Vulture Posted January 14, 2012 Share Posted January 14, 2012 (edited) It was a beautiful winters day here yesterday, so I cranked up the truck and used it for the school run to pick my lad up, a 12 mile round trip. Its pretty cold, about 5 degrees, so I'm expecting it will take a while to get up to operating temp, but the temp gauge stays stubbornly unmoved throughout the entire journey. On getting back straightaway I'm out crawling over the engine and checking the manual. I can't find anything wrong, i.e. no leaks from the tube. I look back in the cab and notice then that with the engine off that temperature is now showing on the gauge. I then start the truck up, and immediately the temperate falls back to bottom. On stopping the engine, it rises again ! I wondered if there was an issue with the water-coolant level, but 1.5 litres of water and anti-freeze brought it up to the rim. Any ideas guys ? Kind regards to all Ian Edited January 14, 2012 by Vulture Spelling Quote Link to comment Share on other sites More sharing options...
Degsy Posted January 14, 2012 Share Posted January 14, 2012 It was a beautiful winters day here yesterday, so I cranked up the truck and used it for the school run to pick my lad up, a 12 mile round trip. Its pretty cold, about 5 degrees, so I'm expecting it will take a while to get up to operating temp, but the temp gauge stays stubbornly unmoved throughout the entire journey. On getting back straightaway I'm out crawling over the engine and checking the manual. I can't find anything wrong, i.e. no leaks from the tube. I look back in the cab and notice then that with the engine off that temperature is now showing on the gauge. I then start the truck up, and immediately the temperate falls back to bottom. On stopping the engine, it rises again ! I wondered if there was an issue with the water-coolant level, but 1.5 litres of water and anti-freeze brought it up to the rim. Any ideas guys ? Kind regards to all Ian Did you attempt to warm it up before moving? this is something that the manual says is essential, also allow the vehicle to tick over before switching off in order for the engine to cool. When you next start the vehicle I would expect it to dump most of the coolant you have added as there is no expansion tank and if you fill to the top it will always dump the excess and settle to it's own level. I would check the thermostat, looks like it might be stuck open or even missing altogether. Hope this helps and good luck with it. Quote Link to comment Share on other sites More sharing options...
griff66 Posted January 14, 2012 Share Posted January 14, 2012 yep thermostat stuck open Quote Link to comment Share on other sites More sharing options...
deadline Posted January 14, 2012 Share Posted January 14, 2012 Do you have any portion of the radiator blocked off? While 41F (5C) is not arctic, when traveling at speed 30-35MPH (60-ish kph) you are down to 29F (-2C) and for a short trip that will suck the BTU out of the engine (I bet the block never got warm to the touch) After work last night my car home (after a 7 mile drive at 30-50mph) never showed a temp on gauge and the outside air temp was 25F (10F or -12C wind chill).. and my thermostat is fine. The reason why you showed a temp when off is because the water was not moving and there was nowhere for the heat to go.... so it actually did get the temp bulb warm enough to register on the gauge. Your t-stat could be stuck open... but before you mess with coolant and hoses block off the radiator with cardboard. Start the engine and let it fast idle (using the hand throttle) till you get normal temps (180ish). Take off the cardboard and go for a spin. If the engine cannot hold operating temp then you know the tstat is stuck open. If the temp stays 180ish then its working.. you might see the gauge swing abruptly as the t-stat opens for the first time... but after that the t-stat will open partially (it generally never completely closes... it finds a happy 'semi open' state). Quote Link to comment Share on other sites More sharing options...
griff66 Posted January 14, 2012 Share Posted January 14, 2012 if my car after a 7 mile drive at 50mph did not register ANY temp rise of coolant i would think thermostat was stuck open or at least not fully closing!( or temp rating of thermostat was incorrect) Quote Link to comment Share on other sites More sharing options...
Tony B Posted January 14, 2012 Share Posted January 14, 2012 You might have an airlock. Try removing the thermostat housing, and check the thing any way. Dump in a jar of hot water and see if it opens and shuts. Then top up the block through the housing, replace thermosts. CHECK IT'S RIGHT WAY round. All cock ups I've made in the past. The jump in temprature when the engine is turned off is common happening. When the pump stops turning the water sits aginst the stat. Quote Link to comment Share on other sites More sharing options...
deadline Posted January 14, 2012 Share Posted January 14, 2012 if my car after a 7 mile drive at 50mph did not register ANY temp rise of coolant i would think thermostat was stuck open or at least not fully closing!( or temp rating of thermostat was incorrect) Your mechanic must be a rich man! To be honest I really didn't let the engine warm up fully either. Even so, cooling systems can be overcome by nothing more than it being to cold out. When we get a stretch of < 20F weather (about -10C) its not uncommon to see a lot of cardboard over radiators. So don't be so fast to rip your engine apart before you have a very good idea what the the problem is. Quote Link to comment Share on other sites More sharing options...
griff66 Posted January 14, 2012 Share Posted January 14, 2012 (edited) ha that mechanic would be me! thermostats are about a fiver or 7.5 dollars bout a 15 minute job think of all that fuel you are wasting by not having engine at correct temp! any cooling system should be able to cope with minus 10 and yes your temp needle should be at normal range after 7 miles at 50 mph . Edited January 14, 2012 by griff66 Quote Link to comment Share on other sites More sharing options...
deadline Posted January 14, 2012 Share Posted January 14, 2012 You might have an airlock. Try removing the thermostat housing, and check the thing any way. Dump in a jar of hot water and see if it opens and shuts. Then top up the block through the housing, replace thermosts. CHECK IT'S RIGHT WAY round. All cock ups I've made in the past. The jump in temprature when the engine is turned off is common happening. When the pump stops turning the water sits aginst the stat. The t-stat is significantly below the radiator cap and the full level of the radiator. Also, there is a built in bypass so water will always circulate and prevent any sort of lock. Quote Link to comment Share on other sites More sharing options...
griff66 Posted January 14, 2012 Share Posted January 14, 2012 think tony b is correct best after thermostat change to fill coolant back up via thermostat housing if u have changed coolant ,then replace serviceable thermostat ! top housing back on then run engine with rad cap off at first to allow trapped air to escape then cap back on check for leaks.:nut: Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted January 14, 2012 Share Posted January 14, 2012 think tony b is correct best after thermostat change to fill coolant back up via thermostat housing if u have changed coolant ,then replace serviceable thermostat ! top housing back on then run engine with rad cap off at first to allow trapped air to escape then cap back on check for leaks.:nut: Not necessary to do that on a normal vehicle ( talking old mv's here), unless it has a heater or is something complex like a CVR(T) or Fox where you have numerous bleed points due to the radiator position. Thermostats often have a jiggle pin or small hole to prevent air locks. Quote Link to comment Share on other sites More sharing options...
griff66 Posted January 14, 2012 Share Posted January 14, 2012 correct, was talking about the 50 mph 7 mile no temp indication scenario :nut: wish my ferret did have a heater though ! Quote Link to comment Share on other sites More sharing options...
deadline Posted January 14, 2012 Share Posted January 14, 2012 think tony b is correct best after thermostat change to fill coolant back up via thermostat housing if u have changed coolant ,then replace serviceable thermostat ! top housing back on then run engine with rad cap off at first to allow trapped air to escape then cap back on check for leaks.:nut: You will be very low on coolant if you only fill as you state. About 2-3 liters low. Fill the radiator till you see fluid. Any excess will blow out the cap as overflow. The engine will find its own level. How is this vacuum forming? The cooling system is not air tight.. and vacuum will fill with fluid and any excess pressure will vent. Quote Link to comment Share on other sites More sharing options...
griff66 Posted January 15, 2012 Share Posted January 15, 2012 yep top up rad and expansion tank if fitted , oh bugger just noticed some swine has fitted a load of cardboard to my rad!!!:-D Quote Link to comment Share on other sites More sharing options...
Tony B Posted January 15, 2012 Share Posted January 15, 2012 Trouble is with old manuals, they say things like fill radiator, and assume you know all the old tricks that machanic of yore took for granted. Talk to a kid about ' De Cokcing a head' and they think your going off drugs. I was taught refill through thermostat as standard procedure. If the themostat is closed it will prevent coolant filled through radiator getting into the top hose, hence air in system. Quote Link to comment Share on other sites More sharing options...
griff66 Posted January 15, 2012 Share Posted January 15, 2012 its just good practice to do coolant fills as outlined not just say oh well the system will eliminate airlocks because its got that fitted etc why risk it hence after topping up coolant have engine running with cap off and watch air bubbles being purged from system( any one want to buy some cardboard:cool2:) Quote Link to comment Share on other sites More sharing options...
Tony B Posted January 15, 2012 Share Posted January 15, 2012 Requirments for Dennis vehicle tests, so I'm told. A gallon of coolant, cable ties and gaffer tape. :-D The other 'obvious' often neglected, CHECK the coolant level over the next few days. Quote Link to comment Share on other sites More sharing options...
deadline Posted January 15, 2012 Share Posted January 15, 2012 What old trick says fill an engine via the t-stat? T-stat valves are not air tight. If you are getting a pressure differential across a t-stat then its probably clogged or rusted shut. No US MV that I know of says anything other than a proper coolant refill is done by filling the radiator till coolant is visible, run the engine and refill. Unless there are some wacky British vehicles (and after owning a MG Midget I can attest to some odd mechanical arrangements on British cars) that you need to fill via the t-stat, while facing east, standing on the left foot and pouring with the left hand (hahahaha I'm kidding) hoses are best left attached and sealed. Feel free to add coolant anyway you like... its always interesting to hear other ways of doing things. Quote Link to comment Share on other sites More sharing options...
griff66 Posted January 15, 2012 Share Posted January 15, 2012 one more go,if u have changed thermostat/ coolant before replacing thermostat fill with coolant to just below where thermostat sits then fit thermostat then replace housing connect coolant pipes top up rad/expansion tank rad cap off heater IF fitted to max run engine 5 mins ish check levels replace cap take for drive let cool down and recheck levels.(CARDBOARD ANYONE) Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted January 15, 2012 Share Posted January 15, 2012 one more go,... And for the last time - WE DON'T WANT YOUR CARDBOARD!! Quote Link to comment Share on other sites More sharing options...
griff66 Posted January 15, 2012 Share Posted January 15, 2012 :D:D:D!!!! ah go on! Quote Link to comment Share on other sites More sharing options...
Tony B Posted January 15, 2012 Share Posted January 15, 2012 Wher's the joke in filling old English vehicles facing West actually, often with both feet off the ground trying to reach the ***** filling place! Now you know why I run a Dodge! :-D Quote Link to comment Share on other sites More sharing options...
Vulture Posted January 15, 2012 Author Share Posted January 15, 2012 Guys, thanks for your thoughts :-). Lots of good ideas :idea: on how to try and tackle this puzzle. Weather permitting I'm going to fire the old girl up in the morning. I'll block off half the radiator with cardboard and see how things go. Excuse the NOOB question :n00b: but I'm assuming I block the front of the rad off ? (i.e. not the side with the fan). I think a call into Rex Ward to get a spare thermostat is also required tommorrrow. I'm curious as to how many people get their engine up to working temperature before driving off. I know the manual says to do so, but I thought that the 'modern' thinking was get vehicles up to working temp as quick as possible (by driving them) but not to work the engine too hard in the process. Kind regards to all Ian Quote Link to comment Share on other sites More sharing options...
Degsy Posted January 15, 2012 Share Posted January 15, 2012 I think the answer to your question on warming up is very few but personally I usually warm up any vehicle to some extent when starting from cold and take care not to work it too hard initially. I have not seen anything for years in an instruction book on allowing a turbo engine to tick over after use in order to have oil flow to the turbo as it cools but it still needs to be done. The manufacturer will no doubt happily sell you a new turbo:) Quote Link to comment Share on other sites More sharing options...
andym Posted January 15, 2012 Share Posted January 15, 2012 This might be a stupid question, but before we get all excited about thermostats are we sure it isn't just a faulty temperature gauge? Does the engine feel as though it's up to working temperature? Andy Quote Link to comment Share on other sites More sharing options...
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