dirtbox Posted November 12, 2007 Share Posted November 12, 2007 OK guys, I know this has probably been covered to death but i cant find anything with the same problem as mine. I have been having troubles with my temp gauge telling me that im getting hot on my 3.5 V8. I fitted the V8 in place of the 2.5 petrol in the summer and changed rad to suit. I kept the 2.5 header as the bottom pipe for the V8 was split and as its slightly different (Got a down ward joint on the 2.5 pipe from header to bot pipe as opposed to the V8 is straight across from rad to pump housing) to the 2.5 fittings i re-used these. It has been great and over the summer it ran really well in the middle of the white. Then, a few months later it has started to overheat. Well the gauge says it is. As the top pipe was not really getting hot, I replaced the thermostat, it had an 82' and the guy in the shop told me about an 88 being better so i went with this. If anything it was now worse, getting right near the red! Changed it again for an 82 as tested them as they didnt open too well at temp stated. Whilst i waited for the new 82 to arrive i drove without a stat to flush the system out- also flushed every thing through with a hose. This showed a cool temp as thought. Fitted new stat and after a run around it ran really well until the last week or so it has started to get hot again! Took stat out again and flushed system out as it seems like a restriction in the flow and on checking the stat, it is fine?? Rad runs clear and freely??? Could my water pump be duff without dumping any coolant?? Checked oil for water, water for oil or exhaust smell, no excess pressure at all in hoses, no kinks, checked exhaust manifolds are tight and no loss of coolant. I'm not sure about airlocks as i filled up as mentioned in other posts but unsure of my set up slowly trapping air???? Any help would be greatfully received. Thanks in advance, Paul Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted November 13, 2007 Share Posted November 13, 2007 First off, does the stat have a small bypass hole in it to allow a little flow even when the main part is closed? If not, you can get an airlock and then the stat opens too late (ask me how I know ) Second - your temperature gauge is probably not matched to the V8 sender. Third - your temperature gauge may be calibrated for a cooler stat than the V8 one, so the "normal" mark may well be at a lower temperature. Surefire cure for 2 & 3 is to buy an aftermarket gauge & sender that will tell you in degrees what the temperature is. Quote Link to comment Share on other sites More sharing options...
dirtbox Posted November 13, 2007 Author Share Posted November 13, 2007 hey, yeah it does have a small bypass and i situated this to the top as it stated on it. would the gauge not have worked from the start or could this have built up? I Know I shouldn't run without a stat but I was trying to work out if it would run at a lower temp and it did? I'l have a look for racetech gauges, thats quite a popular name on here! Also I might have to check the water pump tomorrow and see if it is spinning as it should. Quote Link to comment Share on other sites More sharing options...
dirtbox Posted November 13, 2007 Author Share Posted November 13, 2007 Ok, could someone help with what temp I should be running at? Was looking at race tech gauges earlier and nearly got one but saw the price! suppose its not bad if it saves my engine. Is there any other way to see if the block is getting hot while i save my pennies till next month when i can afford a sender and gauge? have been advised that i replace the cap on my header tank too? What effect can this have on my heating up/ cooling down? :( Quote Link to comment Share on other sites More sharing options...
landmannnn Posted November 13, 2007 Share Posted November 13, 2007 Ok, could someone help with what temp I should be running at?Was looking at race tech gauges earlier and nearly got one but saw the price! suppose its not bad if it saves my engine. Is there any other way to see if the block is getting hot while i save my pennies till next month when i can afford a sender and gauge? have been advised that i replace the cap on my header tank too? What effect can this have on my heating up/ cooling down? :( link Maplins do a £9 electonic temp meter or for £26 a multimeter with temp measuring device. Obviously can't get them in the coolant but the rad is pretty much the same temp. Useful after the problem is sorted. When water is under pressure it boils at a higher temperature. With a leaky cap the water will boil in the block, (steam is not very good at cooling) thats why if you leave the cap off altogether the coolant expands and overflows. Quote Link to comment Share on other sites More sharing options...
dirtbox Posted November 14, 2007 Author Share Posted November 14, 2007 Thankyou landmannnn. This may be the possible cause to my gradual overheating problem then! Well i wont speak too soon as i cant find an expansion bottle for the Carbed 3.5 V8 anywhere! I'l keep a lookout on eblag unless anyone has got a spare for sale! Thanks again, il keep looking! Quote Link to comment Share on other sites More sharing options...
dirtbox Posted November 21, 2007 Author Share Posted November 21, 2007 Well, I took the water pump off now and thats fine too! Fitted the correct expansion cap, and the gauge is the same part no. so all i could think it is, is an airlock! Is it possible that air can pocket in the block? The reason i ask is because it seems like the coolant will not flow. The pipe up to the heater is warm and the top pipe to the rad is only just warm but if i squeeze the pipes to encourage flow i can feel HOT coolant start to move around a bit- hence my thoughts it was the thermostat or pump! This is really confusing me now! HELP!!!!! :( :( Thanks in advance, Paul Quote Link to comment Share on other sites More sharing options...
Coastcard Posted November 21, 2007 Share Posted November 21, 2007 Do you have a pic of your engine bay so we can take a peek at your current setup? What are you using as a cooling fan? Are you 100% it / they are OK? What is the evidence of overheating? Is the needle in the red or just a bit high on the white? Quote Link to comment Share on other sites More sharing options...
dirtbox Posted November 21, 2007 Author Share Posted November 21, 2007 Hey, Got an old viscous unit for fan and it seems Ok although it does spin easily when hot but it always has done! Yeah, needle goes right up to the red every so often but I dont let it get any further! (I have to pull over for a bit for it to cool down!) I did think it was related to the needle as the pipes don't feel hot, until you really encourage the flow by squeezing pipes and then you can feel much hotter coolant start to creep up. Just finished messing around with getting the water pump off completely and on inspection in daylight i can see where coolant has been around the little hole underneath pulley. This shows my seals are probably gone but the rest seems Ok so it should have still pumped right? Will replace this but not sure its going to help! AAARRRGGGGHHHHHH!!!!!!!!!!!! :angry: I also need to replace the pulley as i cracked a lump off of mine trying to get the rusty lump off the pump!!!!!! :angry: I have started to think i might just drill the centre out of the thermostat and see what it runs like! Anyway, thanks for letting me rant- heres what set up i have..... 3.5 with SU's and a Bigas single point LPG kit on top of the transmission tunnel, On the bot of the expansion tank i have a down pipe that tee's into the bottom rad to pump pipe. Quote Link to comment Share on other sites More sharing options...
dirtbox Posted November 21, 2007 Author Share Posted November 21, 2007 Quote Link to comment Share on other sites More sharing options...
Coastcard Posted November 21, 2007 Share Posted November 21, 2007 Bit hard to tell from those pics as you can't see where everything goes, but another option may be the LPG vapouriser. Wouldn't have thought it would make that much difference, but maybe worth bleeding (they normally have a bleed screw in the top). Also wondering whether the fact that you have a feed from the top of the rad into the header tank and also a feed into the bottom hose is having an effect. Brain a bitt frazzled, but will have a look at my Rangie header that has the bottom hose filler. V8 carb stock setup feeds into the top of the rad only (the tube in the tank goes below the waterline). Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted November 21, 2007 Share Posted November 21, 2007 Try wrapping some string around the nut behind the viscous fan to jam it on solid. It may be that your viscous unit has failed/is failing. Or of course fit an electric one.... Quote Link to comment Share on other sites More sharing options...
4.6v8lwt Posted November 21, 2007 Share Posted November 21, 2007 Try checking that there is water coming through the pipe from the inlet manifold to the top of the radiator. Air can build up over a period and give over heating problems. Quote Link to comment Share on other sites More sharing options...
nas90 Posted November 21, 2007 Share Posted November 21, 2007 Where did you buy the radiator. New, secondhand? definitely V8 suitable radiator? V8 core and water flow is different to the oil burning brigade radiators Old radiators can look very clean on the outside but inside they are falling apart and are worse than useless and difficult to visually inspect. I've just put a new rad in the nas after 100,000 miles made such a difference to the temperature especially towing up hills now instead of the gauge shooting to the red and on the downhill slope cooling off from the uphill slope the gauge is rock solid whatever the road conditions. If you are using the 2.5L instrument panel and V8 temp sender probably the temperature is not reading correctly, or from about 10 replies above have you resolved that issue? Quote Link to comment Share on other sites More sharing options...
dirtbox Posted November 22, 2007 Author Share Posted November 22, 2007 Changed water pump in the freezing cold this eve decided to leave the thermostat out for a while until i have some cash to get some bits if i need them! I just cant face the thought of draining coolant yet again just yet! On the last thing to tighten, (the rad top plastic crappy bolt thing)I sheared the bloody thing off pinching it up! :angry: :angry: :angry: :angry: :angry: :angry: :angry: :angry: :angry: :angry: :angry: Couldn't believe it- had to come in and have some red wine to laugh about what a nightmare i'm having!!! Thanks for your replies- this seems like the place to get some help in those evil lonely moments when my missus has had enough of my moaning! The Rad is second hand but I am now reluctant on how good it is. I have had it off and blasted a hose through it but thinking about it, water didnt exactly gush through, it found its way through. I was promised that its been tested, and to start with seemed to work fine but hearing how well a new one can work, my pennies are being saved already! The temp sender is a new one and the dial is exactly the same part no. The guys in a local dealers told me not to worry about it and showed me the part no. going to give both the string and the top hose a go as they're the only things i have not yet done so good ideas! Thanks for the replies again, Will keep you posted, Cheers, Paul Quote Link to comment Share on other sites More sharing options...
landmannnn Posted November 22, 2007 Share Posted November 22, 2007 Also wondering whether the fact that you have a feed from the top of the rad into the header tank and also a feed into the bottom hose is having an effect. Brain a bitt frazzled, but will have a look at my Rangie header that has the bottom hose filler. V8 carb stock setup feeds into the top of the rad only (the tube in the tank goes below the waterline). I have got the same expansion tank, the top pipe is blanked off and the bottom pipe feeds to one of the small outlets on the rad. Not sure whether this could cause your problem though. I would suspect that you have got an airlock somewhere, is it a coincidence that the problem has occurred as the weather has changed? It could be in the heater pipework. I did have a car once where the heater rad was high up, I had to bleed the air out from the highest point to stop the overheating. Also it is not unusual for the top hose not to be fully hot on tickover, the water pump circulates the water much faster as the revs increase. Quote Link to comment Share on other sites More sharing options...
dirtbox Posted November 23, 2007 Author Share Posted November 23, 2007 Yeah, Im going to have to check the top hose as in the top manifold pipe once filled up as i have not done this yet!!! with new rad cap!@!!!!!!!!!!!!!!!!!!!!!!!!! AAAAAAAAAAAAAAAAAAAAAAAAAAAAARRRRRRRRRRRRRRRRRRRRRRRRRRRRRRGGGGGGGGGGGGGGGGGGGGG GGGGHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH Oh sorry, had to let go!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted November 23, 2007 Share Posted November 23, 2007 We've all been there I think A few thoughts; - Your header tank should have a low pickup (some have a pickup tube inside to a high connection on the outside) that goes to the small tube on the top of the rad. Make sure that's right, connecting a vent tube instead would lead to air being drawn in. Your piccy looks right but without seeing where the pipes go it's hard to tell 100% - You can buy brass rad caps (I believe they're a stock BSP thread or similar) or a bling X-Eng ali one - Your rad sounds like prime suspect, you could try running some Rad Flush through although I doubt it'll make enough difference to avoid buying a new one. If you blast a hose in one port, does it come out of the other end at the same speed? Quote Link to comment Share on other sites More sharing options...
tacr2man Posted November 23, 2007 Share Posted November 23, 2007 You usually find that the V8 runs cooler when on gas as heat is taken out of the engine to vaporise the gas , I would supect the rad after the thermostat as airlocks only usually affect the heater or vaporiser circuits, JMHO Quote Link to comment Share on other sites More sharing options...
jules Posted November 23, 2007 Share Posted November 23, 2007 The temp sender is a new one and the dial is exactly the same part no. The guys in a local dealers told me not to worry about it and showed me the part no.going to give both the string and the top hose a go as they're the only things i have not yet done so good ideas! Has it boiled over if you can touch with you hand the hose it's not that hot...... I don't care what he says a V8 defender temp sender and a range rover v8 temp sender are not the same a RR one will read hot in a defender when it should be reading normal I've converted two early 90's and a early 110 to 4.2 V8's from 2.5's with no trouble Quote Link to comment Share on other sites More sharing options...
Coastcard Posted November 23, 2007 Share Posted November 23, 2007 I don't care what he says a V8 defender temp sender and a range rover v8 temp sender are not the same a RR one will read hot in a defender when it should be reading normal IIRC the Range Rover temp sender has a red plastic insert in the top and the Defender one is white. Looking at Dirtbox pictures (no not those ) , his looks white or yellow. I have been meaning to go and have a look at mine to check... just one of those busy weeks!! Quote Link to comment Share on other sites More sharing options...
dirtbox Posted November 23, 2007 Author Share Posted November 23, 2007 sorry, i mean the gauges are the same part no.! Yes, it cant be in the heater side of the plumbing as my vaporizer would freeze and it doesn't. Got the spare rad cap out of my old rad so going to stick that in once i've easy outed the bloody old one! Must be a circulation problem so going to try the rad once i have some cash. Had a look on the Famous Four web site and found a nice one with an oil cooler built in! Anyone tried one? When i put water through the rad it took a while to work its way through- might have loads of rot etc inside the core. Thanks again! Paul Quote Link to comment Share on other sites More sharing options...
Gromit Posted November 23, 2007 Share Posted November 23, 2007 Had a look on the Famous Four web site and found a nice one with an oil cooler built in! Anyone tried one? For some rads, it can be cheaper to re-core them down your local rad place. Was the case for mine (200tdi), but for others it's cheaper to just shell out for a new one. Quote Link to comment Share on other sites More sharing options...
muddy Posted November 23, 2007 Share Posted November 23, 2007 why not go buy a nice ali one for summit racing for pretty much the same price as a stock one B) Quote Link to comment Share on other sites More sharing options...
Coastcard Posted November 23, 2007 Share Posted November 23, 2007 Had a look on the Famous Four web site and found a nice one with an oil cooler built in! Anyone tried one? I looked at this option and popular opinion seems to be that the ones with built in oil coolers (TD?) aren't really up to V8 cooling. Quote Link to comment Share on other sites More sharing options...
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