Pelico Posted March 5, 2006 Share Posted March 5, 2006 Secondhand 1.8 k engine fitted a few weeks ago. All sort test runs have been OK. I have had a few very tiny coolant leaks but nipped up all the hose clips and the water rail bolts. Did notice a 'glug' of coolant shoot though the expansion tank top hose, the one from the inlet manifold, after opening the expansion tank cap when the engine was cold Drove to Goodwood this morning, all perfect on the way there. On the way back within a couple of miles saw the temp gauge move quickly up to 100+. Pulled over straight away, looked under the bonnet and the coolant had risen to 3/4s of the way up the expansion tank. (was filled to 1/2 way up) AA man tested the coolant for exhaust products, none there. He ran the engine and it quickly got up to 120 again, but his pyrometer suggested that nothing was above 90deg. Coolant did run to the top of the tank and overflow when he took the cap off, but did not seem to overflow much more when he was running the engine with the cap off. The coolant is now still 3/4 of the way up the expansion tank, but there is none to be seen at the heater end, looking in the bleed T. Any advice appreciated. Thanks. Peter (Updated at bottom of thread. Good news I hope ) (Second update now below ☹️) Edited by - pelico on 5 Mar 2006 13:06:09 Edited by - pelico on 12 Mar 2006 12:57:25 Edited by - pelico on 8 Apr 2006 19:09:39 Link to comment Share on other sites More sharing options...
Pelico Posted March 5, 2006 Author Share Posted March 5, 2006 Oh and no sign of any mayonnaise on the dipstick or headertank. Link to comment Share on other sites More sharing options...
Cloud 9 Posted March 5, 2006 Share Posted March 5, 2006 Sounds like a airlock somewhere Link to comment Share on other sites More sharing options...
Mick Day Posted March 5, 2006 Share Posted March 5, 2006 You have an airlock which has probably cleared. Plus on cold days like today your thermostat may be just opening enough for a dose of cold water from the rad to promptly close it again. Try running with some blanking in front of the rad. Link to comment Share on other sites More sharing options...
Big Brother Posted March 5, 2006 Share Posted March 5, 2006 "AA man tested the coolant for exhaust products, none there. He ran the engine and it quickly got up to 120 again, but his pyrometer suggested that nothing was above 90deg. " Sounds like a dodgy temperature gauge Steve SE7EN-UP! Incorporating the Caterham Links Database Link to comment Share on other sites More sharing options...
Trevor Newman Posted March 5, 2006 Share Posted March 5, 2006 have you got a heater sounds like an airlock if it gets to 120 that quickly Link to comment Share on other sites More sharing options...
shn7 Posted March 5, 2006 Share Posted March 5, 2006 Peter, I'd go with the airlock theory which may well have cleared itself in what's happened. Try running it at (fast) tickover for 15 - 20 mins and watch the gauge and keep feeling the top rad hose to see if it's getting hot. Run at least until the fan kicks in and see what the temp reads Do you know if the fan was running when it was showing high temps? Was the radiator hot top and bottom? Steve. Link to comment Share on other sites More sharing options...
Pelico Posted March 5, 2006 Author Share Posted March 5, 2006 Thanks everyone. I was worried after reading all of Nick Wood's posts in the past where he had his 'occult' HG failure that did not show any oil/coolant mixing. Link to comment Share on other sites More sharing options...
nickh7 Posted March 5, 2006 Share Posted March 5, 2006 Air Lock, jack up the front or better still a bleed key Its Yellow and Black and makes me 😬 Link to comment Share on other sites More sharing options...
Neil A Posted March 5, 2006 Share Posted March 5, 2006 Excuse my ignorance, (quite at the back), but would not the coolant go down if an airlock had formed? Fellas, smoke me a kipper, I'll be blatting for breakfast. Link to comment Share on other sites More sharing options...
shn7 Posted March 5, 2006 Share Posted March 5, 2006 nickh7, 'tis already fitted with a bleed tee but maybe when we installed the engine we failed to take full advantage of it ☹️. Steve. Link to comment Share on other sites More sharing options...
Big Brother Posted March 5, 2006 Share Posted March 5, 2006 Excuse my ignorance too, but if a Pyrometer is pointed at an engine that is apparently running at 120 degrees C, why does it see no more than 90 degrees 🤔 Steve SE7EN-UP! Incorporating the Caterham Links Database Link to comment Share on other sites More sharing options...
shn7 Posted March 5, 2006 Share Posted March 5, 2006 I guess it depends where you point it and where that is in relation to the temp sender. Steve. Link to comment Share on other sites More sharing options...
Pelico Posted March 5, 2006 Author Share Posted March 5, 2006 OK just to add a further layer of complexity 😬. The AA guy also noted that primary 3 was hotter than the others. Link to comment Share on other sites More sharing options...
alicat Posted March 5, 2006 Share Posted March 5, 2006 Definately sounds like an air lock. Had a similar experience. Alicat Link to comment Share on other sites More sharing options...
shn7 Posted March 5, 2006 Share Posted March 5, 2006 primary 3 was hotter than the others running lean perhaps, but why How much hotter? If you need to borrow a compression tester which would help diagnose/discount HG failure then you're welcome to use mine. Can pop it in the post if needed or if you're around on Tuesday evening I could call in on the way to the Horsham meet which seems to be on the cards. Steve. Link to comment Share on other sites More sharing options...
Myles Posted March 5, 2006 Share Posted March 5, 2006 Excuse my ignorance too, but if a Pyrometer is pointed at an engine that is apparently running at 120 degrees C, why does it see no more than 90 degrees Do you mean a non-contact thermometer? One of them-thar LED/laser jobbies??? If so, they are basically only useful for highlighting *differences* in temperatures rather than the *absolute* temp due to the vastly different emissivity/reflectivity characteristics of materials. Shiny stuff (polished exhausts etc.) are particularly bad targets for an accurate reading - however, as suggested above, they should be able to show temp *differences* between identical materials... Project Scope-Creep is live... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
CageyH Posted March 5, 2006 Share Posted March 5, 2006 As said before, sounds like an airlock. Run the car for a while, keeping an eye on the temperature gauge, and check bottom and top rad hoses. If the top gets hot, and the bottom stays cold, you either have an airlock or a dodgy thermostat. Link to comment Share on other sites More sharing options...
Neil A Posted March 6, 2006 Share Posted March 6, 2006 Excuse my ignorance, (quite at the back), but would not the coolant go down if an airlock had formed? I meant unformed, ie it cleared 😬 Fellas, smoke me a kipper, I'll be blatting for breakfast. Link to comment Share on other sites More sharing options...
Pelico Posted March 6, 2006 Author Share Posted March 6, 2006 Neil, I think I have to conclude that the airlock is still there as the headertank is full but the heater end is empty. I am also worried what introduced air in the first place. Since this happened only on about the 6th time the car was run after the engine swop I would have thought we would have seen an airlock straight away. But I am keeping my fingers crossed and will rebleed over the weekend and see how it goes. Thank you eveyone for your advice . Peter Link to comment Share on other sites More sharing options...
John Howe Posted March 6, 2006 Share Posted March 6, 2006 Peter, when you come to bleed it again, get the nose of the car as high as possible and try filling it from the radiator bleed screw hole. It really does sound like an airlock... fingers crossed JH Deliveries by Saffron, the yellow 230bhp Sausage delivery machine Link to comment Share on other sites More sharing options...
CageyH Posted March 6, 2006 Share Posted March 6, 2006 As you have a bleed tee fitted, just use the Caterham fill process, and bleed via the bleed tee. I fill the system via the heater pipes, until coolant escapes from the other end. Connect up all the pipework, bleed via the rad bleed screw and then via the bleed tee. It is worth double checking all jubilee clips, and the one near my thermostat was slightly loose, and this kept causing an airlock. It is sorted now though, using basically the above procedure. Link to comment Share on other sites More sharing options...
Pelico Posted March 12, 2006 Author Share Posted March 12, 2006 Update Followed this routine today. - Nipped all the hoses up - Filled coolant into to heater bleed T - Vented from the rad bleed screw - Jacked the front up, filled a bit more from the bleed T and vented from the rad again. - Wiggled and squeezed all the hoses Back on the level, I ran the engine, cracking the header cap and the rad bleed screw at little at first. Engine ran up to 80deg then the bottom rad hose went hot (thermostat opening I assume - I wonder if I have a slightly cooler stat installed ?). Even on a fast 3.5k idle the temp refused to go above 80ish. All hoses hot, bottom rad hose slightly cooler than the top. Fan came on happily and ran for a further 10mins with temp nice and stable around 80. I take it this is all good news 😬 Any more checks I should do ? After it cools should I open the bleed screws a little again ? I am still wondering why an airlock suddenly appeared but I guess a proper test drive is needed to test. Blat anyone 😬 🤔 Link to comment Share on other sites More sharing options...
CageyH Posted March 12, 2006 Share Posted March 12, 2006 Sounds fixed Just keep an eye on the coolant levels and temp for the next few blats. After mine did this after some major work, I carried round a spanner for the rad bleed screw and some mixed coolant, until I was sure it was fixed. Link to comment Share on other sites More sharing options...
shn7 Posted March 12, 2006 Share Posted March 12, 2006 😬 Steve. Link to comment Share on other sites More sharing options...
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