Leaky timing chain cover

I am contemplating my leaky timing chain cover but if I remember correctly it cannot be removed without disturbing the head gasket. Is that correct?

Hi JIm,
I took the timing cover off my series 2 car with no damage to the head gasket. Be ready with a very thin bladed tool to carefully separate the gasket from the top of the timing cover as you remove it so that you don’t tear the gasket.

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I’ve had mine off on my Mk2. Head remained in situ but I had the sump off for a re-seal as well, which assisted. Car still has a metal head gasket which made it a little easier than working with a composite, I expect.

It’s not easy to get it out without disturbing the head gasket for sure, and even harder to get back in again. However are you 100% certain it’s leaking from there? It’s exceptionally common for the side down studs on the head to weep and drip down, appearing to be from the TC. They unfortunately drilled the holes for those studs right into the timing cavity. Oil pools on top of the studs and wicks down the threads. Mine are siliconed in place to avoid the issue. You can spend 30 bucks on a dye kit that will allow you to establish exactly where it’s coming from.

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Good thoughts, thanks Erica. I actually have some dye and I am ready for an oil change…

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Erica, are you referring to the vertical stud in the photo below? As you can see there is definitely oil in that area. I have two thoughts, I have actually had some success with the Permatex external sealant that comes in a spray can. That would be easy to do with not much downside. I could also pull out that stud and put thread sealant on it, don’t know how easy that would be or if it is doable at all without turning this into a big job. Thanks…

Jim,

Those appear to be the front/front studs. They could leak if the gasket itself doesn’t seal perfectly. They pass through the front rail of the head gasket, so if oil is managing to creep past the 1/8" or so of gasket between the hole and the timing chamber, it can escape down the stud. It’s definitely possible. But the stud hole dead ends inside the head itself so it is dry there. If you suspect them, and can get a double nut on them, then you can extract them and clean the holes and smear silicone on the stud shank to seal it. But I’d simply start with a new copper crush washer with some sealant on the back. Any oil there is under zero pressure so a crush washer should stop it.

The real nasty ones are the two studs over the distributor and alternator, most especially the forward one because the threaded holes are open inside the timing chamber. They get constantly bathed in oil, and it seeps down the threads and can come out on either side of the gasket or around the nut. They should be withdrawn, the threads cleaned out with a solvent soaked q-tip, and then coat the stud threads with silicone and reinsert. Also use fresh copper washers for good measure.

This may help, or may not. Realistically the head gasket around that whole chamber is a potential leak source. The sealing surface is narrow and can’t be very effectively clamped with those few 5/16" studs. This is why people often use sealant on the gasket around the timing chamber.

I would think an oil leak in that area would be FAR more likely to be from the valve covers or berather than the timing cover, especially if it’s a recent leak. There is no pressurized oil in the timing cover, and if it did not leak after installation, it is unlikely to start doing so later on.

Make sure the bolts are snugged up, thoroughly clean the area with degreaser, a brush, and a pressure washer. Cover it with talcum powder, and see where oil appears.

Unless I am mis-remembering, removing the timing cover requires first removing the pan, and the crankshaft seal, as the cover must move FORWARD, a short distance to disengage the two dowel pins in the top corners, then DOWN, to clear the two vertical studs.

I agree with Ray. The cam covers are notorious for leaks. The breather can be problematic because it’s a sandwich of parts any of which can leak. I have cometic gaskets on all of these parts. If you’re serious about chasing it, I’d degrease the whole mess, then add some dye and use a strong black light to hunt for leaks both before and after a drive. They have some really powerful led black lights for under 20 bucks on Amazon.

I don’t think the cam covers are leaking but I’ll take a look. The breather could be for sure and I’ll look for those studs over the dizzy and alternator and see what they look like. The dye test is a good one, I used that to solve the leak on the SBC in my '77 Vette.