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Hi guys,

 

I got my 4A running well (to be honest, i don't really have a benchmark on how well it should run, but this seems reasonable) with rebuilt HS6 and adjusted timing using the old ear method... but, it's leaking like a pig

Most of the oil seems to be comig from the pushrod tubes, so i'm about to remove the head to have it done - valve seats and guides checked, tubes flared and sealed, and so on -

another But: i'd like to get the engine tuned slightly - fast road head, 270' cam, tubular extractors, electronic ignition, electric fan and eventually balanced bottom end and 87mm p&l, but i wont be tackling the bottom end now.

Would it make sense if i have the head done by Peter Burgess (if i'm going to have it done anyway) fit the Phoenix or TriumphTune extractors now, and expect some power increase - then later on do the pistons, liners, cam and balancing

 

Or should i leave it as is, try to seal the tubes from the outside (not sure if that'd do any good) and do the entire engine rebuild at one go?

 

Cheers

Luka

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Hi Luka,

doing the odd upgrade will not produce what you want until all or most of it is done. But you have to start somewhere.

 

If the head needs work then get that done. The exhaust manifold is simple to add and will improve breathing.

But with the head off and being worked on why not attack the bottom end.

 

As for the push rod tubes.

They will be virtually impossible to seal from the outside as the gap between tube and head will be contaminated and any sealer will not work.

Moss do supply new tubes but they are a very tight fit (over sized) and awkward to push in.

 

if when you try to fit try and get some sealant (RTV Silicon etc) around the end of the tube before flaring. Use two big ball bearings and a clamp.

 

Roger

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Many thanks Roger for the reply!

I guess i'm trying to justify doing things one at a time, to spread the cost as much, but that'd double the workload really...

Regarding the leaks - my theory is that its caused by high crankcase pressure, even with removed pcv valve and a hose going down the side of the engine... funny thing is that after i switch the engine off, oil seems to start going up the silly pushrod tubes and collect on the head, then leaking down the rear end of the engine and the gearbox bell making quite a mess everytime i park the beast..

I guess a breather next to the petrol pump is needed to lower the pressure, but doesn't solve the initial problem - either worn engine, or bore glazing... oil pressure is rather high - 75psi on tickover when cold to 100psi on any rpm higher than 1500, but after 15 min it falls to 75psi - possibly a dirty filter or stuck relief valve?

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If you removed the PCV you should replace the plug in the block near the fuel pump with the snorkel used on non PCV engines. Either that or provide more breathing from the crank case. If you didn't do that I'm not surprised that you have an oil leak.

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Hi Luka,

it is NOT high crankcase pressure. It is capillary action.

The tubes were not really sealed when originally fitted. Just very tight.

Given time capillary action will pull the oil up the miniscule gap.

 

The smaller the gap the greater the capillary pressure. They need to be properly sealed - top and bottom.

But it easier said than done.

 

I have a new Moss head (Mucho Wonga) and at present the tubes are dry. But there will be a day when the weep will start.

Roger

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If you're thinking of a Peter Burgess head then let him sort out the pushrod tubes. Whilst they mostly leak due to capillary action as Roger says, if you have simply removed the PCV without additional breathing then you have a problem which will make the capillary action even more apparent.

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Interesting. I did exactly that, binned the PCV. Back in the 60s a "tuning" garage did that to my Sprite to get it up to speed. No oil leak. Does the vacuum make that much difference? How should I fix it? Put the breather pipe in as in the early engine? All advice gratefully received. JJC

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Roger, i was hoping so (it doesnt seem like a lot of gas coming out of the hose) but the amout of oil that's on the floor is monumental, let's say every time (especially after a long run when the engine is really nice and hot) it leaves a mess up to 20cm in diameter... and all of it seems to have come from the top of the engine somehow, or i'm imagining it, since there's a drop of oil every 5-10 seconds when it's running... - rear crankshaft seal? Although it diesn't seem to come from there from what i've seen...

 

Peejay thanks for the input!

So what would be the best option:

1) having stock 4A system with vented oil filler cap, where PCV maintains a vacuum and fresh air entering through the vent hole

2) stock 4a system but without vented cap to keep the depression in the crankcase and rocker cover at all time (although this doesn't seem like a great idea)

3) stock 4 system with vented block via breather cap and vented rocker cover

4) having electric petrol pump fitted and a large diameter pipe from where the mechanical pump was, together with vented rocker cover - either in the atmosphere or a 2-3L catch tank

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I've done a search on the PCV/breather issue here, and it seems to be a concensus that regular snorkel crankcase breather works OK on stock engines, but spits the oil on the road, whereas on tuned engines it'd be best to have the petrol pump removed and crankcase breathing through there and employ electricity to provide fuel flow.

However i can't seem to find would a well maintained and working PCV be as good/better/worse than open breathing system...

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However i can't seem to find would a well maintained and working PCV be as good/better/worse than open breathing system...

 

My conspiracy theory is that PCV was introduced only as an "emission control" device for US marketed cars but that the PCV valve is unfit the purpose of crankcase ventilation.

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Hi Luka,

the PCV fitted to a nicely sorted engine appears to work OK. Having said that the snorkel on the TR4 also appears to work OK.

I wouls stick with the PCV for now.

 

The push rod tubes will not leak that much. Even if they look very oily there is hardly any flow.

 

If it was me I would get a can of aerosol brake cleaner and wash the engine down. Get ALL the oil removed and then start from the beginning.

The rocker gasket is #1 leaky thing.

The crank front oil seal will let go if the hub has a wear grove in it #2

The rear oil seal will show it self though the drain at the bottom of the bell housing. #3

The oil filter housing/block gasket can leak #4

The petrol pump can leak at the block gasket #5

The alternator/Dynamo bracket attachment screws I believe go through into the oily bit of the engine as do the coil attachment screws - check these.

 

Is it the engine!!!!

Or is it the Gearbox. My GB leaks at the selector rods and leaves quite a puddle.

 

What colour is the oil. GB oil is clean and clearish. Engine oil tends to be black/dark

 

Roger

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Cheers Roger,

 

yeah, definitely engine, as it's dark - true, i need to wash it down fully, but from what i can report is that the dynamo bracket hole isn't leaking as that side of the engine is bone dry. Also, the timing cover looks rather dry as the front of the engine. For some reason, the inspection plate on the bell housing is missing, so if it was rear seal i'd expect the most of the leak to come from there, but it seems dry. Most messy part of the engine is the rear of the block...

The strange thing to me is that it seems to keep on peeing oil for quite a long time after i've parked...

 

So the sequence - clean the engine, remove the rocker cover and seal it properly, clean and put the PCV back, get it to temperature and have a look...

Maybe i don't need to take the head off after all?

 

The compression test showed around 150psi +/-10% across all cylinders, so i guess the gasket is fine and it shouldn't be leaking from the head/block joint?

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Luka,

 

If the small tin closure panel is removed from the gearbox area be careful you don't get small stones thrown in there and meshing with the starter ring when you subsequently try to start the engine.

 

The rear engine crankshaft seal...isn't a seal, it's a 2 piece alloy casting with a curved surface which comes within a matter of thousands of an inch away from the rear of the crankshaft behind the rear main journal. There is a crude screw form turned into crank surface and a corresponding screw form roughly turned into the alloy seal area. These surfaces when being turned against one another "scavange" the oil from off the crank by skimming oil off and transferring it away from the rear main bearing crankshaft seal on the block, there is no actual sealed surface that prevents any oil coming out running against the crank, crude but actually quite effective. However...(isn't there always) it does depend upon the alloy rear oil seal (lets call it that) being positioned correctly, too far away from the spinning crank surface and it doesn't remove any or little oil, or too close and the crank carries out a little more machining on the alloy plate and removes the oil carrying scroll from it (got a collection of those from various engines) which again reduces oil removal from the crank.

It is quite common for an engine which is dry when being used to leak almost copiously when the engine stops, because then there is no skimming of the oil by the alloy scroll seal away from the rearmost section of the crank behind the rear mains journal, every drop of oil deposited there is free to exit the crankcase (don't park uphill) when the oil runs down the inner crankcase wall to the rear. This will continue for a while even after you stop the engine as the reservoir inside is emptied. There is a lip seal available that will cure this and can be fitted behind the original seal, but first you need to diagnose it correctly.

One of the worst things you can do to a Triumph 4 cylinder engine is increase the internal crankcase pressure, it will overcome the rear oil scroll skimming from the crank by squeezing everything in the crankcase not bolted down ...err oil in most cases, out of the rear of the crankshaft housing handily placed behind the flywheel so you can't see where it comes from.

 

Try a little detective work without jumping to conclusions, before starting the engine remove the oil filler cap on top of the rocker cover and see what happens to the oil flow from the rear of the engine when then you start it, hopefully it will reduce or even stop, pointing to excessive crankcase compression.

Clean off the rear of the engine above the gearbox housing mating area with thinners or other oil removal fluid, dry the area very WELL then sprinkle some talcum powder over the rear of engine vertical surface down to the gearbox mating area, that should make any leakage from that area easy to see. As pointed out the rear of the rocker cover over the rockers can leak spectacularly if the cork rocker gasket is misplaced in that area (common) or has been blown out of position by pounds of internal crankcase pressure...hmmm.

 

Have a go and see what you think, DON'T take off the head yet.

 

Mick Richards

Edited by Motorsport Mickey
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Mick -

 

I just love your description of the crankshaft rear oil seal.

Tells it exactly how it is.

 

Problem is that it's just impossible to visualise how the seal

'works' unless you have already gained the knowledge from

dismantling and rebuilding a 4-pot.

 

AlanR

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Wow - if i don't get it sorted now, i never will :)

 

Mick - would you recommend running with PCV or opening the blanked hole for the snorkel - or perhaps going with electric fuel pump and venting the crankcase where the mech. pump was?

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My TR4 had the PCV valve and didn't have crankcase compression but that was because the engine was in decent nick.

 

The fitment of the "snorkel" breather in the side of the engine when the engine is fitted is somewhat hampered by the engine being very close to the bodywork restricting access, it can be done with a 1/4" flat chisel and myriad little restricted taps to puncture the seal and then lever the seal out. However the space restriction can vary upon how the body fitment is situated and it may not be possible in your case, the easiest get around is to use the space of the mechanical fuel pump and make and fit there a sealed plate with a large bore pipe similar to the snorkel size downwards to allow excess compression to be vented to atmosphere, or to a catch tank if you are using in competition. As you say that would then need an electric fuel pump to be fitted but this is a reliable and easy fitment anyway.

 

Mick Richards

Edited by Motorsport Mickey
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You could try something like this

http://www.revingtontr.com/product/rtr1356/name/pipe-breather-engine-block-tr2-4a

Rather than the original "u" shape.

I have similar and it doesn't throw oil out. You also have the benefit of connecting it to a breather tank if needs be.

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I'm afraid I've now lost track of the story. Just to remind you I have the same problem as Luka. Rebuilt engine, running well, rather too much oil pressure. After a good run, much at the legal limit. It does as described- drips about a 10 cm puddle. Not leaking from the rear crankshaft seal, nor from the timing cover. Oil on near side of engine and everywhere behind that. The latest suggestion seems to be something to do with having an open rocker cover vent instead of the valve. And to put a crankcase breather in as for earlier engines. But I don't see how that causes the oil leak nor where it's coming from. If it's the push rod tubes why does the open vented rocker cover make it happen? Or is the best thing to hit the tubes with a tapered drift and hope for the best? JJC

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Hi JJC,

you would need to remove the head in order to press the flare down better (if at all). It is flared both sides.

 

The crank case pressure is not the cause of the tube leaks - that is capillary action.

 

Have you checked the dip stick.? There should be a felt seal on its cap.

Have you overfilled the sump with oil?

 

I know many people can;t do this but if you had an aerosol of chalk then after washing the block down coat it with the chalk - sit back and see where the oil is coming from http://www.ebay.co.uk/itm/Tygris-Flawfinder-crack-detector-NDT-sprays-400ml-Cleaner-Penetrant-Developer-/251860131706?var=&hash=item3aa4089f7a:m:mJmnJ4EPd7u4_bFHzfOrKlg

 

Roger

Edited by RogerH
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Near side (passenger side LHD) check for sealed off coil retaining threaded holes in the crankcase, mechanical petrol pump or gasket leaks same applies, oil filter and case obviously also distributor pedestal leaks or side of the timing cover, there isn't anything else if you are sure the rocker cover is sealing.

 

Mick Richards

Edited by Motorsport Mickey
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If there is oil forward on the right side of the block, check that all the screws holding the dynamo bracket are present and tight, as one of them goes through the wall of the block into the crankcase. As my brother could tell you, quite a lot of oil can issue from there if the screw is missing! Godd idea to apply some sort of sealant (e.g. red Hermetite) to the thread of that screw.

Ian Cornish

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I know many people can;t do this but if you had an aerosol of chalk then after washing the block down coat it with the chalk - sit back and see where the oil is coming from http://www.ebay.co.uk/itm/Tygris-Flawfinder-crack-detector-NDT-sprays-400ml-Cleaner-Penetrant-Developer-/251860131706?var=&hash=item3aa4089f7a:m:mJmnJ4EPd7u4_bFHzfOrKlg

 

 

 

Alternative to chalk and specialist products is a cheap pack of talcum powder from Poundland or market stall. Stuart suggested this when I had trouble tracking down a fuel leak and I've used it ever since.

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