BenEvans 0 Report post Posted October 10, 2009 hey, have just put a M20B25 in my e30 and it is all running sweet except my cooling system... the engine heats up at the normal speed but continues past half way until it reaches 3/4 where it will sit until either i am going downhill on idle (it will cool slightly, sumtimes to halfway) or i am putting strain on the engine like going uphill (temp gauge will contine past 3/4 mark). i had the guys at fredco motors take a look and they seemd to fix the problem but a short while after driving down the rd it started doing the same thing. then ray (hellbm) suggested a blockd pipe where the pipe from the radiator enters the reservoir tank, so i cleaned that out witch again seemd to sort the problem untill i took it for a drive!! the thermostat works as i tested it before i put it back in. the engine is a mix of prefacelift and facelift parts. the temp sensors are prefacelift and the wireing is facelift, would this be a problem? otherwise i havent got a clue as to why its doing this, any ideas would be appreciated. Cheers Ben Quote Share this post Link to post Share on other sites
BM WORLD 1261 Report post Posted October 10, 2009 use the senors for the year of the car . newer ones match the cluster and engine ecu etc how good is the fan clutch (viscous) they wear out with age , if they spin to freely the car will heat up when sitting around . also they will be very oily in the front of the clutch as all the fluid comes out of them . Quote Share this post Link to post Share on other sites
BenEvans 0 Report post Posted October 10, 2009 the viscous looked like a pretty mint one when i put it in. and it seems to run at the right temp when just sitting around. it only heats up to 3/4 when driving Goes beyond 3/4 when giving it some sh*t goes closer to halfway wen there is little or no strain being put on the engine. cheers Quote Share this post Link to post Share on other sites
QuickSilver 0 Report post Posted October 10, 2009 (edited) Have you bleed the system correctly? Edit: If you answer no, do it again. If you answer yes, do it again. Edited October 10, 2009 by QuickSilver Quote Share this post Link to post Share on other sites
BenEvans 0 Report post Posted October 10, 2009 Yes. i did it once, The guys at Fredco motors did it again. still nothing. the water pump is defiantly working but my concern is that it might not be pumping fast enough, is this possible? Quote Share this post Link to post Share on other sites
ducatiss 1 Report post Posted October 10, 2009 Dont let it get too hot on the gauge or you run the risk of cracking the head. I would not be giving that engine sh*t as you put it until you have corrected the problem or you may have additional more expensive ones to contend with! Check that you have bleed the system properly Check for radiator blockage - back flush it (assume that the radiator is the correct one?) Check hoses (bottom and top hoses) I would replace the thermostat anyway. How did you test your viscous fan? Remember they spin anyway when the engine is running but when the clutch operates they really get into it and you should feel them blowing heaps of warm air. Mine always engages at just a hair over the half way mark. If you carefully test it with a rolled up newspaper, when it is just freely spinning, you should be able to stop the fan with the newspaper - when the fan clutch engages, it will chop that paper up. Be very careful with this method of testing!! Are you losing any coolant? It could be a temp sensor issue but until you can correctly measure the coolant temp, check all the other items. the viscous looked like a pretty mint one when i put it in. and it seems to run at the right temp when just sitting around. it only heats up to 3/4 when driving Goes beyond 3/4 when giving it some sh*t goes closer to halfway wen there is little or no strain being put on the engine. cheers Quote Share this post Link to post Share on other sites
BenEvans 0 Report post Posted October 11, 2009 the fan assembly came out of my 2ltr engine witch never had an overheating issue. just so i know, what is it that turns the fan clutch on? heat? Quote Share this post Link to post Share on other sites
BM WORLD 1261 Report post Posted October 11, 2009 try another radiator or water pump Quote Share this post Link to post Share on other sites
ducatiss 1 Report post Posted October 11, 2009 (edited) yes regarding heat - the fan uses a bi metallic spring to sense heat passing through the radiator which then operates a valve to control the silicon fluid transfer thereby activating the fan. Air is still drawn through when at a standstill as the fan still continues to spin (though with no force behind it) - well that would suggest that the fan isnt the issue but I would still test it anyway to rule it out. Often when diagnosing faults, it is useful to be able to fully rule out possibilities. Flush out the radiator next. Check hoses for blockages. Then refill and carefully bleed out the system. Is your coolant expansion tank hot after running your car up to temp? Next will be the waterpump to check/replace though I would spend some time frst to rule out a faulty or incompatable sender/gauge. I used to (before I broke it) have a themometer I used to check water temp. the fan assembly came out of my 2ltr engine witch never had an overheating issue. just so i know, what is it that turns the fan clutch on? heat? Edited October 11, 2009 by ducatiss Quote Share this post Link to post Share on other sites
Docile 64 Report post Posted October 11, 2009 have you got the right thermostat in? Quote Share this post Link to post Share on other sites
mitchE30 0 Report post Posted October 11, 2009 sometimes water temperature gauge in cluster and temperature sensor can be wrong,replace them. Quote Share this post Link to post Share on other sites
Sammy J 1 Report post Posted October 11, 2009 Could be an out of calibration gauge because of the mismatch between facelift and pre facelift. Would suggest using the temp sender that was on your old motor becuase that would match your temp gauge Quote Share this post Link to post Share on other sites
BenEvans 0 Report post Posted October 12, 2009 OK, just did the paper in the fan test. when the engine was cold i could stop it with ease. when it was half way i could still stop it with ease, but when it reached about a needle width before 3/4 it engages and cant be stoped. does this mean its buggerd? because when it did engage the temp dropped pretty quick. cheers Quote Share this post Link to post Share on other sites
wolliver 1 Report post Posted October 12, 2009 ECT sensor, gauge, and ect sensor wires... my guess could be giving you a faulty reading Quote Share this post Link to post Share on other sites
BenEvans 0 Report post Posted October 12, 2009 no i dont think so. i think if that were the case it would sit at a constant wrong temp, but its not it fluctuates between halfway and 3/4. i replaced the fan clutch today and it seemed to engage a little better than the last but is still making weird temp fluctuations. ive just got back from Fredco, we spent a gud 1.5hrs having a look at diffrent temp readings around the engine/radiator, from which it dosent seem to have a blockage anywhere. his next guess was to replace the thermostat, even tho it seems to be working it might not be opening fully or just something weird going on with it. if anyone knows of a better cheaper place to get these than euro Italian parts ($52 i think) although that has been the lowest so far, let me know. cheers Quote Share this post Link to post Share on other sites
rjac001 0 Report post Posted October 12, 2009 I think its the water pump just my opinion, my first E30 325i had the same sort of problem!! and that fixed it, but since thats quite a big job to replace, I would try putting correct sensors on first then if no joy go about changing the water pump and as a bonus you can replace the cam belt too... nothing like the peace of mind knowing you have a new cam belt on and your engine isn't going to Pop out of the blue! Quote Share this post Link to post Share on other sites
BenEvans 0 Report post Posted October 12, 2009 yea i agree with u but the anoying side to that is i just spent $800 odd replacing the head with a new cam belt and everything! (its so cheap coz i did most of the work) but before i give any of u a chance to say it i am an idiot for not changing the pump at the same time, just figured it wouldnt b an issue. im gunna swap the thermostat and temp guages 2morrow and if that dosent do it ill just have to bite the bullet and do a water pump. hopefully will be able to without taking off the cam belt. Quote Share this post Link to post Share on other sites
gmccormack 0 Report post Posted October 12, 2009 I had a brand new thermostat from TMBMW cause the exact problem you describe. The temp would sit way too high at around the 3/4 mark even when the engine was not working all that hard, then when you really pushed to it would get even hotter (almost into the red) then drop suddenly back to normal for a few seconds, then settle back to 3/4 again. Just a dud thermostat striaght out of the box, a replacement fixed it. The fan has no effect on the cooling system once the cars road speed gets above a fast walk, I have driven around with no fan to test just what effect the fan has and it appears to do almost nothing unless the car is sitting still. Even with no fan at all the temp is rock steady as long as the car is moving. Quote Share this post Link to post Share on other sites
BenEvans 0 Report post Posted October 12, 2009 sweet! cheers mate, that makes me feel better about spending the time replacing it. i would hate to have to take the front of the engine apart AGAIN. Quote Share this post Link to post Share on other sites
QuickSilver 0 Report post Posted October 12, 2009 (edited) O.k. First of all, you went and checked the temperature of all hoses/pipes etc around the motor? What temperature did they give back.. I assume you recorded it, because if its sitting at 90C (or there about) this correct running temperature. Did you test the pipes after a drive? Did they vary largely in temp? Did you check when it said the gauge is at 3/4? Did you check when it was at 1/2 way? Thermostats are prone to fail, even straight out of the box. I would stick with Gavin's product (EuroItalian) or go OEM, for a little extra their better in the long run vs those of BNT or similar places. If you do need to replace the water pump the cambelt will have to come off. Don't re-use the belt as they should only be used once. The belt is cheap and there's no harm in replacing it again. Did you re-bleed your cooling system again anyway? This can cause all the symptoms you are experiencing. Even the mechanics can mess up bleeding an m20. They can be a BIG pain. Edit: If it were me, even if it turned out to be the thermostat or another problem, I would go back and replace the water pump anyway for piece of mind. Their not that pricey from Gavin, and its a quick job if you have the know how. Edited October 12, 2009 by QuickSilver Quote Share this post Link to post Share on other sites
BenEvans 0 Report post Posted October 12, 2009 ok cheers for that its given me something to think about. the temps where looked at by aaron at fredco, silverdale. these guys have been bmw trained and are the sort of bmw mechanics that know whats wrong by listening to it. i have faith in them and they know what there doing. they suggested replacing the thermostat, so ill do that and make sure i bleed it a few times after wards like u suggest. and we will c what happens then... Quote Share this post Link to post Share on other sites
QuickSilver 0 Report post Posted October 12, 2009 (edited) But what was the temperature I ask this because if the temperature was within range you've identified the problem! That would mean that its a faulty sender/gauge. I am aware that they are probably good at what they do but they are people. Did you atleast ask them what the readings were? Edit: you cant "hear" water heating up, or a thermostat not opening, or electrical current traveling through temperature sensors, or cluster gauges incorrectly displaying temperatures. I'm not trying to sound obnoxious, but if you do find that its within range you could be hacking away at your motor trying to identify a problem that you've ruled out and never found. Edited October 12, 2009 by QuickSilver Quote Share this post Link to post Share on other sites
BenEvans 0 Report post Posted October 12, 2009 i completely understand, i did c what the temps were, just past half way on the gauge it was around 90 degrees and when it got up towards 3/4 the temp was around 100-110 so i believe the temp sensors are fine for now. i will change the thermostat which needs replacing anyway (coz its kinda old) and its not to difficult, and if that does nothing will look and the senders and then the pump. cheers for the response Quote Share this post Link to post Share on other sites
QuickSilver 0 Report post Posted October 12, 2009 Ah I see, just wanted to get my point across ha! Anything above 90 is infact too high, so the next logical step your taking would be mine too - Thermostat. Good luck. Quote Share this post Link to post Share on other sites
BenEvans 0 Report post Posted October 13, 2009 just replaced the thermostat. it now never runs above halfway! cheers to those to helped me out. my next problem with most certainly be on its way Cheers Again Quote Share this post Link to post Share on other sites
