landroversforever Posted April 1, 2013 Share Posted April 1, 2013 How tight should a vee belt be? When the engine is cold the alternator belt squeels like a like a pig for the first couple of minutes. I'm running what I think is an 85A alternator? How much tension can the belts and the bearings in the alt. take? Quote Link to comment Share on other sites More sharing options...
JeffR Posted April 1, 2013 Share Posted April 1, 2013 I've always tensioned v belts so that you could "turn the longest stretch thro about 90 degrees (if that makes sense) and never had a problem with slippage or bearings. Quote Link to comment Share on other sites More sharing options...
landroversforever Posted April 1, 2013 Author Share Posted April 1, 2013 I'll give that a try . Cheers Jeff! PS: Is this method safe? Quote Link to comment Share on other sites More sharing options...
paintman Posted April 1, 2013 Share Posted April 1, 2013 Number of possible issues including belt & pulley condition. Is the belt an alternator belt - cutouts on the inner side - or smooth? After starting the load on the alternator makes the alternator harder for the engine to turn & this make the problem worse - does it also happen if you have a lot of electrics on? On my RRC I have an alternator belt & have around 5mm of deflection on the longest run. I did have a problem with the adjusting nuts slipping & this extra slackness manifested itself either by squealing or the tacho needle (draws current from the alternator) suddenly dropping at idle. Quote Link to comment Share on other sites More sharing options...
landroversforever Posted April 1, 2013 Author Share Posted April 1, 2013 Not sure on the type of belt actually. Yeah, that's what's causing it. On really cold nights/mornings like back in november I'd notice it when I had all the roof lights etc on. Tacho not getting its signal from the alternator is my cue to drive out of the road on tickover so I don't wake the neighbours with the squeeling! Quote Link to comment Share on other sites More sharing options...
JeffR Posted April 1, 2013 Share Posted April 1, 2013 I'll give that a try . Cheers Jeff!PS: Is this method safe? As long as the engine ain't running when you try it! Quote Link to comment Share on other sites More sharing options...
vulcan bomber Posted April 1, 2013 Share Posted April 1, 2013 Number of possible issues including belt & pulley condition. Is the belt an alternator belt - cutouts on the inner side - or smooth?After starting the load on the alternator makes the alternator harder for the engine to turn & this make the problem worse - does it also happen if you have a lot of electrics on? On my RRC I have an alternator belt & have around 5mm of deflection on the longest run. I did have a problem with the adjusting nuts slipping & this extra slackness manifested itself either by squealing or the tacho needle (draws current from the alternator) suddenly dropping at idle. Tacho's dont draw from the alt via the w terminal it just reads the frequency from the alts charging field. Quote Link to comment Share on other sites More sharing options...
Aragorn Posted April 1, 2013 Share Posted April 1, 2013 Yeh, but if the belt starts to slip and the alternator stalls due to the current draw, the tacho will drop out! Quote Link to comment Share on other sites More sharing options...
Jon White Posted April 1, 2013 Share Posted April 1, 2013 Is yours a disco 200 tdi? If so it seems to nigh on impossible to keep them tight! Quote Link to comment Share on other sites More sharing options...
landroversforever Posted April 1, 2013 Author Share Posted April 1, 2013 Is yours a disco 200 tdi? If so it seems to nigh on impossible to keep them tight! It is Jon! I came to a conclusion driving it earlier. I just adjusted the Alternator belt right before I left, but she still squeeled like a piggy. The PAS was very heavy when she was squeeling so I'm thinking its probably actually the other belt (PAS/Water/Crank) that is slipping? So by the looks of it the load of the alternator is stalling the PAS pump and its stopping that from moving. Logical? I've not yet watched it under the bonnet while its been making a noise. As said above, the tacho is only taking a signal from the alternator,it gets its power along with the rest of the gauges with an ignition switched live. Quote Link to comment Share on other sites More sharing options...
bishbosh Posted April 1, 2013 Share Posted April 1, 2013 As long as the engine ain't running when you try it! What's this? Health and safety advice from Jeff? What is the world coming to!!! Quote Link to comment Share on other sites More sharing options...
Jon White Posted April 1, 2013 Share Posted April 1, 2013 I think you're on the right lines. Iirc the disco only ever came with a 45 amp alternator, so banging a big one on there makes the problem even worse! It's on that proxy little belt as well. I've tried doing the belt really f tight which stopped it squealing, but killed the pas pump very quickly. In short there is a reason they went to poly v belts on newer cars with high output alternators. I've never found a solution to it..... Jon Quote Link to comment Share on other sites More sharing options...
JeffR Posted April 1, 2013 Share Posted April 1, 2013 Try contacting your local conveyor belt company, used to fit em in my long lost youth, we used to have a spray can of goop that helped v belts grip and stopped any squeeling, but I'm buggered if I can remember what it was called. Quote Link to comment Share on other sites More sharing options...
JeffR Posted April 1, 2013 Share Posted April 1, 2013 What's this? Health and safety advice from Jeff?What is the world coming to!!! Just occasionally I put my sensible hat on, not for very long admittedly, but I do put it on. Quote Link to comment Share on other sites More sharing options...
Diff Posted April 1, 2013 Share Posted April 1, 2013 Some makes of belt are better at gripping than others. The belt, and/or the pulley surfaces can get polished to the point that there is not enough grip. Similarly, the profile of the 'v' may not be as well matched to the shape of the pulley as it could be. If the belt squeals after you have tightened it using the 'able to turn the centre of the longest side 90 degrees' method, then I would try a new belt. I would recommend a segmented 'v' belt as they tend to grip better, and use one from a well known maker like Gates. Overtightening the belt to cure the slippage can result in premature bearing failure. You can also try a bit of fine wet and dry on the pulleys. Spray on products are usually called 'belt dressing' and can work sometimes. Don't forget, if you have any kind of oil leak near the front of the engine, even a very slight one, the belt can get slightly contaminated overtime, resulting in slippage. Degrease the pulleys and fit a new belt. (and fix the oil leak). I have a 90amp alternator on a 'v' belt on my 2.5 petrol and it is fine, so you should be able to get yours to run an 85amp alternator without it slipping. Good luck, Regards, Diff. Quote Link to comment Share on other sites More sharing options...
tychoS Posted April 2, 2013 Share Posted April 2, 2013 As an interim work around apply a tiny amount of brake fluid to both sides of the v-belt. That makes the belt shut up and do it's job for a while. Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted April 2, 2013 Share Posted April 2, 2013 The PAS was very heavy when she was squeeling so I'm thinking its probably actually the other belt (PAS/Water/Crank) that is slipping? If the PAS is heavy, then it's the crank -> PAS belt that's slipping not the alternator belt. IIRC a good rule of thumb is that a single V belt will transmit 3kW - dependent on pulley size and speed of rotation. With a 1kW alternator, a probably another kW being consumed by the fan (still got the viscous fitted?) and PAS pump you're nearing the limit of what can be done with a single V belt. Quote Link to comment Share on other sites More sharing options...
landroversforever Posted April 2, 2013 Author Share Posted April 2, 2013 I'll see if tightening the crank/PAS/waterpump belt gets me anywhere. I can't remember when I last did it, hopefully that will cure the problem. I have got a segmented type belt on the alternator, didn't look to see which type I have for the other belt though. If the PAS is heavy, then it's the crank -> PAS belt that's slipping not the alternator belt.IIRC a good rule of thumb is that a single V belt will transmit 3kW - dependent on pulley size and speed of rotation. With a 1kW alternator, a probably another kW being consumed by the fan (still got the viscous fitted?) and PAS pump you're nearing the limit of what can be done with a single V belt. That's the conclusion I've come to. No viscous fan on mine, so just the PAS/water/alternator being run from that belt. Thanks for the info so far everyone Quote Link to comment Share on other sites More sharing options...
Jon White Posted April 2, 2013 Share Posted April 2, 2013 Don't forget you need to tension the pas belt first, and then the alternator belt second. If you adjust the pas belt you will have to adjust the alternator belt well. Jon Quote Link to comment Share on other sites More sharing options...
landroversforever Posted April 3, 2013 Author Share Posted April 3, 2013 Don't forget you need to tension the pas belt first, and then the alternator belt second. If you adjust the pas belt you will have to adjust the alternator belt well. Jon Certainly, but thanks for the reminder Quote Link to comment Share on other sites More sharing options...
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