MajorVery commonFluid Leaks

Nissan Skyline: RB Engine Cam Cover and Rear Main Crankshaft Oil Seal Leaks

RB Engine Cam Cover and Rear Main Crankshaft Oil Seal Leaks is a very common fluid leaks fault on the Nissan Skyline on the 1989–2002 cars, and we rate it major. Putting it right costs $400 to $1,600 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 41 documented faults on the Nissan Skyline.

Vehicle: Nissan Skyline
Engine: 2.0L / 2.5L / 2.6L
Years: 1989–2002
Fuel: petrol
System: Fluid Leaks

This page covers the Nissan Skyline as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All Nissan Skyline faults41 documented faults on this model

What you are looking at

No photograph available

We do not hold a verified photograph of the Rocker / valve cover yet. We would rather show none than show a picture of a different part.

What goes wrong

All RB-series engines (RB20, RB25, RB26) suffer from cam cover gasket and rear main crankshaft oil seal deterioration as rubber compounds age. The rear main seal is the most serious leak path: it sits behind the flywheel/flexplate and allows engine oil to contaminate the clutch or torque converter. Cam cover gaskets and half-moon seals at the cam ends weep oil onto the exhaust manifold, creating a fire risk and heavy oil smell. Given that most NZ/AU examples are 25–35 year-old JDM imports, virtually all unrestored cars have at least minor leaking at these points.

What you would notice

Oil weeping from cam cover edges or half-moon seal areas
Oil smell on exhaust heat
Brown oily residue on bellhousing or transmission front face
Clutch slip or judder (if rear main seal has soaked clutch disc)
Oil consumption without visible external leak

How to check it

Where to look. Cam cover perimeter and half-moon seals on cylinder head; rear main seal behind the flywheel at the back of the engine block

Inspect the top of the engine at the cam cover edges with a torch — look for weeping oil darkening the gasket line.
Crawl under the car and check the bellhousing/transmission junction for oil film; a wet bellhousing almost always means a leaking rear main seal.
Check the clutch engagement feel for slipping.

Parts involved: Rocker / valve cover.

What it costs to put right

$400 to $1,600 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

“Has the cam cover gasket or rear main seal ever been replaced?”
“Is the clutch original? Any slipping noticed?”
“What is the current oil level, and how often is oil topped up between changes?”

Now check the Nissan Skyline you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.

Not sure what you would be paying for? See what a full KickTyres check includes.

Where this comes from

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.

Nissan Skyline buyer questions

Is rb engine cam cover and rear main crankshaft oil seal leaks serious on a Nissan Skyline?

We rate it major and very common on the Nissan Skyline. All RB-series engines (RB20, RB25, RB26) suffer from cam cover gasket and rear main crankshaft oil seal deterioration as rubber compounds age. The rear main seal is the most serious leak path: it sits behind the flywheel/flexplate and allows engine oil to contaminate the clutch or torque converter. Cam cover gaskets and half-moon seals at the cam ends weep oil onto the exhaust manifold, creating a fire risk and heavy oil smell. Given that most NZ/AU examples are 25–35 year-old JDM imports, virtually all unrestored cars have at least minor leaking at these points.

How much does it cost to fix on a Nissan Skyline?

$400 to $1,600 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which Nissan Skyline years are affected?

Our research records this fault on the 1989–2002 Nissan Skyline. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.

How do I check for it before I buy?

Inspect the top of the engine at the cam cover edges with a torch — look for weeping oil darkening the gasket line. Crawl under the car and check the bellhousing/transmission junction for oil film; a wet bellhousing almost always means a leaking rear main seal. Check the clutch engagement feel for slipping. Look here: Cam cover perimeter and half-moon seals on cylinder head; rear main seal behind the flywheel at the back of the engine block