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Stag engine longevity


andy thompson

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Just a quick poser for those that have long term experience of Stag TV8 engines.

What is the maximum mileage someone has managed without a partial or total rebuild? I just ask as my friend David Markich of Markich motors in Perth is currently pulling the heads on his 77 Stag to give it a freshen up as it was starting to pressurize its coolant. It had done about 90k miles since its last heads off job. He does a lot of Stag engines and reckons that 80-90k miles is about the maximum you can get without at the very least a head lift job

The car has been driven daily for about 10 years to acheive that sort of mileage and is serviced very regularly - it probably has its oil changed at least 3-4 times a year (the benefit of owning a workshop, a four post lift and limitless fresh 20W/50) Of particular note is that the  chains and tensioners were  fitted  90k miles ago and still made no noise at all from the front end - so much for new chains being obligatory every 25k miles!!!

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Sorry i have only ever run stags with RV8S,As far as the argument goes for"we have overcome the problems and the engine can now be relied on" I doubt it No doubt  countless Gurus will now come on here,telling you how great the tv8 is,check out the Dark side,hardly a week passes without a problem from that engine for someone,,becouse they are led to believe a stag is worthless without its Tv8 and what the soc says is gospel, many a penny is spent keeping this sows ear going.The engine was an abortion in the 70s as it is an abortion now Just my opinion which i am entilted too, See you all at Stonleigh and Malvern. 8)

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That is nice to hear.  My employers Stag has had some good mileage but I don't think he got anywhere near 90k without a head gasket going.
As for the chains, I don't see why they can't last unless they really are made from chocolate.

Pagan: I read the dark side often and you are right.  Not a week passes without some horror story.  But do put them into context - when you read up about what happened it almost always is the owner using crap parts.
The actual engine design isn't bad at all, but it can suffer dearly when substandard parts are fitted.
My employer used his as a daily driver for years and has somwhere near 300k kays on it, mine less so but I rely on mine daily now too.  Both TV8s and both very reliable.

I'll stick my head out here and say that standstill is the worst thing to happen to a car such as a Stag.  Most owners are 'fair weather drivers' who take them out on dry summer days only, and then wonder why something breaks.  Keep 'em running often and you'll have far less trouble.

Julian

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I don't really want to tempt providence with a rebuilt TV8 nearly ready to fire up, but the biggest issue that I have ever found with original Stag engines, when I have stripped them is wear in the mains and big ends due to dirty oil and blocked filters.

The bores and pistons suffer little wear and even at 100K will usually respond to a hone and new rings.

Timing chain issues seem to be cheap repro parts, the original engines didn't suffer here unless a rolon tensioner failed.

cams, buckets and valves have no particular issues - unless the head has warped - if so the cam bearings will often need line boring which most people don't do after they have had the head skimmed - this makes the cam have increased loads due to friction which I think hastens chain wear - its a simple check in a bare head - bolt it to the block with the head bolts torqued down, fit cam and caps only - no valves - does it spin with little effort ? like the jackshaft - if not you need to line bore.

I believe that apart from long term failure of headgaskets - which I'll cover later - these normally fail due to heads warping due to coolant loss - coolant loss is death to these engines - a header tank with water level alarm is a really really good idea

longterm headgasket failure I think is caused by the thermal loads after the engine is switched off - without coolant circulation you should watch the head temperatures rise often 20 degrees after switch off - well illustrated by a capilliary temp gauge

there was a spell of jackshaft failures caused by faulty gear hardening on the waterpump, relating to a large batch of faulty pumps.

To make a reliable engine -

try and use the original jackshaft / waterpump - if the pump seal faces have gone LD parts are machining impellers to use ceramic inserts

tuftride and polish crank

use iwis (mercedes timing chains)

use payen gaskets

modern screw on oil filter

proper corrosion inhibiting coolant

check the rolon timing chain tensioners have the small oil pressure hole and its clear - some do NOT

pay particular care to the setup of the timing chain tensioners and pretensioning - do NOT skimp here or omit a stage

the rest is just the usual care and attention to detail and preparation

balancing is not essential, the factory did them to a good standard, when I have had it done very little metal has been removed, and if you do have it done make sure its correctly done with dummy weights on the crank

mike

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Pretty good summary Mike - can't disagree with any of that.

One of the few things that I didn't have to do when I rebuilt my V8 was grind the crank - I guess the previous rebuilder had done the right thing and I even managed to get VP2 shells.

My Stag is running pretty well now - certainly very cool even on the hottest Perth days with aircon running constantly it struggles to get to half way on the now accurate gauge. Radiator is the standard 1972 set up but with a cleaned core and export spec shroud. It still seems to use a little water  :-/ - maybe a couple of 100ml over a fortnight or so - escaping into the inlet manifold I think? Certainly isn't pressurising. Is there a reccomended header tank set up that can be modified from some scrap yard modern?

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Andy,

My first Stag had done 132,000 miles before I pulled the original lump for a rebuild due to oil consumption. It was still on standard pistons. Re-bored to +20, crank re-ground and Tuftrided, new chains, heads done, etc. Ran it for another 50,000, then had to pull it again for another re-bore due to an oversight on my behalf (bullsh*t job getting the inlet manifold blasted and powder-coated and didn't wash all the grit out fully  :B - not exactly the fault of Triumph's designers!). The chains were still good and would have lasted several thousand more miles. Re-bored to +40. The car is still running well with its current owner (in N. Ireland) at over 190,000 miles.

The Stag I have now has done 85,000 on its original engine without work, uses next to no oil between changes, and was measured at 139.7 bhp on a rolling road 18 months ago.

TV8 fragile? Not if routinely maintained, as any engine should be.

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Head gaskets lasted about 70,000 on mine, but I had made the mistake of using cheap gaskets.It was pressurising for a year before I got round to doing them, but a header tank let the gas out and kept the water in.
As the engine bay needed respraying I decided to totally strip the motor and see what needed doing, it was fully rebuilt when it was first put in.
Nothing was the simple answer, fitted a new set of chains and crank sprockets, but the crank bearings were perfect even though it was 60 thou undersize, rings were still within tolerances, and the honing marks could still be seen on the bores.
Both head gaskets had failed on the rear of the rear cylinder, though nothing was warped
Biggest fly in the ointment is undoubtedly the water pump, stripped teeth and seized jackshaft from previous owners mid 1990's unipart water pump occured six months after I bought my current stag, and I have had the same on a dolly sprint, but heard that rattling before it got as far as seizure
Neil

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lagerzok wrote:

My Stag is running pretty well now - certainly very cool even on the hottest Perth days with aircon running constantly it struggles to get to half way on the now accurate gauge. Radiator is the standard 1972 set up but with a cleaned core and export spec shroud. It still seems to use a little water  :-/ - maybe a couple of 100ml over a fortnight or so - escaping into the inlet manifold I think? Certainly isn't pressurising. Is there a reccomended header tank set up that can be modified from some scrap yard modern?



I'd certainly try and sort this before it does loose too much water - then you are into a world of pain!

I'd lay odds the water loss issue is the water pump seals, if its not a lot of water it will escape into the V under the inlet manifold and you won't notice it, as it will soon evaporate off - particularly in your hot Country (lucky bugger!) Could be the inlet manifold gaskets weaping too. I have had both issues - the impellers get corrosion on the seal face and its enough to lose a little fluid because of the pits - or the inlet manifold has warped a little - or the manifold needs a little skim if the heads have had a skim so it sits in the V correctly - I always use the proper thick payen inlet manifold gaskets - a lot of the repros are thinner than the originals so the manifold doesn't quite seat correctly - blue hylomar is recommended here - it resolves any weaping issues . Sometimes corrosion in the manifold bolt holes stop the manifold seating down too - always worth running a drill of the correct size down these

Have a look on the stag forum, there's a merc or ford header tank (cannot remember which) that fits nicely on the nearside strut mounts, and its got a level alarm too - failing that and if you want to spend money vmad on the soc forum (I think) does a nice kit with custom tank that fits by the bonnet strut slide.

I will be adding a header tank to my 4x4 estate when I can sort out where to fit it - it may not be original, BUT worth the peace of mind.


mike

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Some Merc header tanks incorporate a low water level sensor.  My 124 series has such a thing.

Lots of modern cars have little electric pumps to keep water circulating for a short time after the engine has been turned off.  My mate's Renault did although it still blew its head gasket at around 60,000 miles...........

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Y'know, credit given where credit is due in regards to the RV8, but not its GM forefather.  Buick cast it off in 1963 after not getting the alloy castings right.  Rover managed to take someone elses trash and make it into a successfull product.

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MarkDeTriomphe wrote:
Can't claim to have long term experience of the TV8 ... but my limited experience suggested 70k miles can be enough for some of them :


(both sides were the same  :-/ )


timing chain / jackshaft failure then ?

mike

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I have a 1977 stag, the car was rebuilt 8 years ago including a total engine rebuild, this after 74,000 miles, now the car is up to 88,000 and still going strong (touch wood) and with regular oil changes / water ways flushed it should go on for many years to come.
I think Mr pagan is being a little unfair about the 'dark side', of course there are many reports about stag engine problems on the SOC website, but then what do you expect on a stag website?, i'm sure if you went on any one make website for a car that is more than 35 years old you would find engine problems, i had a look on the Jenson owners website and found no end of engine problems regarding the so called bullit proof Crysler V8.

so to get back on track 70,000 miles is about right for a well looked after engine before a rebuild is needed, but will the body work last for the car to get to this mileage.

nothing wrong with the buick V8, if ever i'm was rushed to hosital i'd prefer the ambulance to have this engine over a TV8

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sorbs wrote:

Lots of modern cars have little electric pumps to keep water circulating for a short time after the engine has been turned off.  My mate's Renault did although it still blew its head gasket at around 60,000 miles...........



I had a Volvo years ago that had this and it was linked to the electric fan so that the water was circulated and cooled if need be, after the engine was switched off.

Colin.

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i know of one having done 126k from new, no rebuilds oil changed every 3k, and chains every 30k.

buicks are fine..but part of the 'stag' experience is the engine, personally i have not been let down by either of mine i have owned, and have done 5kish a year for 10 years now.

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2798 wrote:

I think Mr pagan is being a little unfair about the 'dark side', of course there are many reports about stag engine problems on the SOC website, but then what do you expect on a stag website?, i'm sure if you went on any one make website for a car that is more than 35 years old you would find engine problems, i had a look on the Jenson owners website and found no end of engine problems regarding the so called bullit proof Crysler V8.

so to get back on track 70,000 miles is about right for a well looked after engine before a rebuild is needed, but will the body work last for the car to get to this mileage.

nothing wrong with the buick V8, if ever i'm was rushed to hosital i'd prefer the ambulance to have this engine over a TV8


Indeedy.  Go onto a VW forum (where they are meant to be bulletproof), and you will come across a few tales.  As a matter of fact, go onto any car specific forum (Japanese cars included) and you will probably wish to run a mile from the cars!

Regarding longevity I cannot comment on my own (I have only owned it for around 6 months!).  However, my Porsche specialist owned one years ago and said oddly enough it was never the engine that gave him any issues, but the wiring did!

Being an ex-Chrysler/BL apprentice he said a number of the TV8 faults were down to:
Poor water pump manufacture (on both the Imp, and Triumph Slant engines)
Unusual maintenance requirements (water pump requires shimming for correct operation where in his opinion most people would fit a too thick a gasket out of ignorance)
Poor chains
Poor cooling maintenance.

He did say a bit more (accountants being stingy, poor workmanship of the time etc.) but you know the rest.

With most classics however I do feel that uprated parts are the only way forward with a lack of OE spec/quality parts to fall back on, with suspension bushes and ignition parts being items of particular note.

Slightly off topic but as for unreliable engines, and old Mondeo 2.5 V6 of mine did over 200,000 miles on its original engine, with it receiving nothing more than services on the dot and Ford Anti freeze used only.  I know a number of people report HG problems and timing chain issues with that engine.  On the Mondeo forum they also seem to paint a similar story.

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[quote=2798]

mad_cyclist wrote:
i know of one having done 126k from new, no rebuilds oil changed every 3k, and chains every 30k.



Nick, are you sure this was not an orginal 'Triggers Broom' engine. ;)


ps - has the spaniel and hunter boots arrived yet!


Haha! Always had the wellies but no dogs for me....I like pussy. The engine was sOc Stuart's.

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