How important is the alternator heat sheild on a 300TDi?

[86mud]

Hi all

Finally am just finishing off putting my 130 back together after the dramas of a sheered alternator bolt (lower).

After 3 weeks I was finally able to drive it today. What a drama. Had to helicoil the bottom mount, and to do that I have to remove radiator and condensor, order new 100 amp alternator, and new water pump as it had a hairline crack near the lower most bolt hole.

Attached is a pic of the alternator...in pieces! It was installed on in August 2010.

The issue is the new alternator. I am unable to mount the original heat sheild to it. There is nothing to bolt onto at the back of the alternator. The previous alternator had extended bolts out the rear of the alternator, but the new one has a smaller sized thread so I can not use the extenders.

Is it cricial to have the heat sheild there? It does concern me being so close to the turbo.

Thanks

[jboot51]

Mine has been missing for 10 years now, with no ill effect.

[rick130]

It was really common in the early days of Tdi's to cook the rear bearing of the alternator in low speed/high load off road stuff.

The Disco 100amp ones use a Bakerlite type heat shield, the aluminium one won't fit.

[mike_ie]

The older 100A alternators had the headshield out on three extended studs, the newer ones don't have them at all. I actually enquired about this at TRS when I was replacing my alternator a few months back, and they said that it's not a problem.

[86mud]

Hi Rick

Is that something I can buy as a part

Cheers

[rick130]

Andrew, I don't know, all I know is that I bought a 100amp alt. a few months back and it came with the Bakerlite heat shield.

The old 65amp ones would stuff the rear bearing as it's such a small needle roller and not sealed.
I used a non-melt high temp, race car bearing grease and it lasted for years, but I also repaired the old heat shield when it cracked and kept it in place.

Have to say I haven't heard of too many carking form the dreaded rear bearing failing for a few years now, but maybe everyone's replaced them with Disco ones by now ? (which have a nice big roller bearing in the back)
I'd want the heat shield just to protect the regulator moreso than the bearings too.

[mike_ie]

The old 65amp ones would stuff the rear bearing as it's such a small needle roller and not sealed. too.

If I'm not mistaken, the standard 65A Lucas that came with the Defender 300tdi didn't have a rear bearing at all, but rather a phosphor bronze bush instead, which is where the problems used to lie. The 100A Disco Marrelli unit has bearings front and rear, and are a hell of a lot more robust.....

[rick130]

Naa, it's a tiny little INA needle roller Mike.
The inner sleeve is pressed onto the alt shaft and is the same OD as the shaft.
I've had it apart a few times to regrease.

[86mud]

Looks like I will jhave to fabricate something....might be able to make a bracket using the bolt that holds the dipstick to the block....and use some flat steel say 25 x 3 coming out behind the alternator then affix a piece of aluminium flat sheet to that....

Cheers

[mike_ie]

Naa, it's a tiny little INA needle roller Mike.
The inner sleeve is pressed onto the alt shaft and is the same OD as the shaft.
I've had it apart a few times to regrease.

I stand corrected