Greta is a Gnasher ! Thrust Washer Query

[Greta]

Oh dear... just when you think things are going well.
I'd convinced myself that the gnashing sound above 3000 rpm was just poor timing or carbs out of balance - But
Following a trip to John Ruddock - Classic Mechanic Alchemist of Tholthorpe near Easingwold, and the GT6's is back on song - ... apart from ... the gnashing at high revs is still there.  John thinks it is the classic "thrust Washer" problem - particularly as the pulley can be seen moving forward and back on hard revving.... However, there seems no obvious change in tone when the clutch is depressed.

Help needed on thrust washer failure diagnosis - ... and perhaps recommendations for where to go for a quick check, out, repair, in, tune, fix !!

[Nick Jones]

Gnashing sound.....?  Thrust washers?  Wouldn't normally associate the two.  More likely something else IMO.  Just something resonating (airfilter housing, radiator grill or similar), timing chain rattle, loose fan, loose pulley bolt......

Crankshaft endfloat is easy enough to check roughly and not much harder to check accurately, subject to certain measuring equipment being available.

First off it would be wise to check that the crankshaft pulley bolt is tight and that the harmonic damper attached to the pulley isn't coming unbonded.  Also, if you still have the engine driven fan in place, this is attached to the front pulley via small rubber bushes which can perish and shrink making the fan a rather loose fit, allowing movement and potentially odd noises.

To get a rough idea of the endfloat you need to grab hold of the front pulley (not the fan) and alternately try to push it into, then pull it out of the engine.  This may be easier from under the car.  A hint of movement and a faint clonk can be considered normal.  Movement measured in millimeters and a louder clonk is not.

If you are not feeling strong or can't get a decent grip on the pulley then an alternative method is to carefully lever something against the front pulley to push it into the engine and get someone to press on the clutch pedal to push it back out again.  Holding something up against the edge of the pulley (steel rule braced against some fixed part) helps get a  fix on the degree of movement.

The more accurate method is basically the same but involves the use of a suitably position dial test indicator (or suitably braced vernier at a pinch).

Book figure new is something like 0.006".  Typical, real world "used" number tends to be 0.010 - 0.016" (0.25 - 0.4mm).  Basically, < 0.25mm  = good, 0.25 - 0.5mm = okish, 0.5 - 1.0mm = action needed, >> 1mm = oh, crap!

Good luck!

Nick

 

[Greta]

Hope ! Your post brings me hope and sends me to bed in a better mood. I'll not get a chance to  tinker until next week but thank you for your useful directions - I'll report back when I know more. 

[aleksandar]

Nuala, until a couple of years ago I used to service the car in a small garage with a sloping floor. This meant I could not put the car in gear and roll her when doing my valve gap adjusting, instead I used a large (1.5 inch A/F) spanner on the pulley nut. On one occasion I forgot to remove the spanner and when starting up there was an almighty bang as the spanner crashed against the chassis, with the nut undoing and flying to the floor. I picked up the nut put back on and used the car for a couple of months with a grumbling at certain speeds(mainly when lifting off). I kept thinking it was either the pump or alternator whilst hoping it was not the thrust bearing or worse. Then, whilst my friendly engineer was around for a cuppa I asked him to have a look. He noticed the slight movement in the pulley and asked how long. When I told him what I had done he asked me to confirm that I had put the shim/washer back before the nut (he called me something rude as well!). Then the penny dropped. When my faux pas happened I pulled out of the garage and went for a test drive. On return parked up outside, then whilst tidying up I noticed this thin shim/washer on the floor. Not knowing what it was for I picked it up and put it in the odds and sods container. So once back in place movement disappeared and so did the grumbling. Mind you the engine eventually went kaput anyway. If I am way off track sorry for wasting your time.

[Greta]

Thanks to everyone for their suggestions.

The weekend saw me avail myself of a friends' workshop and strip the engine. I shall be exploring what re dress, if any, I may have but the list of problems discovered were as follows.

1) The gnashing sound appears to be the result of Valve springs boring themselves into the head due to the fact that NO valve spring seats were fitted!

2) End float into millimetres - both Thrust Washers found in the sump - one perfect - no sign of any wear whatsoever - the other ground to a sliver of a wedge ! - The crank and block also ground & scoured

3) Broken & missing Piston Ring on #1

4) Broken big end bearings in two positions

5) Noticeable Piston slap in one pot

6) Valve seat recession on all pots and no unleaded valve seats.

Given that this engine has done less than 10k, was built by a well known Triumph Specialist and then recommissioned by another Triumph specialist only 2k miles ago who charged for the fitting of replacement "correct valve springs" - I feel that despite the hard use she's been given somewhat aggrieved to say the least. The Block, crank and head are all scrap.

I'd been sold the engine ( without a number on the head ) as being a "Fresh engine" - never fitted - built from NOS stores - yet when grinding the carbon from the Pistons they are clearly marked as 40 thou.

The sorry tale just illustrates that when insufficiently knowledgeable about our engines and cars it is oh so very easy to be taken for a ride.

I'm really not sure how to proceed - I feel I should contact both specialists and describe my findings, and at least ask them for a possible explanation. I'm very conscious of the seriousness of what I'm saying but as I personally assisted with the strip down I'm 100% confident that what I've described amounts to incompetence at best and fraudulent deceit at worse.

If any of you have any advice as to just how I should proceed from here I would be most grateful.

[Pete Lewis]

if the thrust face in the block has just worn away the lugs on the bearing caps that hold the thrust in place i have in the distant past welded and fettled replacement lugs on the bearing cap, needs a bit of care but reclaims a scrap block

if the block  thrust face is  is damaged then ignore this idea 

ive come across many deceitful traders form wheel cylinders atatched with a tyrap to 

charging for 29 ltrs of engine oil in a head gasket change at £1000

afraid the trade historically  is very variable from very good to awful ...

pretty disappointing really 

Pete

 

[sparky_spit]

Oh dear...not good news. On a positive note you now at least know the extent of the problems and what needs to be fixed or replaced.

Without wishing to be pessimistic, it may be problematic in that two different specialists have been involved in your engine build and recommissioning, and that 8k miles have elapsed between each's involvement, giving them some excuse for wanting to wash their hands of it or blame each other.

You are not going to know their stance until you contact them.  Best to speak to them with clear facts, see what their response is, and be clear on what you would like them to do to redress the problem.

I think it will be easier with the people who did the recommissioning and work on the top end; it is clear that omitting valve spring seats has damaged the head. I'd ask for the head to be replaced or repaired correctly at their expense. If you had asked for unleaded inserts to be fitted 2K ago, ask why they were not done. Otherwise ask for them to be done now, probably at your expense.

As for the bottom end and the original supplier, a lot depends upon his view of 10k miles elapsed and someone else working on the top end of "his" engine.  As long as you are specific about worn/broken items which are/were not dependent upon or impacted the work done by the 2nd specialist, I think you may have a chance of getting it rebuilt under "warranty" or at best a substantial discount on the cost of doing so. As I said, a lot depends upon his view of the time and miles elapsed since his work was done, his view of business and life in general, and how you approach him.

Keep a cool head and be factual and specific. Be realistic in your expectations and be clear in what you want from them.

I wish you all the best!

[Nick Jones]

 Uh oh - it's the "Oh crap" scenario with added bad news.  That's rather worse than expected. 🙁

On the valve springs, just be aware that there have been a number of combinations of spring combinations used on the various different models over the years.  Not all have spring seats.  The double springs for example usually have spacers under the inner springs but nothing under the outers, whereas single springs do tend to have spacers.  And then some of the after market spring suppliers recommend not fitting the spacers (probably because the springs are actually too strong).  The springs eating their way into the head is definitely not normal behaviour, even without seats.  This needs investigating further.

As regards the bottom end - you simply should not be finding that sort of wreckage after 8k.  properly built and regularly serviced these engines will go well into 6 figures even used fairly hard.

Clearly a substandard rebuild.  Broken rings are either broken on fitting or break because the gaps are too small.  For the thrust washer to be worn to the point it falls out after 8k - something was done wrong - maybe fitted backwards - it there enough left to tell?  Pics of both sides?

Built from NOS parts is not the same as being a (so called) NOS factory built (or rebuilt) engine. 

Definitely worth tackling the original supplier as there are major defects with the bottom end.  Feel that there is a problem at the top end not yet identified.....

Good luck!

Nick