300 TDi Serp belt length - 1575mm or 1580mm?

[86mud]

Hi all

Further to my previous thread re lower alternator bolt sheering on my 300Tdi, I was running a serp belt that was 1575mm in length. It was easy enough to take on and off, but last Friday when I took the belt off and got a replacement (as I thought the issue was a squeeky belt) the new belt supplied was 1580mm in length.

Question is.....could the shorter belt cause an issue on the alternator mounting? ie putting adverse tension on the lower mount causing the bolt to sheer?

Bear in mind that the alternator, belt, tensioner, water pump, alloy bracket and p gasket were all replaced with new parts 18 months ago.

[steveG]

No - it wouldn't cause the bolt to shear.
5mm less length would cause negligible tension increase on the belt with the automatic tensioner, and the shear strength on a sound bolt of 8-10mm is tonnes.

Steve

[weeds]

which alternator are you running, i am now running a disco alternator and always have to remember to order the disco belt as i d didn't swap the pullies over.........the pullies are different sizes, buggered if i can remember which has the longer belt

[460cixy]

Defender has the longer belt

[wrinklearthur]

I think I will dig the parts book out and tell you all when the change over VIN's and engine numbers are.

Basically the longer belts were first fitted, then they fitted a smaller pulley with the shorter belt.

(E) = engine number, (V) = VIN
For the Defender,
item Part Number Description Change point
2 STC1796 Pulley-polyvee alternator - 61mm
2 STC3691 Pulley-polyvee alternator - 49mm Part of alternator Part/No's AMR4248, AMR5425
5 ERR 3287 Belt-polyvee coolant pump To . (E) 16L 25164 1595 mm
5 ERR 5911 Belt-polyvee coolant pump From (E) 16L 25165 1580 mm

For the Discovery,
5 ERR 3287 Belt-polyvee coolant pump To . (V) MA 163103 1595 mm
5 ERR 5911 Belt-polyvee coolant pump From (V) TA 163104 1580 mm
also From (V) TA 501920
use belt ERR3287 or PQS000030 for the non squeak version
----"--- ERR5911 or PQS000040 ----------"-------------- .

Enough info to confuse the socks off someone.
.

[steveG]

Enough info to confuse the socks off someone.
.

Definitely ;)
And only valid as long as the alternator is the same as original.

Been a few years, but I'm pretty sure the difference in lengths is more than the 5mm that the OP was referring to... (Edit: Doh - just realised you'd included the lengths and its 15mm)

I've found the way that causes the least brain pain is to get the correct belt for a start (by either luck or swapping the incorrect one you get first), and then straight away buying a spare. Everyone carries spare belts dont they :angel:
As soon as you use the spare - buy a replacement.

Steve

[wally]

I think I will dig the parts book out and tell you all when the change over VIN's and engine numbers are.

Basically the longer belts were first fitted, then they fitted a smaller pulley with the shorter belt.

(E) = engine number, (V) = VIN
For the Defender,
item Part Number Description Change point
2 STC1796 Pulley-polyvee alternator - 61mm
2 STC3691 Pulley-polyvee alternator - 49mm Part of alternator Part/No's AMR4248, AMR5425
5 ERR 3287 Belt-polyvee coolant pump To . (E) 16L 25164 1595 mm
5 ERR 5911 Belt-polyvee coolant pump From (E) 16L 25165 1580 mm

For the Discovery,
5 ERR 3287 Belt-polyvee coolant pump To . (V) MA 163103 1595 mm
5 ERR 5911 Belt-polyvee coolant pump From (V) TA 163104 1580 mm
also From (V) TA 501920
use belt ERR3287 or PQS000030 for the non squeak version
----"--- ERR5911 or PQS000040 ----------"-------------- .

Enough info to confuse the socks off someone.
.

IIRC the change for Defenders came in 1998. The later ones have the smaller pulley and the shorter belt. I think getting the right belt is definitely important as 15mm is a significant difference.