MkI Square Four - my problems continue

[paul.jameson]

20-50 oil is a thin oil which behaves like a thick oil. So it may be that because of the thin characteristic, more oil is coming out than I would expect from the straight 40 oil which I use in my Squares.
With the engine cold, I would expect much less oil to come out BUT I am thinking along the lines of my straight 40 oil which is much thicker when cold. So there may not be a problem.
You have the machined washer present. It was that washer that I wondered whether it was badly worn. If so, it could let more oil out.
End play on the crankshaft is difficult to measure with the shock absorber assembled on the primary drive. No figures are usually quoted in Waller for the Square but the KH/KG uses the same main bearing and the end float given for that is 0.002" to 0.004". A greater end float will again give the opportunity for a higher oil flow into the timing case.
Up and down movement indicates a worn timing side bush which you should not have, but might if the bush has "picked up" for some reason. Another possibility might be the bush rotating in its housing having come loose due to insufficient interference fit. There are no pegs preventing the bush from rotating on a Mk I.
As I tried to indicate in my previous posting, the oil in the timing case forms a "blob" in the top corner by the dynamo drive and oil from this blob is expert at getting into the end of the breather pipe and emerging accordingly. Take the extension pipe off the breather /oil pump, clean it up and then refit it into the end of the breather using a gasket sealant. This should reduce the amount of oil coming out. I see this pipe is held in place by a wire onto the pump bolt. This will allow the pipe to vibrate quite a lot, giving a poor fit into the end of the breather and the opportunity for more oil to find its way out via that joint. A better option is to solder a piece of copper or brass plate onto the extension pipe and put that on to the pump bolt. I will try to remember to take the timing cover off the Healey and take a photo so you can see the lengths I have gone to in order to address this problem on my own bike.

I do wonder if your pressure relief valve is working as it should. The easy (but messy) way to check is to take of the cover from the end of the front crank then start the engine (from cold) and see if oil sprays out - as it should. I have made a test rig for testing the relief valve consisting of length of 3/4" brass rod with a hole down the centre. One end is shaped with a centre drill and tapped to take the pressure relief valve. The other end has the brass valve assembly from an old inner tube soldered in to it. I fit a tyre valve and the pressure relief valve and can then check what pressure the pressure relief valve opens at using the type inflator on my compressor. It may not be wholly accurate, but it does give a good idea of how the thing is working. I have made similar test rigs for testing oil pressure gauges.

My KH(A) will go up to 100psi when started from cold but will then back off to run at about 30psi, lower in hot weather, and down to 10psi or so when ticking over. I have the rockers fed from the return now but previously, when they were fed from the pressure side, zero psi on tickover was the norm. So if your rockers are fed from the pressure side, I would expect zero psi on tickover when warm and this will not harm the engine. You have a high capacity Morgo pump which will make sure you have lubricant where it matters - and the pressure will increase as soon as you open the throttle prior to putting some load on the bearings.

Looking at the head problem, 2 to 3 mm skimmed off is about equal to a head gasket thickness. The higher compression MkII pistons in a Mk I is also a recipie for trouble. I would be tempted to try using 3 head gaskets - really - in the order otto - copper - otto and torque them down very carefully and minimally, using Bruce Longmans figures. I would re-torque at 5, 50, 250 and 1000 miles with great care. That might prevent the head blowing again but you would lose performance - particularly in terms of mpg. But the engine would be smoother and less harsh. Alternatively, as you say, replacement head and cylinder is another possible option.

Good luck, and keep us posted.

[camstevens]

Hi Gui
You may get this message twice, as my initial response seemed to vapourise.

What happend on my MK1: I bought a new front crank aluminium inspection cap....the one you take off to access the relief valve. I was provided a thick copper compression seal with the gasket set. This would have worked as it was thick enough to hold the inspection cap off the crank end and components. Instead of using the copper seal I cut my own paper gasket, which was much much thinner (.008" I recall). Because my gasket was much thinner, the flat inner surface of the aluminium inspection cap actually contacted the flat surface on the large nut that retains the float-setting washer on the crank end. This essentially sealed off the relief valve output, which was "conveniently" encapsulated within the hex recess of the cap. Therefore, I got super duper high pressure (in excess of 100psi) upon startup, and this didn't drop until the oil became hot. Essentially, the whitemetal bearings would have been relieving the oil at this very high pressure.....very unhealthy, I'm sure. I have now fitted the copper seal, and with 20w50 I get start pressures of around 60-70psi.

I've lived and breathed this MK1 engine for some time now, and if the correct relief valve spring is used, one should not see pressures anywhere near what you're getting. This overpressurisation caused all manner of symptoms on my engine, to the point that I stripped it and replaced the whitemetal bearings. Painful, but I'm pleased I did it.

Hope this is clearer and helps

Cam

[Gui.dorey]

Here‘s a picture of the amount of oil found in the crankcase. I measured it to be about 350ml. It seems a lot to me, but maybe some of you can say if that‘s normal or not.

I trimmed a bit off the end of the scavenging pipe, so that is now free of the bottom of the mesh and sump plate. BTW the sump plate is a new one from drags with the magnet in it. I started it back up and just went up and down the street, but I will have to do a longer run to see if this helped anything. I didn‘t really notice any difference in the oil return to the tank.

I also checked the front crankshaft cap as Cam suggested. I do have the thicker copper seal and on the inside there are no signs of it rubbing against the crankshaft nut. All nice and looking new without any scratches. The relief valve is working fine. Oil spurts out as it should, although it doesn‘t seem to be in the same quantity as on the rear crankshaft. And yes it is a big mess as it really spurts out the relief valve and not just flow out.

Going back to Paul Jameson‘s suggestions, I couldn‘t detect any movement on the crank, but to be honest without disassembling the timing chain I don‘t think one can detect anything. I shall leave the breather pipe alone for now until I test what I described above to see if it had any effect.

Regarding the head gasket, I take it you would recommend the gasket sandwich rather than a plate under the cylinder barrel? I am willing to try it, but I need to find one more set of copper gaskets. You, Paul, kindly sorted me out with one set last year - you don‘t happen to have another one lying around, do you?

I‘ll keep you updated on further progress.

Cheers,
Gui

[Gui.dorey]

And here a video of the return to the tank for your expert analysis.

[paul.jameson]

Please see below the breather pipe in my Healey. You can just make out the gasket sealant between the pipe and union. A standard breather pipe is shown for comparison. Significant oil came out when using the short pipe.

[simon.holyfield]

Gui,

I think we are homing in on the problem - the return pump should not be leaving 350 ml in the crankcase. I'd be surprised if there was much more than 35 ml in mine, not that I have measured it but whenever I remove the plug there is hardly anything there.

How about leak testing the return pipe? Blow down a plastic tube connected to the pick up pipe, with the other end blanked off? You'll have to remove the pump obviously.

[Gui.dorey]

Paul, thank you for the pictures which are a very good reference. The breather pipe I made is like your standard pipe, only a bit longer, ending more or less where your assembled pipe curves down.

Simes, also a good idea on testing the scavenge pipe.

However, before trying that out, I want to test if what I did until now (clearing the scavenge pipe off the mesh and sump plate) has had an effect. Might take a bit as the weather has been miserable with no end in sight

For the head, if anyone has a set of copper gaskets available, pls let me know. I‘d like to try Paul Jameson‘s suggestion.

Cheers,
Gui

[camstevens]

Hi Gui
I have a set of (used but re-annealed) copper gaskets you are welcome to. I was going to use them on my MK1, so very servicable. I'll send to some pics of them so you can make a call.

Cam

[daveleek]

Gui , these two photos show my new breather pipe the original let a lot of oil out ,it is made of 15mm copper pipe bent with a bender with a bird beak on the end , a 15mm male/female bend ,I found an elbow to be too short , these fittings are commonly called street elbows , the male end goes on the fitting through the crankcase nice and tight ,I did not solder the elbow it was Loctited , I silver soldered the brass clip to the pipe in position when finished

[Gui.dorey]

Hi Cam, I‘ve sent you a PM with my email address.
Cheers,
Gui