Reading K.Langskog Tuesday 31st. My 740 suffers from some of the symptoms experienced also. It seems to surge 75o-850 rpm and also shudders the body also accompanied by a hesitation and stall when first stared up and put in drive.

I checked the idle control knob underndeath the throttle body and will not increase the revs. It will only have any effect when screwed all the way in (I think or maybe out, can't remember). I am starting to think the throttle body may need cleaning. I unscrewed the idle knob the other day and whilst it had black gunk and grease on it, it did not seem excessive. Any help. The car runs perfectly other than that.

P.S. Replacing worn shocks and springs on rear of brick. Any advice on brand.

JAY 87 740GL 220,00 miles stock.

Jay -

My "turf" is the B230F in a 240, so this is general. There is positive pressure developed in the crankcase normally, and the PCV (vacuum hoses, flame trap, et al) is to pull that pressure and fumes out for re-burning. Check the hose and other items that provide vacuum to the crankcase. The hose pulls oily vapors and can clog up.

BTW: Pressure in the crankcase will eventually blow oil through the front or rear main seals, maybe the camshaft seals. If you already have such a leak, fixing the PCV system will lessen or stop it.

Good Luck,

Bob

:>)

I had a similar situation with my 87 740, it turned out to be a deteriorated intake manifold gasket. 15$ for he part, 200$ for installation (plus TB cleaning). Not cheap but it runs like new.

Good luck

I am trying to resolve a similar idle speed problem (see my post on idle speed fluctuation) on my 1987 760GLE, B280 engine. I haven't tried the inlet manifold gasket, how do you test if it is defective?

What I have started to look at is the crankcase ventilation system which is very minimal on my variant, seems to be only a hose from the oil filler cap over to the throttle body and air intake. There is no flame trap. I did discover that the rubber sealing ring on my oil filler cap is defective. Volvo tells me I can only buy a complete filler cap, does any body know if the rubber ring can be bought as a universal part separately?

Also discovered that the vacuum at the oil filler cap is positive, i.e. blowing rather than sucking. Is that correct? If it should be sucking at the cap then maybe I have a vacuum blockage or leak somewhere?

Any ideas on the above?

KJ,

The oil fill cap gasket is available through thepartsbin.com/ Their part number is A6150-23408 for $0.90 The shipping will be more than the cost of the part. If your order is over $50, the shipping is free.

Regards,