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Whilst replacing the exhaust on the Vitesse I noticed some oil dripping from the bottom front edge of the bell housing/engine back plate. The oil is fresh and clean and the more I looked I could see the gearbox was covered in clean oil and dripping off the gearbox mount. Followed it up to the top of the gearbox. Appeared to be leaking from the join between the remote selector and top of the gearbox. Replaced the gasket, cleaned the gearbox/engine, ran the car to a local Asda and back, maybe 8 miles in total, removed tunnel cover, gearbox covered in oil.

When replacing the gearbox oil on Triumphs over the years I usually make sure the car is on level ground and fill until oil comes out of the filler hole, squirt a bit more in and quickly replace the plug. I wondered if it could have been over filled. I have a J type box fitted, had a quick search online and came up with 1.3 litres. I drained probably 1.4, 1.5 litres out, and couldn't quite get 1.3 litres in before it poured out. Took the car for another run, seems to have cured the leaks, so must have been over filled? Not sure if the pressure built up and forced oil out of the selector. I still have a small leak at the front of the remote selector by the overdrive inhibitor switch, so must be leaking past the O rings in the remote. These were replace previously, but maybe the rubber was Shite as with so many other rubber parts I've bought.

Thought that had solved my oil leaks dripping on the exhaust and wanted to get the interior back in. Final degrease, another run, put the car up on ramps and there is still oil dripping off the bottom of the engine back plate/bottom of the bell housing. Gearbox is dry. So it appears either the rear of the sump gasket is leaking, or worse case the rear crank seal, or something behind the engine back plate. Rear crank seal was replaced several years ago and the engine has done less than a 1000 miles.

Clutching at straws, but possibly the sump bolts may need torquing up, doubtful but I will give that ago first. I do not want to have to take the box out and remove the engine back plate.

20210309_155545.jpg

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Try nipping the bolts up.  The sump joint can relax and you loose the clamp on it.

....but be careful with the central ones, they go into the aluminium crank seal housing - and have a habit of stripping.

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Posted (edited)

Thanks for the reply.

As soon as I get a chance I'll give it a go. That is what I was concerned about, it's the two centre bolts that seem to be where the leak is coming from. Iam hoping it's not leaking from further up above the sump. Oil seems to bead along the centre edge of the sump. Presume it then blows off the edge and onto the back plate. Can't see any oil streaks above the edge of the sump.

I did lay under the car for ten minutes with the engine idling after a run and think I could just make out a tiny bead forming, but after a run 70mph it's clearly wet. I could put up with a little leak but this drips onto the exhaust, so can't put the tunnel/ interior back until it's cured.

Edited by Mark
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Check under the oil filter/block joint too. They do like to leak here and the trail goes straight down to the sump joint and tracks around it.

Rocker cover and head gasket can also weep on the sly with the same effect.

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Engine and gearbox oil have a distinctly different smell!   So you can dscriminate that way.

Then . a good cleran and a dusting of talcum powder (!) will show uop the source

Just tightening up the sump bolts rarely solves the problem, in fact makes it worse is the sump gasket is leaking.     The sump is thin steel, and more than the recommened 16lbs-ft of torque can crush the gasket and 'bell' the holes in the flange.    Then the gasket cannot be gripped and leak is inevitable.      The belling must be corrected before fitting a new gasket - see: https://forum.tssc.org.uk/topic/108-correcting-the-sump-flange-to-prevent-leaks/?tab=comments#comment-730

John

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If it is engine oil rather than g/box, what is your crankcase breathing arrangement? A restricted breather results in oil forcing its way out all over the place, I have discovered! (in fact I think it was via a thread here that I realised that was one of my issues).

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Thanks all.

Good points and advice as usual.

It is engine oil, and I did degrease the engine, and look from the top down.  Rocker cover seems ok, back of the head ok, I have a Mocal adaptor for a spin on filter which appears dry.

The point Pete makes got me thinking. I have the Smith breather valve still plumbed into the rocker cover incorporating a catch tank. Can't remember how I plumbed it, but there is a possibility I'am pressurising the sump.

Previously I had a pipe from the rocker into an open catch tank and didn't notice any leaks. Also there were a couple of small drops of oil around the rocker cover nuts and I was going to fit some fibre washers. This could also point to a pressure build up.

Think firstly I'll revert to a basic catch tank without a breather valve and see if it makes any difference.

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Worth a try I reckon. My 1300fwd was dropping progressively more oil everywhere I parked it, until I discovered the gauze filter in my catch-tank was totally caked in filth. Chucked the gauze away, wiped all the oily mess off the block and it was still dry as a bone after 60 miles up the motorway.

Unfortunately this led to me feeling pleased with myself, which provoked the spiteful gremlin who evidently lives in the car, and the clutch plate snapped 15 miles later. But at least it didn't drop any oil while I was waiting for the AA.

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Crank fumes are blowby gas, that leaks around the piston rings.   The amount of that depends on the state of the rings and bore walls.   It's the same as exhaust gas, CO2, CO, N2, N2O and not much oxygen, plus water vapour.    All waste products.

Then, the oil the fumes carry is vapour from hot oil in the engine, plus splash droplets.   That is a loss to the engine, a reason why your oil level falls slowly in use, even without leaks!

The first needs to be got rid of, but the second to be conserved, and it is possible to do so.    The usual catch tank set up involves a vent from the rocker cover to a can somewhere below, often to the front of the engien where it is cooler.     The gases pass through and away, but both the water and oil vapour condense into the liquid and run down into the can, in a horrible emulsion!

Better, is to arrange the connection to the catch can so that the oil is returned to the engine while the water escapes.     You can do this if you fit an electric fuel pump by using the hole in the block for the fuel pump as a vent.     A hose UP from there to a catch tank, say on the shelf of the bulkhead runss next to the block, and will stay hot enough to keep the water as vapour, but let the oil condense and drop out, to flow back into the engine, while the water vapour vents via the can.    Any water that condenses in the can will be oily water, rather than that horrible, 'mayonnaise' emulsion.

I use this arrangement, and never have to empty the catch can, as all that get there is water vapour, that passes through.  any water than does condense in the can, evaporates in the heat behind the engine.

John

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To add to this briefly.....

A simple orifice doesn't work - or at least not over a wide enough range of conditions to be useful.  Likewis, there are MANY different PCVs out there and they all have slightly different characteristics.

The Smiths "flying saucer" valve works pretty well but in my experience cannot handle sufficient flows to handle sustained WOT loads.  On the Vitesse at least it works fine in general use but a good thrash around the mountains or a track day-day leads to significant "sweating".  It's on my to do list but I'm not quite sure what to do....

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Mark

I also have a catch can plumbed between the rocker box and the Smiths PCV. The can collects a small but worthwhile amount of condensed fumes and I can see globules of condensation in the sight tube when the engine is warming up. Suction applied to the catch can via the Smiths valve should make it more efficient than a catch can with just a filtered vent.

Ian

DSC_7770.JPG

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Posted (edited)

Hi Ian

Think I may have got the idea from you, it was on this forum anyway. Probably not the cause of my oil leak but I just want to rule it out. I also need to check its correctly plumbed in. I need to start labeling things or making notes, as when I've revisited various mods on this car, my minds a blank. I haven't seen any evidence of oil or moisture in the catch tank inspection tube, so need to take it of and open it up. I would expect to see something based on the amount of fumes that were coming from the breather, the main reason I went this route.

IMG_7252 (2).jpg

IMG_7251.jpg

Edited by Mark
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Hi Mark

Looking at your photos (same can as mine, by the way), it appears that you have pipe from the rocker cover to the outside fitting on the can (let's call it the inlet). I assume that this fitting is connected to an internal tube of some sort and that you have something inside the can to help condense out the moist/oily fumes. The other fitting (let's call it the outlet) should connect to a compartment at the top of the can, that is separated from the lower section by a filter plate. I managed to get some sintered aluminium sheets from a specialist supplier. The outlet from the can then goes to the original inlet side of the Smiths valve, which I think is what you have done. On my car (fitted with Stroms) the return is into the inlet manifold, whereas on yours with SUs you have reused the original ports on the carbs. This shouldn't make any difference as far as I can see.

When I was designing the can install, my research suggested that the can should be installed as high as possible, which is why I went for the position at the front end of the engine. I have bracketed off the fixings for the front engine lifting eye. I can give you more detail of the can internals and the fixing arrangements if it would help.

PS where are you based?

Ian

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Hi Ian

Thanks for the advice. I need to get to the lock up where I keep the car and see  how i have routed the pipe work and think it through. I used the can as supplied, so didn't add any material inside to help condense the fumes, can't remember taking it apart either. I didn't do any research at the time which I probably should have,  and will do so now. On a previous Spitfire I had a pipe from the rocker cover into a catch tank, which did the job. I am curious if there is anything in my catch tank, so will open it up and  have a look. I live in Eltham SE9 London.

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Hi Mark

If it the same can as mine, then it will have nothing, ziltch, zippo, sweet fa inside it and therefore not much to make the oils and moisture drop out of the stream.

I will try and find the sketch of what I fabricated. Also I think that the position might be important as the Smiths valve has to draw the vapours up against gravity if it is too low.

There is quite a bit online about catch cans and I recall a good description of the function of a Mishimoto one.

Definitely worth pursuing in my opinion and my inlet is noticeably cleaner as a result....and better for the environment.

Ian

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2 hours ago, Mark said:

I live in Eltham SE9 London

That's not far from me Mark. Might have mentioned it before - my lockup is in Kennington. I saw a GT6 down your way a couple of years ago, when I was en route to Orpington. Mk3 I think, can't remember clearly though. I'd have been in my Spitfire.

As mentioned above, my catch-can still collected quite a bit of condensate after I'd removed the gauze inside it. Gravity must help it collect, and I guess the gas slows down & depressurises slightly when it enters the can so more fluid drops out at that point.

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"draw the vapours up against gravity"!    These are vapours, and gases, they will have a mass of 1-2 grammes/litre, and have the pressure of the flow of blow-by gas behind them.   Gravity has nothing to do with their flow towards the outside!

But gravity can help persuade condensed oil and dropped-out droplets (with a specific gravity slightly less than water, oil weighs about 960grammes/litre, so approx a thousand times more than blowby gases) to go the right way.    That's why a catch tank HIGher than the engine is a good idea - the condensate runs back into the engine.

Edited by JohnD
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OK John, so perhaps I should have said draw the 'cleaned air', with the oily deposits remaining in the catch can.

Having seen what is collected in the can I think it preferable not to put it back into the sump and I certainly feel it is right to be collecting and disposing of the small amount of accumulated oily condensate rather than burning it! Luckily it doesn't need draining very often.

I just know it seems to work well on my car and is certainly one of my better mods. 

Ian

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Some moderns (typically ones with turbos) use little cyclonic devices. I have one stashed somewhere as these seem to overcome the “no vacuum” problem. The soot monster has one - a double no-vacuum scenario being a turbo diesel, and that is still working in disturbed after 330k.

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Checked the breather set up today before I start taking the sump off/gearbox out to identify and cure the oil leak. Couldn't feel any vacuum at the top connection of the PCV which connects to the catch tank. Removed the tank and there was 50ml of water, no milky residue and no oil. The gunk at the bottom of the tank is rubber sealant. There are no baffles, pick-ups, just two threaded hose barbs at the top of the tank. Seems to be doing its job, and I don't appear to have any visible oil blowing past the rings. 50ml over a total 800miles seems pretty good to me. Cars covered a total of 61000 miles.

Cleaned away any oil that had previously leaked, and ran a hose from the rocker cover into a bottle, to rule out any problems with my breather set up, and took the car for a run. Checked on my return and the oil is still leaking from the same area. I'll start by removing the sump, reseal and see how it goes.

20210320_165755.jpg

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That definitely looks very watery. At least it's in the can not the engine. Mine does collect a small amount of 'modified' oil, see attached.

It sounds as though you now think the leak is not breather related. Let's hope it's the sump rather than the rear crank seal.

Ian (PS I have found the sketch of my can internals if you are interested)

DSC_7943.JPG

DSC_7944.JPG

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On 3/17/2021 at 1:05 PM, Nick Jones said:

Check under the oil filter/block joint too. They do like to leak here and the trail goes straight down to the sump joint and tracks around it.

Rocker cover and head gasket can also weep on the sly with the same effect.

Don't want to count my chickens, but I think Nick was right.

I just couldn't face, taking off the exhaust, and all that entails with removing the sump, especially when I couldn't see exactly where a leak was coming from. Also been suffering with tennis elbow, bad back etc.

Numerous runs in the car, de-grease and repeat, back up on the ramps, dabbing with thin pieces of tissue, I thought I could see a tinny weep of oil from the bottom of the Mocal oil filter housing where it mates to the block.

Removed it and dug out the large o ring from the engine block, which looked new. Cleaned the edge of the Mocal casting, O ring and mating surfaces, smeared with gasket sealant and refitted.  Ran the car and now I could see a definite leak from the same spot at the the very bottom of the Mocal housing/block, so had disturbed something.

I replaced the large O ring with a new one, tightened everything up took the car for a run, and its still leaking. A tiny bead of oil builds up on the edge of the sump lip and then runs along the back edge, as Nick suggested earlier. This is after 15mins of the car on tick over up on the ramps. Very hard to see, black on black, and only confirmed when dabbed with tissue.

Noticed a witness mark on the edge of the Mocal casting where it looks like, when it was previously fitted to my GT6, it went further into the recess of the block when pulled up tight. This could be due to a fresh O ring being slightly thicker. I then looked at the the oil seal that fits inside the centre of Mocal adapter. I must have fitted this, as the spin on adapter was second hand when I bought it, and I didn't come with any seals.

I was wondering if it was to thick, stopping the outside edge of the adapter sealing tightly. I found a thinner o ring that just sits a little proud when fitted inside the recess at the centre of the adapter.

Fitted the adapter back to the block, but changing the inner seal hasn't allowed the adapter to be pulled  any further into the engine block recess, going by the witness mark on the edge of the adapter, so this is probably due to the new thick outer o ring, and not the smaller inner o ring being to thick.

Ran the car and after a few miles I still have a leak from the bottom edge of the adapter. I think I will order a new correct inner seal from Mocal, because I have a feeling it should be a flat rubber seal fitted in the centre and not an o ring, but this will not cure the leak.

Its bolted up tight, and you cant rotate it. I will take everything off again, clean out the recess in the block once more, and have another go.

Although this is a PITA far better that having to remove the sump. There is a definite leak, especially since I disturbed it, so hope this has been the cause all along.

Any thoughts or suggestions appreciated.

 

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20210327_140451.jpg

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These are a PITA. Later ones have a spring loaded centre section with a flat seal to self-adjust, but on the early ones you really need to do a dry build with only the outer seal in place and a piece of plasticine/blutack or similar inside, so you can see what gap there is and pick the o-ring accordingly. I’ve only ever seen o rings there, though I have been know to find my own in an in-between size having decided the kit ones were too big and too small......

Before this you also need to double and triple check there isn’t the rock hard remains of a second seal lurking at the bottom of the outer groove. Guess how I know that.....

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  • 1 month later...

Managed to stop the leak between the oil filter adapter and block. Used some blue tak to take an impression for the centre O ring between adapter and block as Nick suggested, which showed the thin centre O ring I was using was about right and wasn't stopping the outer O ring sealing.

I then fitted the original type canister housing with a new filter and O ring to rule out any issues with the Mocal adaptor. Ran the car and still found a small amount of oil dripping off the rear edge of the sump, but no oil leaking from the filter. 

Refitted the Mocal adapter and brand new outer O ring and filter and couldn't detect any oil leaking from the seal. The first O ring I had been using was unused and new, but old stock i had bought probably fifteen years ago. So it may have gone hard, although I couldn't feel any difference between the two O rings, I've binned the first one incase I forget and reuse it in the future.

So unfortunately I still have oil leaking from the rear of the sump, or possibly back of the engine. 

I'll have to remove the sump which Iam not looking forward to as it looks like removing the exhaust, carbs, rad, rack, etc. Lifting the engine to get enough clearance to remove the sump.

What gasket sealant do people recommend? Looks like I used Hylomar Blue with the gasket previously, and looking around the join, it looks wet, enough to get an impression on tissue. 

Want to make sure I seal it properly this time.

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