Jump to content

Alternator / Belt / Wheel / Length


Recommended Posts

I'm gonna ask this here and also in the parts request place. I'm sure this may generate a lot of opinion so i'd like to see what others have done. Sorry for cross posting but not many people seem to respond in parts, except the loyal few. :)

My Alternator failed so its being replaced with an 100A Denso AMR5425 G. The old one has a bigger wheel than the new one.

So the 100A alternator has a smaller wheel on it. Should i go with it as is and go for the shorter belt or should i swap the wheels and use the same belt as per the old setup???

The belt on the old one was a 1595 and i have both lengths of belt in my hand just in case (i.e 1595 and 1580).

My thinking is the unit is designed for the smaller wheel so use the one fitted as manufactured and use a shorter belt. I'm presuming the shorted belt is designed for the smaller wheel???

Also whats B+ , D+ and W ????as the old one only had two wires on it a thick one and a thin one.

Link to comment
Share on other sites

It would probably just be easier to fit the old pulley to the new alt and keep the same belt as before.

B+ output terminal goes to battery + (thick wire)

D+ goes to charge light (thin wire)

W is ac output for tacho (if no tacho then don't use/connect)

Link to comment
Share on other sites

Thanks guys, Thats the wiring sorted.

Now for the belt. The larger wheel on my old Alt had the longer belt. So the smaller wheel on the new Alt should need the slightly shorted belt. Its only 15mm difference which i reccon is perfect. Plus the fact i don't have the ring spanner to get the damn thing off so i'm going to see if it fits. :ph34r:

Someones done this before surely without changing the wheel?

Link to comment
Share on other sites

OK so i completely ignored both Ralph and Mike..... :ph34r:...and i've fitted it with the small wheel. Might as well as i had both belts to hand.

I might very well swap them if someone can tell me why a 300Tdi Aternator from a Disco (AMR5425) has the smaller wheel? And since my 300Tdi IS out of a Disco which belt I would use if it were still in the Disco???

Tried the old longer belt first and its seemed OK but the tried a new 15mm shorter one. It looked like the large wheel and the longer belt did visually before i took it off. i.e Tensioner wheel seemed to be in same position. So i stuck with that.

The tensioner is a spring so the tension should be the same irrespective of long or short belt if my Physics is accurate as a spring exerts the same force along most of its extension. The short belt just seemed 100%.

Am i a lunatic?

BTW the 110 is dead anyhow as theres something seriously worng in the transmission. Its going to have to go into the Gargage on the back of a Lorry. Wouldn't make it on its own. :(

Link to comment
Share on other sites

Smaller wheel means the alternator will spin faster, which means you'll probably have more output at idle. Always a good thing!

The only issue would be exceeding the alternators design speed, but given the fact its a diesel with a relatively low RPM limit, i wouldnt think it would be a problem.

Link to comment
Share on other sites

Aragorn, since the Alternator came with that pully/wheel i'd presume its designed for the generated speeds anyhow.

This seems to be a bit a grey area. I've seen pages of posts here and there with numerous opinions on the subject and some quite heated arguments.. :o .. My main concern is the belt and not the spin speed as it came with the pully, was designed for a LR so it must be fine.

If i changed the pully the output will go down as you suggest due to the lower gearing (not wanting to start another argument on this subject ;)) So I think i've done the cautious thing as swapping the pully is surely affecting the design on the unit. I'm sure there's no wrong or right here but as long as my Alternator and Belt run for the normal serivicable life i'm happy. The concern is i've not considered everything and my vehicle will kill all its occupants in an Alternator disaster of biblical proportions..... :D

p.s is there a way to test to removed unit. Tried a drill (to spin it up) and a volt meter but no V output. Either its faulty or it needs a load ?

p.s.s Ralph and Mike. Thanks for the help. I've now seen the other forums where you've both posted. Food for thought....i might be buying a ring spanner on the weekend!

Link to comment
Share on other sites

p.s is there a way to test to removed unit. Tried a drill (to spin it up) and a volt meter but no V output. Either its faulty or it needs a load ?

p.s.s Ralph and Mike. Thanks for the help. I've now seen the other forums where you've both posted. Food for thought....i might be buying a ring spanner on the weekend!

best to take it to a auto elect place, they will/should have the proper test rig to give it a bench check.

no probs, don't get the ring spanner caught on the bolt & not be able to remove it.

Link to comment
Share on other sites

Neil

There isn't a difference between the 300Tdi Discovery alternator pulley and the Defender pulley.

It's a year difference thing. The smaller pulley was fitted to the later vehicles. SUPPOSEDLY.

Believe me it makes no difference. My alternator came with the large pulley. There are two pulleys. One 49mm dia and one 61mm dia. My alternators only been on for four years with the small pulley fitted.

Link to comment
Share on other sites

Thanks Mike,

to be honest i need to go out and measure the wheel as i'm convinced its smaller than 49mm which seemed to be the size on the one i removed. I need to check both and i'll report later. Currently sat in a car park doing this on my phone!

BTW they want £75 to take the 110 on a flat back about 10 miles. Seems pricy. Does anyine know anybody in Doncaster with a transporter?

Link to comment
Share on other sites

Can't get out of H on the low ratio/diff lock leaver. Not even sure it will go into N. I'm no expert on the "normal" operation of this as i've used it like twice. (thats so noob :unsure: )

Plus the below.

nasty noises in 3rd. Possibly they are there in 2nd and 1st. But seems to drive in 1st and reverse without concerning me where as i get into 2nd and get worried...and in 3rd i sort of think this isn't right and i'm doing damage. Not perticularly loud noises just doesn't feel right and there is certainly a grinding. Actually feels like its below but infront of the stick so could be front diff but that would be in any gear i think.

I really need someone with more experience than me to drive it. I drove it 3 or 4 times since i did the swivels/bearings and for only about 5 miles on each trip,,,, i could have done something. Although it made it 30 miles on the motorway before the noises mentioned below made me stop. Thus highlighing the Alternator as i couldn't start it again once i'd stopped. (thanksfully in services) Made it about another 20 miles back before the below made me stop for good.

Although the failiure happened at the same time as the alternator and i'm convinced they are not related. There was a squeeling from the engine bat at certain revs then there was the rattling sound like a penny in a washing machine. That stopped and then the loss of mechanical power. Sort of a jerk and then picked back up. This progressivle got to the stage where i didn;t want to go past third so i stopped for good.

I've not drive it since other than round the block in 1,2 and even 2nd seems dodgy.

Hopefully someone might have an idea. Thanks

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy