still pissing oil!!!!!????

[jerry]

took the 750ss for a 10 mile run its lovely but still pissing oil from rear head , im totally wanting to take a large hammer to this beauty im so frustrated every seal and gasket in this engine is new ,,rear head has had new seals and gaskets 3 times but still oil is getting out all over the engine from the rear head ,,
tired of this

solved the plastic rocker cover seal leaks on my V6 saab after 4 sets of new gaskets over 2 years today with some aluminium rocker covers off an old vectra V6 the aluminium covers ones wont warp and the gaskets are 6mm wide instead of 3mm

[Mark64]

Hi Jerry,
Looks like you'll have to bite the bullet & lap the head/barrel together, I know it's a ball ache - I've been there, but it will be worth it in the end.

Good luck mate & ride the storm

[jerry]

yes may have to get it to a machinist mate who has all the gear he can measure barral and head and do the business bummer is dropping engine what a palaver

[Darren69]

Mr Punisher, sir.

HI Jerry

Is it definetley leaking from the head/barrel join and not from the crankcase breather? They do blow a light oil mist usually, but you would have other more serious problems I'm guessing if a load of oil is blowing out of the crankcase?

[jerry]

Darren its definitely the head barrel joint ,, spoke to Peter at Moto di Marino today he said he has seen this issue many times it needs lapping BUT more interesting is that he said the O ring spigot may be too tall from the factory its rare but many early 750ss and 900sss had spigots that are too long and then the O rings dont seat and the head can warp so spigot nees a little filling off too ,

[jerry]

OK engine is out ,,rear head is off and one can see a definite leaky area around the O rings ,which are both in perfect nick as they are newly fitted , Im waiting for some engineers blue so i can see what the state of contact seal is on head on barrels and make sure they are flat and not warped as its been messed around with by previous owner

but the head is missing 1 of the 2 big Orings ,around the oil galleries , its only ever had one in but for a long time it was OK so i now realise that this may be the problem all along looking at the parts lists for 750ss show it should have 2 big orings !!!!!

[utopia]

According to my Haynes manual, the horizontal head has two O-rings and the vertical head has three.
I think the extra one on the vertical head is smaller than all the others.
Incidentally, both also have a dowel which has to be put in the right way up .. ie smaller hole outwards.

The genuine Ducati workshop manual for my 750 makes no mention of this that I can find anywhere in the text but it does show it in the associated drawings.

[Dukedesmo]

The drilled dowel is the oil feed to the head, through the cylinder and so is under pressure whereas the return holes work by gravity drain.

That said the returns seem to leak just as easily, I've completely blocked the feeds from cylinder to the heads on mine (and fitted solid dowels for location) as I have external oil feeds to the heads, so only the returns are active and despite lapping & new 'O' rings etc. the rear still weeps a little. Not enough to make me want to remove it for re-sealing though.

[jerry]

looked at a dealer microfiche today and it only shows 1 oil way oring required but stein diense online manuals show 2 as does my ducati workshop manual ,, haynes only shows 1

well my bike definitely needs 2 im also going to check the dowel measurments to make sure its not one of the too long ones

also will use some 3 bond sealent or wellseal when assembling

and the front head also only has one big oring but has not leaked yet it will also get 2

[Darren69]

Just a thought, so excuse if you've already considered it, but if I remember your 750SS is an early one with the dry clutch so it might be the 750 Sport engine which knowing Ducati may well be different?

[utopia]

Originally Posted by jerry

........ haynes only shows 1 ......

My Haynes manual (2-valve, '91 -'05) shows two.

That is, two larger ones for the oil return passages.
.... as well as the smaller one around the dowel on the delivery side.
Section 2.13, photo 8.19 .. vertical cylinder.

The previous page, photo 8.13 .. horizontal cylinder
.... shows that it only has one of the larger, return seals.
.... and again a single smaller one around the dowel on the delivery side.

[Dukedesmo]

750 maybe different (although I would guess the design is the same)? but IIRC 900 has 2 return 'O' rings on the vertical and 1 one on the horizontal.

Both have a dowel/oil feed with 'O' ring around the base.

The vertical also has an 'O' ring between cylinder base and crankcase for the feed whereas, oddly the horizontal has no 'O' ring there and relies on the base gasket/sealant.

My guess is that the rears are more prone to leaking because they run hotter and so are more likely to suffer from warping/expansion etc.

Slightly O/T but the early 4-valve engines (916 etc.) share the same crankcase castings and also have the rear cylinder oil feed hole from case to cylinder, despite there being no corresponding hole in the cylinder base and leaks there are fairly common.

The standard cure is to tap the hole and loctite a grubscrew in it. For some reason they don't have the 'hangover' hole in the horizontal crankcase cylinder face though...

[slob]

parts book for '01 (earliest available online at ducati.com) shows 3 on vertical, 2 on horizontal

[jerry]

methinks someone n the distant past only looked at front head ,, i mentioned this to ducati spares guru and even he addmitted that he screwed up as well when he looked at microfiche .... doh s;ap on the wrist all round including me

[utopia]

I did wonder about the microfiche, but didn't like to say anything.