Timing belts on diesels

more dire !!! i had one dragged into today, diesel ford, "blown" the engine to bits, smashed the tops of the pistons.

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Almost universally worse, not better.

LDV/transit diesels being an exception, the rockers bend before the valves.

And the old 1.7 GM diesel breaks the rockers before bending valves. Normally anyway.

John

How about the LDV with the perkins prima engine?

Steve

No, this is a dieselised O2 series petrol, effectively, inwhich the cam operates the valves directly (via shims) no rockers no nothing. If the belt breaks > piston hits valves either it snaps the cam or breaks the cam bearings from the head, in the same way a Ford 1.8 Lynx engine does. i.e. a mess.

Thankfully, its very very rare for the Prima to snap or throw a belt, the same cannot be said for the Ford offering...

Yeah I had an L reg Escort 1.8 diesel non-turbo which chewed a replacement cambelt up at 18,000 miles and I was only setting off from the lights at barely above tick-over. Guessed what it was immediately and didn't attempt to restart it thinking that it died at such low revs and no mechanical bangs that I'd got away with it. How wrong was I! Bent valves aplenty and camshaft snapped in three places. Fortunately, Halfrauds (who fitted the belt) accepted liability and fitted a recon head saving me what they estimated to be a £750 job!

Not exactly the sort of failure one would want on a motorway in the middle of fast-moving traffic, so maybe you were lucky.

In message , Tim.. writes

I almost had one. I was doing an interim oil change on my 3 year old Montego TD and while waiting for the old oil to drain, I happened to take the upper cover off the cam sprocket. I was horrified to see a 3mm tear across the width of the belt. I was lucky that the engine had stopped with the tear at the top where I could see it.

The one mile drive to the Rover dealer was excruciating, even though the tear had been there for hundreds if not thousands of miles. I asked the dealer to look into why the tear was there when the belt had only done half its life. They found that the belt had been removed by someone and refitted with the wrong running direction. They found witness marks on the cam spocket showing that a screwdriver had been used to pry the belt back on (presumably without releasing the tensioner) hence the tear.

I had owned the car from new and the car had been serviced exclusively by an authorised Rover dealer in Germany. My local Rover dealer in the UK submitted their report to Rover UK who to their credit paid for the cambelt replacement without question. I never found out why the German dealer took the cambelt off. The engine had never missed a beat and I never reported any problems with it.

In message , Dave writes

I took my son's Mondeo TD to a local garage last year for a belt change and the new belt snapped when the mechanic was road testing the car after the job. I never found out what they had did wrong but after they replaced the head they cocked up the valve and pump timing and I ended up doing it properly myself.

I spent most of yesterday replacing the belt again after only 19k because the water pump had sprung a leak and needed replacing. The water pump looked original and as the car has 170k miles on it, I suppose that's not bad.

Dunno, I must admit , that despite having persuaded them to make rather more than their rated hp I've never seen one snap a cambelt.

Belts snapping on the ford 1.8s is pretty much lucky dip as to the extent of the damage.

Seen them snap cams/cam carrier caps after having belts snap at low speed, yet seen engines survive relatively unharmed having failed at motorway speeds. And the usual cause is the tensioner/idler failing (they do usually rattle for quite a while before they finally fail).

I think that's a bloody good argument for changing the water pump with the cambelt regardless of what it's currently like.

Not really. The cambelt interval on these engines is 40k The engine went

If the cambelt interval was 100k like the Ford petrol engines then I would agree about doing it every time.

You're a lucky man - In some respects

I have an Audi 90 TD 1600cc and had engine trouble twice. Same problem the last time the more serious: the main pulley bolt loosened - broke the keyway - cam belt slipped resulting in cam shaft in 4 pieces - knackered head, luckly no damage to pistons but had to strip the engine to replace the crankshaft.

I believe this was caused by the torque this engine produces. The torque on that bolt from what I remember is ~ 275 ft/lbs

I have a list somewhere of all diesel engines which will be damaged on cam belt failure.