Valve adjustment in 740

I bought a 1991 740 wagon back in December. It now has about 170K. It is a good idea to have the valve clearance checked? Do any of you ever see much variation in valve clearance at this mileage. My mechanic(Volvo trained)seems to be of the opinion that they don't often get out of adjustment and doesn't speak about it as being a good maintenance item. Any thought shall be appreciated. The car runs well except for the problem I've stated in earlier post. Doesn't use oil. Thanks, James

Reply to
James B.
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Only if the engine has started to sound "tappetty".

All the best, Peter.

700/900/90 Register Keeper, Volvo Owners Club (UK).
Reply to
Peter K L Milnes

As fate would have it, I am familiar with this.

Bought a '91 740 last year for the wife, about 165K.

There was a little valve tapping noise.

I checked all the valves, they were in spec except for one, which was way out.

I corrected it using a different sized valve shim, it quieted right down and has been a great car.

No idea what caused just one to go out of spec, but it is an interesting DIY.

You'll need a special tool to compress the valvetrain, a feeler gauge, and a selection of different sized shims.

There is math involved.

Reply to
zencraps

After 240K miles our '85 has never been adjusted.

Mike

Reply to
Michael Pardee

My experience has been that the valves that wear lose about .05 mm clearance per 90K miles. As the mating faces of the valve and the valve seat wear the valve clearance decreases as the valve recesses deeper into the head. If you hear a clackety sound then the valves are either set way too loose or the rubber cushion that sits between the valve stem and the bottom side of the tappet (bucket) has finally hardened and broken away.

The factory service manual calls for checking valve clearances every 30K miles and adjusting as necessary. Since the shims come metrically sized you should measure the clearances and the shims with metric tools. The checking spec is .30-.40 mm. I usually set them to .40mm cold.

Bob

Reply to
User

It's the QUIET valves you need to worry about... those are the tight ones, from Valve seat wear... and those are the ones that will burn.. and then, engine damage.

loud valves are better than "hey... that's super super super quiet"... with a burbling sound out the exhaust

Reply to
M.R.S.

Quiet valves are what you need to worry about. If a valve seat wears enough to make the valve tight, well, then you've got issues. It will get too tight and burn the exhaust valve.

I'd at least check them. It's easy, and the shims are readily available everywhere... I've got a Fiat, and they're the same ones!!! (same with Ferrari 2V 308s ;)

Reply to
M.R.S.

for those running propane: Fiat do thinner shims than Volvo. Vauxhall shims fitt too

Reply to
M-gineering

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