Sturmcrow

I am going to be changing the timing belt and adjusting the valve clearances pretty soon here. I am toying with the idea of replacing the valve stem seals at the same time, as the engine is 21 years old with 180K miles. It does use a little oil, though it seems to be getting better now that it is being driven regularly (I also bumped up the oil to 15w40). It does leak a little at the valve cover, which could explain the missing oil.

I've checked a few times now and do not see any smoke coming out at startup.

The reason I am considering this is because I am planning to have the cams off anyway to get at the valve shims, and figured for such cheap parts, I wouldn't mind having new seals in there. OTOH, I have read that the stem seals get brittle with age and can be tedious to remove.

So, what would you do? Replace them to be on the safe side, or leave well enough alone?

Also, I am planning to change the u-shaped coolant bypass hose and PCV valve while I am in under the plenum. Anything else I should consider swapping out for preventative maintenance? The main radiator hoses and heater hoses that I could reach actually feel pretty good.

jreyes94

for preventative measures, yes. if you're going in that far into the motor, its the perfect time do it. pop the seals off and bend them with your fingers, if they break or are very stiff, they are in need of replacing. even so, valve cover kits usually come with the stem seals anyways.if they are a pain to remove, use a flat head screwdriver and carefully pry them up.
even if you where to pull them off and have them check out okay, you would at least know hands on that they are still in working order.

vital22re

iTrader: (2)

careful you don't drop the valve when you pull the retainers. Theres a kit that basically uses compressed air to keep the valve against the seat.

scope103

Ordinarily, you need to remove the head to replace the valve seals. You need to remove the retainers, and an "ordinary" valve spring compressor reaches under the valve.

There are valve spring compressors that work from above by lever action, but as vital22re points out, you've got to keep the valve from falling down into the cylinder. There is a setup that uses compressed air to hold the valve closed, but I would be afraid to use one (that compressed air is going to try to turn the crank).

If you want a genuine shade-tree substitute for all these real-world tools, check out (about minute 5:00). Pretty scary ....

Sturmcrow

I am planning to do the rope in the cylinder trick to hold the valves up.

I've read good things about this tool. It has a magnetized inner bit to pull the retainers off after you press the spring down. Somehow it is supposed to magically reinstall the retainers too. Best of all, RockAuto has it in stock (and Aisin water pumps), so I can get almost everything I need from one place.


jreyes94, I think you might be thinking of the spark plug stem seals that some engines have (my old Honda D16Z6, for example). The seals I'm talking about are around the stem of the intake and exhaust valves themselves.

scope103

You might want to think how few extra steps it would take to remove the heads. Then you could (if you wanted) have a valve job done. (Though at least one person on this forum priced a head-job against a "new" engnbldr head, and bought the new head.) You can check the head and block for flatness. You can look at the cylinder walls. And know that your head gasket is new when you wrap it up.

Almost every maintenance job requires you to consider "I'm in this far, should I keep going?" Personally, I would go through replacing the head gasket, but stop before I removed any pistons. YMMV

Sturmcrow

scope, I know exactly what you mean. Of course, if I've got the manifolds off for the HG replacement, I might as well do the exhaust crossover elimination. At that point, I may as well pull the engine to replace the clutch, since it chatters a bit.

Someday, I may do all those things, but that will probably be the day after the HG blows on me and I may find myself in the market for a gently-used 3.4L.

I'm debating changing out the valve stem seals since I've decided to pull the cams for the valve clearance adjustment. From there it seems a small step.

I put my VIN in the toyota online database thingy and it basically came back with nothing. Would there be a record there if the original HG had been replaced under the service campaign?

Gevo

I know this is a bit late.. but I'm all over this forum last couple days and.. here is some contribution for future readers.

Just call toyota dealer, ask them to see if you have recalls, give them your VIN and they tell you which are done and which you can still get. Apparantly there is an ac valve thingy recall I can still get..

Stevesk88

I didn't read much of this but you can use a compression tester to keep them from droppin in, and sometimes if you have the right kit you can hook an air line directly to your tester line from the kit.

Gamefreakgc

I second this. To get the valve covers off (removing air chamber, hoses, etc.) is a decent amount of work. Unless you need to drive the vehicle like I did, I recommend just doing it all. That is, if you have the money. If not, the perhaps just doing a valve adjustment is good enough and don't worry about removing the cams or valve stem seals.

And yes, replacing the valve cover gaskets will eliminate some, if not all of your oil leak. You shouldn't have to run anything thicker than 5W30, unless you live in Alaska or something.

Gevo

Gamefreak, this is more or less what's happening to me... Luckily I don't need to rush to get the car on it's toes. I've been doing some research about remanufactured engines vs. rebuilding my heads...

For Scope103, I will +1 your response, once I realized most of the work taking it apart was up to the heads, I decided i'll at least for sure get the heads rebuilt.