gmoneygo

OP I'm sorry for your trouble. Thank you for sharing your situation so others may learn.

I have PAUSED the process of doing the timing belt replacement in my 2008 GX470 using the Aisin TKT-021 kit. There is a need to take in more information and get clarity on the correct next steps.

I have been using volume one of the "Lexus Repair Manual" for the 2008 model year. (I bought all three volumes). Additionally, I cross validated with this video that has been shared several times in different places on the ClubLexus forums.

While running through the process Saturday morning, I set the cams and crank to the TDC "I" location assuming this would be correct procedure. It's in the manual printed by the manufacturer, so it must be right... right?? Like others here, my cams turned after the belt and tensioner was removed. I had stepped away briefly to get some water, and almost jumped through the garage roof when I returned to see that the markings on each cam had rotated out of alignment nearly a quarter turn on each side. Immediately filled with dread and self-doubt, I started searching for resources on the topic and I found this thread.

I decided to proceed carefully and rotate the cams back into alignment with the "I" groove before again verifying the crank is in the correct position. After confirmation I placed the belt in alignment with all markings. So at this point, left cam (driver) and right cam (passenger) are in TDC "I" alignment, crank is in TDC "I" alignment, belt markings are seated in TDC "I" alignment in all three locations. However, there is significantly more slack in the belt on the left cam (driver) side than on the side with the tensioner. I have not yet installed the tensioner. I rotated the crank slightly and the belt displaced from the left cam by a couple teeth. I repositioned cam and confirmed placement of the belt again and stepped away. I decided to STOP and confirm the next steps and ask for advice.

Questions:

1. Is a quarter-revolution turn of the cams from TDC a cause for concern?
2. Has damage been done?
3. If I am safe, my gut tells me that I should rotate the crank bolt clockwise while securing the left cam to pull the belt slack from that side cam and pass the slack to the tensioner side so it can do its job. Then, install the tensioner and perform the two revolution test. Does this sound like a reasonable process?

MrJason

you want as much of the slack as possible on the side with the tensioner....

also... make sure your belt is pointed the right way. I’ve seen engines where people lined up the marines backwards because the left can mark was on the right cam and “vise versa”..

if you’ve lined everything up, rotated the engine over four times, and nothing touched... you are good to go. Just use a torque wrench.

Ive done three 4.7L Toyota/Lexus T-belt jobs in the last couple of months. Timing belts and timing chain repairs are my favorite type of side work.

Good luck,,,

gmoneygo

I appreciate the response. I went forward with my initial direction. The timing marks line up perfectly after the tension was transferred to the correct side. I'm hoping nothing happened to those valves. Feeling better now, but I'll feel better if she cranks and runs.

MrJason

The valves are fine if you didn’t crank the engine or try like hell to turn it over by hand. I’ve had several cams hop after the tension was taken off the timing belt and no issues occurred.

As as long as everything is lined up and you’ve got tension on the belt... rotate the engine 2 complete cycles(4 rotations)... if it’s smooth and all the notches line back up... you are good to go.

gmoneygo

Hmm, I did crank pretty hard on the two complete cycles. I used a torque wrench rated at up to 250 ft lbs. I definitely hit some resistance.

It it would be cool to know what ft lb rating one could set a torque wrench to in order to avoid causing damage, that would be super useful.

i took a video of me rotating the crank.

MrJason

The resistance you hit were the compression strokes on each cylinder. If you are changing spark plugs also.. remove them and turn the engine over by hand. That way you don’t have the easy then tough then easy turn cycles.

MrJason

Also... remember.... there are 2 style 4.7L engines from where they added the valve timing. This is why the locations are different from the first 2 years to the last.
The early 4.7 didn’t have the variable valve timing. So the marks were set and the engine didn’t move the cam gears with oil pressure.

Thats probably where some confusion is coming from on the “I” vs the “T”...

campfire

https://www.ebay.com/itm/TOYOTA-4RUN...temCondition=4

MrJason

Theres another company online that sells the older and newer 4.7L GX/4RUNNER/Tundra for $1800-$2000... they have an excellent warrant too.
Ill find the link and post it.. just for future reference.

gmoneygo

She cranks! She is alive! No problems! No leaks.

MrJason

Awesome news!!! It always feels good to repair/service your car or home by yourself. As a technician... I have seen some pretty shaded work done by other facilities and as a land lord I was ripped off on several occasions by plumbers and a/c guys(mostly plumbers)... I now do every repair on my own... from the lawnmowers to the roofing... and the cars to the TVs/phones, I fix it all.

I refuse to to be ripped off again.


So keep saving that money... it’s amazing what you can save when you do “self repairs”.