'98 Corolla engine noise

[earthmover]

Hello all Forum members. New guy here from Montreal, Canada

Toyota Corolla 1998
1.8 Liter w/ app. 140,000 Km

Here is my problem:

When I start the engine it sounds fine. There are no unusual noises.
When I put it in drive or reverse and and step on the gas there is a knocking sound coming from the engine.
This sound is present throughout it’s warmup period for a good 5 minutes or so.
Once the engine has warmed up, the sound is gone. The engine runs fine.

This is the 1ZZ-Fe engine that may have some problems and is apparently a noisy engine by design. I won’t even hazard a guess as to what the knocking sound might be. The strange thing about it is that I don’t hear the sound when the engine is idling or after it has warmed up. It’s only there during that 5 minute warmup period.

The engine burns about 1 liter of oil every 800 km or so if that means anything. Technically speaking I’m wondering about a few things:

a) what other moving parts in the 1ZZ-Fe could cause a knocking sound. The mechanic at Toyota thought it was the exhaust manifold gasket and changed it. But that wasn’t it.
b) When the engine is idling and once the engine has warmed up the sound is gone. Do connecting rods behave in this manner? How much is too much bearing clearance?
c) 1 liter of oil every 800 km does not worry me. I’ve driven much worse. Would a thicker or thinner oil help in the case of too much connecting rod bearing clearance?

I just bought this car a few months ago. I love it but I hate that knocking sound. This is my first post on this forum and I hope I’m not asking too much all in one shot. I’m hoping that you all can shed some light on this problem for me.

Thank you!

[Flashmn]

Bottom end bearing, Piston slap, come to my mind at first.

[Chinsan]

I had a similar problem with the noise that you discribed in my 99 Corolla and it turned out to be the Serpentine belt tensioner.
As for the oil consumption I was adding a little over a quart between oil changes when i purchased the car (@ 117,000 miles) a little over a year ago. I recently noticed, however, that my oil consumtion has reduced as I am now adding about half a quart between changes. Right now I'm not sure now if it was just teh switch from Castrol to Penzoil (about 8 mths ago) or if its because the car is now being better maintained. As a side note the Fuel consumption has improved as well it was 24mpg when i got it and now its 33mpg.

[stubborn1]

I have a 98 Prism and I've had a similar noise during the first few minutes when cold. I've always figured it as a noisy lifter and haven't thought much about it. I've had the noise for the last 20k miles. I've also been burning oil, but not quite as bad as you (1 quart per 800-900 miles). A thicker oil should help consumption. I still run 5W-30, but I buy it on sale by the case.

[tPartsExchange]

Is it a metal-on-metal "knock" sound? If so, you might have a rod bearing going out. I do not have any experience with your particular engine, but pending on the mileage and strain you put on it, you might have a bad bearing. I have a '92 Corolla with the 4A-FE, and it used to make a metal-on-metal knocking sound everytime I started it up. Once it idled for a few minutes, it would cease. When I took the engine apart after doing a transplant (old engine had 230,000+ miles on it), my No.3 cylinder rod bearing was worn down badly. I assume that since the oil had not circulate well enough yet, the bearing made only noises at startup, and once the engine was up to temperature and circulation, lubrication stopped the noise. You might want to look into it, a thrown rod is nothing you want.

[bapu]

Have you found the problem? I have 98 corolla at 240K now. Last 2 years I am noticing exactly same problem as you mentioned.