I have noticed on several 1987 thru 1990 240s that there is an engine knock when the car is first started and usually goes away after 3-4 minutes. What is this knock and is it a problem?

Hey ddp,
My 90-240 has been knocking for at least 60 thousand miles now. Probably longer as it was knocking when I got it. I run hell out of it, and it doesnt seem to bother it at all.

It knocks all the time, cold , hot, whatever. But when Im on the freeway at 80mph you cant tell the difference. I may eventually look for another engine. Maybe one with the oil squirters. But the word is the B230 will run a very long time in said condition.

Ditto knocking on the 87-740(B230). Its got 215,000 mi now. Still knocking happily along.
I think about getting rid of it, but my wife says(its her car)"nothing wrong with that car". End of discussion. And it does run good. And very reliably.
In almost ten years its only stranded me once.

Yeah, volvo should be ashamed.

good luck

The 1990 and later B230 engines got better. I think in 89 or 90 they started building them with heavier rods again. The squirter engines from 93 on are supposed to be pretty good and, as I understand it, have less piston slap. From what I've read, the 85 through 88 or 89 were the relatively weak years, mainly a problem in extra-boost turbo applications.
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Thanks for all the help. DougC 1981 242, Turbo bars and wheels, M46 ----------- 1993 245, B230 NA L-Block, M46, Turbo bars.

It's a problem all the way back to 1985, and involves the B230F and FT engines. The noise is caused by piston slap, and usually goes away as the engine heats up and the piston expands. In some cases it is present even after warm-up. The pistons in these engines lack any normal kind of skirt, and were fitted to very close tolerances to keep them straight in the bore. Any amount of overheating collapses the piston and causes the excessive clearance that produces the characteristic noise.
The noise can be quite benign for many miles, although in some cases the engine will begin to burn oil and need rebuilding, which will require new pistons.
Volvo should be ashamed of themselves for building the B230 engines, considering the durability of the earlier B21-23 engines.

After hearing this sad description of my engine, what should I do to avoid problems? Scrupulous oil changes? Cooling system maintinance? Avoid heavy towing?

Yours, With a BF230 at 240K km. martin

The big thing is to not allow the engine to overheat, even for a short period of time. So keep good coolant in it, and good hoses. I normally swap the 150kpa cap for the earlier 75kpa cap to prevent damage to the pump and the rad, and make things easier for the hoses.
Changing the oil is always a good thing.

thanks, martin

Oh, I wouldn't put it that strongly... never saw a Chevy or Ford or Mopar engine or ANYTHING British go 250K without burning oil or serious reduction in compression. B230's do this routinely with just simple maintenance. Maybe not as good as the earlier models, but... still way ahead of the competition.
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Thank goodness we don't get all the government we pay for. -- Will Rogers

Well I've never seen a school bus powered by a B230, but lots of domestic V-8s have, and they stand up to it. Volvo Penta even dropped the B230 as a marine engine and now uses Chevs exclusively, because of the trouble the small crank B230's gave. I have had to have B230 blocks main bearing bores align honed because the block has distorted after an overheat.
I've repaired them all, and the B230 WAS a retrograde step for Volvo, a big one, not maybe.
I'll agree with you on the British stuff.

Wasn't the small-bearing B230 a short-lived version in the mid-late 80's?
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Thank goodness we don't get all the government we pay for. -- Will Rogers

My understanding is that the 85-87 had the smallest main bearings. Half circumference thrust washers as well. I rebuilt one of those first. Narrow rods too. It was in one of those that I saw enough end play to put the flex plate into the back of the block. The thrust washers disappeared, and the block was destroyed. In 1988 the crank mains were made a bit bigger, and the thrust washers were full circumference. I have rebuilt several of them. Called the K engine I believe. In 1990 the crank returned to thrust washers on the rear main, and big rods were installed. Somewhere around 1993 the engine got oil cooled pistons on the turbo, and ended up very nearly the same as the B23E/F in the crank and rods, but still with the short (or no) skirt piston. I haven't heard an oil cooled piston engine knock yet. I haven't rebuilt one newer than 1990.
I had a customer (female for what it's worth) with a 1984 760 Turbo (the rare B23FT) have the wastegate hose drop off - that's when the hose could do that on the early turbos. She drove for weeks with the engine in full detonation from just off idle to cruise rpm. I test drove it - very briefly - and it pinged constantly as it revved. I thought the worst - installed a new hose - and sent her on her way. The engine behaved (for the next two years I serviced the car) as if nothing had happened. I am convinced that the B21-23 engines are about the toughest 4 cylinders ever put in a car. I spin my carbureted B23E ( a mix and match engine I built for myself) to 7k regularly, and never think about a failure. I re-ringed that one -something that can be done with the long skirt pistons. This is why I made my rather strident comment about the B230's - Volvo got the B23's so right, so strong, that I can't imagine what made them change it.