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BY REFERENCE COMETIC - Reinforced cylinder head gaskets
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BY REFERENCE COMETIC - Reinforced cylinder head gaskets
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Athena O-Ring reinforced gasket, sold individually: one gasket per engine.
The 2.5 litre petrol straight-six engines B6244FS, B6254FS and B6254S, with four valves per cylinder, power the Volvo 960 II, S90 and V90 from 1994 to 1998. This page covers these three engine codes; the B6254F is not listed here.
The original gasket is listed as 1 397 727 according to the TecDoc parts database; the manufacturer publishes neither its thickness nor its construction. It is sized for the standard combustion pressure; as soon as that rises, the clamping load fades, the head lifts and coolant seeps into a cylinder.
Sealing does not rest on the gasket alone: the fasteners clamping the head to the block contribute as much. The stainless ring of the O-Ring keeps its shape after every combustion. On these Volvos, new bolts at every refit limit head movement and leaks.
This page presents the part number from Athena, an Italian maker of racing gaskets, in one construction only: the O-Ring, a steel sheet dressed with aramid fibre and ringed with a stainless steel ring. Its bore is 82.5 mm and its thickness 1.50 mm. It is sold individually: a single gasket fits one engine.
| Gasket bore | Thickness | Gasket volume | Gasket type OEM not specified | Brand | Part number OEM 1 397 727 |
| 82.5 mm | 1.50 mm | 8.02 | O-Ring | Athena | 330259R |
Gasket volume is the space it keeps free above each cylinder. It comes on top of the combustion chamber and therefore reduces the compression ratio. Only a comparison between gaskets of the same bore makes sense. Here, the bore offered is 82.5 mm.
| Fasteners | Engines | Tightening torque |
| Original cylinder head bolts | B6244FS, B6254FS, B6254S | not published by the manufacturer |
Before fitting, check the flatness of the head and block with a straightedge, and have them machined flat if needed. Athena delivers this gasket ready to fit: apply no sealing paste. The head and block need no modification.
 | Athena O-Ring A steel sheet dressed with asbestos-free aramid fibre, in which each cylinder is surrounded by a stainless compression ring. The ring concentrates the clamping load on a narrow band, at the exact point where sealing is won or lost, while a silicone bead isolates the water and oil circuits. In the range, it is the construction that takes high pressures best. |
Gasket bore. The Athena O-Ring exists in 82.5 mm (330259R), with no other bore.
Thickness. The manufacturer does not publish the thickness of the original gasket for these engines. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.
| Your goal | Thickness to choose |
| Keep the original compression ratio | Original thickness not published by the manufacturer: read the one on the removed gasket and compare it with the only gasket offered, 1.50 mm on these Volvos |
| Skimmed cylinder head, make up the lost height | Only one thickness is offered, 1.50 mm: compare it with the removed gasket plus the material taken off on these Volvos |
| Forced induction build, lower the ratio | 1.50 mm, if the thickness read on the original gasket at removal is smaller |
| Naturally aspirated build, raise the ratio | 1.50 mm, if the thickness read on the original gasket at removal is greater |
Since the original thickness is not published, measure with a dial gauge how far the pistons stand above the block, especially if the removed gasket is thicker than 1.50 mm: that value gives the clearance left between piston and head. On these Volvos, the measurement is made with a dial gauge, head removed.
 | An Italian maker of gaskets and engine parts, Athena S.p.A. is based in Alonte, in the Veneto, where its head office and main plant stand. The group also runs sites in Spain, the United States, Brazil and India. Its multi-layer gaskets are fitted by car makers as original equipment, and its competition range is entirely designed and made in Italy. Part number 330259R is the one on this page. |
| Criterion | Original gasket 1 397 727 | Reinforced gaskets |
| Construction | Construction not stated by the manufacturer | Steel and aramid fibre with a stainless ring (O-Ring) |
| Gasket bore | not published by the manufacturer | 82.5 mm |
| Thicknesses available | thickness not published by the manufacturer | 1.50 mm |
| Compression ratio adjustment | None | Through the gasket thickness (1.50 mm) |
| Resistance to overpressure | Limited to standard output | Designed for forced induction |
| Model | Engine code | Power | Years |
| Volvo 960 II (964) 2.5 | B6254S | 170 hp | 1994-1996 |
| Volvo 960 II Break (965) 2.5 | B6254S | 170 hp | 1994-1996 |
| Volvo S90 I (964) 2.5 | B6254FS | 170 hp | 1996-1998 |
| Volvo V90 I Break (965) 2.5 | B6254FS | 170 hp | 1996-1998 |
| Volvo S90 I (964) 2.5 | B6244FS | 179 hp | 1996-1997 |
| Volvo V90 I Break (965) 2.5 | B6244FS | 179 hp | 1996-1997 |
OEM part number: 1 397 727.
Important: the part number on this page suits the B6244FS, B6254FS and B6254S engines: check the engine code of your 960, S90 or V90 before ordering. The B6254F is not dealt with on this page: enquire before ordering.
When the standard gasket can no longer keep up, the reinforced gasket steps in: at higher combustion pressure it keeps its shape and does not get crushed. Volvo B62 engines find here a gasket with an 82.5 mm bore.
When power climbs thanks to a turbo, a supercharger or a raised compression ratio, the head gasket is the first part of the top end to suffer. A reinforced gasket rules out the risk of a leak and the cylinder head removal that would follow, with the labour and parts cost of doing the job twice. This holds for the 960, S90 and V90 as for any hard-driven engine.
