Hello, I recently purchased a 1991 Volvo 240 with 243,00 miles on it. When I first start it I hear some valve clattering almost like a diesel. Once warmed it does not make much noise at Idle but as soon as i give it any fuel I can hear the noise again. When I listen to it at start up using a stethoscope it sounds like it is coming from the top part of the motor under the valve cover. Clattering like a diesel. Would valve adjustment be a good starting point? Any other ideas? The PO had the timing belt replaced last year at a service garage. Power is fine and idle is smooth. I would like to have it quieter as it is irritating. Thank you

 

yeah, valve clearances should be checked. they need to be shimmed to adjust the clearance if they are off spec.

 

While you're doing the valve adjustment get some of these:
https://www.fcpeuro.com/products/vol...damper-3514432
Their purpose is to quiet noisy valves.

 

Are you sure we are talking about valve noise? These engines are pretty famous for wrist pin/piston slap noise which on idle sounds like a diesel. Ours has been noisy since around 150K miles and now with 360K it still makes the same noise. Just waiting to get to 500K then maybe we'll rebuild the engine.

 

It seems to be coming from the camshaft area. How would I differentiate between piston slap and valve noise? It does quiet down once warm at idle but I do hear it as soon as I give it some fuel or accelerate. Also, how many dampner's will I need. Thanks to each for the replies. Swen

 

there are 8 valves, 8 cam lobes and shim stacks... you'd need 8 dampers.

 

One other possibility for noisy valves at start up is a leak in either of the 2 seals that go on each end of the oil pick up tube. It's a hollow, metal tube that connects the oil pump to the block. My '93 940 had this problem and after a valve adjustment and new dampers it was still there. As soon as it ran for a while the tube would fill up(faster than it was leaking) and finally get oil up to the valves and they would quiet down. But once I turned the engine off and waited longer than 2 minutes the tube would empty again and I would have valve "chatter" again. Ironically, during a cold start(when the oil was too thick to leak out) it wouldn't do it. Only when warm and after a 2 minute shutdown. One thing that might help is to take off the oil fill cap and put a piece of paper over the neck of the filler and start the car. Do this when the noise is loudest. Then look at the paper to see how much oil has been "flung" up off the cam. Then do it again when they're quiet. You should see a lot more oil on the paper. If that's the case, it's not piston slap but a similar problem to mine - no oil getting to the valves.

 

Thank you. Is there a good method to diagnose if the noise is piston slap or the valves? I would think piston slap would not change much and would sound like it is lower in the engine? Is that accurate? Thank you each

 

Yes, that's pretty much how you would do it. Try and listen where it's coming from. Also, piston slap should be less after the engine warms up as everything expands. The later 240's didn't have this "piston slap" because they redesigned the crankshaft and pistons back to the very early layout. It was the in between "low friction" engines that had the slap. Basically, they we're trying to increase gas mileage, the way I understand it. Pierce, if you're watching, what years had the "low friction" engine? I don't think your '91 has it.

 

Thank you for the guidance. It would be interesting to know if my 1991 is a low friction motor or not. The sound does get quieter after warm up but increases some when any load is applied. Would valves clatter a bit more under load vs. at idle? Thank you Swen

 

all b230f's are low friction. the b23f was only used for a couple years in the early 80s....


edit: oh, right, the later modded crank bearings, um, not sure what years, but they were still considered low friction.

 

If it is the valves (and not piston slap) then it gets back to not having enough oil or loose valve clearance. Do the paper test I mentioned and if that looks ok then do the adjustment with new dampers and see if that fixes it.

 

They also had short piston skirts(less friction) which allowed the piston to rock in the cylinder quite a bit. And rocking makes noise. Later, when they redid the engines they went back to a longer piston skirt.

 

If you remove your cam cover and you find all of the valves to be either in spec or +/- .001 then the noise is most likely the pistons.