Classic Volvo engines B4B, B16, B18, B20, B30 and the redblocks B21-B234 - reconditioning and common faults
A family guide to Volvo's classic petrol engines: from the pushrod engines in the PV444, Duett, Amazon and P1800 to the redblocks in the 240, 740 and 940. The same cast-iron philosophy throughout, almost indestructible and very rewarding to recondition. Here you can identify your engine, see the common faults and find the right guide with workshop data.
Volvo's classic engines are built to be reconditioned, not scrapped. From the B4B in the PV444, through the B18 and B20 in the Amazon and P1800, to the redblocks B21, B23, B230 and B234 in the 240, 740 and 940 series, the same thread runs throughout: a cast-iron block, a robust bottom end and a design where every wear part can be machined or replaced. That is why these engines are still running after 50 years, and why a well-planned reconditioning almost always beats a used replacement engine with an unknown history. We carry out complete engine reconditioning, cylinder head reconditioning with unleaded conversion, crankshaft grinding, crankshaft balancing and carburetor rebuild (quote after inspection) mainly in our own machine shop. Send the engine in by post or bring it to us in Stockholm.
The family at a glance
Nine engines, five decades. The six most common have their own guides with specifications, factory-verified torque figures, common faults and workshop prices.
| Engine | Year | Configuration | Volume | Power | Vehicles | Guide |
|---|---|---|---|---|---|---|
| B4B | 1947-1957 | R4 OHV | 1,4 L | 40-51 hk | PV444, Duett | On request |
| B16 | 1957-1961 | R4 OHV | 1,6 L | approx. 60-85 hk | PV544, Amazon, Duett | On request |
| B18 | 1961-1968 | R4 OHV | 1 778 cc | 75-115 hk | Amazon, P1800, PV544 | B18 guide |
| B20 | 1969-1976 | R4 OHV 8v | 1 986 cc | 82-135 hk | Amazon, 140, P1800E/ES | B20 guide |
| B30 | 1960s/70s | R6 OHV | 3,0 L | - | Volvo 164 | On request |
| B21 | 1975-1984 | R4 SOHC 8v | 2 127 cc | 97-155 hk | 242/244/245, 240 Turbo | B21 guide |
| B23 | 1979-1984 | R4 SOHC 8v | 2 316 cc | 112-136 hk | 240, 740 (early) | B23 guide |
| B230 | 1985-1998 | R4 SOHC 8v | 2 316 cc | 114-190 hk | 240, 740, 940, 760 | B230 guide |
| B234 | 1988-1995 | R4 DOHC 16v | 2 316 cc | 155 hk | 740 16V, 940 16V | B234 guide |
We rebuild the B4B, B16 and B30 on request following the same process as the rest of the family, indicative price after inspection. Describe the engine in your quote request and we will get back to you within 24 hours.
Which engine is in your Volvo?
The pushrod engines (B4B to B30)
The camshaft sits in the block and operates the valves through pushrods and rocker arms. The camshaft is driven by gears, not a belt. The B4B and B16 belong to the PV era, the B18 and B20 to the Amazon, P1800 and 140, and the six-cylinder B30 to the Volvo 164. Robust, simple and very easy to service.
The redblocks (B21 to B234)
An overhead camshaft driven by a toothed belt, with the block canted towards the exhaust side. The B21 and B23 are the early variants, the B230 the most-built, and the B234 the 16-valve with twin overhead camshafts. The name comes from the blocks' red factory paint.
The engine code is stamped on the block. If you are unsure which engine or variant you have, send a photo along with your quote request and we will identify it for you.
Common faults on classic Volvo engines
The faults are rarely design flaws. They are age, mileage and sometimes decades of standing idle. Engine-specific weaknesses are covered in each individual guide.
Worn bottom end
SeriousValve seats worn by unleaded petrol
CommonWarped sealing faces and tired head gaskets
CommonCarburettors that have aged
MinorWhat we do on classic Volvo engines
The whole process, mainly in our own machine shop: cylinder boring with oversize pistons, sleeving when the block calls for it, crankshaft grinding and balancing, resurfacing, complete cylinder head reconditioning with unleaded conversion, and carburettor reconditioning. Workshop prices per engine are in each engine guide, and an exact quote is given after inspection.
Engine guides in the family
Specifications, factory-verified torque figures, common faults, prices and tuning stages for each engine:
The marine versions of the redblock (Volvo Penta AQ131-AQ171) have their own family guide: Volvo Penta AQ petrol sterndrive.
Questions and answers about classic Volvo engines
Do you recondition all classic Volvo engines?
Should I recondition my old Volvo engine or buy a replacement engine?
Do you do unleaded conversion on the B18 and B20?
What does it cost to recondition a classic Volvo engine?
How do I know which Volvo engine I have?
Do you balance crankshafts for classic Volvo engines?
Time to wake up your classic Volvo?
Describe the engine and what it needs, and we will get back to you within 24 hours. Quote after inspection. Send it in by post or bring it to us in Stockholm.
Other engines we recondition
We recondition more engines than we have time to write guides about. Here are more that we see often.