Should I replace both valve cover gaskets?

[gimlithepirate]

I've got a leak that I'm dearly hoping is just a valve cover gasket, and not a cam shaft seal (yay vvti). Based on a clean up and diagnosis, I'm pretty sure it's a valve cover gasket (the bits of gasket coming off of it didn't hurt that conclusion). However, only one side is leaking.

My question: is it better to do both sides, or is it better to let sleeping dogs lie on the side that's not currently leaking? With. A lot of the older engines I've worked on, the answer has been to not disturb a gasket until it failed, but wanted opinions on the toyotas.

 

[Drcoffee]

I must did my valve cover gaskets while replacing the fuel injectors. Its not as intimidating as it looks. Just buy OEM TOYOTA plenum gaskets. Mine was leaking at the intake man/plenum joint. Also get a throttle body gasket, because its easier to leave the TB hoses connected and lay it to the side than to disconnect the coolant hoses. BTW you can clean the backside of the TB while its off. You can technically reuse the gaskets but the plenum gasket will be rock hard and oily. I used black permatex oil rated silicone for the joints in the head. No problems. Do it once and never worry again.

Okay so that is for my V6. Your V8 is probably less involved.

 

[gimlithepirate]

Yeah, I don't have to touch the plenum on the v8. Valve cover gaskets are relatively easy on the v8.

That said, I did go felpro instead of OEM. I've had good luck with their stuff, and their gasket kits is made in Japan. Had good reviews, but if it sucks I'll report back.

 

[xtremewlr]

Do both sides. If one side is leaking, the other is too or will soon be. You're already in there, so might as well do the job right the first time.

 

[gimlithepirate]

Do both sides. If one side is leaking, the other is too or will soon be. You're already in there, so might as well do the job right the first time.

That's generally my first impulse. The main reason I've asked is the only other engine with this kind of mileage I've worked on was notorious for replaced seals never being quite the same, even if you used OEM. Thankfully, the v8 valve covers don't look too bad.

Just hoping and praying this fixes the issue, and I don't have to get the cam seal done. On a VVTI that is firmly outside of DIY territory.

 

[xtremewlr]

That's generally my first impulse. The main reason I've asked is the only other engine with this kind of mileage I've worked on was notorious for replaced seals never being quite the same, even if you used OEM. Thankfully, the v8 valve covers don't look too bad.

Just hoping and praying this fixes the issue, and I don't have to get the cam seal done. On a VVTI that is firmly outside of DIY territory.

I didn't do the cam seals on my 03 and they have been fine so far.

 

[gimlithepirate]

I didn't do the cam seals on my 03 and they have been fine so far.

Yeah the driver behind all this is I do have a leak somewhere where it could be either. It doesn't appear to be coming from the bottom of the timing cover, so I don't *think* its the cam seal. Also, on the VVTI engines replacing the Cam seal involves removing the camshaft which is a pretty serious business repair.

 

[Drcoffee]

I stopped using felpro. The last two times they got hard and leaked in 1.5 years. Victor reins work well but I try to find Japanese gaskets.

For the crank and cam seals try AT205 its a polymer that restores the rubber seals and works best on shaft seal applications. Not so good on valve covers

 

[BlackWorksInc]

Cam Seals on the V8's tend to leak more on the VVTi equipped vehicles ('05-'08) and those are basically a 10hr job requiring partial disassembly of the camshafts to replace them. You don't see the older non-VVTi ones leak that much but they're also easier to replace when you're doing a timing belt.

In general for things like shocks, brakes, valve cover gaskets, etc. doing them in pairs is usually the best way to go.

 

[gimlithepirate]

I stopped using felpro. The last two times they got hard and leaked in 1.5 years. Victor reins work well but I try to find Japanese gaskets.

For the crank and cam seals try AT205 its a polymer that restores the rubber seals and works best on shaft seal applications. Not so good on valve covers

That is exactly my plan. Gonna replace the valve cover gaskets, see what happens. If there is still a leak, I'm going to do an oil change to Valvoline Maxlife High Mileage blend and AT205 and hope that takes care of the cam shaft seal.

My hope is, if that's the issue I can at least get it reconditioned until the next timing belt change, or at least get a few more miles out of my current timing belt.

 

[gimlithepirate]

Cam Seals on the V8's tend to leak more on the VVTi equipped vehicles ('05-'08) and those are basically a 10hr job requiring partial disassembly of the camshafts to replace them. You don't see the older non-VVTi ones leak that much but they're also easier to replace when you're doing a timing belt.

In general for things like shocks, brakes, valve cover gaskets, etc. doing them in pairs is usually the best way to go.

That's what I had seen in terms of the labor on it. And disassembling a cam shaft is beyond my DIY guts. Timing belts I can do, but it gets much more complicated than that and I'm drifting into mechanic territory.

Basically planning on about an 1800$ service to get timing belt and cam shaft seals replaced, as my sneaking suspicion is that if the cam seals are leaking, there is oil on the timing belt, which is all kinds of bad juju.