What Could Have Caused This?

LexLuthor400 · August 10, 2011

Ok gang, I have a problem that occurred and I have no idea how it happened. First let me give you a little background:

I bought the car (1998 LS400 Fully Loaded) four years ago and it has been great. I bought with about 110,000 miles on it and it had just had all of its services done i.e timing belt, water pump etc. Fast forward four years and 59,000 miles and still no problems with the car at all, other than the stupid PS pump. THEN last Saturday I was arriving at work and had noticed that it was making what seemed to be like lifter tick just slightly louder. The tick was also intermittent and NOT rpm dependent, meaning I only heard it from idle to about 1500rpms. At that point I just figured it was time for another oil change since it was due for one. After leaving work I started my car and again that ticking noise, it almost made the car sound like a diesel. But since the car was running just fine, smooth and strong, I decided to take it home that night and thought it might just be a bad pulley or something. The next day I had no choice but to drive a few miles to run an important errand so I did that, however upon returning home it made some other weird noises. Remember the WHOLE time the engine is running flawlessly and strong, no vibration, no hesitating, NOTHING.

Then I decided to take another look inside the engine to bay to try and pinpoint the noise, and to my BIG surprise the is a hole in the RH No2 VVTi controller housing (see pics). Inside the housing is a 1" long 10mm bolt just sitting in there loose. So my guess is that the bolt backed itself out and fell into the void of the housing where it was tossed around and chewed up by the end of the camshaft timing tube. Funny thing is with the bolt gone it fires right up no problem and is quiet??????

I am so confused as to how this happened. The only thing I could think of is that if the mechanic who did the timing belt replacement did not do it right it might have been the case, HOWEVER the timing belt was done 59,000 miles ago. I would think that if he did something wrong, it would not have lasted four years or 59,000 extra miles with no problems, right?

ANY help would be greatly appreciated thank you,

A frustrated LS lover!

curiousB · August 10, 2011

Well I think you've called it right. A bolt wasn't tightened properly and/or no locking compound used on the threads. The TB grabbed it and shot it around. There could be some substantial damage inside the housing as this thing probably was launched around for a while before it broke the cover casting. I would get it looked at soon as this is an interference engine so a snapped TB is an additional headache you don't want.

billydpowell · August 10, 2011

one thing you better do, is find out where that bolt came from. I suspect one of the four bolts that hold the cam gear on..... check it out. might not have been torqued right. Torque: 7.5 N·m (80 kgf·cm, 66 ft·lbf)

dont take a chance on ruining your engine....

the old saying (only ones I know) a stitch in time saves nine.... think it over.

landar · August 11, 2011

You need to get in there ASAP and find out if there are any crucial missing bolts or whether the mechanic left something loose. It looks like something got launched from the inside to out at fairly high velocity. Here is a pic of a 98 RH cam for comparison.

LexLuthor400 · August 13, 2011

I am glad you replied Billy. I was just reading about your 10th LS, so I know you might know few things about them.

You were right too. The four bolts that hold the belt guide to the cam gear were the culprit. The timing belt was damaged slightly, and the guide for the cam gear was busted.

So I found an Aisin timing belt kit that included a water pump, pulleys, and tensioner. So now I just have to find a new housing, and the guide with new bolts. Oh and some thread lock!

billydpowell · August 13, 2011

great, fix it right, you will be good for another 100k.

oldskewel · August 13, 2011

one thing you better do, is find out where that bolt came from. I suspect one of the four bolts that hold the cam gear on..... check it out. might not have been torqued right. Torque: 7.5 N·m (80 kgf·cm, 66 ft·lbf)

...

I think there's a typo in the torque specs. 7.5 N-m is about 66 INCH pounds, which seems to make more sense anyway.

billydpowell · August 13, 2011

one thing you better do, is find out where that bolt came from. I suspect one of the four bolts that hold the cam gear on..... check it out. might not have been torqued right. Torque: 7.5 N·m (80 kgf·cm, 66 ft·lbf)

...

I think there's a typo in the torque specs. 7.5 N-m is about 66 INCH pounds, which seems to make more sense anyway.

IF so, the manual is wrong.. page 1206 section EM-24, item 13.