How bad is it to rotate the engine backwards

excessive · 07-26-11, 08:42 AM

97 LX 450

I did a search, but did not come up with any answers.... so anyway, while doing the replacement of the oil pump seal I accidentally rotated my engine in the wrong direction (counter-clockwise) when trying to loosen the crank pulley bolt. How bad is this? Anything I should check for damage? I have done some goggling and it seems that it could damage the timing chain / tensioner

This little project just may cause me my sanity

Kernal · 07-26-11, 09:09 AM

There's been a few threads about it and someone did it in the past without any issues. Wait for someone who's actually pulled an engine apart to chime in with a better answer.

kidglove13 · 07-26-11, 09:18 AM

I did it with out issue, I did not rotate it alot but I did rotate it backwards FWIIW

Tools R Us · 07-26-11, 09:26 AM

Not going to damage anything.

excessive · 07-26-11, 09:50 AM

thanks for the info guys.

I was trying very carefully not to rotate backwards, but my 14mm socket slipped off the flywheel and the engine rotated about 1/4 a revolution in the wrong direction.

robertaleon · 07-26-11, 10:20 AM

Same job - wife helping while I was underneath watching the 14mm, she rotated about 1/6 of a turn on the 30mm counter-clockwise ("Ooops - I'm a girl"). No harm done.

Did you find the socket?

excessive · 07-26-11, 10:53 AM

Quote:

Originally Posted by robertaleon

Same job - wife helping while I was underneath watching the 14mm, she rotated about 1/6 of a turn on the 30mm counter-clockwise ("Ooops - I'm a girl"). No harm done.

Did you find the socket?

not yet, i bought this today, when i get home from work i will check out the inside the bellhousing.

js93cruiser · 07-26-11, 11:00 AM

i know on the 22re engine it will loosen the tensioner and skip teeth on the timing chain....might be the same for the 1fz

alia176 · 07-26-11, 11:06 AM

you're fine. I've rotated engines backwards more times than I can count.

Tools R Us · 07-26-11, 11:37 AM

Quote:

Originally Posted by js93cruiser

i know on the 22re engine it will loosen the tensioner and skip teeth on the timing chain....might be the same for the 1fz

Maybe, if the chain is big time stretched, parts are very worn, but I have never seen it happen. Have done or seen to done tons of times. Attempt a big obstacle, fail, slide backwards, the tire force kills the engine, turns it backwards, collect your thoughts, start the engine, make the obstacle, no harm, no foul.

excessive · 07-26-11, 01:52 PM

Quote:

Originally Posted by Tools R Us

Maybe, if the chain is big time stretched, parts are very worn, but I have never seen it happen. Have done or seen to done tons of times. Attempt a big obstacle, fail, slide backwards, the tire force kills the engine, turns it backwards, collect your thoughts, start the engine, make the obstacle, no harm, no foul.

I think the chain tensioner in our motor works by simply pressing on the timing chain, so hopefully that would not cause timing to be messed up. I know in the shop manual it says do not turn the motor in the wrong direction.

Hopefully it will be ok - I guess I'll find out if/when i get everything back together.

Pin_Head · 07-26-11, 03:09 PM

Quote:

Originally Posted by js93cruiser

i know on the 22re engine it will loosen the tensioner and skip teeth on the timing chain....might be the same for the 1fz

My buddy's son parked his Toyota pickup with 22re on a hill and left it in 4th gear without the parking brake on. Overnight, it slowly rolled down the hill with the engine turning backwards about 200 yards to the bottom of the ravine. After winching it out, it started right up. No damage!

YMMV

CJF · 07-26-11, 03:19 PM

^^^
Too funny.

My own bone-head maneuver was to try to push start my 82 Toyota Longbed (22R) by letting it roll backwards and then popping the clutch. Guess what gear I *wasn't* in.

That was back in 1995. Still driving it today with no issues.

Tools R Us · 07-26-11, 06:08 PM

Quote:

Originally Posted by excessive

... I know in the shop manual it says do not turn the motor in the wrong direction. ...

Most shop manuals say that. Likely not because of causing damage but, it is bad technique. When a motor is turned backwards, the timing relationship between the crank (timing mark) and the cam (distributor, etc) changes, so parts can be installed out of time, etc. You can turn it backwards, then just need to turn it back forwards enough to remove the slack, restore the timing relationship.

TX Cruiser · 07-26-11, 07:25 PM

You mainly worry about that on interference motors. One of mine requires that you rotate the engine 10 degrees CC to properly tension the timing belt. Once the timing is verified, I always have to rotate it backwards to get the balance shafts to sync. Belt stretch.

It's going to be a damn good "pop" if harm was done. Matters not what you have, belt or chain. As reiterated above, no harm.

Wrench · 07-26-11, 07:34 PM

The engine runs backwards when you drive in reverse. So no harm done.

excessive · 07-26-11, 08:13 PM

Thanks for the replies everyone, i don't feel worried about it anymore! I knew i was just being paranoid, but I am building this rig for ultimate reliability, so I wanted to make sure im not jeopardizing reliability in any way.