Timing belt destruction....

Quote:

---

Originally Posted by Brian Hjelm

Are you kidding? A full tear down is required. Clean, visually inspect, and measure everything. Pistons, rods, valves, combustion chambers, cam and bearings, cam bearing tunnels. What the hell do you think happens when the camshaft stops turning and the crankshaft does not? Bang, wallop, whack, is what happens. Engine builders who will not clean, inspect, crack test, and measure, deserve everything that happens to them.

---

LMFAO...

Thing is... I get the feeling that you're actually serious??!!??

Have you ever looked at the insides of a TDi? What makes you think that a push rod would _ever_ be strong enough to cause a con rod to bend???

You might get that sort of damage in todays modern OHC engines but not the TDi. The TDi is based on a design that's 30+ yrs old! When the rubber band lets go on this engine, rockers and push rods are typically the only casualties.

M

PS... Service intervals on the cam belt is 'officially' 100,000 or 4 (or is it 5) yrs, which ever is soonest. However, IMO, you can never change the belt too often!

Quote:

---

Originally Posted by camel_landy

Service intervals on the cam belt is 'officially' 100,000 or 4 (or is it 5) yrs, which ever is soonest. However, IMO, you can never change the belt too often!

---

Which is why I've never had a timing belt let go on me (yet). So an 80,000km 1998 Defender Tdi that has spent all its life in the tropics is well and truely overdue for a new rubber band. Well that's the first project sorted out!

Did mine a couple of weekends ago.

Read the manual, it said 11Nm.

Read the kit instructions, it said 45Nm.

So it got 45 of the buggers. The belt was tighter than 11Nm without tension anyway.

Quote:

---

Originally Posted by up2nogood

Did mine a couple of weekends ago.

Read the manual, it said 11Nm.

Read the kit instructions, it said 45Nm.

So it got 45 of the buggers. The belt was tighter than 11Nm without tension anyway.

---

Nooooo...... Way too tight! You will bugger the belt. If it was already that tight before tensioning, something was wrong.

M

Quote:

---

Originally Posted by up2nogood

Did mine a couple of weekends ago.

Read the manual, it said 11Nm.

Read the kit instructions, it said 45Nm.

So it got 45 of the buggers. The belt was tighter than 11Nm without tension anyway.

---

For a 300 TDi RR or Disco - In the manual is says

Tension timing belt to

Used Belt - 12 Nm
New Belt - 15 Nm

Keeping timing belt at the correct tension tighten tensioner bolt to 45 Nm

..............if you have 45 Nm on the belt - that's toooooooo much

Quote:

---

Originally Posted by camel_landy

LMFAO...

Thing is... I get the feeling that you're actually serious??!!??

Have you ever looked at the insides of a TDi? What makes you think that a push rod would _ever_ be strong enough to cause a con rod to bend???

You might get that sort of damage in todays modern OHC engines but not the TDi. The TDi is based on a design that's 30+ yrs old! When the rubber band lets go on this engine, rockers and push rods are typically the only casualties.

M

PS... Service intervals on the cam belt is 'officially' 100,000 or 4 (or is it 5) yrs, which ever is soonest. However, IMO, you can never change the belt too often!

---

We've had dozens of belts go over the years. The rockers & pushrods act like a fuse. We pulled the heads & sumps off the first few to check but there was never any signs of internal damage. Since then, it's just replace the belt & broken rockers/bent pushrods.

The belt change interval was initially 100000km but it was revised down to 80000km I believe.

Quote:

---

Originally Posted by ladas

For a 300 TDi RR or Disco - In the manual is says

Tension timing belt to

Used Belt - 12 Nm
New Belt - 15 Nm

Keeping timing belt at the correct tension tighten tensioner bolt to 45 Nm

..............if you have 45 Nm on the belt - that's toooooooo much

---

Yes, that is like what I remember from the manual. But before people who might be about to do this, a service bulletin issued in 1998, (after the manual) says:

Quote:

---

a) The timing belt tension has changed from that published in the Workshop Manual. The new method is as follows, it is essential that this procedure is adhered to precisely:

b) ...

f) Using a dial type torque meter with a maximum length of 250 mm apply a torque of 11 Nm with the torque meter positioned vertically as shown, (illustration B).

g) Tighten the tensioner locking bolt to 45 Nm.

h) ...

---

I guess, under pressure from the bean counters, Rover did a number of things, which lead to premature timing belt failures in the 300Tdi.

They did not do a proper fix, but fiddled around with the problems and have rectified some over a period of time and made procedure changes such as reducing the belt pre-tension.

They have not fixed one of the main causes of the problem - the cheap and nasty pressed pulleys, which deflect and cause the belt to track off.

Reducing the belt pre-tension, slightly reduces the load on the injector pump bearing, and slightly reduces the flex of the pulleys. It helps, but can't fix this problem because there is considerable operating belt tension required to drive the camshaft and injector pump. The complete fix (for good belt life) would be cast and machined pulleys.

BTW this operating belt tension results in a reduction of the belt tension at the fixed tensioner (which is why the pre-tension can't be reduced much further).

Quote:

---

Originally Posted by JohnM

Okay,
Back from being away in Canberra for the week due to work, I have just installed the new timing belt kit with new crankshaft gear. Flywheel and fuel pump are pinned and cam shaft mark lines up. Put in new pushrods and replaced two rockers and adjusted valve clearances to spec. Kicked her over and it seems to idle okay, little smokey(blueish), put under mild acceleration and just a sea of smoke.......Thought I must be a tooth or two out in the timing, redid the timing and had a similar result, but with less smoke. Could the timing be out by another tooth (parallex error) or is it something else caused by the belt letting go the other week(no smoke prior to this happening). Doesn't appear to be any oil in the water or visa versa and whilst I haven't taken the head off the valves appeared to be okay....


Thanks

Ilandro - The belt was changed last time by LR. The crankcase gear is spot welded on the one side only, didn't find any metal bits from the front... I suspect this gear wasn't changed but I'm not certain. I have had the disco since new as well, purchased 98 and it is a Jul 97 build.

---

Smoke like you described can result if the injection timing is retarded.

Quote:

---

Originally Posted by camel_landy

LMFAO...

Thing is... I get the feeling that you're actually serious??!!??

Have you ever looked at the insides of a TDi? What makes you think that a push rod would _ever_ be strong enough to cause a con rod to bend???

You might get that sort of damage in todays modern OHC engines but not the TDi. The TDi is based on a design that's 30+ yrs old! When the rubber band lets go on this engine, rockers and push rods are typically the only casualties.

M

PS... Service intervals on the cam belt is 'officially' 100,000 or 4 (or is it 5) yrs, which ever is soonest. However, IMO, you can never change the belt too often!

---

Given that I started my apprenticeship as a a fitter/machinist with a heavy transport company in Western Qld. in 1957, and since worked on motormowers, bikes, cars, trucks of all sizes, even owned a few: ships main propulsion engines, steam up & downers, turbines, race cars (owned 'em, built 'em, drove ' em, prepared 'em. )Went to Indianapolis for training at DDA. Built and dynoed Offy's, I think I might have seen a few catastrophic engine failures. A catastrophic engine failure is when parts that aren't supposed to meet do so, and impact occurs, and/or impact damage is caused. In each and every case this (possible) damage must be inspected. Ships stop, aeroplanes fall down, truckies go bankrupt, tourists in 4wd's die of thirst when failures occur. Motor mechanics are generally not trained as skilled fitters and engine builders. Nowadays they are parts replacers. Cheap fixes cause court cases and sometimes loss of life.

Quote:

---

Originally Posted by Bush65

Reducing the belt pre-tension, slightly reduces the load on the injector pump bearing, and slightly reduces the flex of the pulleys. It helps, but can't fix this problem because there is considerable operating belt tension required to drive the camshaft and injector pump. The complete fix (for good belt life) would be cast and machined pulleys.

---

OK... So it's easy enough to have a pop at the 'bean counters' but IMO it is all 'fit for purpose'. The revised belt tension does petty much solve all the problems too.

M