timing belt change Vs gas mileage

[hgbee]

My 01 camry (4 cylinda) just had a timing belt change 9months ago.

Car is runing ok. But there are differencies:

1. the gas mileage drop from 31miles/per gallon to 26miles/per gallon after timing change. I tried change air filter, add oil system clean to gas tank, there is no improvement.

2. The Engine noise is loud than before at 1900 - 2000rpm range. Over 2000rpm or lower then 1900rpm, the engine seem sound like before timing belt change.

One of mechanician told me that may be caused by timing belt misalignment of one teeth. But the mechanicain who did the job claim the timing belt change will do nothing with gas mileage.

I am worrying about the small misalignment may hurt the car in the long run.

Any advise, I like to appreciate in advance.

Ben

[hgbee]

31mpg is high way drive before timing belt change. 26mpg is highway mileage after timing belt change.

[zythr]

Are you sure they did not mess with anything else. There are a few items that need to be removed to access the belt? Of more concern, if the belt is jumping a tooth, it may not last as long.

[Nervous]

check tire pressure

[73sport]

There are many variables which could attribute to this.
Primary is driving style and route. Maybe more idle time and/or hills could make the difference.
-Types of oils in the engine and differential
-Tires, tire pressure (Nervous )
-Spark plugs, plug wires, ignition.
-Fuel, fuel grade and winter/summer mixes
-Plugged and/or leaking fuel injectors
-Temperature
-Worn O2 sensors
-Plugged or failing CAT

just to name a few . . .

If the engines t/b were installed a tooth off, you may be able to get the ignition timing correct but it would be A) be powerless {kills mpg}, B) very torque'e {kills mpg}. Either way it would not like to idle and would likely trigger a CEL.

Has anyone successful ran an engine a tooth off either Advancing Cam timing or Retarding the Cam timing? Stretched belts (rare) and stretched chains retard the CAM timing reducing power output. So the 31mpg was not a result of a stretched belt.

[ghettosled]

thats what i was thinking. a timing belt being just one tooth off would probably make the car run aweful. you would certainly know right away there was something wrong. as for the fuel economy, there are a ton of variables. how are you calculating your fuel economy? where did you get the fuel from? same place as before? is the air temperature cooler than it was before the TB change? tire inflation? driving different roads?...

[Rattlin_Steele]

Originally Posted by 73sport

Has anyone successful ran an engine a tooth off either Advancing Cam timing or Retarding the Cam timing?

When my 5SFE threw a rod bearing last year, I ultimately discovered that it was a tooth off on the timing. Six weeks prior that engine had it's crankshaft and all rod and main bearing replaced by a mechanic. When I took delivery I felt something didn't seem quite right, but it seemed to perform "OK" overall. Given the overall shoddiness of his work, I believe it was very likely his doing, but it might've jumped later possibly at the time it untimately failed. My son was driving it more often than I during that period, and he seemed to think gas mileage was less. Even when it failed after six weeks the car seemed to idle fine and was driveable at slow speeds other than the knocking noise.

[hgbee]

Thanks for all your advise.

I seems have same condition as Rattlin_Steele has. After belt changing, the car seems perform OK overall. Only a little noise at 1900 to 2000rpm.
A mechanic who did the job is senior tech in local Toyota Dealership. At this moment, I have to trust his work. But it is possible something is messed up.

Car was only at 73000miles before belt was changed. I have this car since it was new. I change oil myself, always use Farm filter and Castrol Oil. I always buy gas at Costco and calculate the MPG everytime when I put gas. So city drive is 25mpg, highway is 31mpg. Car runs smooth without any abnormal noise up to 4000rpm, before belt change.

so I immediatly caught MPG change after belt change. My wife mentioned she feel steer wheel become is a little bit heavyer than before.

Idle speed is at about 700rpm after warm up. When it is idle, engine is very smooth.

Zyther: I check tire pressure all the time, I set it at 33psi. 1 psi higher than spec.

73sport, thanks for your input. Spark was change 2years ago, but it is Bosch. Do not know how to check O2 or CAT.

Ghettosled: thanks. The tempurature is similar as before. I will pay more attention on it. I always get gas at same place and use same way to calculate the MPG every fill.

Another Mechanic suggest to access the timing belt to check alignment.

I will continue working on it

[zythr]

I hope you can get the problem solved. Since so many things have to be removed maybe a part or two was not put back correctly. From Photos I've seen the T-belt looks like a bear to change

[Mr. Camry]

I have a 4.5 Gen 5sfe now with 186k miles and now on 3rd timing belt. I don't check gas mileage as closely as yourself but it seems to be fine and has always run smoothly without any noises. Hopefully,u'll get to the bottom of it. Did u change the water pump with it?

[hgbee]

Yes, I did have water pump changed when changing the belt. after it done, I notice there are dry red coolant mark at edge of pump, I guess it may leak a little right after changing. Now no leaking.