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How to knacker up an engine


Derrick
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One thrust washer for crank  was fitted the wrong way round. It wore in to the crank and ended up with 5 mm end float. This caused stress on the camshaft via the chain an induced wear on the camshaft slot causing end float of about 5mm . Eventually this end float was sufficient for a cam follower to drop into path of lob of camshaft and seize the camshaft. At this point the camshaft sprocket was ripped off and chain snapped. Engine has only completed 10k since rebuilt and sounded fantastic with no indication it was about to spit its dummy out. Engine out and off to the engine guys to see what can be saved :-)

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I have a exact cppy of that thrust , one in my 2000 was fitted back to front   its not done the crank any favours

Shes now running with right way round re bedded  (allowed to wear in) to suit the wear on the thrust face and then re gapped for float

Its still ok after 2000 miles so fingers crossed 

Derrick thats pretty nasty to  have wrecked the cam 

Pete

 

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  • 2 weeks later...

It's not the long stroke -- that makes them more vulnerable to big end failure but not thrusts. The reason the 2.5 is more prone to it is that the clutch needs heavier springs to take the torque, meaning the thrusts work harder. You almost never see worn thrust washers on an auto ;)

I've seen terminal thrust washer failure on an 1147cc Spitfire engine. I don't know whether they'd been fitted the wrong way round because by the time we looked they were both in the sump. Needless to say, that engine was scrap.

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A mate had a lovely 1500SE Dolomite back in the mid 1980's it was used all the time for work etc, mileage wasn't massive, 50K or so.

One lunchtime he asked me to help investigate why he was struggling to get it into reverse gear, on dipping the Clutch the Fan was seen to be moving forward nearly 1/2"!!!

This turned out to be the Thrust washer problem, he ended up putting a 1300 Engine in it from a local scrapyard.

I think the longish stroke of the 1500 and 2500, together with the smallish Big end journals was a stretch to far by Harry Webster and his team considering the original engine was only 800 odd cc?!!! 

 

 

 

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We repaired a 1300fwd dropped thrusts by welding new location lugs on the bearing cap , a metal spray and regrind restored the crank and the engine ran for 10 years 

The thrusts do only their main  take load from operating the clutch , and the clutch on 2000,25000, 2500pi  vitesse 2ltr and all Gt6 use the same clutch cover the big saloon has a better withdrawl system but that does not save the thrusts 

Its more down to the limited half moon design and type of driving  clutch duration like  urban or motorway use

Pete

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i think thrust tec has moved on from the old designs we suffer, and the clutch press or apply brake is now quite normal safety feature 

of push start self start cars equipment ,when they are 40 year old we will know how the trusts survive this operation ??

olde days some had so much cold oil gearbox drag  dipping the clutch relieved the starter load and its thought to aid starting 

firing it up to fast idle from cold is hardly going to dregrade a thrust designed to take clutch thrusts at anything up to 6000rpm 

the wear takes place at premium rpm not ticking over 

Pete

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39 minutes ago, Nick Jones said:

Cold start thrust will be largely unlubricated though..........

most moderns have full circle thrust washers though - and formed as part of a main bearing shell too so they can't fall out.

Nick

unlubricated especially as now modern oil is like water....

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Yes, that's 30,000 that I know of. I hadn't properly measured it before, just noted that it had a "small amount of clonk". So the figure could have been fairly constant for a lot longer.

It did just under 70k with me but had been in 3 cars before mine so the total will be considerably more. It's an original Triumph build and still hanging on my engine stand awaiting post-mortem , though was actually still running well apart from it's oil habit.

I never start with the clutch down, and don't do much town driving in that car.

Nick

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I should explain. The PO (I'm No.2) used the car to tow a boat far too heavy for it, consequently the suspension and the engine were knackered after 30k miles.  He didn't believe in maintenance, trunnions not oiled since it left the factory. I oiled them, but too late, broken vertical link shortly after. His name was Keith Chitty, a serial Triumph abuser.  :angry:

Doug

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