Valve Seals

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Valve stem seals. Datsun 1200 originally use an umbrella type fitted to the intake valves only. Later A-series engines moved to a Lip-seal type that fits over the valve guide (positive seal) and were fitted to all valves.

Overview

B110 used umbrella seals on intake valves only. B210 used positive seals on all eight valves.

Aftermarket seals come in various types, as this MGB graphic shows:
photo

diymark: I used the positive type seals on the inlet so oil doesn't get sucked in under vacuum and the umbrella type ones on the exhaust as the extra oil allows better lubrication and cooling of the exhaust valve.

The O-ring is an original A-series item. The later spec is the positive seal (fits on the guide).

ddgonzal: I like the umbrella seals best -- they just fit on the stem, not on the guide. Umbrella seals shield the valve stem from getting oil in the first place, so keep oil from going down the guide. For racing where the heads rebuilt regularly either will be fine. For new heads, Nissan chose to use the positive seal.

If it's totally white and disapates into the air, it is water vapor. If it is white with a tinge of blue that blows away, but doesn't evaporate into the air, it is burnt oil, yes probably from the valve seals. Sometimes just replacing the seals will help (and you do not need to remove the head). But replacing the valve guides is usually needed to clear it up 100%.

Diagnosis

Also see Smoke

Symptoms of bad valve seals include 1) Puff of bluish smoke on starting the engine. But no smoke when revving the engine.

• worn or cracked valve guides
• incorrect size valve stem seals (not tight enough around the valve stem)
• Hard and brittle valve seals
• Torn valve seals
• Improperly installed valve seals

Remove the Rocker Cover and use a flashlight to look between the valve spring coils. If you see torn or missing seals, time to replace them. Or if you see one or two that have popped up off the guide, time to replace them.

Do a wet Compression Test to verify that the rings are still good. Otherwise, no valve seals won't fix the smoking problem.

Replacement

Part Numbers

A-series valve seals (positive seal type) are the same as the Nissan SD25 engine.

Aftermarket

• Fel-Pro SS27283
• Beck/Arnley 0221446
• Sealed Power MV1796 (Umbrella type)
  • Upper Inside Diameter: 0.315
  • Overall Length: 0.718
  • Inside Length: 0.625
  • Seal Outside Diameter: 0.89
  • Type: SS

B110

• 13207-18000 SEAL-OIL VALVE (INTAKE ONLY) 8 A12 -672 2 $1.11
• 13207-H2301 SEAL-LIP VALVE OIL (INTAKE ONLY,KEEPER) 4 OP A12
• 13207-H2310 SEAL-LIP,VALVE,OIL (INTAKE ONLY,NOK) 4 OP A12 - $4.62

B310 - positive seal type

• 13207-H7200 SEAL-OIL VALVE (8)
• 13207-H7210 SEAL-OIL VALVE (8)

L-series

L20B

• 13207-21002 SEAL-OIL,VALVE
  • Upper Inside Diameter: 0.27
  • Overall Length: 0.56
  • Inside Length: 0.35
  • Seal Outside Diameter: 0.64
  • Type: TP

The lip-seal type is different for A-series and L-series. This is the type that fits over the valve guide. It is the "normal" type for L20B, is the same as Chevy 4, Isuzu, KA, VG and L-series.