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hello, i have a 1999 2wd / 4 doors RAV4... for few months ago i've been having this engine-piston-like-noise, is like a rattle, mostly when the engine is already hot (not in the morning) i got injectors cleaned, spark plugs changed, air filter, gas filter, new vsv valve (for EGR system). The noise comes up when loeaded up, when accelerating and asking some power to my rav, and sometimes when the transmision changes gears (automatic trans.).... i don't know what else to do.
 
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the miles are a little more than 80k... and no, i haven't replaced the water pump... i have the rav4 for 10 months now, and i don't think it was replaced by the previous owner... so, i will have the water pump checked....

any other ideas??? i'm trying everything, cause a lot of things have been tried... it's been for 3 days (twice) at the service and they can't find the reason
 

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If you are hearing it with gears changing it may be transmission related... When was the last time you had the transmission fluid changed/filled?

Also have you checked your oil lately? How often is the oil changed? there could be some sludge/oil build up inside that is causing poor oil circulation???
Are you losing oil, as in burning oil.. do you see blueish-white smoke come out of the tailpipe during heavy accelerations?

Also, what makes you think it's the pistons? There is a good possibility your valves may be making noise due to lack of lubrication... if it really is your pistons there could be some more serious issues.... Definitely worth getting it diagnosed properly before continuing to drive it on a daily basis...

Just my .02 cents...

Good luck... keep us posted on what you find out..


--DJ Sueno
 
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last full tune up was weeks ago, everything is fine(as i was told at the place that's working with my rav), no oil lose, injectors and valves and all that stuff were cleaned weeks ago, no smoke at all...

i hate to think about it... but, is it possible that the problem was really the vsv valve, but, it took me so long to have it replaced (months) that maybe the rings around the pistons got damaged?
 
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If the rings around your piston is damaged, you will definitely have oil use.

As with the rattling, how does it sound like? If you can record a sound and post it, we might be able to help you with it. No oil use means the rings are ok. I suspect it's not seals, but rather a loose nut somewhere.
 
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my mechanic says is about the fuel, he put racing fuel and stopped doing that noise (i wasn't there, i'll try it in a few days when the fuel level is lower, but let's say that's the cause, low octane on my premium fuel (in my country that wouldn't be rare), what can be wrong??? cause ok, is not the best fuel, but not ALL the cars in my country are doing this noise (only pretty old bad looking cars - and believe me, i really take care of my rav) what can be wrong that gets worst with a low octane fuel?

kidong, is hard to record the noise cause i can hear it only while driving and is not that loud. the rattling is what we call here something like "pistoning" (i don;t know if it's the right word but in spanish, all mechanics agree that sound is "pistoning"
 

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That all sounds strange... It does sound fuel related, sounds like the car is running lean and could be pinging... I hope your mechanic doesn't foul your O2 sensor or burn out your catlytic converter putting in that race fuel... :roll:

Anyways, I would have him check the timing... although the distributor is a fixed distributor so it can't be the timing from the distributor....

Hard to tell what it is...

I'm still a bit confused because you say there is a sound when changing gears, which would make me think transmission related... again, has the transmission fluid been changed, or when was the last time?

Hope you get things worked out...
 
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well... about the O2 sensor and catalytic converter i hope he didn;t cause he's asking me to try it again with the VP fuel....

i asked him about timing, and he told me they checked... i think the last thing to check is the transmission, i don;t know when was the last time the it was serviced at all, and i've been with my rav for 10 months.... i'll tell him to take a look... cause it's sometimes when switching gears... but when just running forward too.... (but i hink, if it sounds when is pulling the rav, so then it is when the transmission is pulling)...
 

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there's a "knock" sensor which will detect pinging and retard the spark timing until it stops! could be that this knock sensor is busted or loose or otherwise not detecting the ping (it's a mechanical thing inside tuned to resonate at the frequency of the ping & make a contact!). there's a fault code for defective knock sensor (52/53 for OBD1 & P0325/P0330 for OBDII), so i don't know if your CEL didn't come on..

could also be a partial miss-fire! if there's a large carbon build-up on the back of the inlet valves acting as a spunge to absorbe the unburned gas, it could be a mild miss-fire due to a too lean mix! this absorbed gas is released back into the manifold when the valve closes! mostly noticed when the engine is cold and on acceleration!

many other things can cause too lean or too rich misfire too, but also a fault code will come up (P0300-P0306 for OBDII, but none for OBD 1)

when was the last time you had a 5 gas exhaust gas analysis? this can tell if there is a miss-fire is from too lean or too rich or if it's pinging.

are you sure the rattle is coming from the engine? could be a loose heat shield or something on the exhaust or something else which is loose!
 
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the "5 gas exhaust gas analysis" was made twice last week... before and after replacing de VSV valve... and everything was ok... i really don't know if they have that OBD1 or OBD2 thing... i will ask... and no, is not something loose... is coming from the engine

i tryed to record the sound, but is not possible from the inside...

i'm goona go to the mechanic with all the things you people have mentioned here... something has to solve this problem... i'll keep you guys up to date
 
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From what I know, I really can't help because I don't want to give assumptions and dissappoint you. Unless I drive it, I really can't tell.

About the pistoning noise, It could be a bushing somewhere that's worn that causes it when you change gear. It maybe something that simple and makes you wander around in circles for expensive parts.
 
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i understand you kidong, but something happened yesterday that makes me thing that is something important, i had 3 more persons in my rav (4 with me) and it was making the noise all the driving time.... i mean, the more loaded it is the more constant is the noise... i wasn;t able to drive normally with 4 people on the rav, it didn't had strenght enough and made that noise whenever i stepped on the pedal... i'm gonna take it to the mechanic and tell him this situation and see what happens...
 
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If it's more load and doing it, I'm pretty sure it's knocking. What sort of spark plugs are you using? If something standard, change it back to either the platinums or iridiums, also the spark plug gap is important too.

Advcance your timing a bit. within 5 degrees instead of 10 and try using higher octane gas. Try each of those one by one and see what the results would be.
 

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it's a '99 model so i think the timing can't be adjusted!! look at the knock sensor and the spark plugs as kidong suggested. but, if i remember correctly, the timing is retarded to stop knocking, not advanced.

the sequece for knock compensation is: knock detected - retard timing in stages until knocking stops - advance timing in stages - knock detected - and so on..... in other words, the ecu should be able to stop the knocking... unless it's so bad due to low octane gas, carbon build-up in the cylinder, piston, or spark plug that no amount of retarding of the spark can stop it! of course, it is most pronounced at lower engine speeds (less advance) and when loaded, i.e. higher temperature!

other causes that can cause "knock-like" sounds and signals are: an excessivly worn connecting rod bearing or a large cylinder ridge.

retarded ignition will cause lower power and make your engine run like [email protected]!!
 
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Hey Peter, according what you said about the computer is right, but low octane gas usually detonates pre-maturely, hence I ask him to try and advance the timing. You can get more HP with higher octane simply by retard the timing so the ignition time is right to the edge limit of the piston cycle. Advancing it will prevent pinging and the lower rpm ranges to be more torqee....
 
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well... i just got from my mechanic, looks like he knows where he's standing, cause he told me most of the things all of you have mentioned here (5 gas test, all sensors working, no error code on obd2, knock sensor timing) and everything is JUST FINE... but, there is one thing (already mentioned by peterpogi2005), if everything is allright then is "carbon build-up in the cylinder" that's what my mechanic said, the problem is, they don't do that kind of work there and he will send me somewhere else...

kidong, he didn't do that timing advance thing, cause he told me that everything there is just fine... and told me to try with a higher octane gas as i will do as soon as i can...

my question is... is it really possible that "carbon build-up in the cylinder" can cause this noise?
 

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yes it can. the carbon buildup can have a spot that gets hot enough to ignite the air/fuel mixture while it is still being compressed and before the spark. the niose you can hear is the flame front advancing before the piston reaches TDC (Top Dead Center) and trying to push it back down. in normal combustion, the greatest pressure is obtained at about 5 deg. after TDC when the piston is going on it's down stroke already. prolonged and heavy preignition can damage your engine..

the reason for advancing the spark before TDC as rpm is increased is to keep the highest pressure at 5 deg after TDC. as you can imagine, the flame front will advance at the same speed no matter at what rpm the engine is running, so the faster it runs, the less time there is before it reaches 5 deg PTDC, therefore you should start the combustion earlier..

as for retarding the timing to stop preignition. well, starting the flame front later means that the maximum pressure in the cylinder occures as the piston is further down the cylinder so that less overall pressure and heat is created. this cools down the cylinder and avoids the hot spot that would preignite the mixture.

if the timing is advanced, the maximum pressure will occure while the piston is closer to TDC and overall pressure and heat will increase.... making the carbon deposits hotter.... which will ignite the air/fuel mixture at an even lower pressure and causing even worse knocking coz it's trying to force the engine to run backwards!!

ok, why is the octane number important: octane is a chain of 8 carbon atoms with hydrogen atoms bonded to it. this fuel is the hardest to make preignite. heptane, however has 7 carbon atoms and combusts very easily and would rate an octane rating of "zero" at the gas pump!!! the "octane rating" is something like the ratio or percentage between octane and heptane in the gasoline. the higher the number, the less heptane. so, higher "octane" gas tends to require higher pressure and temperature to self-ignite and is required for high compression ratio engins.

there are some alternatives depending on your budget and how long you plan to keep your rav:

1, live with it. but it will run like a dog and finally damage your engine.

or

2, run higher octane rated fuel until the buildup is so bad that it'll preignite again.

or

3, pull the head and have the deposits removed..

it's up to you, but the only permanent solution is #3..

sorry for the long post guys....
 
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wow... don't worry about the long post, i am really amazed and glad about that answer... now i really understand and know what is happening... and my mechanic told my exactly to do your #2 and #3 choices... #2 just to try and see how it fixes... and #3 to make it permanent... but your explanation makes me understand the "why" of everything... and the tell you a little more, i was thinking about changing it for a rav 2003 or something like that, but, i really like it, and it would be a sacrifice changing it now, so, i think i'll take the mopre expensive, but permanent, choice... cause it would brake my hart to take choice #1... she's my little baby, hehehe...

tell me something about choice #2, "until the buildup is so bad that it'll preignite again"...... that would be so bad or just good... i really didn't understand....

anyways, i want to know that just to fully understand everything, cause i'm going to have the head pulled and everything cleaned up
 

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option # 2 isn't good or really bad!

first, it'll hurt your pocket coz you'll be paying more for gas.

second, it won't really fix the problem.

third, there is probably a reason the the carbon buildup in the first place and it may continue to a point where even higher octane rating fuel will preignite!

i'd have them look for the reason why there's a buildup in the first place.. things to look for are maybe oil leaking into the cylinders from valve guide seals. a small burr or chip on a valve or valve seat. a small burr or piece of metal from the spark plug thread. actually, amy irregularity in the head or piston crown that could get hot!!

mostly though, the flame front is extinguished before it reaches any metal surface since too much heat is lost to the metal. so usually the "hot spot" is something sticking out that can get directly heated by the flame before it goes out.

hope this helps.. glad to hear you'r keeping your rav though even it's giving you some small problems. ravs rock (especially 4.1's)
 
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