Valve Stem Seals Replacement

1991 4cyl 3SFE DX auto 104KM During the last 4 years I tried to get used to the smoke during start-up. The car runs great and passes the CA emission test like a champ. Nevertheless, I am still getting embarrassed every time I start the car. On the other hand, I am not so excited about removing the timing belt, distributor an all other components that are needed to be removed in order to get to those little seals, and I am also not excited about paying someone else to do it. I never opened the head cover and I would like to hear advice/opinions regarding the following questions:
  1. Is it possible to remove only the exhaust camshaft (without removing the timing belt and the distributor)?
  2. Is there a point in replacing only the exhaust stem seals? my theory is that they go bad faster since they are exposed to more heat, but I am not an expert.
  3. Should I go with OEM seals, which would probably fail again 2-3 years from now, or should I try Viton or Teflon or any other recommended type (please add you recommendations)?

Thanks, Boaz

Reply to
bauz
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before you tear your engine down have you been using a high mileage oil? They contain additives to swell the seals slightly. I had the problem on my 97 camry at 60,000. Now over 200,000 with no smoke on Pennzoil high mileage oil.

Reply to
Rob

Thank you for the tip - I heard about this solution. If it turns out to be too difficult to replace the seals, I would probably try it. I heard some other opinions against using any additives, therefore I would like to try the conventional way first. The other reason that I would like to do it is because I enjoy working on the car. Therefore I would like to hear more tips about replacing the seals. My goal is to complete the job in one weekend, which would be impossible (for me) if I have to remove the timing belt - in that case I will switch to a high mileage oil.

Reply to
bauz

How are you going to remove the head without removing the timing belt? ~~~~~~~~~~ I believe it is possible to replace the valve seals using compressed air to hold the valves closed. Something like a large socket with the side ground away can be used to compress the valve spring and remove the keepers. You still have to remove the camshafts. Doesn't make any sense to me to try just the exhaust to avoid removing the timing belt. What is so difficult about removing the timing belt? Let me answer my own question. The most difficult thing about removing the timing belt, is removing the side engine brace with very limited clearance to reach the lower two bolts. Secret? Remove the crankshaft pulley first, then you can reach those bolts much more easily from beneath. How to remove the crankshaft pulley bolt? Electric impact wrench worked on mine. Then later acquired a high torque air driven impact gun for the axle nut. This would be more than adequate for the crankshaft pulley bolt. An impact gun allows you to remove the bolt without the engine turning. ~~~~~~~~~~~~ My personal opinion. Not worth changing the valve guide oil seals if they're just going to start leaking again. However, that puff of smoke on cold start could shorten the life of the oxygen sensor, and I was getting (sometimes) a large cloud of blue smoke which just didn't seem right. The following worked for me. First, having acquired the car with 80,000 miles - conventional oil changed at 5,000 mile intervals, I changed the oil more often several times. Then added auto-rx (auto-rx.com) and drove 500 miles on the freeway, drained the oil, added Mobil 1 10W30 and 3 cups (20%) Lucas heavy duty oil stabilizer. Problem solved. That was in August of 2002, still no problem. Oddly, I too, will not use most motor oil additives. Many have been proven useless or harmful and the companies fined for deceptive advertising practices by the FTC. I do not like the idea of adding anything that doesn't belong in the engine or could alter clearances. The Lucas is a pure petroleum product with no solvents or particulate additives. If the viscosity is 50w, the effective viscosity of the blend when warm is 34W - not excessive in my view. But the Lucas is different than

10W40 for example, in that it clings to parts and doesn't seem to drain off over night. I searched these groups extensively before first use, and of those actually having tried it, they seemed to have around 300,000 miles on the engines and be pleased. It does not "swell the seals", so in theory, you can just drain it back out and be back to the original state with no harm done, but I've continued to use it because that blue smoke on cold start is gone.
Reply to
Daniel

Seems like low mileage (65,000 miles) for the valve seals to go bad. Have you made sure you PCV system is in good order? I suppose the valve seals may have hardened becasue of the age. If this is the case, the high mileage motor oils as suggested by others might be worth a try.

No

Actually, the intake valve seals are more critical. The exaust seals are on the positive pressure side of the engine (exahust side has a positiove pressure compared to the atmosphere). The intake valves are on the suck side of the engine. It is possible for oil smoke to be generated from oil leaking from either side, but doing just the exhaust side is likely to result in disappointment.

I don't believe Toyotas are noted for leaking valve seals. I'd recommend going with the OEM parts.

You seem hesitant to remove the timing belt. However, sooner or later it is going to need to be replaced. Why not combine the belt replacement with the valve seal replacement? Do you have the equipment needed to do the job (air compressor, spark plug adapter for the air hose, valve spring compressor, etc.)? If not, you might consider letting a professional handle the job. Have you considered just removing the head, and letting a local shop do a complete valve job? If your engine is smoking badly, it is likely that you have worn valve guides as well as bad seals. You might also investigate the cost of a rebuilt head.

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lists a head for3SFE engine at $350. If you do the work yourself, you can probably do thejob for less than $500 and you will have a new timing belt and head gasket. Personally before I started spending a lot of money, I'd make sure that the PCV system was OK and then I'd try the high mileage motor oil. If this didn't address the problem, and if I was planning to keep the car for a long time, I'd probably look at a rebuilt head.

Ed

Reply to
C. E. White

Thank you for the detailed reply. I guess I'll just try the additive solution. Even if I had an electric impact wrench, removing the timing and putting it back is just too much work, and I'll probably wouldn't be able to finish all the tasks in one weekend. This car never had any problem, therefore I do not have good familiarity with the internals of the engine, and it would take me much more time than someone with experience. Sorry that my first post was too short and missing some details: I meant to replace the seals without taking off the head. My intention was to remove only the exhaust camshaft, which is not connected directly to the distributor or the timing belt. Instead of removing the head cover, crank-pulley, timing belt covers, timing belt, cruise control, distributor and the camshafts, I thought I could just take off the head cover and the exhaust camshaft. Much shorter job. I will post the outcome of the additive solution, and maybe I will try to implement my theory.

Thanks!

Reply to
bauz

As far as I understand, this model does not have conventional PVC system, and it is not serviceable.

The smoke appears only for few seconds, after the engine was off for a long time. when the engine head is hot (few seconds after the engine starts), there is no smoke and the overall oil consumption is very low. Therefore I still believe that the exhaust seals are in a much worse condition, and when they are cold and shrunken, more oil can leak through them.

Good question, the answer - bad decision. half a year ago I was a broke student and the timing belt was way over due (sorry about the confusion -I meant 104000 miles [I'm used to kilometers]). Since most of my trips were above 300 miles each way, I decided to pay someone professional to change my timing belt. As a student, I didn't care much about the startup smoke and didn't want to spend more money to repair it. Now I have a nice job, and having a car that leaves a cloud of smoke is not appropriate anymore. But I love this car, it runs (almost) like new and I am not planning to replace it until the wheels will fall off.

The engine is excellent, the only problem is way the neighbors look at me after I start the car in the morning, therefore I do not see a reason to replace the whole head.

I agree. I will try it soon. My father is sending me a special additive that is made in Germany (I don't remember the name), and he sworn me over the phone not to try anything else before I try this one. If that doesn't work, I will try the treatment that worked for Daniel from the previous post.

Thank you very much for answering my questions. Boaz

Reply to
bauz

Here's another reason to be glad you're not replacing the valve seals. Was reading the factory service manual last night, and there is are several special procedures for removing and replacing camshafts. The one that caught my attention is the way to avoid _breaking the head_ when installing or removing them. Because the thrust clearances are so close, if the hardened steel camshafts are inserted into (or removed from) the aluminum bearing holders at a slight angle they can crack, so one needs to observe the angle of the locating pin on the end of the camshafts such that they rest evenly on, for example valves for cylinders one and three, and with the exhaust camshaft it has to be carefully "rolled" into position along the cam gear.

Reply to
Daniel

If you were only gonna do the exhaust ones, I think all your money and effort and time would be wasted and you could possibly do more damage. Change that oil to Pennzoil high mileage and put on a toyota or purolator filter first. Then if you need to add the additive you mention...I hate any additives myself but at least try the oil change first. You would not put that additive into dirty oil would you? Not sure what oil or viscosity you are using but if your running 5w-30 maybe its time for 10w-40 which I use during the summer heat. Here is another reason. Camrys rear main seals when they get old will harden and leak oil, PLENTY of oil on your engine and the ground. I had one fail on my old camry before they made the high mileage oils. Transmission has to be pulled to replace seal, very costly.

Reply to
Rob

Have exactly the same startup puff on my '99 Camry 4 cyl. and have found that changing to 10W-30 has greatly reduced the embarressment! Since oil consumption is minimal, that's the only fix I'll go with unless condition worstens.

I do wonder though if it's valve stem seals hardening that causes the problem or if its inherent in the design of the head ie. from studying the Haynes Manual, it looks as if the valve lifter bore clearance determines how much oil seeps past the lifter and down into the well containing the valve/spring /seal. Unless there's a return drainhole, whatever gets past the lifter will pool around the valve seal and has nowhere to go but into the cylinder eventually. The accepable production lifter bore clearanance is very small but spans a range from 0.5 thou to 0.8 thou (over 2.5 to 1) so it would be easy to see why some engines (or some valves) might have greater seep down than others.

If this is correct, replacing seals would be only a short term fix.(mine started puffing at about 75000 km). Anyone comments on my theory or anyone have any longterm experience with replacing the seals ??

Thnx Allan

Reply to
Allan

snip

To reinforce what Rob and others are telling you, I have a riding lawnmower that is getting a little age and starting to smoke. It got a lot worse after I switched it to sythetic which cleaned it out TOO good and it REALLY started to smoke. :-) I switched to oil for high mileage engines and now smoke is almost non-existant. I normally run 10w-30 but am going to try 20w-50 next season to see if that stops the smoke completely. HTH, davidj92

Reply to
davidj92

My '96 had some blue/white smoke on start-up. It had at some stage been oil-change abused, as it has some black tar-like deposits in the oil-filler neck. I changed the oil using 20-50 as indicated in the driver's manual for summer here, and the smoke disappeared. In winter, I use 10-40,..still no smoke.

Jason

Reply to
Jason James

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