Inigo Posted February 1, 2015 Share Posted February 1, 2015 I used my winch in anger for the first time at the weekend and it didn't go well. Pulling a short distance up a steep hill and I quickly ran out of juice. Single battery only, recently uprated alternator from original 65 Amp to 100 Amp - but I didn't upgrade the cable to the starter as suggested. Battery was obviously low and lots of smoke from the engine bay, particularly when revving engine. Got back on the road home and noticed that volt meter was reading around 10 volts, rev counter was stuck at about 1000 rpm and if I ever was at high revs for a period, the battery charge light would come on accompanied by a burning smell. Eventually got off the motorway and the charge light was now on permanently, rev counter dropped to zero. Crawled the last mile or so home and as I pulled up, heard the radiator boiling and noticed the temp gauge at 100+. I had been checking the temp earlier, but had been distracted by the bright battery charge light, so not noticed the temp gauge being in the red. Too dark and cold to investigate now, but any tips on what I should be looking for? My feeling is that as I drained the battery, the uprated alternator was trying to add charge back through the inadequate cable, which burnt some of the insulation. Rev counter is fed from W terminal of alternator, but I did get a chance to briefly check that and it doesn't seem to have melted. Not sure how it is affected by damage to main alternator cable. Can't think of a mechanism for alternator problems leading to overheating unless alternator has seized or damaged the belt and so the water pump is not running. Quote Link to comment Share on other sites More sharing options...
nickwilliams Posted February 1, 2015 Share Posted February 1, 2015 What engine? Reckon you've shagged the alternator and then its drive belt. Quote Link to comment Share on other sites More sharing options...
Inigo Posted February 1, 2015 Author Share Posted February 1, 2015 V8 Oh, that does make sense for the symptoms. What do you think was the fatal blow for the alternator? Quote Link to comment Share on other sites More sharing options...
Frax Posted February 2, 2015 Share Posted February 2, 2015 I would think the alternator or if lucky just the fan belt. Yer V8 wont have liked the over heating - hope the belt is the only damage that is done. Quote Link to comment Share on other sites More sharing options...
Inigo Posted February 2, 2015 Author Share Posted February 2, 2015 That's what I'm more worried about. Alternator is easy to replace, if need be. I guessIng should be checking oil for water to see if head gasket has gone. Any other symptoms of overheating? Quote Link to comment Share on other sites More sharing options...
AMB Posted February 2, 2015 Share Posted February 2, 2015 Sounds very much like a failed alternator closely followed by the fan belt. Smoke on load probably the fan belt slipping on a partially seized alternator. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted February 2, 2015 Share Posted February 2, 2015 Smoke from under the bonnet, and you continued running? Braver man than me Smoke from under the bonnet of a petrol engine is either an electrical/fuel fire or a belt letting go, either really need investigating pretty sharpish. For my money, it could well be just the belt slipping and shredding itself, but the alternator may be OK, just under load the old/tired/stretchy belt gave up -this runs the water pump as well and hence the over heating... and yes, V8's don't like to be overheated... good luck Quote Link to comment Share on other sites More sharing options...
Tanuki Posted February 2, 2015 Share Posted February 2, 2015 What's the alternator belt? Single, Twin, or Serpentine? Driving a 100-Amp alternator via a single vee-belt will rapidly destroy the belt if the alternator's expected to kick out 100A for a long period. A twin-vee-belt setup will still stress the belts a lot if you're trying to put 1.5Kilowatts through them on a regular basis. I'm suspecting the smoke you saw was the belt burning up as it slipped on the alternator pulley. This would also explain the overheating and the charge-warning light coming on (the belt also drives the water pump). There's a reason pretty much every production vehicle built this millennium has given up on old-fashioned vee-belts and gone serpentine. Quote Link to comment Share on other sites More sharing options...
Inigo Posted February 2, 2015 Author Share Posted February 2, 2015 Single v belt. I knew it was marginal at best when I replaced the alternator, but thought I didn't have much load. This was before I added the winch. I currently have a 3.9 with oil pump driven distributor. I understand it might be possible to convert this to a serpentine system. Quote Link to comment Share on other sites More sharing options...
nickwilliams Posted February 2, 2015 Share Posted February 2, 2015 I can't see how this: Got back on the road home and noticed that volt meter was reading around 10 volts, rev counter was stuck at about 1000 rpm and if I ever was at high revs for a period, the battery charge light would come on accompanied by a burning smell. is consistent with just a knackered belt, which is why I suggested the alternator may also be shagged. Quote Link to comment Share on other sites More sharing options...
AMB Posted February 2, 2015 Share Posted February 2, 2015 I agree with Tanuki I'm guessing that overload on the belt caused it to slip (causing smoke). That overload could be faulty alternator or transferred load through the alternator from the winch. Whatever the initial failure, the alternator was at least partially working on the way home because the battery charge light was off and the rev counter was reading. I'm assuming that the V8 takes it's rev counter feed from the alternator like the diesels. If so, a constant 1000rpm would suggest a slipping belt and going to high revs for any period would probably lose any remaining grip, hence rpm dropping and charge light illuminating. RPM dropping to zero is consistent with either a failed belt or a failed alternator, but, as overheating the belt has gone. However, that would be the least of my worries, forget the alternator, have you still got a useable engine. Quote Link to comment Share on other sites More sharing options...
Inigo Posted February 2, 2015 Author Share Posted February 2, 2015 Had a look tonight and found the remains of my v-belt snapped and scorched. I think AMB got all of the details. Only had a chance to refill rad (only half empty), check oil for mayonnaise, fit new drive belt and ran it up to temp briefly. By some miracle, it seems OK, alternator charging as expected, rev counter back, no nasty clunking sounds from engine. Thanks everyone. So, longer term solution? Go back to a 65 amp alternator? Don't use the winch? Upgrade to a serpentine belt front end? Make sure drive belts are properly tensioned and stop if anything begins to smoke? Quote Link to comment Share on other sites More sharing options...
cackshifter Posted February 2, 2015 Share Posted February 2, 2015 There are different quality V belts around, they aren't all the same, and they can transmit a lot of power; Fenner used to do some that were rated at more than twice the standard. I think vehicles use a Z section. You need to get the length of your existing belt and shop round. Before performing major surgery on anything, I'd get hold of one, tension it properly (are the pulleys worn? - there has to be a gap under the belt) and try it out calmly rather than under 'battle conditions'. You might get away with it. And if it works buy another and keep it handy. Quote Link to comment Share on other sites More sharing options...
deep Posted February 3, 2015 Share Posted February 3, 2015 I read this with interest. I am putting together an ex-Singapore Air Force 110 diesel which originally had a huge 24volt generator. I had a good 100 Amp alternator off a 3.9 Discovery already, so it was natural to fit that. However, the military set-up is quite unusual, with a separate V-belt just for the generator. As this means the belt wraps right around the pulley (contact area being an important consideration), I am hoping it won't give problems. So far, so good but I see I will have to be very careful once that winch is in use! Thanks for the information. By the way, serpentine just isn't going to happen on my motor - I'll find another way if I have to. Quote Link to comment Share on other sites More sharing options...
Inigo Posted February 3, 2015 Author Share Posted February 3, 2015 Belt was Dayco and new-ish. When I came to replace it with the same size belt that I had in stock, it just slipped over the pulley which suggests that I hadn't tensioned the previous belt very well. I have now found something to lean on while tightening up the alternator, there is a few mm of movement when I try to deflect belt by pushing on it. Collegiate, what do you mean by a gap under the belt? Quote Link to comment Share on other sites More sharing options...
deep Posted February 3, 2015 Share Posted February 3, 2015 Belt was Dayco and new-ish. When I came to replace it with the same size belt that I had in stock, it just slipped over the pulley which suggests that I hadn't tensioned the previous belt very well. I have now found something to lean on while tightening up the alternator, there is a few mm of movement when I try to deflect belt by pushing on it. Collegiate, what do you mean by a gap under the belt? If I have this right, the belt should be connecting via the v-section (sides), which it can't do if the flat centre part is sitting on the centre of the pulley. I hope that makes sense. I have just looked at mine and realised I need a much bigger pulley on the alternator and corresponging belt to match the crank pulley. How did I not see that before?? The belt is right on the alternator but no gap at all on the crank. Quote Link to comment Share on other sites More sharing options...
Inigo Posted February 3, 2015 Author Share Posted February 3, 2015 Ah, OK. All clear now. I'll check mine later. Quote Link to comment Share on other sites More sharing options...
cackshifter Posted February 4, 2015 Share Posted February 4, 2015 Run the new belt for a few days then re-tension. They always stretch a bit when new then settle, so it's good practice to check - in fact I think a lot of failures are caused by that getting missed, and the belt running slack The tension is going to be esp important for something that's a bit marginal, but too much will wear alternator bearings.. Quote Link to comment Share on other sites More sharing options...
Tanuki Posted February 4, 2015 Share Posted February 4, 2015 As has been mentioned, belt "wrap" on the pulleys is important if you want to get maximum energy-transmission without the belt slipping. Rather than just cranking more tension on to the belt [which will wipe out alternator/water-pump bearings as well as shortening belt life] you could see if there are any ways you could fit a longer belt, but then add a tensioner/guide pulley running on the *back* of the belt at a strategic place to get the belt to have more wrap-contact on the various pulleys. In times past I used this approach on a racing Hillman Imp engine - at 8000+ RPM the engine-driven fan was taking rather a lot of horsepower to turn it and the belt wouldn't last an hour. A spring-loaded tensioner/wrap-modifier/guide-pulley improved belt-life dramatically and let us go to 9500RPM for short bursts without the belt turning itself inside-out or throwing itself off the pulleys. Quote Link to comment Share on other sites More sharing options...
mickeyw Posted February 5, 2015 Share Posted February 5, 2015 I have a similar situation. I recently uprated my 110 V8's 65A alternator to a 100A unit. I had to fab brackets to bolt it on, and I am still using the single vee belt. I did however uprate the charge cable to 25mm2. When I was perusing the scrap yard I noticed big Volvo estates (740 etc) that had 100A alternators that ran on single vee belts. It could be that they were the wider type, but I didn't study that in detail. My reason for this upgrade was two-fold - I have a PTC heater that draw IRO 90A when on full power, but also the winch needs a better supply. Anyway, what I can say is that my belt squeals a bit when engine is on tickover and the alt is working hard. A little more revs and the squeal goes away. I am still running a standard single battery, and even with the bigger alt, it's nowhere near what the winch needs. I can flatten the battery just spooling 100ft of cable on. On my old V8 90 I had twin batteries, charged by a 140A alternator (on a serp V8) and that provided a good reserve for sustained winching. Future improvements for me include either twin batteries, or a single huge one, and adapting the pulleys to run a serpentine belt. Quote Link to comment Share on other sites More sharing options...
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