Celica GT4 Spark Plug & Cam Cover Replacement

Ben Tyrie

Whilst pulling everything off the top of the engine to get to the spark plugs for a compression test, I found oil residue on top of the cam cover and around the edges, particularly at the rear of engine.
This is a common area for the 3SGTE to leak as over time, the cam cover and it's gasket can loosen up and the angle of the engine encourages oil to leak from the rear edge.

Inspection & Removal

It was easy to see once I started removing the cam cover why there was an oil leak. The retaining screws were less than hand tight. One screw is particularly tricky to get to at the rear and this was barely done up!

You can see from the below picture that the oil leak was also affecting cylinder #1. An oily HT plug and pooling oil around the spark plug indicated a failing inner cam cover gasket.

3SGTE Cam Cover Inner Gasket Oil Leak

After disconnecting the breather pipes from the cover, removing the throttle body/inlet manifold support bracket and then negotiating the wiring loom at the cam gear end of the engine, the cover was finally off.


Before repainting, the cam cover first needed to have the various layers of gasket sealer removed from the mating edge. This was done using a blade edge from a Stanley knife and a screw driver blade for the hard to reach areas.
Next came a thorough wire wheel brush (fitted to a power drill) over the top side of the cover to remove the worst of the crusty dirt, followed by a clean with POR-15 Cleaner & Degreaser.
Once happy all dirt and grease was removed I used POR-15 Metal Prep on the top side for a final clean and to etch ready for painting.

For the paint I went with high-temp but wanted something shiny so opted for VHT's Anodized Purple. Purchased along with the silver base coat from
A couple of coats later and I ended up with this:

It's not perfect but then it's going to spend it's life sat under an intercooler so a semi-ok finish is fine for this application.
I also did not bake the cover once painted. My hope is that I can take care of this when using the car again!


As with most things, refitting was the opposite of removal but with a few new parts and fixings used to smarten the job up.
New rubber gaskets (both inner & outer) were fitted to the cam cover (baught from TCB Parts), along with a bead of gasket sealant (similar to the classic Toyota Black) which was then left for 10 mins before fitting the cover to the engine to allow the sealant to go off slightly. This stops it oozing everywhere and makes a better seal.

Also replaced during the refit were the retaining screws. I binned the posi-drive headed screws and opted for a set of stainless steel allen-head bolts with new washers (purchased through an eBay shop). These allowed me to ensure the cam cover was correctly tightened down to the head. In doing so I did have to loosen and move the throttle body assembly out of the way in order to get everything done up to torque.

One final piece when replacing everything was cleaning and painting the throttle inlet support bracket and the throttle cable bracket. May as well tidy as you go on jobs like these!

Spark Plug Replacement

With the cam cover refreshed, the oil leak fixed and the top of the engine back together, the final thing to do was swap out the spark plugs for new items.

The old plugs were well used but came out easily. Cylinder 1's plug had been sat in oil but on closer inspection, this hadn't made it any further down the thread to the piston chamber.
I replaced all 4 with new platinum NGK BKR6EP-8. These and all the gaskets for the cover came from

With these small service jobs completed, a little piece of mind is given that the GT4 will survive a drive or two!

More Celica GT4 resto jobs to come - the list is long!