B18A Valves

[sleek lemur]

Valves.jpg

Hi All, Am dismantling a B18A for rebuild. Some of the valves have what looks like some sort of a cap over the springs. Obviously These are an optional extra (LOL), as half the valves don't have them. Looks like they need to be removed before I can apply the spring compressor. Question is, how do I get them off? Have tried some gentle levering with a screwdriver, but I thought I'd better ask an adult before I destroy anything.

Many thanks.

[Ron Kwas]

SL;

Those are the stock rubber "Umbrella" style "Valve Seal" installed on B18s (they are typically included in the top end gasket kit, lock into a groove in the Valve, B20s had a different style, actually located on top of Valve Guide)...the missing ones have hardened, fractured, broken and fallen away...you will likely find the pieces laying on the Cyl Head. If you are disassembling Cyl Head, just pop the remaining ones off Valve before applying valve spring compressor tool...they will likely fracture as you do this...no worries!

Cheers

[Nullifie]

Hi, all of the valves should have these "caps". They originaly are of flexible rubber, but harden over the many years of hot oil and eventually break and the remains disappear in oilsump. You have to remove them, break them if neccessary. The pupose of these is to keep the downrunning oil as far as possible away from the valvestems and avoid the oil flowing along the valve stems in the combustion room. This only at the B18, the B20 has valvestem oilseals, the B18 can be remanufactured for valvestem oilseals similar those of the B20, but not the same for the valvestem diameter of the B18 valves isn't the same as the diameter of the B20's.
edit: Ron was quicker

[sleek lemur]

Thanks to Nullifie and Ron. Great explanation!

I plan to upgrade with K cam and higher CR with dual SU's. I guess a later setup with valve stem seals would make sense.

[Derek UK]

Keep an eye on those caps. The quality of those supplied now is variable. Some split after a few thousand miles. Pop the valve cover off now and again, even if you aren't going to do a valve adjustment. I think(?) that you can just about fit new ones if you take the adjuster screw right out. Need confirmation on that.

[sleek lemur]

Hi All,

If I go for a K cam, would it be ok to retain the standard valve set up from the B18A (am rebuilding the head in any case)?

Many thanks.

[Derek UK]

Yes. Full cam kit should include followers. If buying just the cam you will need new followers. Old ones will wreck your new cam. As you are doing a full rebuild, it's a good idea to fit new cam bearings. Looks like you will be fitting a new core plug at the back of the cam so that helps.

[sleek lemur]

Thanks Derek.

How about the valves and guides themselves? Will be renewing anyway; just thinking if the standard valve set up with the rubber oil sealing washer "hats" are up to the job.

SL

[Derek UK]

New valves and guides obviously a good idea, especially if you are having lead free exhaust valve seats. Volvo have used the rubber caps at least since the B16, maybe even the B14. At least 10 years worth of engines. They are tried and tested. Changes to rubber and plastic composites seems to mean that the latest ones can be prone to going brittle and splitting. You might be able to get better quality with current genuine Volvo ones but I wouldn't bet on it. It's pot luck what you might get with generic or no name gasket sets. They are there to seal off the recess in the valve retainer collar. That stops oil pooling there and running down the valve stem. It doesn't stop oil being sucked down the valve guides. The B20 ones do try and do that. As I said, the B20 guide is much shorter than the B18 one so can get away with a bit less oil for lubrication. They both need some.

[sleek lemur]

Thanks very much Derek. Sounds like I may as well stick to the standard B18 setup.

Just dismantled the rocker shaft and am investigating whether the actuating arms need refacing.