Piston Slap Near Tdc For 1 Zz-fe - Corolland: the Toyota Corolla Forums

Hi all,

After a particularily gruelling winter (for fuel efficiency) I recently changed back to my summer tires only to discover that fuel efficiency is still down in my 01 Corolla. I'm getting about 570 km/ tank which works out to 6.8 L/ 100 km (mostly highway driving) compared to my usual 5.7-6.0 km/ 100 km in the past. Also, I'm noticing that oil (Mobil 1 synthetic) is disappearing at a rate of 1 L/ 6000 km so I decided to get a compression test and vacuum test. The dealer report is summarized below:

cyl 1: 175 psi

cyl 2: 175 psi

cyl 3: 175 psi

cyl 4: 175 psi

vacuum - steady

scope indicates piston slap near TDC

I'm told that the piston slap is probably the cause of both my oil loss and fuel efficiency problems and that the slap (the tech hears on the scope) must be near TDC if my compression numbers are so good. So the engine now has 240 000 km on it and I'm told that it'll need to be short blocked, or replaced at some time (barring an engine rebuild) as the piston slap will only get worse over time. Two questions:

1: I'm moving to the States so in the future, will a short block, long block, or scrap engine be my best bet for repair? Is engine rebuild really expensive in terms of man hours?

2: If I switch to 10W30 (from 5W30) can I decrease the oil consumption and reclaim some fuel efficiency in the interim?

Thanks,

You could go with 10w30 to help with some oil consumption - fuel economy is a different manner. It may go up, may go down - still 6.8L/100km vs 6.0L/100km is not too terribly bad. Mine dropped about the same amount when it when past 100K miles.

As for piston slap at TDC - I assume that the head was not shaved down or a thinner headgasket used in the prior rebuild. The 1ZZ-FE uses a unique combustion chamber design via a "taper squish combustion chamber". Usually not an issue unless there is a significant amount of carbon buildup on the top of the piston (a very likely case with significant oil consumption and reduced fuel economy). May not need a short block or long block - might just get away with a cleaning. Most might opt for engine swap - since the amount of hours needed to rebuild the engine and parts cost alone make it not very cost efficient. But if you have some extra time and a second vehicle for transportation - a rebuild can be a good solution. If I knew I had a good bottom end and a positively identified problem with te current engine - I would rebuild it instead of swapping in an unknown engine. A reman or new engine would be really nice - warranty, clean, everything fresh - but cost alone could be quite prohibitive. No sense dumping in more money into a car in parts, when you could just go out and buy a similar one for less money and time spent.

You could go with 10w30 to help with some oil consumption - fuel economy is a different manner. It may go up, may go down - still 6.8L/100km vs 6.0L/100km is not too terribly bad. Mine dropped about the same amount when it when past 100K miles.
As for piston slap at TDC - I assume that the head was not shaved down or a thinner headgasket used in the prior rebuild. The 1ZZ-FE uses a unique combustion chamber design via a "taper squish combustion chamber". Usually not an issue unless there is a significant amount of carbon buildup on the top of the piston (a very likely case with significant oil consumption and reduced fuel economy). May not need a short block or long block - might just get away with a cleaning. Most might opt for engine swap - since the amount of hours needed to rebuild the engine and parts cost alone make it not very cost efficient. But if you have some extra time and a second vehicle for transportation - a rebuild can be a good solution. If I knew I had a good bottom end and a positively identified problem with te current engine - I would rebuild it instead of swapping in an unknown engine. A reman or new engine would be really nice - warranty, clean, everything fresh - but cost alone could be quite prohibitive. No sense dumping in more money into a car in parts, when you could just go out and buy a similar one for less money and time spent.

Hey Fish,

Thanks for the reply... I'm wondering if there are any fuel additives I can use to burn off some of that carbon residue on the piston head (if that's the problem). Maybe if I ran a couple tanks with fuel treatment? Do you think that might be a "soft solution" to address the possibility of carbon buildup?

Seafoam (or GM top end cleaner) seems to do a decent job removing carbon from the tops of pistons.

I just finished rebuilding my 1ZZFE last month due to excessive oil consumption. Since I had a spare vehicle and a little extra time, I tore it apart myself and replaced the worn components. If I were short on time, I would have thrown in a junkyard engine. I could have bought an engine with 60k miles for around $500 US. My costs actually ended up being higher:

Complete gasket set $150

Piston rings $60

Head bolts $50

Machine shop valve job/clean parts $350

Machine shop clean pistons and rering $50

Total $660

Here's a picture of the pistons that was interesting. You can see how the oil ring gets "stuck". It had no spring to it whatsoever - I had to pry it out.

https://i65.photobucket.com/albums/h209/rmy...m/engine017.jpg

Seafoam (or GM top end cleaner) seems to do a decent job removing carbon from the tops of pistons.
I just finished rebuilding my 1ZZFE last month due to excessive oil consumption. Since I had a spare vehicle and a little extra time, I tore it apart myself and replaced the worn components. If I were short on time, I would have thrown in a junkyard engine. I could have bought an engine with 60k miles for around $500 US. My costs actually ended up being higher:
Complete gasket set $150
Piston rings $60
Head bolts $50
Machine shop valve job/clean parts $350
Machine shop clean pistons and rering $50
Total $660
Here's a picture of the pistons that was interesting. You can see how the oil ring gets "stuck". It had no spring to it whatsoever - I had to pry it out.
https://i65.photobucket.com/albums/h209/rmy...m/engine017.jpg

Wow, that's quite a bit of carbon that's built up on the side of the piston, I can see how you get stuck piston rings from that... now I did take my car to a Mr. Lube this morning to get the Run-Rite treatment and after that it seems to idle and accelerate more smoothly, perhaps fish was right about the carbon buildup on top of the piston... I'm also thinking my oil loss issues could be related to carbon buildup on the intake valves thus not allowing the valve seals to work properly on the stems. In any event, I'll be monitoring the fuel economy after this service and just for good measure I'm going to run over to auto parts and get a similar kit from Wynn (combustion chamber cleaner) and repeat the procedure. I just hope I don't hydrolock the engine!

friendly_jacek

Here's a picture of the pistons that was interesting. You can see how the oil ring gets "stuck". It had no spring to it whatsoever - I had to pry it out.
https://i65.photobucket.com/albums/h209/rmy...m/engine017.jpg

I couldn't tell from the picture what happened with the oil ring beside all that oil varnish. Could you please elaborate?

Also, what oil and what change intervals did you use?