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Mechanic says vaccuum low, wants to replace valve covers

My 2000 Lexus RX300 just had a visit to the dealer for a coolant flush and A/C repair. While it was there, the tech did a vacuum check and found the vacuum was “below spec” (I don’t have the exact value.) He recommended that they pull the valve covers to check for gelling (none found) and then replaced the PCV valve. The vacuum is apparently still low, and they’re recommending replacing the valve covers and gaskets for vast sums of money.

I’ve looked at vacuum leak information on line, and haven’t seen any symptoms–the car drives great, and haven’t noticed any roughness in the engine.

Does this sound like a reasonable diagnosis? Is it something important to do (other than allow somebody to make this month’s boat payment, of course) or is the vehicle probably ok to drive?

It seems like with a 10-year old car replacing the vacuum lines might be a better place to start, but what do I know?

IMHO you are being “taken for a ride”. If you had a vacuum leak

  1. you’d be experiencing performance problems
  2. replacing the valve covers would not be one possible “fix”
  3. what the H*** was he doing checking the vacuum anyway?

Your Lexus is 10 years old now. Find a reputable independantly owned and operated shop and stop going to this crooked dealer.

So far I can only see one thing you did wrong. Why are you having the dealer do this work?

Dealers are no better (or worse) than independent mechanics for almost anything you might need done on your car.  They will almost always charge more per hour and often more for parts and supplies.  They also tend to look at repairs a little different than the independent. 

A dealer may well recommend work that strictly may not be needed, but could be connected to the problem or maybe replace a part when a little repair would fix it ALMOST as good a new.  

There is no need to bring your car to the dealer for any service other than service that is going to be paid for by a recall or original warrantee.  During the warranty period be sure to have all required (as listed in the owner's manual) maintenance done and to document all maintenance work.

I suggest that most people would be better off finding a good independent (Not working for a chain) mechanic. 

Note: Never ever use a quick oil change place. They are fast cheap and very very bad.

Other than that, I believe you are on the right track BTW I would want to know the answer to that The tech did a vacuum check and found the vacuum was "below spec

Lucretia–This guy seems to be putting the cart before the horse. When the customer complains about an engine running problem, sure, a tech may do a vacuum test to point himself in the right direction, especially if there aren’t any fault codes. Here it seems he’s just out of the blue doing a vacuum test.

Ask why he did the vacuum test and what the reading was. Also what were the operating conditions of the car? Like: Was it idling, cranking, or 2500 RPM. Does the gauge needle oscillate or jump all over the place? Things like that

Please post back!

We’ve been going to an independent mechanic for the past several years, but they’ve had some changeover in personnel and done some 180s on previous advice–for example, last time we had the coolant changed, they told us it needed Toyota red. We noticed a while back that the coolant was low, took it in to get checked and mentioned that it used Toyota red, and the new guy told us that they would top it off with DexCool and it wouldn’t be a problem. Did a little research on DexCool, and you can imagine how that went–if nothing else, we were uncomfortable with them mixing it with the Toyota Red in the system. Took it to the dealer for the coolant system flush because we figured we’d get Red without an argument.

We had the same #3 reaction–especially since they hadn’t done the work we’d asked them to at the time, and they had to keep the RX a second day to get done because they had “too many walkins” (we had an appointment). I didn’t even mention them suggesting replacing the rear seal for another vast sum of $$$. Don’t think we’ll be going back there.

Checked with the husband–he says that when he asked them why they did a vacuum check, they said it was SOP on a vehicle with this many miles (146K). Will have to call Lexus for the details on the test.

Hmm…SOP? This is the first mention of it over several years and thousands of posts on this board. Even more puzzling - there are a gazillion places for a vacuum leak, next to none of them having anything to do with the valve covers! Verrrry odd.

Lucretia, you might ask them to run you off a copy of the SOP for diagnosing a leaky valve cover gasket with a vacuum meter. In my best efforts at diplomacy, this sounds like a CROCK.

There’s nothing wrong with performing a vacuum check as part of a service, and especially at high mileage. As a matter of fact, a mechanic should be commended for doing it as it only takes seconds and can reveal instantly whether any internal engine problems exist.

Here’s the issue I have with this; and I’m assuming the vacuum gauge was connected to where it was supposed to be. (intake manifold vacuum, not ported vacuum)
Replacing the valve cover gaskets and(?) valve covers seems misguided to me and if the vacuum is out of spec I would suspect something else is behind it.

Leaking vacuum line, low compression, timing belt off a tooth due to a replacement error, etc, etc. are some considerations.
Without knowing exactly what the reading was and what the needle behavior on the gauge was (it makes a difference) it’s hard to say but at this point hold off on the valve cover thing.
Have another shop connect a vacuum gauge (intake manifold ONLY) and note the reading and needle behavior. Post the results and maybe we can sort this out.

I agree that mechanically the dealer is a reliable as your independent mechanic, but you should also keep in mind that especially in these tight economic times for car dealers, the dealer is trying to make up for lost revenues any way he can and a lot of times, that will come from the service dept. Not necessarily saying that it’s a scam, but a lot of times they will recommend things that are not stictly speaking necessary.

OK, a getting a little more info here—it’s a lot of talk to someone who talked to someone else who heard it from someone else sort of thing…

The valve cover gaskets are showing some leakage, and they suggested replacing the gaskets and at the same time replacing the valve covers with a some having a different baffle design to prevent oil gelling. I’ve found one comment on line that said the valve cover baffles from my model year had insufficient clearance that caused gelling, and they were redesigned the next model year. Seems like that should have been a recall item if were a big problem, given the gelling class action suit–also seems like a letter to Lexus is in order to find out why they would charge to replace a part if its design is known to contribute to oil gelling…

The dealer said that replacing the valve covers was the highest priority repair. He also said the cam seals and main seal were leaking and needed repair. Nothing else said about checking the cause of low vacuum.

There hasn’t been any sign of oil on the garage floor. My gut feeling is to check the oil regularly, find a good local mechanic, and next time it’s in for an oil change have him give it a good going over. Also thinking about switching to synthetic oil. It sounds like the cam seal leak could affect the life of the timing belt, which is a concern. Other than that, if there are just small leaks, are there any problems with just topping up the oil on occasion if it’s not leaking that much? Seems like that’s just something to expect with an older engine.

Leaking valve covers are not going to cause low manifold vacuum and without knowing what the spec was and what the needle was doing I can’t tell you what the reason is, or may be.

If the timing belt has never been changed then it’s about 4 or 5 years past due and you’ve just been very lucky up to this point.
Oil gelling, or sludging, is most often caused by failure to change the oil on a regular enough basis, overheating, etc.

With respect, this is very different from your original post. I wish the details had been posted up front.

And, with the utmost respect for OK4450’s expertise, I still feel that a vacuum check on a vehicle brought in for a scheduled coolant flush and AC work is inappropriate without approval from the customer, however I now realize that we didn’t have all the information up-front.

Sorry that the details have changed–they change with every person I have talked to. That was the information I had been provided before a lot of digging.

We took it in for a coolant flush and a/c work–things escalated from there. They said the vacuum was low, and we could be lucky and it was the PCV valve, or we could have gelling and recommended removing the valve cover for inspection. They replaced the PCV valve, said it didn’t improve the vacuum, and then recommended the valve cover/gasket change. They didn’t make any further recommendation regarding the vacuum.

It doesn’t sound like I’m going to be able get all the data, and it’s due for an oil change pretty soon, so I’ll plan to try a good independent mechanic and have it checked out when I get the oil changed. It’s running like a top right now.

The timing belt has been changed, but I’ve read that the cam seal leak can get oil on the belt and reduce its life, so I’m a little concerned about that one.


At this point, I would hold off on the need to replace ANYTHING.

Take your car to a different mechanic.
Ask them to do an oil change, since your car needs it, and then ask them to go over the car with a fine toothed comb, and see if there’s anything that stands out that looks like it might need to be replaced in the near future.

DON’T give him any info about the work you have had done recently, and all the things that the dealer wants to replace, and says is leaking. Let him give you his own list, or no list at all.

I doubt your car has any troubles.
If your car actually does have low vacuum, valve covers and gaskets are not going to fix the issue, as they don’t contribute to it in any way, shape, or form. I personally would look for cracked hoses, faulty sensor that is attached to a vacuum line, leaking intake manifold or head gasket, or finally, valve clearances.

Your dealer has happily removed plenty of money from your wallet already, and the fact that they couldn’t get their story straight when you asked them for a solid explanation of why they want to do what they want to do, speaks volumes about the fact that you were going to be their personal profit center until they bled your wallet dry.


That sounds like a really sensible thing to do. It’s time to get it ready for winter anyway; a good reason to give it a good checkup.

Thanks to all for the good advice.

The part that surprises me the most about this is that a vacuum check was actually done seeing as how very few mechanics use a vacuum gauge at all; even when diagnosing a problematic car.

Whether it was connected correctly or whether there’s a legitimate problem is something else altogether.

Many of the older Sunscopes used for tune-up work, diagnostics, etc. had a vacuum gauge built into the unit. The vacuum hose from the scope was connected along with the test leads and checking manifold vacuum was standard operating procedure.