Bottom end refresh.

[Blue cedar]

My TR6 1970 has 107k on the clock , genuine mileage and smoke free ,even at start up. Oil pressure is excellent.The engine is quiet. I am thinking about replacing all the bottom end crank related bearings( big, little , thrust washers and piston rings) . The engine has not had any work done on it, so rather than wait until a regrind or rebore etc is needed, thought it would make sense to replace the items with new same size ! Also, can the thrust washers be replaced with the engine in the car and box attached ?

[AlanT]

First rule of engineering maintenance:

 

"If it ain't broke, don't fix it".

[ijonsson]

First rule of engineering maintenance:

 

"If it ain't broke, don't fix it".

I agree fully with Alan, don't mess with the engine if it's OK. Just change oil and belts, check rockers, spark plugs and points.

[dblenk]

mine was broken well old and covered in hay

yes just enjoy but if you do take the plunge

i was told doing the bottom end get it all balanced and crank crack tested

doing any racy stuff then harden the crank

david

[AlanT]

The second rule is:

 

"when you have to fix it, do it all, do it properly and right first time".

[Denis]

Agree all above, but it's always worth dropping the sump and checking the Thrust Washers which is the Engines main weakness!

[Blue cedar]

Isn't prevention better than cure.

[Tony Millward]

Why doesn't Blue Cedar have a proper name?....

 

Whoever you are, all of the above.

 

Cheers

 

Tony (real name)

[Blue cedar]

Hi Tony Millward,

 

How do I change my title name, sign off ....Peter Triggs

[Stanpartmanpartwolf]

What is your annual milage?

If everything is as you say, crank endfloat is in limits & it is oil tight, leave it, be kind to it (right foot & oil changes) & don't worry.

When the time finally comes, you will do a thorough rebuild from top to bottom & marvel at how useless asbestos-free gaskets are.

Never renew small-end bushes without first trying a fresh gudgeon pin, and for now, how about collecting some OEM or equal spec parts, such as gasket sets, bearings, timing chain & tensioner?

My first TR6 had 122,000 on its original happy & healthy engine before I stupidly let it overheat one night & had to rebuild it.

Most TR engines were very well-built; balance was very good, component failures were rare & most issues arose from abuse & skimped maintenance. You plainly have one of the best.

[Tony Millward]

Hi Peter,

 

If you email webby I'm sure he will organise this for you as he did for us. It's good to know who you are talking to and a warm welcome to the TR forums.

 

Cheers

 

Tony

[Andy Moltu]

Given that the engine is quiet, oil consumption and pressure Ok I'd wouldn't even do anything other than check the end float.

If too much then drop the sump and swap the big ends. mains and thrusts.

I wouldn't try and do the little ends because that would mean head off, pistons out so you are effectively doing a rebuild before it's necessary.

[Blue cedar]

Hi Tony

Yes agree. I also show as a non member, even though I am . Could I ask who 'webby ' is and how to contact please. By the way a good pal of mine moved to Autralia about 20 years ago, a massive classic car enthusiast, Paul Collier. He left the Uk as the out door pace was too slow. Cheers Peter

[Nigel Triumph]

I have exactly the same dilemma about whether to rebuild the engine on my GT6. It's covered a similar mileage at 110k though oil pressure is a little low (struggles to hit the specified minimum 40psi at 2,000rpm when hot), burns a bit of oil and mechanically sounds a little noisier than my TR6 engine. Using Millers 20/60 oil helps with oil pressure and it's a bit quieter but its nearly twice the price of Halfords Classic 20/50, But the little GT still goes as well as ever, so what to do?

 

I'm inclined to do a light, low cost rebuild soon (new rings with honed bores, new bearing shells and thrust washers, new oil pump, new timing chain) and hope for another 50-60,000 miles of good service. The alternative is to wait until it's really tired and face the expense of rebore, new pistons, crank grind, new everything. I don't fancy that because of the cost and also, where's the pleasure in driving the car when the engine is gradually dying.

 

So when time allows, I'm going the "light rebuild.refresh" route with the GT6 engine.

 

 

Nigel

Edited November 1, 2013 by Nigel Triumph

[Alec Pringle]

Hi Nigel,

 

the "light rebuild refresh" principle doesn't often seem to prove successful with the long stroke 6, not in the way it might with a shorter stroke 4-potter - an extra 15-20K might be a more realistic expectation than 50-60K. That's a lot of effort and cost for a relatively modest return.

 

I can't help but suggest you might be better to forego the refresh, and keep adding to the eventual rebuild fund . . . . . even having a proper rebuild professionally with all relevant items renewed, lightened balanced and tweaked, shouldn't come to much more than £3K for a GT6.

 

Cheers

 

Alec

[Nick Jones]

The 2L version of the 6 is particularly tough and dies very slowly. The one in my Vitesse (Mk2 engine) is still the original Triumph-built bottom end with an unknown, but probably very 6-figure mileage (65k hard miles in this car, at least 2 previous cars!).

It has a fairly severe oil habit now (Wynns keeps it in check to an extent) but oil pressure is still pretty good and no nasty noises on cold start. Biggest issue is steadily declining valve lift on 1 & 6 exhaust valves, which is now starting to have a noticeable effect on its performance.

 

I declared it dead in 2009 after using over 5L of oil in 3000 miles on the CT Ten Countries, but it's done two more of those events and alot more running around besides since then. It's successor is finally taking shape and once it's swapped I'll be taking a interested look inside. It'll be rebuilt as a spare as it's a been a good one and deserves to live on. It'll need reboring and pistons for sure along with a camshaft/followers/chain, but crank and oil pump may just be ok.

 

As an aside, l spent some time last weekend preparing an oil pump for the new bottom end last weekend and was somewhat displeased to discover that the brand new one I have didn't measure up well at all and both used ones I had kicking around measure better - the best having around 1/2 the clearance between gears compared to the "new". That one has now been fettled ready to install.

 

Nick

[Blue cedar]

Me again, i started the post.

Surely dropping the sump and putting in a set of std bearings and washers, a mornings work, if you have an industrial pit in your home garage can't hurt, as supported by Nick ?

[peejay4A]

Yes, if you're sure it's all standard down below. If a previous owner has gone, say .010", undersize on the crank journals your standard shells will fit - for a while So you need to measure the crankshaft endfloat, then if it's excessive you'll have to measure up the thrust washers you have in place in order to buy the right ones to get you into spec. Same goes for the crank journals, you'll have to measure them or look for undersize markings on the existing shells to see what size you need to order. More than a morning's work there.

Edited November 1, 2013 by peejay4A

[Peter Cobbold]

Me again, i started the post.

Surely dropping the sump and putting in a set of std bearings and washers, a mornings work, if you have an industrial pit in your home garage can't hurt, as supported by Nick ?

I did that three times in the first 150k miles (because pistons kept cracking, not for fun). Crank now at 280k, never reground, with vg oil psi.

Personally I would do it, if you can get reputable shells. But I'd not change the oil pump for a possibly rubbish repro.

I found after about 180k the oil psi dropped off on long hills at speed. Blow-by was the cause, so had to rebore. But consumption was not obviously raised.

Peter

 

 

You can check TW end float with dial gauge and someone to actuate the clutch, before dropping the sump

Edited November 1, 2013 by Peter Cobbold

[Nick Jones]

Me again, i started the post.

Surely dropping the sump and putting in a set of std bearings and washers, a mornings work, if you have an industrial pit in your home garage can't hurt, as supported by Nick ?

 

Sure, you can do this if you want and it could be argued that your crank would last longer because of it. If nothing else, the sump and oil pump pick-up gauze will probably appreciate a clean! The caveat is that you do need to take the trouble to find good quality bearings and the OE VP2s are now hard to find/expensive as they haven't been made for years.

 

If you are still getting good oil pressure even with "high mileage" bearings then your oil pump is likely fine and any light scoring on the end plate can be lapped out easily and the gear end-float reduced by lapping the body.

 

The Vitesse engine mentioned above had crank endfloat measured at 0.010" nearly 10 years (35k) back and is still the same today. Thrust washers are cheap so you can buy a selection of sizes. Also consider spending a bit more and getting something like this to future proof.

http://www.customthrustwashers.com/ (NFI - just satisfied customer)

 

If compressions are good and not using oil I'd leave the pistons/rings undisturbed.

 

Cheers

 

Nick