TR4A1965 Posted July 30, 2017 Report Share Posted July 30, 2017 The ignition light was staying one. So I thought alternator. (I have one of those that looks like a dynamo but is actually an alternator). I checked all the wiring and nothing was loose. I looked at the fan belt and it looked glazed and worn. So I thought I would start by replacing the belt (It was only 2 years old with about 2000 miles on it) I also had blade split on the cooling fan and I had a replacement so I thought I would fit that too. To get the new belt on, I undid the engine mounts and jacked up the engine - fairly straightforward. I have attached pictures of the belt that came off and the new one. On inspection. the one that came off had a massive split in it. This was not the issue with the charging however. Putting the voltmeter on the alternator, no charge is being given. My question is, should after only 2000 miles a fan belt deteriorate so severely and an expensive alternator pack in??? It seems very little time for such failures? Best. Paul Quote Link to post Share on other sites
peejay4A Posted July 30, 2017 Report Share Posted July 30, 2017 (edited) The design of those lookalikes is compromised because there insufficient cooling. The odds are the regulator has died. It's repairable but quite likely will fail again when you least want it to. This isn't speculation by the way. I bought one and it failed in just this way. I fixed it and it's now on the shelf and that's where it will stay. Edited July 30, 2017 by peejay4A Quote Link to post Share on other sites
RogerH Posted July 30, 2017 Report Share Posted July 30, 2017 Hi Paul, is that a fat fan belt - it looks like it. Originality is fine but there are benefits to modern items. Halfords fan beltrs work a treat - but they are narrow. Ditch the dyno/alternator - it isn't one thing or the other, but they are prone to failure. Get a decent Prestolite etc and a narrow belt conversion. Roger Quote Link to post Share on other sites
RobH Posted July 30, 2017 Report Share Posted July 30, 2017 I beg to differ about the belt Roger - no need to go narrow if you want to avoid the faff of replacing the crankshaft pulley. A decent cogged 17mm ( or wider) raw-edge belt will work fine with the original pulleys and is far more flexible than the original 'solid' type. The replacement one in Paul's picture looks fine to me. Quote Link to post Share on other sites
RogerH Posted July 30, 2017 Report Share Posted July 30, 2017 Hi Rob, no question about the quality of the belt. It is just a pain to remove the engine each time to do a belt change. Roger Quote Link to post Share on other sites
RobH Posted July 30, 2017 Report Share Posted July 30, 2017 You don't have to do anything like that Roger - a cogged belt is thin enough top-to-bottom and flexible enough, to go through the gap, (at least on a sidescreen car that is). Might be different for one with R&P steering. Quote Link to post Share on other sites
Geko Posted July 30, 2017 Report Share Posted July 30, 2017 (edited) Hi Paul, This is about the time you start figuring out that proper heat management is a prerequisite when it comes to choosing and fitting expensive upgrades...A big fat flexible air duct running from the front grille to the carb side of the engine can help preventing lots of problems especially if you have one of those super-duper SS exhaust manifold. Edited July 30, 2017 by Geko Quote Link to post Share on other sites
Guest ntc Posted July 30, 2017 Report Share Posted July 30, 2017 The design of those lookalikes is compromised because there insufficient cooling. The odds are the regulator has died. It's repairable but quite likely will fail again when you least want it to. This isn't speculation by the way. I bought one and it failed in just this way. I fixed it and it's now on the shelf and that's where it will stay. Yes Pete Just ask the Healey boys had to sort three out with replacements at Le Mann Quote Link to post Share on other sites
Nigel C Posted July 30, 2017 Report Share Posted July 30, 2017 Hi Roger, You mention "Get a decent Prestolite etc and a narrow belt conversion" are they that good? I have a standard "go rummaging at the auto store for something that will fit" alternator and over the years I guess I've had about four of those...guess they get to hot in the long run. Why I'm thinking about changing is that with the headlamps/2x fans on my ignition light is faintly glowing...not good me thinks? Quote Link to post Share on other sites
ianc Posted July 30, 2017 Report Share Posted July 30, 2017 An alternator needs a heat shield to prevent the electronic control system, which is located at the back (connectors) end, getting cooked by the heat from the exhaust manifold. Ian Cornish Quote Link to post Share on other sites
PYU940F Posted July 30, 2017 Report Share Posted July 30, 2017 Perhaps I have lost the point, but what is wrong with the original dynamo? Mine was fitted at build, I think I changed the brushes and cleaned the commutator in about 1990. It doe not overheat/blow the regulator/chew up belts and my battery never goes flat. If it ain't broke why try and fix it? Simon Quote Link to post Share on other sites
peejay4A Posted July 30, 2017 Report Share Posted July 30, 2017 Decent lighting, electric fan, city traffic. All made doable with an alternator. Quote Link to post Share on other sites
PYU940F Posted July 30, 2017 Report Share Posted July 30, 2017 Pete None of that I doable when it keeps packing up. Anyway, the only one of your points that has any validity is the lighting that can be easily sorted with modern bulbs that consume less power anyway. Simon Quote Link to post Share on other sites
TR4A1965 Posted July 31, 2017 Author Report Share Posted July 31, 2017 Thanks for the advice. (Geko:-):-) I had no problem fitting the belt - Just undo the 2 engine mounts and jack up the engine. The belt easily slips between the steering rack and fan column. I have been doing a bit of research and I have found a heat shield that goes on the back of the Dynamo/alternator. I think it was made for E-types but it does look like it will fit. Ian and Stef I think you are right on this one. I'll report in once fitted. Many thanks. Paul. Quote Link to post Share on other sites
ctc77965o Posted July 31, 2017 Report Share Posted July 31, 2017 Be aware most alternators flow air from the back to the front (cool air to the back is most important) and that the fans are generally designed to be effective in only one rotation direction. The alt works fine going either rotation direction, but the cooling only works one way....make sure the alt suits the installation. Such parts should do 25000 miles min. Quote Link to post Share on other sites
RogerH Posted July 31, 2017 Report Share Posted July 31, 2017 Hi Dave, assuming that the pulley on the Alternator is at the front and also assuming that all engines rotate clockwise looking rearwards at the front of the engine then alternator rotation will not be affected on either side of the engine. Sucking in form the rear could be a serious issue though. Roger Quote Link to post Share on other sites
ianc Posted July 31, 2017 Report Share Posted July 31, 2017 The Competitions Dept fitted heat shields to the TR4 Rally cars in 1962/3 to protect the dynamo from the considerable heat produced by the SAH 4-branch exhaust manifold, and the shield is visible in one of the photos taken at that time. The shield was still in place on 4VC when I acquired the car in 1969. When Neil Revington re-built the car for me in the early 1990s, I decided that an alternator was a sensible upgrade, so the old heat shield was fitted to protect it. I am pretty sure that when Neil brought back 6VC and then 3VC from America later in the 1990s, each still had its heat shield. When Neil put an alternator on 6VC, he didn’t re-fit the heat shield – and very soon, the alternator got cooked! Whoops! Neil made copies of the shield and flogs them. At engine speeds of 1100 rpm or less, a dynamo (even a high-output one) will not be able to generate sufficient power to prevent battery discharge when dipped headlamps and electric fan are in operation – and in modern motoring conditions such conditions are not uncommon e.g. the M25 parking lot (and it could be raining, too!). My rather old-fashioned alternator, rated at 35 amps, manages to cope with this sort of load at 1000 rpm, so the battery has a very easy life. Ian Cornish Quote Link to post Share on other sites
Nigel C Posted July 31, 2017 Report Share Posted July 31, 2017 yea I use my car all year round and increasingly (in this country) sit in traffic...in fact this year I crawled half a mile in 90 mins...in 32* sun and that was in Jersey (its only four miles wide!). I did start out with the dynamo as all my other resto's have had but it was soon apparent it wasn't up to the draw of wipers/headlamps/overdrive net alone fans. Would it make sense to change the direction of the alternator fan so it blew into the unit? I'm sure the airflow from the radiator is cooler that drawing in exhaust heat? And getting back to TR4a1965 (sorry to hijack your thread) I have checked my belt and its in perfect condition and its been on 8 years+. I think you had a dodgy supply (it is known to happen!) Quote Link to post Share on other sites
peejay4A Posted July 31, 2017 Report Share Posted July 31, 2017 Pete None of that I doable when it keeps packing up. Anyway, the only one of your points that has any validity is the lighting that can be easily sorted with modern bulbs that consume less power anyway. Simon Well I'm not going to get into a lengthy slanging match but if you have a dynamo that charges at idle in summer traffic with an electric fan running then good on you. If originality is your desire, that's fine too. Quote Link to post Share on other sites
TR4A1965 Posted July 31, 2017 Author Report Share Posted July 31, 2017 (edited) Thanks Chaps. I thought the belt must be dodgy. Thanks for the tip on the heat shield at Revington I'l investigate. Best. Paul. Edited July 31, 2017 by TR4A1965 Quote Link to post Share on other sites
stuart Posted July 31, 2017 Report Share Posted July 31, 2017 Thanks Chaps. I thought the belt must be dodgy. Thanks for the tip on the heat shield at Remington I'l investigate. Best. Paul. As they are a tad expensive its not difficult to make a neat one yourself. Stuart. Quote Link to post Share on other sites
ctc77965o Posted July 31, 2017 Report Share Posted July 31, 2017 Hi Dave, assuming that the pulley on the Alternator is at the front and also assuming that all engines rotate clockwise looking rearwards at the front of the engine then alternator rotation will not be affected on either side of the engine. Hi Roger, Yes agreed, but on some cars the alt is mounted pulley pointing backwards (late etype) and turns backwards... dave Quote Link to post Share on other sites
TR4A1965 Posted August 2, 2017 Author Report Share Posted August 2, 2017 Thought I'd post a picture of progress. Here's the new Dynomator, Manifold Heat Shield from Revington on the left. (It affixes with a metal cable tie - the original TR race cars were welded on). The Heat Shield in the middle is from an E-type - I thought it might be a solution but the Revington Heat Shield is made for the job. I'll post a picture once installed Quote Link to post Share on other sites
Nigel C Posted August 2, 2017 Report Share Posted August 2, 2017 this is was the heat shield I made a good few years ago to cover not just the alternator but help with the carbs as well. Still didn't seem t to help either case. I have removed, set the carbs on better thermal blocks and taken the air intake straight through the flitch. Runs a lot better and starts better when hot. The alternator shield did curl round the back but to be honest it was forever fracturing its brackets so perhaps the steel cable tie is a good option Quote Link to post Share on other sites
TR4A1965 Posted August 2, 2017 Author Report Share Posted August 2, 2017 (edited) And.... here is the heat shield installed - really simple job - you bend it to your set up/shape. Holds in place on the manifold stud and with a metal cable tie around the manifold. The only thing I think that could be an issue is the development of a rattle? We'll see when it is on the road. Annoyingly, the Dynomater tipped on the workbench and the woodruff key has gone AWOL!!!!! Tomorrow's issue! Edited August 2, 2017 by TR4A1965 Quote Link to post Share on other sites
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