Can anyone ID this sound for me? upon start up about 50% of the time I am getting a fast tick, tick, tick, tick sound. Sounds like metronome set to fast time time. It sounds as if it is coming from the the rear portion of the block. Any suggestions, ideas?

Thanks.
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'95 854 GLT/'98 V70 GLT

If it's just the enging warming up then don't worry abouut it (like an old radiator in an old building), but if it's valve sound then it could be a concern. Are you using a Mann filter (which is OEM) what has a valve in it that keeps oil on top of the engine? If you're using some crap 3rd party filter, the top of the engine can be dry and this is the sound before oil reaches that area and lubricates it.
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1998 S70 T5 Emarald Green Metallic (125K), 2004 V70 2.5T Ruby Red (45K), Previous Owner of Black '94 850 Turbo Wagon (Sold at 140K and miss her). My cars have been running so well lately they've got me worried.

Yeah I'm using a Mann filter. I didn't check it but I just got the oil changed at an indy volvo shop which said they were using volvo parts. I'll double check when the wifey gets back.

Not sure what a valve sound is.
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'95 854 GLT/'98 V70 GLT

So long as the tick/tick sound goes away after 5 minutes or so, you are OK. It sounds like the hydraulic lifters, at least one, is dry and when it gets oil it is back to normal. This condition will not harm the engine. It means that there is sludge build up in some parts of the block, but only a complete overhaul will eliminate it. Remember, no harm will result unless it continues for the entire time the engine is running (hours and hours).

Klaus

I get this ticking sound on my 99 S70 if it sits at an idle for about 5 minutes....Any idea????

Time for a real mechanic to look at it. It sounds like you are loosing oil pressure at idle. Not a good situation.

Some on the rear wheel drive board reccomend flushing the engine with kerosene. I would try Seafoam first. Just add a can to your oil and run the engine for the reccomended time to clean out sludge, then change your oil immediately.
You might also want to remove the oil separator and clean that out.
Talk to a mechanic...

Klaus