Yesterday, when i started the camry after 20 mins break, the car was showing variable rpm and was making noise like increase engine noise, decrease engine noise. there was slight vibration too.

the rpm was around 750-900 rpm and was continuously varying in that range.

what could it be?

one of the mechanics said, timing belt may need a change soon since its loose. could it be because of this? please advice

thank you

 

Use a section of rubber hose as a stethoscope to attempt to narrow down the area of the noise.

The timing belt is under plastic covers on the side of the engine facing the passengers fender. Determine if the noise is coming from this area.

 

thanks for the reply.

there is indeed lots of noise coming from the timing belt area. the mechanic says he will have to inspect the whole area and replace belt and other stuff too. all in all its around $350.

he is sure its not because of that, just needs a little tune up. don't know what he means by that.

he will give a quote on monday and i will update it here.

i guess since its aging, this is bound to happen. its approaching 142k miles.

 

Mechanic may be stating the noise may not be the cause of the RPM problems.

There should not be any noise from under the timing belt cover except for timing belt whine.

 

the RPM problem is occasional. I didn't face it the whole day yesterday and today. Should i replace spark plugs? May be they are misfiring or something like that.

 

i have a questions toyomoho, i checked the coolant level and it is around minimum. so i thought may be its because of that there was vibration and rpm varying. so i bought prestone 50/50 antifreeze coolant to top it off.

so just wanted to make sure that i open the reservoir tank and just put the coolant in right. i made sure i bought the pinkish/redish coolant so colors are not mix and match.

i hope this is a good coolant to use. its suggest by tech at autozone. can you please confirm before i put it in. thanks

 

When was the last time the timing belt was changed?

Plugs are good for 80-100K when was the last time these were changed?

A misfire would be more dramatic. If the RPM is just going up and down smoothly as if your foot is moving the throttle pedal this is not misfire.

Is the rpm variation better or worse engine hot or cold?

You can try cleaning the IAC which control idle speed. A google search on cleaning IAC valve 5SFE engine should produce hits on doing this.

Could be a vacuum leak, look at the various hoses on the engine for damage and listen for hissing.

Even though most folks would state to only add antifreeze if in a pinch add distilled water to make up the difference. A few pints mixed with around 7 quarts of antifreeze is OK. If you read the antifreeze container (not premixed), coolant mix ranges are around 30-60% depending on the freeze protection desired. A 50/50 premix coolant is apparently something the coolant manufacturers came up with.

Coolant mixing has been the subject of numerous discussions! However coolant chemical make up does vary. The colors can be more then just for show. For maximum corrosion protection and water pump seal life its best to use a coolant that is compatible with the engines coolant system.

Prestone Extended life coolant seems to be OK to mix with Toyota brand. In the future when deciding when to change the coolant use the length of time the Toyota brand was in the radiator.

Read the container. If the coolant is Prestone extended coolant it should be OK. The container would state OK to use with all makes and models of cars.

 

there was a 120k service check up done by Toyota when previous owner took it for evaluation. i observed following things from it.

- spark plugs history not found, so may have never been changed. (currently at 141k)
- oil leaking from valve cover gasket
- right upper engine mount cracked
- water pump leaking - says to remove and replace timing belt and water pump and thermostat and can reuse drive belts.

but i do have to mention that cooling and heating is very very good.

should i still go ahead and add the prestone extended life coolant?

i am going to schedule a service to take care of above issues, but i don't see that happening until 2nd or 3rd week of january. and since this is used as a commuter car, i just want to be on safe side.

thanks

 

In changing the water pump the coolant will need to be drained. Typically new coolant is installed but it is possible to reuse the it.

Thus up to you.

If you want to save money use distilled water. Ask your mechanic how they will deal with the antifreeze, do they use their own coolant. Why open a new container of coolant if only a small portion will be used.

In the future you can buy a low cost coolant tester. This will allow you to determine the coolants freezing and boiling point and adjust it to your climate.

 

hi toyomoho. thanks for the suggestion. i haven't yet used the new one.

i decided to look at how much actually is there in the reservoir tank. right now it is exactly in line where LOW words start from top. It hasn't got down to the low level line. Between LOW and FULL lines i would say it is about 25%. is it good for a month before i get the water pump and timing belt changed?

can i just add distilled water to this much coolant?

update: the variable rpm is no longer happening. don't know why it happened 2-3 times.

thanks