Post-Thruxton Post Mortem

[JohnD]

You got in so quickly, Andy, I was still editing the diagnosis!    Kastner-type oil flow failure to the front end, I think, and I had a solution and in the excitement of getting to Thuxton forgot to fit it!

[JohnD]

As for ornaments, I already have this:

Not sure I want any more evidenceof my misdeeds!

 

[Escadrille Ecosse]

John. Really sorry to see the carnage done to such a good engine. Hopefully you'll bounce back as you have before better than ever.

[rogerguzzi]

Hello John

                   This is how I did Spitty's thrust washers(I did both sides a bit OTT)

I think your block and cap are badly damaged and would need to be machined as a pair and have special thrust washers made and pined to stop them rotating.

So probably a non starter!

This is the way I have done the oil feed pipe on Alans Vitesse.

Roger

[Nick Jones]

4 hours ago, JohnD said:

I curse myself for not fitting the Aeroquip bypass to equalise pressure between No.6 and No.1 main mearings, because I fear that, as Kastner warned, poor oil flow to the front is the price of high performance.      No.1 big end went, took all the oil flow  and so deprived everywhere else.

I think it's something more fundamental John.  That would have knocked out no 1 big end right enough but one big end doesn't drop the oil pressure that much.  My feeling is that something started chewing itself apart and the swarf from that ate the the oil pump, so the whole engine started seeing less oil (starting at the front, furthest from source), then bearings started failing, progressively dropping the pressure further.

I wonder about the thrust washers as the origin of the problem as that area is really chomped.  Normally takes quite alot of miles to get that level of damage as the forces are (or should be) very low except when you have your foot on the clutch pedal.

Is the loose ragged-crescent shaped object above the main bearing cap the remains of the thrust washer itself?  What did the front one look like?

Are there any signs of contact on the sides of the other main bearing journals/caps or on the sides on the big end journals/rod caps?  Crank could have been 2 - 3mm forward of it's running position - but what was pushing it there?

[Nick Jones]

2 hours ago, rogerguzzi said:

                   This is how I did Spitty's thrust washers(I did both sides a bit OTT)

Nice job Roger.  I've also seen similar where they've also drilled and tapped for a couple of brass counter-sunk screws to make absolutely sure.  Don't see the need on top of what you have done though.

[rogerguzzi]

Hello Nick

                 That is why I did it that way I did not fancy the screws

Roger

[PeteStupps]

Nothing to add but sympathy John, such a disheartening wreckage. Commiserations 

[flatter4]

 

Beautiful job on the thrust washers Roger.  Well done

 

John, what a shame.  I feel for you, frustrating / time consuming / expensive.

As Nick has indicated, and I'm sure you're on it, but understanding the root cause is vital.
Did the BE lose clamp (bolt), bearing rotate, lose oil pressure......
Is there any indication on the bolts as to the failure?  I can see one section in the pics with a slight bend, so that one was probably the second to fail (though could have bent from an impact when flying around)
The fact you had 4 hot rods does tend to indicate a lubrication failure though - and No. 6 was hot too, so I don't think an oil 'balance' pipe would have made much difference.  Thrust washer wouldn't have caused such a gross lubrication failure either.
...look at the pump and the filter.

As with everyone else on here I'm happy to look at pics and comment, but I know receiving these comments is sometimes rather annoying
- so sending sympathy.
 Will.

[flatter4]

 

On a (trying to be) positive note, how many hp did you get from the engine?
....and what increase are you looking for from the new engine!

[thebrookster]

I'm going to follow the others, and go with general lubrication failure.

I also suspect the original engine issues may be a leader. This would then suggest that the oil pump was not the root cause.

My thoughts go with one of Nick's earlier comments, PRV. It looks like you lost oil pressure pretty much across the engine, the heat marking on the rods alone tells you that. One rod/bearing failure should not cause that as Nick mentioned above. So you are looking at a failure that affects everything. So Pump, filter and PRV. All three would cause full loss of oil pressure, however your earlier failure is what leans me towards the PRV, the other two items would usually tend to straight failure. PRV's tend to be a weak point in any system, and they do cause sporadic failures (as in fail, fine, fail, fine).

Phil

[Bumblebee]

I am reading this with great interest as those with much more understanding offer suggestions, along with their evidence. 

I have nothing to add in terms of why, I dont have enough knowledge, but watching threads like this offer a sharp learning curve for those like me who want to understand. I echo Will's comments though, I hope my comments do not become annoying, like picking at a scab. 

 

 

[zetecspit]

This is intriguing, and we will probably never know exactly how it happened. But in my little brain, is it plausible no1 failed , and that failure caused almost complete lubrication failure? Stuff happens VERY fast in engines, it is difficult to get your head around the piston moving up/down 100 times a second. 

But hopefully some rooting about will give some more clues. But I do feel for John, very disappointing. Still, correct attitude about getting on with it. Chin up.

[PaulAA]

Goodness, John... haven't tuned in for a couple days and so only just seen the carnage.

You seem remarkably philosophical - I would be wiped out...

Paul

[thebrookster]

5 hours ago, zetecspit said:

This is intriguing, and we will probably never know exactly how it happened. But in my little brain, is it plausible no1 failed , and that failure caused almost complete lubrication failure? Stuff happens VERY fast in engines, it is difficult to get your head around the piston moving up/down 100 times a second. 

I'm of the view that this would be unlikely. This is based on what the oil system is supplying, which in this case is 6 big ends, 4(??) Mains, plus camshaft/rocker etc. So the loss of one cylinder is maybe 10% of the system? However the oil pump already over supplies the system (hence the PRV), so this is why I think this is unlikely.

To continue that thought process, had the number 1 failure caused the lube failure, I would have expected the other damaged units to be #2 etc, as being the next in line to lose oil pressure.

I'm leaning towards a general lube failure because the damage is across the full crank. I may be wrong of course, I only have these photos to go by!

[zetecspit]

39 minutes ago, thebrookster said:

I'm of the view that this would be unlikely. This is based on what the oil system is supplying, which in this case is 6 big ends, 4(??) Mains, plus camshaft/rocker etc. So the loss of one cylinder is maybe 10% of the system? However the oil pump already over supplies the system (hence the PRV), so this is why I think this is unlikely.

To continue that thought process, had the number 1 failure caused the lube failure, I would have expected the other damaged units to be #2 etc, as being the next in line to lose oil pressure.

I'm leaning towards a general lube failure because the damage is across the full crank. I may be wrong of course, I only have these photos to go by!

But....(and I am happy to be told I am wrong) if no1 went "open circuit" would that not allow a big pressure drop to the others? I know the oiling system is not that simple, but robbing pressure certainly wouldn't help the others out.

Anyway, poor old John probably needs a few cuppas and a whole pack of chocolate hobnobs to help him get over this. Hopefully the issue will be identified and eliminated on the new engine.

[Escadrille Ecosse]

Wishing to avoid picking the scab here if I can.

PRVs, a bit of a pain in the posterior on the Triumph although only had it happen to me twice.

Once was while trying to get initial oil pressure on a newly rebuilt 6 cylinder engine so no drama and honestly can't remember what the issue was. Many years ago and it was very early in the morning after pulling an all day and all nighter on the thing to get it ready for going to work.

The other time was on the 1300 in the Mk1 after doing an oil change. Got pressure turning over on the starter motor with the plugs out but stuck open when I fired it up. Very slight radial marks on the outside of the plunger and the end of the spring wasn't exactly square so I replaced both and all well since. Odd as the thing had done a good few thousand miles without bother.

Fundamentally using the spring as the centring method for the plunger is less than optimal for a start. Anyone got any recommendations for the PRV?

[Escadrille Ecosse]

3 minutes ago, zetecspit said:

Anyway, poor old John probably needs a few cuppas and a whole pack of chocolate hobnobs to help him get over this. Hopefully the issue will be identified and eliminated on the new engine.

This... and sure you will John

Edited May 11, 2021 by Escadrille Ecosse

[JohnD]

Excellent!    Thanks for all the forensic opinions and ideas!

Phil, I can only give you pics, but what else/where else would you be looking?   I can look and photo if it will pursue the cause.  As Escadrille says, best to cure that while building anew.

Nick, that No.4 Bearing cap and the concentric ring appearance (my last pic previous page) - is that wear?     I've looked at another and it's very similar.

Roger, your pic shows block above, cap below, yes?     You do this work yourself?     I'm thinking I need that mod, even if it isn't the precipitating factor.

Flatter, it got 160BHp on Neil Revington's dyno, and then I crowed about it.   It's a judgement!

 

And now, fate seems both cruel and kind!  Or else she is teasing me.

    Phil pointed me to someone who had a 2.5 in bits for sale, in Lancaster!   What are the chances?      So I went to have a look, and dear readers, I bought it, because when I looked at it I saw that the crank has been cross drilled!!

The original oilway has been terminated by a small orifice, and a normal sized oilway drilled through the journal at a right angle to that.   Then, there is a plug in the side of the web - to provide a plenum between the two oilways?

Anyone seen anything like this?

John

[rogerguzzi]

Hello All

              Didn't all the 4 cylinder TR's go on to that?

Roger  

[rogerguzzi]

1 hour ago, JohnD said:

Roger, your pic shows block above, cap below, yes?     You do this work yourself?     I'm thinking I need that mod, even if it isn't the precipitating factor.

Hello John

                  Yes all my own handy work!

I will do yours for you I just need the depth of the recess in the block so they are the same!

But I can leave a few thou on the thrusts and you can flat them down to suit(on the back of course!)

What I did was make standard size for the front then adjust the back ones to give the clearance required!

As I said I machined the front face as well so I have full circle both sides which really is over kill!!!

Roger

[RogerH]

Hi John,

 as RogerG has said shortly after the TR2 was launched the crank got its cross drilling.

The very small plug that bungs up the original oil way.has itself got a vert small hole (5/64" rungs a bell)

it has a wicked dog leg in the oil gallery within the. web/journal. The new TR 4 pot cranks have a sligtly better arrangement. 

RogerH

 

This is the new route - direct from web to centre of journal - neat

 

 

[RedRooster]

Feel a bit sorry for you, could a pro help you out?

[RedRooster]

Thinking Denis Vassey not a school girl...

RR

[Nick Jones]

3 hours ago, JohnD said:

 

    Phil pointed me to someone who had a 2.5 in bits for sale, in Lancaster!   What are the chances?      So I went to have a look, and dear readers, I bought it, because when I looked at it I saw that the crank has been cross drilled!!

The original oilway has been terminated by a small orifice, and a normal sized oilway drilled through the journal at a right angle to that.   Then, there is a plug in the side of the web - to provide a plenum between the two oilways?

Anyone seen anything like this?

John

This is the "holy grail" of factory 2.5 cranks - the early Mk1 PI or possibly TR5/early TR6 crank with cross-drilling.  One thing to watch is whether it is a long or short back crank.  That is whether the rear of the crank where the flywheel attaches is longer, moving the flywheel backwards.  All Vitesses and GT6s would be short back from the factory as is all the later stuff.  Not sure exactly what cars the long-back cranks came with (they also exist in non-cross-drilled form) or why Triumph thought it necessary to do this and have two versions, but I suspect that a long back crank would be difficult to accommodate in a Vitesse bell housing.

Provided it's in usable condition it's a good find either way as there'll be plenty happy to trade it for one you can use.

Hopefully the block comes with a full set of matching main bearing caps and is intact in the thrust-washer area?

The rear main cap should definitely not look like that John.  There are no wear surfaces on the cap as the rotating wear is taken by the bearing shell and there will be no contact between crank and and the end faces of the cap unless the thrust washers have come out, so any rear main cap bearing marks like that has seen thrust washer failure.  That one has suffered badly.