved the engine a bit, the water temp did drop back under 200F for a bit then came back up. So Where the heck is the Air coming from? Obvioulsy it only occurs at sustained high revs. I'm definately going to relocate the expansion tank to a higher point. It definately seems that the car runs well for 15-20 minutes at moderate revs but once It is pushed the pressure/air builds up and cooling is impaired. Once again, your thoughts are appreciated. Tom

Rob, I did pull out the thermosat and temps still got up to 220F+ after several hard laps even in 30F air temp last week. I let the car warm up prior to going on track, by running around in First gear in the paddock and took it easy on track for several laps prior to opening it up. Tom

Thanks again guys. First order of change is to move the coolant tank up to the highest point in the system. I don't think I've been able to keep my right foot down long enough to ever get above 7200rpm. As Croc said, I'm a big chicken. I will also replace the cap again, and install a small bleed line off the top bolt in the radiator. Hopefully that will solve the issue. Unfortunately I probably won't know the results until next spring, as it takes a few hard laps to have the issue. Blat Chat Rules!!! Tom

Croc was right. Hung out with a bad crowd last night at dinner. Waaay too many bottles of wine. I did change the cap prior to the switch to Evans. I have another new one I'll switch to. I have not yet moved the expanion tank and now that the trackday season is over, that is on the list of winter to do items. Yesterday's air temp at the track started at 28F and got all the way up to 40F. Coolant level rose slightly in the tank but never puked. Although there were a couple small droplets on the tank around the cap. Temp got up to 205 during the first session and did briefly hit 220F during the 3rd session of the day. Temps are from the gauge, but I did check the gauge temps vs an IR reading at idle and the IR reading at the hot spot on the back of the head near the sender was within 5 degrees of the gauge. 189 vs 185. Anyone know what size waterpump pully is the correct one for this application? I've looked at the SBD website and they have a diagram of the cooling system layed out for their electric water pump installation that looks interesting as it incorporates several bleed points. Tom

Jonathan, I can pretty safely say that after draining and refilling the system 3 times that it was done correctly each time. I took significant care to make sure it was bled well and would idle for over 35 minutes without any temperature issues before taking it out on the track. The EVAN's coolant definately cured the pressuriztion issue. Yes, to be scientifically correct, you would revert back to the old coolant and see if the pressurization reoccured, but The swtich to Evans was costly enough, that I don't want to spend the extra money at this time. My other Caterham has a K series, so I'm pretty confident in my ability to bleed a coolant system after 15 years of ownership. Like I said, I'll try the ducting around the radiator before next weekend's trackday to see if that helps the cooling. Then do a few of the other suggestions, before the final track weekend in two weeks. The car will then go into the shop at the end of the season for a thorough going over. I don't have any links to Evan's coolant. One of the other members of the drivers club at the track has an R500 that had a puking issue as he came into the paddock after a 25 minute session on track. He switched to Evan's and it resolved that boiling over issue, so that's why I gave it a try. I'm just glad it wasn't my head gasket. Tom

Update. I drained and flushed the system and refilled using EVAN's Coolant. It's a waterless coolant that claims a 375F boiling temp that helps prevent hot spots due to boiling. I did two trackdays this weekend and I'm happy to report that the coolant level remained stable and there was NO leaking/Puking out of the expansion tank. The bad news is that I still have an overheating issue when running hard for several laps. The Air temp this weekend was in the High 50'sF and the coolant temp still hit 220 after about 6 laps running hard. It would quickly cool to 210-200F by lifting. One of the other members at the track suggested moving the oil cooler from infront of the radiator, and to try some sheet metal ducting from the radiator to the nose cone to ensure no leakage of fresh air around the rad. Also suggested a small bleed vent drilled in the top radiator bolt, with a line to the expansion tank. I maybe able to fab up some ducting before next weekend's trackday. Will keep you posted. Tom

Thanks for the pointer to that link Jonathan. Roger's issue sound very much like mine. The location of the expansion tank is on the right front next to the dry sump tank. As pointed out in an earlier thread I started the tank is below the level of the head and is definately not the highest point in the system. I might be able to find room on the scuttle on the left side. I have the paddleshift compressor and valving mounted on the right and center of the scuttle. Hopefully Roger will see this thread and post a drawing or picture of his solution. (hint, hint.) Tom

As Croc said, I have replaced the cap, But I have another and I'll replace it as a precaution. The radiator is the C400 race version, so it is upgraded from the standard one. Don't know what coolant is in there as It was replaced before I bought it. As for the oil cooling. there is an oil cooler mounted at the front on the lower third of the radiator. Oil temp takes a few easy laps to come up but when running hard it sits right around 200F. When I backed off the throttle to cool down the water temp, the oil temp dropped down to around 180F. I have the triangular dry sump tank mounted in front of the engine. Mark, any pics and details available of the swirl pot set up? Oh, And I saw that the F60 America is all sold out, are you one of the lucky 10?* My wife still tells the story of you picking me up in the 308. Thinking I'm a loon getting in a car with a complete stranger. Thanks for the help guys. Keep em coming! Tom

My lastest addition to the garage, a second Caterham. is a very high spec SV with a Cosworth 2.3L duratec, with 13:1 compression ratio, that has been suffering from a pressurization of the coolant in the expansion tank which then pukes out a little coolant usually after 15 to 20 minutes on track. I feared the dreaded Head gasket, and as My other car has a roverK series, I'm well versed in the history and dealings with Oily. I had the system tested for exhaust gases in the coolant, but the test was negative. I found two small leaks in the Radiator, and had those repaired, and I removed the thermostat as the lower hose was not getting warm. Fan works and comes on at 195F. On track yesterday, during the first session the car ran well for about 15 minutes of spirited driving and then the temp started rising from the steady 185F to wards 220. I backed off and went in and the temp was back down by the time I got to the Paddock. A small spray of coolant was visable on the expansion tank, cam cover, dry sump tank and even back as far as the scuttle. On the remaing runs yesterday, I held max revs to 5500 on one session and then 6500 on the next session. At 5500 rpm max, the car made the whole 30 minute session without issue, no coolant leakage, no temp above 200F. At the 6500 level, the temp came up again to 220F but no coolant leakage. Today I ran it hard, in all sessions, and Revs got into the 7000+ range often. On the first two sessions this morining I could run hard for about 4 laps, (2.25 mile track) before the temp got to 220F but once I lifted and slowed down a bit, the temp would get back to 185F and then I'd go at it hard for another 4-5 laps till it did it again. Every time when I lifted off the throttle the temp came back down. The last session today I did about 8-10 laps before it hit 220F. So after that lenghty description, I'm concerned that the temp keeps rising if I don't back off. I should be able to get thru a 30 minutes track session without overheating. Any suggestions as to what the issue could be? Tom

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

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

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

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

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

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

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

Chris, I assembled my Caterham 14 years ago and just bought another one. 😬 So I'm stuck with them. My new one has A lot more HP (309) and is cycle fendered and vs my Clammed (195hp) one is ALOT quicker and has a higher top speed, but I seem to still be about 10 to 15mph short of the Vettes and GT3's down the straights. Yes, I do have an advantage coming out of the turns and in the braking zones, but it's just frustrating having them run me down after working so hard to put some distance between us. An extra 2-5mph would be nice. Just looking for options besides loosing more weight. 😬 Tom

Speaking of top speed, here is an old MIT video re: aero/drag. Realizing that our whole car is a brick, do you think the drag from the roll cage is significant, and do you think the addition of something like this would reduce drag enough to be worth the cost? here Always looking for another couple MPHs to keep up with the GT3's and Zo6s on the straights. Tom Edited by - TomGaval on 23 Aug 2014 00:09:35

I just bought another Caterham and it has that wheel. Didn't think I'd like it but after my first session on track yesterday it didn't feel too bad. I think having the flappy paddles attached to it and 300+ hp took my mind off it. *eek* 😬 Tom

Thanks guys. I was so embarrassed by my initial attempts at starting off and driving that I almost reconsidered purchasing the car. Croc, I admit it. with over 114 more horsepower than my VHPD K series, I'm like a frightened little girl out there. The acceleration is just amazing. But what I'll blame the lack of full throttle on the fact that the prior owner is 6 foot 8 and I'm only 6'1" and the seat wasn't on sliders so I had trouble reaching the pedals. That's my story and sticking to it. 😬

Thanks, Second session that I took it out, I was smoother, and had to start a second time as I got held up on pit row waiting for the signal to proceed onto the track. Yep, this one has the paddle shift set up as well. I did buy it so, I guess I'll just have to practice more. 😬 😬 So much for all my practicing the heel toeing. Might keep the docile little Superlight R spec car as a sunny Sunday street toy. Just don't tell the wife.