Classic Alfa Forums

I've got smoke on start up. 95 bhp engine
Four good compression figures.
I suspect valve stem oil seals.

Is it possible to replace these with the heads still on?

Somehow compress the springs?

A guy on you tube does it on a Pinto ohc engine with a special tool.

There's another guy on uTube who does it on an MX5 by stuffing nylon rope in through the spark plug hole and then bringing the piston up a little to compress it. That should prevent the valve from dropping into the cylinder.
I suppose you have nothing to loose if you were planning to take the cylinder head off anyway.

Dave. It is certainly possible on some engine designs but Not a Sud. To get at the seals you need to remove the valve collets, caps and springs, to get to them you need to remove the buckets this means removing the cams. Which means removing the cam carriers . You also need to undo the head bolts so you’re gaining nothing but you are making the job a lot harder for yourself. Just take the heads off and do it on the bench.

Lou,
I had thought of removing the camshaft housing and camshaft together. Then removing the buckets.
Leave the head bolts intact.
Then figure out what tool I need to compress the springs.
Quite a job, but not as bad as head removal?

Also maybe remove the exhaust manifold, and see which cylinder is burning oil.

alfadave wrote: ↑Mon Mar 27, 2023 7:58 pm Lou,
I had thought of removing the camshaft housing and camshaft together. Then removing the buckets.
Leave the head bolts intact.
Then figure out what tool I need to compress the springs.
Quite a job, but not as bad as head removal?

Also maybe remove the exhaust manifold, and see which cylinder is burning oil.

But, as Lou stated, you can't remove the cam houses alone, the head bolts go through the housings so you have to take the head bolts out! And even if you could it'd be a real faff trying to get the collets and springs out, what are you planning on using to compress the springs?
Just take the heads off, they'll come off easily enough with the engine in situ, no need to take it out. Much simpler to work on them on the bench and you can do a proper decoke then.

Dave. Removing the heads on a boxer is easy. you don’t even need to remove the inlet Manifolds or carbs if you don’t want to.
Steps as follows for twin carbs engines.
1. Drain the water system ( there’s drain plug in the block under each side of the block)
2. Undo exh manifold
3 remove cam covers
4. Time engine and drop cam belts off
5. Undo throttle cable (the actual linkage cross bar will stay with one bank I think,it’s RH)
6 make sure all relevant hoses and wires are disconnected
7 undo the six head bolts (there is a special tool but it can be done without it) you can’t remove the bottom three head bolts from the head until the heads are out of the car just make sure they’re all undone
8 grab hold of the carb with one hand and the head with the other and wiggle the head off it’s dowels and lift it off the block and put it on the bench
9. have a nice cup of tea or coffee. and a chocolate digestive or a hob nob (or any good dunking biscuit)

Thanks both.
I'm guilty of reading Haynes. P23 section 15. Para 1.
" The camshaft housing with the camshaft installed can be removed from the cylinder head with the head still attached to the crankcase".

I don't fancy the head job right now.
Maybe I'll try using patches?