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MG MGA Judson , cooling and fans etc.. BBS discussion at MG-Cars.net
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MG MGA - Judson , cooling and fans etc..
| Took my 13 yr old grandson for a drive a week ago on a warm day, 28c , and on a hilly road. My car has twin electric pushers on thermostat control ( kick in 190c ) and no fan driven fan. It also has a Judson supercharger. I have used above set up for many years.. All went well for about 40 mins and then the temp went up rapidly to 230 plus.....I stopped and steam etc.. After a cool down and then having my grandson work as a 'coolant runner' to a roadside tap with a small bottle. I started again but could not get the fans to kick in... Filled the radiator and did a low energy drive/coast back home. I checked from fan end ....fans ok on separate power ( relief) ...and from ignition to relay and battery power to relay...all ok ( more relief).....so it had to be the probe or thermostat controller.. I removed the top hose and found the probe covered in greasy c..p. I cleaned and tested in hot water .....fans kicked in. No idea where c..p came from..non in drained water and surprised it stopped all signal . I use corrosion inhibited rainwater as coolant . Whilst hose was off I tried to get my old heavy steel mechanical fan Into position but would not fit . The blades fouled the Judson belt tension roller. Queries to the wise. 1.It would seem that if I wish to put the old fan in for a 'belt and braces' coolant solution I need a spacer behind the fan to get it away from the pulley and probably also to move the radiator forward . Dominic ..you probably know the answer to this as I recollect you have the standard fan still in. 2. Does the 7 blade plastic fan referenced by Steve avoid above problem....are the blades shallower.? ( Steve ?) 3 . Any ideas re the deposit on the probe? |
| Neil Ferguson |
| Neil With my metal 6 blade fan I had to use two washers as spacers to get blade clearance with the alternator shaft nut. With the asymmetric fan I did not need them and there was about 1cm clearance. There was also 1cm gap to the front face of the radiator support pillars. Steve |
| Steve Gyles |
| That sounds hopeful...I eyeballed that I needed about another half inch divided behind and in front.. Will need to get my internal calipers about and get precise. can you advise the depth of the blades? I always kept my metal fan in the boot jic.. So may buy 7 blade plastic as insurance ..but if fairly quiet ( as Barney G mentioned ) may install the insurance permanently .......and put up with slight loss of umph .. |
| Neil Ferguson |
| Neil, If you put a manual bypass switch in the system you could also use that as a backup. Mark |
| M Wellard |
| Neil I fitted a toggle switch to the relay on my twin fan set up, it just connects in parallel to the thermostatic switch relay so you can over ride it any time you want. Before a recent trip to the Pyrenees I went out and bought a spare thermostatic switch in case the original one failed, then I realised that if I just fitted the overide switch,I already had a backup in place. Fitting an engine fan by the roadside would wear away far too many of my knuckles for my liking, you would need lots of elastoplasts handy. Colyn |
| c firth |
| Neil It came in a box that was 4cm wide (inside measurement) so is quite slim. The rear of the fan is almost flush with the front edge of the pulley boss, with the curved fan blade protruding just 4mm towards the engine 2.5cm outboard of the central body. The rest of the fan blade is forward of the pulley boss Steve  |
| Steve Gyles |
| Neil A point worth making though is that I think you would have trouble accessing the 4 attachment bolts with the radiator in situ. Unlike the conventional MGA fan the bolts are recessed well back inside the central housing (almost 3cm). If you intend using this fan for roadside recovery you will have a major fiddly exercise fitting it. Steve  |
| Steve Gyles |
| Hi Neil There should be a spacer between the water pump pulley and the fan, this m over the fan forward by about a centimeter. The spacer is simply a metal donut, inner whole is the diameter of the water pump nose, outer diameter that of the OD of the pulley part that fits over the disc on the water pump. Add four holes as on the fan center and some longer bolts to pass through the fan, spacer, pulley into the water pump. When mounted, before starting the engine rotate the fan to manually recheck clearance between the tensioner and the fan blade tips - if the any fan blade is out of plane it will possibly strike the tensioner pulley. I assume that you have already used spacers to move the radiator forward by about a centimeter too..... |
| dominic clancy |
| Like this Dominic? This one is 4.5cm between opposite holes and 5mm thick. It was no good for me when I had the MGA fan and found I did not need it with my non supercharger configuration with the 7-blade fan. Steve  |
| Steve Gyles |
| From the general design, yes, but it needs to be thicker for the Judson because the fan blades have to clear the idler/tensioner and the drive belts for the supercharger. I haven't been in the garage in working clothes since mid December (I spent almost four weeks on holiday in Asia), so I'm starting to get withdrawal symptoms, but I can measure on Saturday when I have a few jobs to do on my own car before I start working on the queue of requests for others 1. Twin Cam five speed conversion (floorboards out, that engine is staying put!) 2. Coupe full brake line replacement 3. midget window rubbers replacement (i.e.. a door rebuild) 4. Midget steering rack and front suspension overhaul (rubbers, wheel studs, new rack) 5. MGB full service 6. MGA engine swap (this one is easy) 7. MGA hood, carpets, trim panels installation 8. Supercharger installation 9. MG YA head removal, refurbishment and reinstall (head to PB I think) 10. MGA brake service 11. Midget charging system fault find and fix Most of this has to be done by the mid May, and I'm away for three weeks, as well as having a busy job, so it's time to get busy again. Dominic |
| dominic clancy |
| Thats a fair old to-do list Dominic, I have just taken out my engine and gearbox and have planned to have it all back in and running by the end of March. Your list would probably take me 6 months. Colyn |
| c firth |
| Neil Following on from Dominic's comments, I have 1.8cm clearance between the radiator and the fan. My radiator is in its standard position with the rubber mounting strip between it and the the mounting strut so the 1cm spacer he discussed will close that gap to 8mm. Without moving the radiator forward I would suggest that fitting the fan by the roadside would be nigh on impossible. Steve |
| Steve Gyles |
| Colyn/Mark....your simple suggestion makes good common and will do. Dominic....never did move the radiator forwards .....the pusher fans obviated the need for such Steve .... Thanks for dimensions .....in Melbourne right now but back to Narooma and car am ( 700km) and will get the calipers out and see how dimensions and comments from yourself fit . ...but hopeful from your good pics that I will not need to move radiator forward ..just at worst space it slightly forward from pulley. Agree the bloody nuckle and bolt access comments . The plastic fan would need to be in position or is a radiator removal job...not a roadside solution. |
| Neil Ferguson |
| Re mechanical fans and space out . My existing steel 6 blade fan ( not installed ) weighs about 800gm , has blades 3 cm deep and the contact face of its central mounting boss is 1.16 cm forward fron the rear of the blades. The calipers put the face of the Judson jockey wheel to radiator distance as 3.66 cm. and the Water pump pulley mounting face to the radiator as 3.7 cm . ( the strange thing is when eyeballing the Judson wheel looks further away....and when I put a spirit level on the radiator I found out why ....the radiator is not vertical ..the top is closer to the engine .....is this usual I ask!) Any way back to the main topic ...the above distances mean if I install the heavy existing fan I will need the spacer donut to be greater than 1.16 cm ....and the fan blade to radaitor clearance at the Judson wheel level would be about 0.6cm .....and less higher up because of the radiator inclination. Looks like a donut of 1.25 cm and move the radiator forward by the 1cm Dominic referenced. The radiator also is screw whiff laterally ..seems to be about 0.5 cm further forward on driver side( uk ) . ..and it would seem the plastic 7 blade would never fit without major changes if the blade depth is 4 cm.j (Ahhhhh the joys of 1960 car tolerances and fitters..get the podging bars and clamps out and make it fit !!!! I had a period of 4 months in Stothart and Pitt in Bath about 1962 during my student/apprentice days ....and saw some horrors being performed getting parts together. I pitied the poor git who ever took them apart during maintenance .) |
| Neil Ferguson |
| Neil I did say that the asymmetric fan slid inside a 4cm box, so it is slightly narrower, the hub looks about 3.8cm. The blades are not a constant width down their length. The leading edges are straight and in-line with the hub front face. The rear of the blades are curved and at the tips are just 2.5cm wide. I put the spirit level on my tank and it's vertical. Steve  |
| Steve Gyles |
| Neil, You could simply modify the ends of the fan blades a little to get the clearance you need. So long as you trim each blade by approc the same amount, the blades are so light that there shouldn't be any balance issues. My friend Vin Rafter fitted an NTG fan to his MGA when he had it and the blades rubbed against the top tank a little. So Vin decided to let the situation take care of its self, he just ran it like that until the plastic blades wore down enough not to catch any more! Colyn |
| c firth |
| Steve/Colyn..thanks for the suggestions. Here is how I see it... To avoid any in situ plastic machining as per Colyn I would need about a 5mm thick spacer between the fan boss and its mounting.The 5mm is to allow for the rearward bulge ( seen quite clearly on one of Steve's pics) and clearance to the judson wheel . Given the boss is 3.8 cm deep and the fan blade leading edge is inline with the boss then the total sitckout of the assembly would be 3.8cm ( ex Steve ) plus spacer i.e. 4.3cm. The distance of the mounting face to the radiator front is 3.66cm ( as per my previous post ) ...so there would be interference with radiator of about 4.3 - 3.66cm i.e. about 0.7cm ..so the radiator would need moving about 1 to 1.25 cm forward to give clearance. It sounds a similar amount of modification as that required for the steel fan but more cooling productive and I will not be accelerating a near 1kg weight through the rev. spectrum..... I am going to buy the plastic fan and then take the radiator out and then measure the exact dimensions spacers etc ..se if I can correct the radiator attitude ..plus maybe allow a little in situ machining if necessary to 'tailor' the fan I will then have my belt and braces system . i.e. twin fans ( thermo with manual backup switch as per previous suggestion ) .plus effective plastic cooling fan . Dominic ....apart from spacers for the radiator are there any other complications in the radiator move forward...? |
| Neil Ferguson |
| Neil That spacer I have shown above is, I believe, a standard MGB part (Moss CAM1599). It looks thicker in their diagrams though, so you will need to check. Otherwise I guess you could machine one. Have you got the 4.5cm holes in your pulley and water pump? Steve |
| Steve Gyles |
| Neil My measuring is up the creak this morning. My eyesight must be failing me. I just put calipers on the fan hub. It is 3cm wide! No idea where I got the other 8mm from. Steve |
| Steve Gyles |
| Steve...Your new vision delights me ...it makes any movement of the radiator minimal and maybe when I correct its attitude I possibly can get enough clearance . I just stuck my bonce under the bonnet again and it looks like i can move the radiator approx 1 cm without obvious problem at the bottom and since it is leaning with its top edge towards the engine and the driver side is also further forward then I can get more at the judson wheel level ( it is above fan centre and on pax side ?????) I may still need spacer for the backside to clear the judson wheel . but will get fan first, take out radiator etc .....and measure many thanks to you, dominic ,colyn and mark for help. Will advise after all installed . PS Colyn/Mark..after looking at the location of the controller I have decided to just put a bypass switch local to the controller and under the bonnet to keep wiring simple. |
| Neil Ferguson |
| Neil, assuming that your fans are switched via a relay, then the simplest way to wire an override switch is to connect a single wire to the earth terminal of the control side of relay. I ran this through the bulkhead to a pull switch that I fitted to the underside of the dashboard brace within easy reach. The other side of the switch connects to earth. Now I can override the fan thermostatic switch from the drivers seat. Will send you wiring diagram if you need it. Colyn |
| c firth |
| Neil Yes. I found too that the radiator is about 5mm further forward on the RHS. This meant moving the radiator forward required cutting and remaking the lip at the rear of the duct panel. Moving the radiator forwards means you also have to move it down 8-10mm to avoid the bonnet frame catching on the corners of the header tank. I achieved this by enlarging the holes in the vertical struts for mounting the rad and using penny washers behind the bolt heads. Looks very neat. Moving the radiator forwards and down makes access to fitting the air tubes very difficult, fitting them first is necessary, but then squeezing the rad between the flanges with tubes in place is very tight because they are angled inwards towards the front of the car. I leave the bottom hose, angle to water pump and hose/ copper pipe to heater all mounted to the rad, drop the rad loosely into position, fit the hose stub to the water pump, and then fit the vertical spacers, securing with the top bolts each side and then working down. Fitting my radiator blind in front of the rad is then best assigned to a contortionist. The top grille nuts have to be done standing on your head.... Maybe Mr. Gyles ' mod is something to do next time I have the grille off. |
| dominic clancy |
| Neil. I think I have just solved all your cooling issues. Steve  |
| Steve Gyles |
| Steve....many thanks ....an idea from an aviator methinks ? Dominic .....about to reinstall radiator today so your comments very useful....will slot the mounting flanges ....it was a bastard to get out . I do believe the car designers/ maintainers of the past must have had horny skin all over their hands ..especially the nuckles..and prehensile fingers with an extra joint. NB attach a pic of my toes (in oz day thongs) plus the new molded plastic fan together with the old heavy metal clunker ...latter from the age of Riveted ships and Isembard Kingdom Brunel (my hero engineer ). A giant step for technology ?  |
| Neil Ferguson |
| Steve, nice bit of aeronautical engineering but shouldnt you have fitted two contra-rotating props to prevent the torque steer from causing your car to turn Right off the runway? :-) Neil, got myself into some trouble a couple weeks ago when I commented on my nieces facebook page, she is in the RAAF and was just about to take the day off to celebrate Australia Day. She said something like she was going to take her tinnies and thongs down to the beach and play on the water slides all day. I replied saying something like "tiny thongs may not quite be the ideal swimwear for going on water slides" She soon put me right! Maybe having a mad uncle was one of the factors in her deciding to emigrate? Colyn |
| c firth |
| Colyn..the word is used down under for flip flops ( onamatopoeia?) and also for the uncomfortable looking female jocks and swimwear ......it leads to some communication confusion ....and some terrible sights ! |
| Neil Ferguson |
| Dominic ....Have been presenting the radiator and spacers ...cannot get the radiator forward far enough to get clearance for fan at bottom ...fan impinges on bottom reservoir. I need about 10mm between the mounting flanges ( same as you I recollect) and I cannot get it ..guess why..the front duct panel is about 5mm longer on RH side and radiator butts up against it ..opposite to you. |
| Neil Ferguson |
| Hi Neil I guess manufacturing / restoration inaccuracies are OK when everything is standard, but once we start adding grunt there is not really much room to play with I have a Twin Cam in for a gearbox change, and I'll never complain about the lack of space under a pushrod MGA ever again. I have left the engine in and taken out the floor and goalpost pane, as this is the expert tip apparently. I am 13 hours in, and have the old gearbox out and the new five speed on the bench ready to go in when I have a couple of extra bodies to help with lifting and jiggling into position. It also needs a brake cylinder rebuild and new brake hoses, a complete flush of the braking system and some electrical work, so should keep me busy for the next few weeks. Dominic |
| dominic clancy |
| Finally got the new fan tailored to my configuation and the radiator back in. The fan was touching the bottom radiator reservoir . I trimmed a tapered wedge (about max 3 mm ) from the leading edge of the fan for about 2 cm near the ends ....where the fan had obviously been impinging and I reshaped those edges. I reinstalled the radiator but this time got the bottom 1 cm spacers ( between flanges ) and the associated bolts in first and then worked up to the other two spacers/bots each side with same spacers. ....spun it on the battery and sweetness was the result. So finished everything else up quickly incl .reconnecting the twin electric fans and setting them about 195f cut in and got the car on the road. I got about 500n from home up a hill and the temp was up to 230..oh hell. Lifted the bonnet and realised haste was a mistake ..I had connected the twin fans backwards and they won the air movement challenge . Switched them over and ok on a 15 min run. All that was yesterday ..today took the car for a 4 hr drive up from the NSW coast over the East Coast dividing mountain range and up to near the Thredbo ski resort ..... The ambient started off as 25 c and climbed to about 32c during the drive . I set the twin fans to cut in about 195f . Results were excellent ... In cooler ambient the car on the flat or gentle hills ran at about 165 to 175f just using plastic fan.much lower than it did with the metal reverted beast . As day got hotter the coolant temp climbed to 175 to 185 on the flat or gentle inclines . On the very steep continuous ( for about 20mins ) climbs and switchback curves the coolant temp rose to 195 and the twin fans cut in and dragged the temp down to 185..then cut out and so on. The capacity of the 7 blade fan is of course being impeded by the restriction caused by the twin fans ..when they are not operating...and it is possible the single plastic fan could bring the whole temp regime ..even on very steep inclines ....to a lower level if twin fans removed. But I am content so I won't .... No noticeable affect on performance ... Read separate thread for problem I had on the very steep hills .... |
| Neil Ferguson |
| This is really useful - thanks! I'm currently doing a belt and braces anti overheating upgrade (mainly in traffic on a hot day) Bob West radiator recore. Twin fans (Davies Craig 9inch) Blower for carbs New zircotec coated heat shield Felt seal above radiator 4 inch pipes Open grill slats (found an original grill!) The big question was whether to keep the mechanical fan or not. After reading this I think I will - and probably fit a shroud. Last summer we got to the point where we wouldn't take the coupe out on a hot day in case we got into traffic. Roll on summer! |
| C Wilson |
This thread was discussed between 20/01/2016 and 10/02/2016
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