Oil leaking from.......?

[Expat]

Got both types of O ring and plucked up the courage to take the head off.

Can anyone confirm that the two central rocker box bolts, the one's going through the head steady, barely unscrew out of the head so the rocker box can be removed, before clashing with the frame?
I had almost decided they weren't going to play ball, and they only just did so.

The push rod tube seals were in a bad way and there are definitely no plain washers in the head. The dished one's had been fitted on top of the rubber seal, not down on the shoulder of the tubes.

Filled the combustion chamber with kerosene and none leaked away, so not inclined to disturb the valves as there had been no indications of any problems, in fact everything seems good, so just cleaned away carbon from head and piston crown.

Piston is marked with letter 'B' then 'A60 w142' and N underneath. Also The letters BHB in a circle. Any significance there?

The bore looks in good shape and measures up to be standard size which is pleasing.

So just got to get hold of the plain washers and put it all back again.

One more thing. Should the rocker box mating surface be dead flat? Mine is somewhat high in the central area where the meat is, so rocks slightly when placed on a flat surface.

Cheers for any replies and suggestions.

Steve

[clive]

The rockerbox cover should be flat but I guess it depends how badly it is distorted. Given you were experiencing a bad oil leak if you have the facilities I would flat it out. However if not I still suspect the pushrod seals were your problem as a leak from the rockerbox gasket is much easier to find. It is also easier to remove the rockerbox if there is a problem, and you will have to do that anyway to tighten the head bolts after a 100 or so miles. so for my money I would just replace the rockerbox as it is and see what happens. But I would get a spare rockerbox gasket next time I made a spares order just in case!

[robcurrie]

Piston is marked with letter 'B' then 'A60 w142' and N underneath. Also The letters BHB in a circle. Any significance there?

BHB is the manufacturer and the A60 is probably the month and year (my 1962 BHB pistons are stamped E62), not sure what w142 means. There might be a six digit AMC part number somewhere as well.

Rob C

[robcurrie]

Found some info in Grace's Guide on BHB:

[Mick D]

Hi

Yes the central bolts are a tight fit - make sure you install them in the rocker box before you place it on top of the head.

I'm with Clive re the distortion on the rocker box - leave as is and revisit when you re-torque the head bolts.

Usual caveat when re-fitting the rocker box - ensure the bolt holes are clear, (no muck in the bottom to obstruct full engagement). I used a torque wrench, (set to 6Lbs/ft), to ensure I had the bolts tightened evenly.

Regards Mick

[Expat]

Thanks all for your replies chaps, much appreciated.

Fascinating stuff re the piston advert, so along with the stock bore size, it could all be original . Well I like the idea of that, so will dream on.

Will follow advice and replace rocker box as is, bolts in first and will put in an order with club spares for another gasket.

Removed chaincase today to investigate and try to reduce oil leakage. I replaced the gasket early last year and used Wellseal on reassembly but think the leak got worse : . As before, I've meticulously cleaned all old gasket off, slightly worrying as it seemed to have stuck well all round on both faces, almost tearing in half through it's thickness on splitting the join this time.

Will heed good advice gained since then and check flatness and slightly countersink tapped and clearance holes.

Anything else to look for would you suggest?

Thanks again, onward and upward

Steve

[Expat]

I'd be interested in any learned opinions on what I found with the outer chaincase and if I'm being over finicky with my expectations. Also about possible remedies.

So, put the case on a surface plate at work and could feel a bit of rocking going on. While applying hand pressure to it, a 0.006 inch feeler gauge would slide under the edge in two areas, both likely leak sources along the lower edge. Applied engineers blue to the surface plate and offered up the case, then could see the higher areas.

My question is, has anyone had luck carefully 'lapping' the edges of something like this using abrasive cloth/paper on a surface plate?
Is a six thou tell tale like this likely to cause leaks when bolted up tight with a gasket using Wellseal?

I had thought next to bolt it all back up without the gasket and see if a feeler will enter at any point, before attempting any lapping operation. I'm very keen to greatly reduce if not eliminate leaks from this joint.



Steve

[Mick D]

Hi

Rather than checking the outer case against a surface plate I think you would be better off offering it up to the inner case and then checking for a gap or excessive rock, (pop in a couple of screws loosely to hold the orientation correct).

6 thou will easily pull up when the case is tightened against the gasket.

Are you sure it's this joint leaking and not oil migrating from: the inner case to crank case joint - the chain oiler - the alternator lead feed through - the chain case breather - the clutch shaft seal - chain case drain plug?

Regards Mick

[Expat]

Hello Mick,

Thanks for that, you have tipped me in the direction I was contemplating going, so will try it next. Thing is, what to do if there is rocking there?

Yeah, there are a multitude of alternative escape routes aren't there? I'm pretty sure the main leakage is from this joint. Hope I'm not barking up the wrong tree, though it wouldn't be the first time that happened.

If I can convince me self the joint is good then at least it will be eliminated from the equation along with (hopefully) the pushrod tube leak!

Cheers

[Expat]

Got it all back together with much help after researching here and reading loads of advice and posts which have been extremely helpful, so just reporting on a couple of observations made along the way.
Thanks to all those that posted, you know who you are.

Did a dry run with three O rings at the top end of pushrod tubes, flat washers above, coned below, new Viton rings at the lower end and after just nipping up on the old head gasket there was a lot of movement possible at the lower end of the tubes when just levering gently. Going by all I've read here, there would have been leaks so added another ring and tightened down on the new, annealed gasket. There's not much of a gap under the tubes' lower end but they are definitely not touching the crankcase.

Then, despite advice and what I said previously, I ended up lapping the rocker box and chaincase gasket faces so there was no rock, mainly because the opportunity arose when I could get it done at work, plus I couldn't see the harm in it.

Rocker box sat nicely on the head, so stuck the gasket on with Wellseal and used grease on the top surface, just nipping up the bolts starting in the centre, then working on opposite sides. Poured a good amount of clean oil over everything and down the tubes before buttoning up.

Offered up the chaincase without gasket, lightly nipped up all the screws and found a three thou feeler wouldn't enter the joint anywhere so figured that was good. Refitted with new gasket using Wellseal both sides and new fibre washer on drain screw. Added oil of choice.

Started engine when all was done and she seemed to run nice and even. Rocker inspection cover was off so could see oil being pumped up and in......... good. Also oil running down outside of head, not good. The new piece of flexible tube in the rocker feed pipe was not such a tight fit on the copper and was leaking, so added a couple of clips to cure that.

Just ran for a few minutes to warm up and finally adjust rocker setting before riding to end of my street and back, no more than 100 yards. Parked up, switched off and took a look underneath.

There are signs of clean oil leaking from somewhere and I'm just hoping that it's from the chaincase mainshaft aperture as I suspect I had put a bit too much oil in there, way over the bottom edge of the chain and there is no seal there, so I am advised. The actual joint seems to be dry and I took particular care to minimize the possibility of oil finding it's way out of the alternator wire exit point, looping wires downwards and refitting grommet in hole.

May drain some oil out and obviously need to run engine for longer period to see what happens but pushrod tubes and rocker box joints look good and oil free, so fingers crossed!

Reading through the above I can see I've rambled on somewhat so apologies for that but It's such a long time since I attempted anything like this and going through all the steps helps me to pick up on anything missed or for modding next time. Found the whole thing a very satisfying exercise, any further tips welcomed.

Again, thanks for the help and advice.

Steve