24 years restoring a Sprint in New Zealand

[Robert 352]

Jeroen has asked a very valid question, a question which upon reflection had me puzzled too, puzzled for I should have asked the very same question myself before I prepared my earlier posting.

However I now know what it was that was embedded in the top of the #3 piston.

Jeroen is absolutely right of course for it would be well nigh impossible for a piece of broken valve spring to get out from under the cam follower/bucket and somehow find its way into the cylinder/s.

The photograph here shows the bent valve.

20130511-4102Pttw Sprint bent valve in the cylinder head.jpg (149.47 KiB) Viewed 5097 times

It is likely that this is the sequence of events; the valve spring breaks, the valve “drops” and is hit by the piston. Hit several times, so it would seem as it is steadily bent into the position seen here for there are several very light moon shaped marks in the top of the piston itself. In bending the valve, several small pieces are broken off the end of the valve guide and it was these small pieces which were “pumped” out of the #4 cylinder, passed back up the inlet manifold and, perhaps “sucked”, back into the #3 cylinder.

What looked like pieces of a valve collet are in fact pieces of valve guide, similar in shape.

I consider myself lucky that all the damage has been confined to one inlet valve and guide and one exhaust valve, one spring, the top and bottom collars that sit on that spring, the split collets, and the cam follower which is fairly badly marked in the area where the pallet shim sits.

Had the valve broken then I expect the damage would have been much worse.

I have to be patient now and wait for an exhaust valve to arrive from the UK. I have time now to prepare/cut out some gaskets and refit the #3 and #4 pistons for it will not take me long to refit the head and timing chain once the valves have been fitted.

Robert

[Jon Tilson]

Nasty but at least you have a diagnosis and a prognosis....

I would be serioulsy looking at the other valve springs too. We have had some issues with these in the past.

Jonners

[Toledo Man]

What Jonners said.

Didn't mikeyb have a similar problem?

[Robert 352]

I am delighted to see that Mike/MikeyB has put up the link to his earlier thread on the problems which occurred on his cylinder head and which was perhaps, a reasonably common problem on some of the early Sprints. It is a timely reminder to us all to carry out a quick check when we are doing some headwork. The exhaust valves can be checked by observing and measuring the gaps between the coils on the spring itself when that particular valve is fully open. Mine measure somewhere between .030 and .040 of an inch between each (visible) coil of the spring which would suggest that when you add up the gaps between each successive coil that there is more than adequate clearance – and no chance of the valve spring binding. It was this that Mike suggested might have been a possible cause of the failure of the valve spring.

Here is the outcome of that broken spring, one very bent inlet valve and the spring itself along with two badly damaged split collets.

20130608-4144Ptw #8 Inlet valve and spring.jpg (144.01 KiB) Viewed 4987 times

It joins the collection of broken bits and pieces, further offerings to that demon God of Speed.

The cause? I am unable to tell you at this time. This head appears to have been machined to the later specifications. Rod, who machined the head in the first place and who dismantled it and removed and replaced the bent and broken bits said that in all the 40 odd years that he has been working on engines that breaking a valve spring is a very rare occurrence. I suppose all I can do is to cross my fingers and hope that this was purely some sort of random failure.

While I have had the sump off to remove and check the pistons/piston rings for possible damage I have photographed the two bushes which I roughly machined to go into the two oversize holes in the base of the block through which two 5/16 bolts are passed.

20130524-4124Ptw Crankcase sump bushing.jpg (149.75 KiB) Viewed 4987 times

The workshop manual suggested that the nuts on these two bolts be tightened to 20 ft/lbs. If you do that then you will distort the sump itself for it will crush the sump gasket and cause a leak. I have overcome this problem by fitting these bushes – one you can see in place, and the other sitting above it (which goes in the second hole). There is quite a substantial chamfer on the hole in the block but both bushes have been turned down to approximately .005 less diameter than the hole which measures .625 of an inch. All the sump bolts have been torqued down to 10 ft/lbs and will be checked again before the engine has run. I expect no further oil leaks from this area!!

Meantime I am waiting for some oil pump seals to arrive from the UK. The oil seal, (see the green arrow) - the o-ring that sits on the end plug which holds the relief valve spring in place had gone quite hard.

20130617Ptw Oil pump parts.jpg (122.93 KiB) Viewed 4987 times

I wonder too whether it might not also be worthwhile running a little bead of gasket sealer around the end of the plug once it has been reinstalled back in the pump body and the split pin fitted which holds it in place?

Robert

[Robert 352]

The shortest day here has just past and its proving rather difficult to find the motivation to go out into the workshop after dark and press on with the reinstallation of the engine into the car.

As I said in my last posting, the cause of the valve spring breaking has not been determined, so my intention is to drive the car – as if the valve spring breakage never occurred, and hope that it was purely a random event.

While the engine was out of the car I renewed all the three o-ring seals in the oil pump. I remain puzzled as to why these o-rings were not included in the bottom overhaul gasket set which came from Rimmers. Perhaps it is thought that the pump should not normally be disturbed. The new seals arrived during the week past and were promptly fitted. However I was a bit puzzled by the o-ring seal which I received which goes between the oil pump and the block which when I removed the oil pump looked like this.

20130619-4153Ptw O-ring oil seal Dolomite oil pump.jpg (117.43 KiB) Viewed 4863 times

It looked more like the seal which sits under the oil filter – a square section rubber ring. I removed this seal to find that the original o-ring was encapsulated in what looks like some hard gasket cement. There was no evidence of gasket cement on the flat faces between the pump and the block for had there been it would have suggested that some might have found its way into the pump itself. The o-ring groove was carefully cleaned and the o-ring supplied, installed, along with a new o-ring under the oil pump cover and one on the relief spring end plug/cover. This o-ring on the relief spring cover had gone quite hard suggesting that it was possibly the original fitting.

Once that was fitted, then the engine was mounted back on the subframe, the clutch, gearbox, starter motor, alternator and carburettors installed. Some eagle eye expert is going to spot the 1850 fan fitted in lieu of the original fan.

20130622-4160Ptw Engine assembly ready for reinstallation.jpg (139.87 KiB) Viewed 4863 times

This is a temporary fitting until such time as I find a suitable electric fan and temperature sensor.

Then it was time to wheel the complete assembly back under the car.

20130622-4171Ptw Engine reinstall.jpg (144.32 KiB) Viewed 4863 times

This I might add is the easiest part of the operation. For I hate to confess how many times I have done this but it is certainly quick, and for myself working on my own, the safest way of doing it. The engine is now in, all mounting bolts torqued to the correct settings and this week I shall reconnect the prop shaft, refit the exhaust, connect up the fuel and water (fit the radiator) and reconnect the electrics.

And turn the key on and see (and listen) to what happens.

I shall not acknowledge that demon god of speed on whose altar now sits the bent valve and other sundry bits but hope that the other God will look more kindly on me and allow the car to run as it should. Surely there is nothing else that can go wrong now. There are no “spare” bits left over so everything has gone back on that came off, all bolts torqued and the engine turns quite easily by hand.

Robert

[soe8m]

Good luck.

Jeroen

[straylight]

likewise, good luck Robert, makes me realise how lucky I have been with my engines. Utter novice but no problems so far !

stu

[RRM]

Hi Robert;

Lovely car and a well-written up account of its story.

Back on the first page, your second photo shows the damaged car on a trailer being towed home by an almond coloured 2.5PI, the registration number of that car isn't GF8883 by any chance is it?

[covcourier]

Hi Robert;

Lovely car and a well-written up account of its story.

Back on the first page, your second photo shows the damaged car on a trailer being towed home by an almond coloured 2.5PI, the registration number of that car isn't GF8883 by any chance is it?

Can't get it clear enough to be sure but it certainly looks like it could be.

[Robert 352]

GF 8883 it was. Another shot of the same car taken front on.

198702-04Pw Triumph PI's GG500 about to be sold .jpg (177.03 KiB) Viewed 4611 times

I have had three 2.5 PI Triumphs. The one on the left in this photo, GG 500 was used as a company vehicle and was replaced by GF 8883 after GG 500 had done well over 160,000 miles. I purchased GF 8883 from a deceased estate; it was like new having done only about 30,000 miles. It was sold later when my employer supplied me with another car.

There is a photo of the third 2.5 PI elsewhere in this thread, a Station Wagon, very rare in this country. Perhaps I should have restored it, rather than the Dolomite Sprint.

Robert

[RRM]

I thought it might be. GF8883 is in my garage now, and it was my wedding car last year. It's interesting to learn that the car has had a bit of history with Triumph people!

She has had a large number of owners and along the line she has gained power steering (which looks like a retrofit as the engine has a non-PAS front end), a 2500S anti roll bar, facelift PI front seats with head rests, and a set of 14" mag wheels that look a bit like Minilites.

Unfortunately a large amount of rust has recently started to appear through what is now obviously a recent paint respray, right about the same time as my son was born and we bought a house, so she is currently off the road while I ponder her future as well as my own!

(The car was bought so I could stay mobile in a real car while I undertake a gradual restoration of my Carmine Red 1971 PI. GF8883 is mechanically nicer than that car, and has a lot of nice optional extras, however the body has always seemed noisier than my red car, and the tin worm is such a grave problem on these cars as not many panels can be unbolted..)

Reading this forum I think if I was starting out with Triumphs now I might look for a Dolomite, they are a newer design and just seem to be better in a number of ways. However the big six cylinder cars are well and truly in my blood, since I learned to drive in my father's 2000 Mk2.

But enough about me & my car, back to your restoration thread!

Richard

[Robert 352]

This time following the exercise of refitting of the head after replacing the broken valve spring and installing a new inlet and exhaust valve I seemed to have reduced the amount of oil which has been dropping on the ground. I am much happier.

The engine started and ran without any drama whatsoever after my posting of the 23rd of June. However I still had a couple of oil leaks one of which I traced back to the o-ring beneath the distributor which had, upon examination, gone hard and cracked. Perhaps it had been there since the car was built in 1975! A replacement was purchased locally for just a few cents/pence.

I traced the second oil leak to the rear of the head gasket for it was dripping down onto the gearbox adaptor ring. I am really rueing the day I had those fine copper o-rings installed in the block when it was reconditioned over 20 years ago. They were fitted following the success another local Dolomite Sprint owner had following his attempts to get his head to sit down and seal correctly on the block. Perhaps the head gaskets available back then did not perform as well as those we are fitting now. You can see these fine copper o-rings here

20120118-2727Ptw Sprint block showing copper o-rings.jpg (145.35 KiB) Viewed 4501 times

which are supposed to cause a little bit more “crush” in the head gasket itself. However in my case they also make it difficult to pull the head down and seal it across the face of the block and the head above it and I have found that with the latest head gasket, which came from Rimmers, that I have had to change the head tightening sequence for the head has been “rocking” on these o-rings and not sealing properly across both faces. I followed the pattern of tightening, starting with the centre head stud and working outwards followed by the head bolts and that did not seal correctly. So I have had to tighten all the head bolts and studs in a sequence starting at the front head bolt (adjacent to number one piston) and working back towards the back head bolt and then tightening the studs in the same sequence. I have then slackened them all off and repeated the exercise starting at the back head bolt and working towards the front. Five hundred miles from now when the head has had a chance to settle I shall retorque the head down but in the accepted manner starting from the centre head stud and working out and see if that has fixed the oil leaks.

I have taken the opportunity while the subframe was out of the car to fit some poly steering rack mounting bushes, for it was an easy task to do when I lifted the engine off to put in the engine stand. The steering feels much more positive.

I seem too, to have reduced the oil leaks in the vicinity of the gearbox. The leaks were coming from the o-ring seals on the gear selector push rods. They have been replaced with new ½ inch imperial sized o-rings rather than the close 13mm equivalents I was sold earlier.

Henk, in his recent thread, removing engine and gearbox viewtopic.php?f=4&t=25409&p=243591&hili ... ox#p243591 asked about the various methods of removing the gearbox off the back of the engine while it was still in the car. I refrained from making comments on that thread for I have offered my comment on this thread before about the ease of dropping the whole subframe assembly out of the bottom of the car and then working on the engine and or the gearbox in the open. I am, like Jonners, too old to try and fight fitting a gearbox in from below whilst the engine remains in the car, and the thought of trying to unbolt and lift the engine and gearbox assembly up through the bonnet opening does not appeal to me either.

I can report though that if you do try to drop the whole subframe assembly out through the bottom of the car it is not even necessary to remove the radiator although it is necessary to slacken the alternator and swing it past the bottom radiator hose connection as the body is lifted up or as the body is relowered back onto the subframe.

I still have one significant task to do and that is to recondition the rear axle assembly for there is a noticeable whine from the wheel bearings. That task can wait until our spring arrives. I also have a leak from the rear carburettor and it seems to be coming from around the gasket on the top of the float chamber. I shall attend to that shortly.

Finally, as a bit of a distraction from car matters I took the week off last week and headed south to the Lake Ohau region to do some work around one of the houses in the Alpine Village. The Southern Alps were resplendent in their winter coating of snow. Here then a couple more photos to tease Ian a little.

20130711-4272Ptw2.28 Hopkins river valley from across Lake Ohau.jpg (138.22 KiB) Viewed 4501 times

This picture was taken just after dawn watching the sun rise on the peaks.

20130711-4291Ptw2.28 Mt Cook from Ohau skifield road.jpg (125.43 KiB) Viewed 4501 times

This picture was taken later in the morning looking up the head of the lake to the high peaks of the Southern Alps in the background.

I hope I will not have a reason to put up another post until I have covered a few more miles and and can then report that everything is fine. Fingers crossed as they say!!

Robert

[Robert 352]

I have done a little over 1,000 miles since I had the cylinder head off and replaced the broken valve spring and reinstalled the engine. I have now torqued the head down again and will check it at the 5,000 mile mark – and then probably leave it undisturbed until such time as the head has to come off for some reason.

The engine is still going through a sort of settling down phase - running in, I suppose. My first full tank of fuel yielded just under 29 miles per gallon. I am hoping for something better and I am anticipating that this will improve.

From time to time though I smell petrol in the car and when I check I find the top cover of the rear carburettor wet with petrol. The reason is not yet clear. I have tightened, and replaced and retightened the flexible hose which comes up from the petrol manifold to the carburettor cover but that does not seem to have cured the problem. I have fitted new float valves to both carburettors. I have fitted a new gasket on the float chamber cover, and I have scratched my head on numerous occasions trying to figure out why it is happening only on an occasional basis.

I have a question and that is why is the rear carburettor not vented like the front one? Is there a build-up of vapour, that is a build up of pressure, in this float chamber which is forcing the float down and not allowing the float valve to seat?

My engine is not 100% oil tight either which is disappointing. I had hoped that by following the instructions in the factory manual to the absolute letter that I would achieve a clean engine. But no that is not the case.

And nor have I been able to stop the gearbox from leaking. I will take the front carpet and the cover over the gearbox out and run the car without that cover for a few minutes/miles and see if I can pinpoint where that oil is coming from. I have fitted a new seal to the rear of the gearbox, new o-rings on the selector rods and used some of my expensive gasket “goo” as thread seal on all the bolts which bolt into the gearbox casing.

Very frustrating.

And there is a whine from the back axle which I need to fix as well. However the space in my workshop is occupied by another car at this moment so I am unable to bring in the spare Sprint rear axle I have and refurbish that. I will need to do it soon for there is a very slight weep of oil from the right rear hub which has unfortunately wet the new brake linings and which is causing that wheel lock under braking just as the car comes to a halt.

There are other tasks still to be done as well to complete the restoration. I have ordered a set of silver stripes from the Club stock and when they arrive I might also fit the front spoiler and rehang the driver’s door which is not sitting correctly.

But overall I am enjoying the drive and I am also enjoying the reaction of some of those others I see on the road and who seem to appreciate the effort which has gone in to make a 38 year old car look like new again.

Robert

[straylight]

well the good news is that you can give it a bit of wellie now Robert !

my diff is also whining, I figure I can nurse it around or drive like I usually do and have some fun, either way it will eventually be replaced.

29mpg off the cuff is pretty good, depending on the way you drive obviously. I reckon I got around 30mpg in the 80's, when we still bought fuel by the gallon, but that was driving carefully.

so ? what is the new car taking up the space ?

good to hear it is all back together after your misfortunes and being driven around. Well done on your patience and persistence.

stu

[lazeruspete]

And there is a whine from the back axle which I need to fix as well.

Robert

my diff is also whining, I figure I can nurse it around or drive like I usually do and have some fun, either way it will eventually be replaced.

i wouldn't worry about the whining diff, the unit in the vermilion sprint shown has been whining since the car was rebuilt (16 years) and is still going strong!



secondly, fantastic work. i am in awe of the standard of work in this thread!