Volvo B20 Rebuild, common faults & everything you need to know
The complete guide to Volvo's classic 2.0-litre pushrod four - the evolution of the B18 with the same block and 5 main bearings. From head gasket to complete rebuild, with workshop pricing.
Robert has built and rebuilt Volvo's classic pushrod engines for decades. The B20 is the direct evolution of the B18 and shares the same basic architecture: cast iron block, 5 main bearings and a gear-driven camshaft in the block. The larger 88.9 mm bore gives 2.0 litres. The cast iron block is almost indestructible and takes an oversize rebore without trouble. With the right craftsmanship a rebuilt B20 lasts as long as a new one. We carry out everything from cylinder head reconditioning to complete engine reconditioning with a 12-month warranty. Want to read about the predecessor that shares the block? See our B18 guide. See also the later redblock series in our B230 guide.
The B20 at a glance
All dimensions and data for the B20 series. Read from original Volvo documentation.
| Variant | Power | Torque | Compression | Fuel system |
|---|---|---|---|---|
| B20A | 82 hk (DIN) | 157 Nm | 8.7:1 | Single carburettor (Zenith-Stromberg) |
| B20B | 100 hk (DIN) | 152 Nm | 9.5:1 | Twin carburettors (SU / Zenith-Stromberg) |
| B20E | 124-135 hk | 176 Nm | 10.5:1 | Bosch D-Jetronic injection |
| B20F | 98-118 hk | 157 Nm | 8.7:1 | Bosch D-Jetronic / K-Jetronic |
Power and torque figures are identity data for the engine variant (output), not tightening torque. Power is stated in DIN/SAE net where documented; older SAE gross figures are higher. The B20D (90 hp, twin SU HIF6) is a spec-DB entry and left out of the table.
Torque specs
Verified against Volvo factory documentation. Two generations are documented separately: the early 140/1800 era (Volvo TP 10516/1, B20A/B20B) and the late 200 series (Volvo 200 data sheets, B20A/B20F). The values differ between the eras and must never be mixed or averaged. Volvo stated the original values in kgm with an Nm conversion.
Cylinder head - late 200 series (B20A/B20F)
Cylinder head - early 140/1800 (B20A/B20B)
Engine block & bottom end
Cam gear, crankshaft & timing
Intake, exhaust, other
NOTE - two generations: The B20 is documented in two separate factory sources. The early 140/1800 era (TP 10516/1, B20A/B20B) and the late 200 series (B20A/B20F) give genuinely different values for several fasteners. Identify which engine and which document applies to your B20 and never mix the values. On the late 200 series you tighten the head in three stages: 40 Nm, 80 Nm and finally 90 Nm after approx. 10 minutes of warm-up, oiled threads, from the centre outward. The early era used single-stage tightening 83-93 Nm (8,5-9,5 kgm) with a warm re-torque.
NOTE - con rod bolts: The late 200 series specifies two torques depending on whether the bolts are old (63 Nm) or new (70 Nm). Meksta always fits new con rod bolts on disassembly and uses 70 Nm. The early era gives a single value, 51-57 Nm (5,2-5,8 kgm).
NOTE - gear-driven camshaft: The B20 is a pushrod engine (OHV). The camshaft sits in the block and is driven by gears, not a belt or chain. The steel gear on the crankshaft (21 teeth) drives the camshaft gear (42 teeth) in a 2:1 reduction. Permitted backlash when new is 0,04-0,08 mm. There are no overhead cam bearing caps - the camshaft runs in 3 bearings directly in the block.
NOTE - crankshaft centre bolt: The late 200 series splits the torque by the number of pulley grooves: 95-105 Nm for a 1-groove and 120-140 Nm for a 2- and 3-groove pulley. The early era gives one value, 69-78 Nm (7-8 kgm). Check which pulley the engine has.
NOTE - flywheel: Always use new bolts. Late 200 series 70 Nm; early 140/1800 49-54 Nm (5,0-5,5 kgm).
The cylinder head in detail
Cylinder head design and valve data. Sources: Volvo TP 10516/1 (B20A/B20B, 140/1800) and Volvo 200 data sheet section 2 Engine B 20 (B20A/B20F).
The B20 has a cast iron cylinder head (OHV, 8 valves) on a cast iron block. The whole thermal path is cast iron against cast iron, which makes the head gasket more forgiving than on later aluminium heads - but overheating can still blow the gasket and warp the head. The valves are actuated via pushrods and rocker arms with adjustable (mechanical) valve clearance. The B20E/B20F have larger intake valves and reworked ports.
Valves & seats
Cam drive (gears)
Common cylinder head and engine faults on the B20
- Flatness deviation after overheating - the head gasket blows if the head has warped. Fix: resurfacing and pressure testing.
- Valve guide and valve seat wear - at high mileage the guides develop oil clearance. Symptoms: blue smoke on cold start, oil consumption. Fix: replace guides, recut seats.
- Worn camshaft gear (fibre gear) - the original cam gear is composite and can wear or crack. Symptoms: ticking/squealing noise, misfiring. Fix: replace with a new gear, check backlash.
- Carburettor wear / injection faults - SU and Zenith-Stromberg carburettors wear; the D-Jetronic on the B20E/F has aged sensors and connectors. Fix: recondition or convert.
- Cylinder wear & ovality - normal after 200 000+ km. The cast iron block takes an oversize rebore without trouble.
Common faults on the B20
This is what we see most often when a B20 comes into the workshop. Symptoms, causes and how we fix them.
Head gasket blows
Common • High- Symptoms
- White smoke from the exhaust, coolant loss with no visible leak, "mayonnaise" under the oil filler cap, overheating.
- Cause
- Overheating that warps the head, an aged gasket or corrosion in the coolant passages. Cast iron against cast iron is forgiving but not indestructible.
Worn camshaft gear
Age-related • Medium- Symptoms
- Ticking or squealing noise from the cam drive, rough idle, misfiring, in the worst case teeth breaking off.
- Cause
- The original cam gear is fibre/composite on a steel hub and wears or cracks over the years. Driven by gears in the block - no belt or chain.
Cylinder wear & ovality
250 000+ km • High- Symptoms
- Rising oil consumption (>0.5 L/1000 km), blue smoke under acceleration, poor compression, an oil film on the spark plugs.
- Cause
- Normal mechanical wear after 200 000+ km. Made worse by short trips and driving with a cold engine.
Crankshaft bearing wear
Uncommon • Critical- Symptoms
- Knocking from the bottom end under load, low oil pressure, metal filings visible at the oil change.
- Cause
- Worn big-end and main bearings, oil pump failure, oil starvation or contaminated oil. The 5-bearing crankshaft is robust but not maintenance-free.
Valve guide wear
150 000+ km • Medium- Symptoms
- Blue smoke on start-up (especially in the morning), gradually rising oil consumption.
- Cause
- Natural wear in the valve guides and seats. Made worse by long service intervals and worn valve seals.
Carburettor & injection faults
Age-related • Medium- Symptoms
- Hard cold start, rough idle, high fuel consumption, jerky throttle response.
- Cause
- Worn SU or Zenith-Stromberg carburettors on the B20A/B/D, or aged sensors and connectors in the Bosch D-Jetronic on the B20E/F.
B20 rebuild pricing
Prices based on B20 specifications: 4 cyl, 88.9 mm bore, 8 valves, 5 main bearings. All prices excl. VAT and parts.
Cylinder head reconditioning
Bottom end
Full rebuild
Performance
Cylinder machining
| Service | Price |
|---|---|
| Cylinder boring 4 cyl inline block (88,9 mm) | 3 318 kr |
| Plateau honing 4 cyl | 1 050 kr |
| Stress boring 4 cyl | 4 603 kr |
| Cylinder liner replacement, dry, 4 cyl | 6 216 kr |
| O-ringing block 4 cyl | 2 800 kr |
Crankshaft work
| Service | Price |
|---|---|
| Crankshaft grinding (5 main + 4 big-end) | 3 010 kr |
| Polishing standard | 1 022 kr |
| Cleaning 4-cyl crankshaft | 784 kr |
| Straightening (medium) | 1 190 kr |
| Camshaft journal grinding 3 pcs | 1 540 kr |
| Remove/refit 8 counterweights | 2 044 kr |
Valve reconditioning
| Service | Price |
|---|---|
| Cutting 8 valve seats (standard) | 910 kr |
| Cutting 8 valve seats (large) | 1 386 kr |
| Valve guide replacement 8 pcs | 1 274 kr |
| Manufacturing valve seat rings 8 pcs | 1 540 kr |
| Bronze sleeves fitting 8 pcs | 1 134 kr |
Cylinder head resurfacing
| Service | Price |
|---|---|
| Resurfacing cylinder head 4 cyl (standard) | 1 330 kr |
| Resurfacing cylinder head 4 cyl (large) | 1 596 kr |
| Resurfacing block 4 cyl (standard) | 1 988 kr |
| Resurfacing block 4 cyl (large) | 2 114 kr |
| Resurfacing manifold 4 cyl | 2 842 kr |
| Deck decking block 4 cyl | 1 974 kr |
Con-rod work
| Service | Price |
|---|---|
| Replace con-rod bush 4 pcs | 2 240 kr |
| Manufacture con-rod bush 4 pcs | 2 898 kr |
| Length adjustment con-rod 4 pcs | 2 898 kr |
| Replace press-fit piston 4 pcs | 1 582 kr |
| Piston ring replacement, cleaning 4 pcs | 1 106 kr |
| Resizing big-end housing 4 pcs | 2 352 kr |
| Check / straightening con-rod 4 pcs | 1 414 kr |
| Full reconditioning con-rod 4 pcs | 3 164 kr |
| Steel shot peening con-rods 4 pcs | 2 268 kr |
Pressure testing & balancing
| Service | Price |
|---|---|
| Pressure testing cylinder head 4 cyl (small) | 1 876 kr |
| Pressure testing cylinder head 4 cyl (large) | 2 800 kr |
| Pressure testing cylinder block | 1 400 kr /h |
| Balancing rotating assembly straight 4-cyl | 3 742 kr |
| Weight matching con-rods 4 pcs | 1 316 kr |
| Weight matching pistons 4 pcs | 1 092 kr |
| Flywheel balancing | 2 100 kr |
| Balancing flywheel + clutch | 2 842 kr |
Tuning the B20
From street car to historic race engine. The B20 is one of the most build-friendly classic Volvo engines - the cast iron block with 5 main bearings handles serious load and shares a lot with the B18.
- 1
Twin carbs + exhaust
Twin Weber/SU or reconditioned D-Jetronic, free-flow manifold and a mapped ignition curve. Classic B20E spec.
120-140 hk - 2
Camshaft + porting
Sport-profile camshaft, porting of the intake and exhaust ports, larger valves and a resurfaced head for higher compression.
150-180 hk - 3
Internal strengthening
Forged pistons, a balanced rotating assembly, uprated con rod bolts and balancing for high rpm.
180-220 hk - 4
Full race build
Twin horizontal carburettors, a hot cam, a fully ported head and full race specification. Historic rally/circuit.
220-250 hk
B20 camshaft profiles
We grind our own camshaft profiles for the B20 from blanks, on our own camshaft grinder. Every shaft ships with a complete grind report. Two series: The M series with the original base circle for street cars and folkrace, and The MB series (Race) with a modified base circle for higher power demands. The profiles are shared with the B18 since the engines have the same valvetrain and pushrod mechanics.
The difference? The MB series' modified base circle gives more lift at the same duration, but requires uprated valve springs and Race shims. The M series runs with standard components.
The M series Original base circle
| Profile | Stage | Application | Working range | Duration / Lift |
|---|---|---|---|---|
| M1Street | Standard | Daily driving | 700-5 600 rpm | 240 degrees / 9.0 mm |
| M2Street+ | Stage 1 | Sport / cruise | 900-6 000 rpm | 248 degrees / 9.6 mm |
| M3Race | Stage 2 | Road racing | 1 400-6 400 rpm | 256 degrees / 10.2 mm |
| M4Race | Stage 2 | Road racing | 2 000-6 800 rpm | 264 degrees / 10.8 mm |
| M5Race+ | Stage 3 | Sprint / track | 2 800-7 200 rpm | 272 degrees / 11.4 mm |
| M6Drag | Stage 3+ | Track only | 3 500-7 600 rpm | 280 degrees / 12.0 mm |
The MB series Race Modified base circle
| Profile | Stage | Application | Working range | Duration / Lift |
|---|---|---|---|---|
| MB1Street | Standard | Daily driving | 1 200-6 200 rpm | 252 degrees / 9.8 mm |
| MB2Street+ | Stage 1 | Sport / cruise | 1 800-6 600 rpm | 260 degrees / 10.4 mm |
| MB3Street+ | Stage 1 | Sport / cruise | 2 400-7 000 rpm | 268 degrees / 11.0 mm |
| MB4Race | Stage 2 | Road racing | 3 000-7 400 rpm | 276 degrees / 11.6 mm |
| MB5Race | Stage 2 | Road racing | 3 600-7 800 rpm | 284 degrees / 12.2 mm |
| MB6Race+ | Stage 3 | Sprint / track | 4 200-8 200 rpm | 292 degrees / 12.8 mm |
| MB7Race+ | Stage 3 | Sprint / track | 4 600-8 600 rpm | 298 degrees / 13.2 mm |
| MB8Drag | Stage 3+ | Track only | 5 000-9 000 rpm | 304 degrees / 13.6 mm |
| MB9Drag | Stage 3+ | Track only | 5 400-9 400 rpm | 310 degrees / 14.0 mm |
Questions & answers about the B20
The questions we hear most often from B20 owners.
What does it cost to rebuild a B20?
A cylinder head reconditioning costs roughly SEK 4,000 - 6,000 (labour), a complete engine reconditioning roughly SEK 18,500 - 29,500. On top of that come parts (gasket, bearings, piston rings etc.), typically SEK 5,000 - 15,000 depending on condition.
What is the difference between the B18 and the B20?
The B20 is the evolution of the B18 and shares its basic architecture: cast iron block, 5 main bearings and a gear-driven camshaft in the block. The B20 has a larger bore (88.9 mm vs the B18's 84.14 mm) and therefore a full 2.0 litres. The B20E and B20F got fuel injection (Bosch D-Jetronic and K-Jetronic respectively). See our B18 guide for the predecessor.
How long does a rebuilt B20 last?
With a properly executed rebuild and regular maintenance: 200 000 - 300 000 km or more. The cast iron block with 5 main bearings is extremely hard-wearing. A quality rebuild with OEM parts is effectively like getting a new engine.
Does the B20 have a timing belt or a timing chain?
Neither. The B20 is a pushrod engine (OHV) where the camshaft sits in the block and is driven directly by gears. The crankshaft's steel gear (21 teeth) drives the camshaft gear (42 teeth) in a 2:1 reduction. The original cam gear is often fibre/composite and may need replacing at a rebuild.
Is the B20 an interference engine?
No, the B20 is considered a non-interference engine. Because the camshaft is gear-driven it cannot jump timing the way a belt can, and the piston-to-valve clearance is sufficient. This is well documented in specialist literature but not stated explicitly in the factory documentation.
Can you tune a B20?
Absolutely. The B20 is a classic to build on. The five-bearing block is very tough and shares a lot with the B18. With twin carbs, a hot camshaft and a ported head you easily reach 150-180 hp, and with a full race build up towards 250 hp - all naturally aspirated.
How long does a B20 rebuild take?
Cylinder head reconditioning: roughly 3-5 working days. Complete engine reconditioning: roughly 2-4 weeks depending on scope and parts availability. We ship worldwide.
Got a B20 that needs looking at?
Call us directly or send in a quote request. We reply within 24 hours.