S/V/C V70 cold start tapping noise

Recently my 1998 V70 AWD with a LPT motor has started making a tapping noise during cold starts. It lasts about 2 minutes before going away. The tapping noise does speed up when revving the motor. Within about a minute the tapping noise becomes irregular and then it disappears completely after about 2 minutes. I feel like the sound is most audible with my ear facing into the wheel wells.

I did recently change the serpentine belt and spark plug gap. I went back and double checked the tightness of the spark plugs thinking that one might not have sealed well enough. The oil levels looks good. The car has 5w-30 synthetic oil in it.

The car has recently has had some mystery boost control issues after sitting, which caused it to overboost a couple of times. The noise did start on the next cold start after some aggressive driving to collect a log. I would expect engine damage related noise to only get louder as the motor warmed up though. In my one experience with a damaged Volvo 5 banger, that was definitely the case.

I feel like it has to be something that's expanding as the engine warms. Exhaust manifold gasket? Should I toss in a new set of plugs? Any ideas?

I would guess ticking lifters. Noise going away as oil works its way in there.

Mixing in some thicker oil helped mine.

I vote tappet..my buick did that then the lifters fell apart one day and it started missing...I had a Lumina that did it for years and never changed

I thought the B5254T had bucket shims like the B230FT.

A little update. The noise is still occurring but with less consistency if it's warmer out. We still have yet to see 60 degrees outside.

I tried IPD's little test for bad pick up seal o-rings, and didn't see any bubbles present on the dipstick. No bubbles=good.

I'm starting to wonder if I have an injector that's extra noisy on cold mornings, a exhaust manifold crack or bad manifold gasket. The fuel injectors are supposed to have been cleaned and rebuilt.

I had the oil sump o-rings replaced but it did not cure the tapping noise. The only cure I've discovered so far is warm days. On a 70 degree day there is no tapping noise even after the car has sat for two days. I'm not sure what that means exactly.

ovlov760 said:

I had the oil sump o-rings replaced but it did not cure the tapping noise. The only cure I've discovered so far is warm days. On a 70 degree day there is no tapping noise even after the car has sat for two days. I'm not sure what that means exactly.

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Would this not still indicate tappet? Warmer oil better lube colder oil tick tick tick

It's getting colder again and the tapping noise hasn't returned. It has been down to 32F this month. The only thing I've changed is the type of motor oil I'm using.