lrem Posted June 29, 2004 Share Posted June 29, 2004 The manual tensioner wheel for my dry sump pump came loose this morning, allowing the belt to slip off the pulley followed by a loss of oil pressure. I managed to kill the engine within a few seconds of the pressure loss so I'm praying that there was little time for engine damage, especially since it's only recently been DVA'd ☹️ Could someone please advise how tight the tensioner wheel should be? Should it be able to freely rotate, or does the DS belt just rub along it? I can't get it to be rigid and yet rotate - if it can spin freely it also starts wobbling and then works itself loose... any help is much appreciated! Link to comment Share on other sites More sharing options...
Peter Carmichael Posted June 29, 2004 Share Posted June 29, 2004 Everything should be parallel and there shouldn't be any wobble. The tensioner should be able to "tension" the belt and still run - that is what bearings do 😳. The bolts securing it should be "locked". Either spring washers or loctite or both. This should stop anything working loose. The alternative spring loaded tensioner is generally considered to be inferior, but it is easier to put a sensor on it to sense for a dropped belt - this approach has saved me more than once. Link to comment Share on other sites More sharing options...
lrem Posted June 29, 2004 Author Share Posted June 29, 2004 Thanks for the advice Peter, it sounds like the bearings must be knackered I guess... As soon as I had the belt tensioned correctly, I tightened the wheel so that the adjuster screw couldn't move, but the wheel then locked. So I slackened the nut slightly allowing wheel to rotate, but I guess this is how it loosened itself allowing the belt to be thrown ☹️ I don't suppose you have any idea how likely I am to have sustained damage to the engine? It was ~5 seconds (max) between me watching the oil pressure needle plummet and the engine being killed, and I was pootling at ~4000rpm at the time. Link to comment Share on other sites More sharing options...
MikeE Posted June 29, 2004 Share Posted June 29, 2004 Peter, Out of interest what method do you recommend for sensing a thrown belt? My dry sumped Duratec is on the dyno today so I should get it back from Raceline on Thursday. The config I've gone for is a Titan 2 stage (scavenge) belt driven pump and utilising the standard internal pressure pump. I guess one of the effects of this will be that if the belt gets thrown then I'll still have a few seconds of pressure before the pressure pump drains the dry sump tank. So if I can detect a failed drive belt then this can warn me well before I loose oil pressure? Sorry for the slight thread high jack Lionel 😳 cheers R400 Duratec 230bhp Link to comment Share on other sites More sharing options...
lrem Posted June 29, 2004 Author Share Posted June 29, 2004 No worries Mike, I'm interested in a warning switch too after the belt slipped off this morning! Link to comment Share on other sites More sharing options...
Peter Carmichael Posted June 29, 2004 Share Posted June 29, 2004 On a spring loaded tensioner, the tensioner position can be used to tell whether the belt is still in place. If the belt has failed or fallen off, the tensioner springs back to its end stop. I use a courtesy light switch to sense the tensioner position - when the belt falls off a light shows up on the dash. Systems which retain a direct driven pressure pump are my preference, exactly for the buffer of safety you have after a belt failure. Link to comment Share on other sites More sharing options...
Sheds Moderator Posted June 29, 2004 Share Posted June 29, 2004 Peter's system as I recall used an LED and LDR (light sensor) on either side of the belt. LDR reads darkness, OK. LDR reads light - switches on a warning lamp. It's a simple cicuit costing pennies to build and i'm sure Peter has full details. Setup and installation will be laborious, I'd imagine. EDIT - OK so PCs system was simpler but I do remember him talking about an LED/LDR sensor to detect a belt's presence or absence. Edited by - batteredoldsupersport on 29 Jun 2004 14:44:08 Link to comment Share on other sites More sharing options...
Peter Carmichael Posted June 29, 2004 Share Posted June 29, 2004 Mike Bees uses an optical sensor. Too complex for me! Link to comment Share on other sites More sharing options...
lrem Posted June 29, 2004 Author Share Posted June 29, 2004 Hi all, I've just ordered the automatic tensioner from Caterham, so will try setting up a courtesy switch warning device along the line of Peters'. Thanks everyone for your advice Cheers, Lionel Link to comment Share on other sites More sharing options...
Mike Bees Posted June 29, 2004 Share Posted June 29, 2004 I have a proximity sensor which 'sees' the spokes on the scavenge pump pulley going round, firing a stream of pulses to a simple (probably) electronic circuit. When it doesn't see a pulse for more than a second or so (i.e. the pulley's not going round) then it lights a lamp on the dashboard. My dad designed & built the circuit for me, I've probably got his scribbled version of the circuit diagram somewhere, but doubt I could find it... The downside is that the proximity sensor is a bit too heat sensitive - if you sit at rest with the engine running for a while it gives up the ghost and stops sending pulses, so the lamp lights. It takes a minute or so of driving to get enough air circulation under the bonnet to cool the sensor enough to be happy again. I guess higher temp capability sensors must be available. Mike Link to comment Share on other sites More sharing options...
V7 SLR Posted June 29, 2004 Share Posted June 29, 2004 This is my interpretation of Peter's dry sump pump bracket/switch: The bracket Bracket on the tensioner assy Assy on the car Link to comment Share on other sites More sharing options...
Jason Plato Posted June 30, 2004 Share Posted June 30, 2004 It should be added that unless the belt type has the incorrect number of teeth or the tensioner is not fitted correctly , failier of the DS belt is rare . Link to comment Share on other sites More sharing options...
Peter Carmichael Posted June 30, 2004 Share Posted June 30, 2004 Yes, ! agree with Dave. First of all there is something wrong with the existing equipment. When everything is working correctly a belt sensor adds security. It is also worth considering that debris in the pump itself could cause belt problems. A momentary increase in resistance to turning the pump will cause high belt tensions which might damage the tensioner. Link to comment Share on other sites More sharing options...
Jason Plato Posted June 30, 2004 Share Posted June 30, 2004 There has also been issues reported with the Gold pump shaft and bearings . Lotus 7 Club Speed Champion 2003 South Wales Area Organiser C7 TOP Link to comment Share on other sites More sharing options...
lrem Posted June 30, 2004 Author Share Posted June 30, 2004 Hi Dave, what sort of issues with the Gold pump? Now you've got me paranoid 😳 Link to comment Share on other sites More sharing options...
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