I have a 1988 Toyota 4runner that I have recently got back on the road after sitting up for many years. It has a 2.4 engine and an automatic transmission. It had about 3000 miles on the rebuilt engine and everything has been going great until I started to work this morning. I was about 13 miles from my house and it was running perfect. I stopped at a red light but just as the vehicle started moving forward there was a loud grinding sound and the transmission stopped working. I coasted down a small hill into a parking lot. The engine was still running but it was only making the grinding sound when the accelarater pedal was pressed. I turned the engine off and sit there a few minutes trying to figure out what was causing the noise. I attempted to restart the engine and the grinding started immediently so I turned the ignition off before the engine had time to start. It did not give any warning that something was wrong. I had a mechanic helping to install the engine but I lost confidence with him once he got the engine bolted up to the transmission so I finished installing the engine myself,with the help of you guys on Yota Tech. Is it possible the torque converter came loose causing the grinding sound? It sounds too loud when the starter is turning the engine over to be something internal on the transmission but i'm no mechanic.When I stopped at the traffic light everything seemed fine but just as I pressed the accelerater the grinding noise started. Without looking at the vehicle does anyone have any idea what could be the problem?

 

This is near to impossible to diagnose online, and if it is something inside the transmission then we really can't help. Maybe get underneath and check for any obvious driveline issues or anything of that sort to start with.

 

pull the inspection plate on the bellhousing and have a look. Come to think of it, I could imagine a similar description if your exhaust pipe came apart except for the noise starting when cranking and before the engine starts.

 

I've looked underneath the vehicle and everything seems to be normal. I haven't removed the inspection plate yet but will do that tomorrow. On an automatic transmission does any gears turn inside the transmission when the vehicle is in park and the engine is running? The sound it was making sounded like gears grinding but I can't imagine the gears turning fast enough to make such a noise when the starter is turning the engine, before the engine is actually running. I'll agree with xxBLOOD88SHOTxx, without looking at the vehicle in person this would be a very difficult problem to diagnose but I do appreciate all advice.

 

If you don't find anything looking into the bell housing and turning the motor over by hand to check all the way around the ring gear and torque converter bolts you could try having someone crank the engine while you are underneath to see exactly where the noise is coming from. Just be sure it's in park, wheels chocked, e-brake set or whatever makes you safe.

 

I'll try looking into the bell housing but it will have to be this weekend, it's almost dark by the time I get home from work. I hate to wait that long to hopefully find out whats wrong,whether it's a simple fix or transmission replacement. When an automatic transmission is in park and you attempt to crank the engine,using the starter, does anything rotate inside the transmission, not counting the torque converter, or does it only rotate when the engine is in gear?

 

The pump and some of the internals will be spinning, not too sure how much though, I'm not a tranny guy. Yet. I think your best case scenario at this point would be that the torque converter bolts were not tight and fell out or sheared off. you may be able to put new ones in one at a time while turning the engine over with a wrench on the crank if the treads aren't buggered up. I always put them in loose first then go around one at a time with locktight and torque them down. Let us know what you find!

 

Oh, and check the bolt holes on the flexplate if the bolts came out. If they are elongated you may be pulling the engine or tranny to replace it.

 

The mechanic who was helping me install the engine at my house, installed the torque converter. When he installed it he did not use a torque wrench nor locktite. After we placed the engine on the engine mounts in the vehicle he asked if I cared if he took it to his shop to finish installing the engine since all of his tools were there. I didn't have any problem with that however, a day or two later he called and said I needed a new flexplate because mine had a crack in it. I never understood how he knew it was cracked because the engine was already in place when he took it to his shop unless he pulled the engine again. If he did, then he could have tightened the torque converter again and applied locktite but it's highly unlikely. In this case I hope that is the problem. Thanks for all the advice. I'll check it out this weekend and give you all an update. I appreciate all the help you guys on Yota Tech have provided me this far. If you can bare with me a little while longer maybe i'll get it back on the road again, for the second time, but maybe next time it will last more than the approximately 1500 miles it lasted this time.