I need some advice. I'm changing the timing belt on my 2003 Acura MDX w/ 3.5L V6 engine. I've removed crankshaft pulley and timing belt covers after aligning crankshaft at TDC and observing the front camshaft aligned on the timing marks. Rear camshaft is difficult to see w/ upper TB cover in place.

I'm now confronted w/ a puzzle. The rear camshaft is apparently 180 deg. off, aligned vertically down instead of vertically up.

The engine was running fine before I started this job and I don't see how I could have misaligned the rear camshaft.

Question 1) Is it possible for the engine to run OK w/ this alignment? Is it possible to install the camshaft sprocket 180 deg off? I've removed other camshaft sprockets and they are keyed, making 180 off installation impossible Maybe a sprocket from another vehicle was installed. There is a temptation to leave "as is" since it was running fine before I started.

Question 2) Should I attempt to rotate the rear camshaft to correct alignment? I think yes, but wonder if valves will contact pistons on one cylinder before I reach 180 degs of rotation.

I admit I'm stumped.

Thanks in advance for help.

Regards

 

Don't spin the camshaft. Just so I understand, you haven't removed the belt yet so that rear camshaft must have been this way?

With a 4-cyl, you can spin the CRANKshaft 90 degrees to put all 4 pistons at mid-stroke & spin the cam. I'm not real sure how that translates to the V6.

Got a Helm book for that car? I've never seen the definitive layout of timing marks for the V-6. (are you sure it's 180 out?)

 

False alarm. I mis-observed the forward camshaft after removing the crankshaft pulley. During my exertions to remove the pulley, I rotated the crankshaft 360 and realigned. So after removing the crankshaft pulley, I checked front camshaft pulley, I thought I saw same alignment I had observed before beginning to remove the crankshaft pulley, however I was mistaken. Both front and rear camshafts are 180 off!

Whew!

Now, all I have to do is reattach crankshaft pulley and rotate 360 on the crankshaft pulley to realign all.

Thanks

 

You would have been a lot worse off if you reacted quickly and spun the rear camshaft...

 

Well, I finished the job. It took about 11 hrs of hard work, but MDX is running fine.

This is the most challenging TB job I've done. Everything on the 3.5L engine is heftier and requires more effort to disassemble/reassemble.

The crankshaft bolt almost beat me. I first tried my Ingersol Rand impact for 5-10 mins w/o budging the bolt.

Next I tried rigging restraint tool and using jack stand to support long extension to the bolt and a breaker bar w/ cheater pipe. This arrangement was too flexible and I felt that 1/2" extensions were going to fail.

One good thing about the 3.5L V6, it turns the crankshaft CW, so you can rig a socket to the bolt w/ breaker bar jammed against frame, and use the starter on the bolt. I tried this twice and got quite a loud noise, but bolt seemed still tight.

I got my propane torch and heated bolt for 5 mins and tried IR impact again. This time it spun off easily. I may have loosened the bolt w/ the starter impacts.

Rest of job is a lot of tedious equipment removal to access TB. I found the TB installation challenging. Even w/ the automatic tensioner pinned, there is zero slack in TB, and you have to force TB over a loosened idler into position. First two times I tried this, I pulled the front camshaft out of alignment during the engagement (front camshaft is close to idler). So I aligned the front camshaft one lug CCW, and tried once again. This time alignment was very close. I rotated by hand and alignment stayed good. I temporarily installed crankshaft pulley and started to see if engine ran OK. Success!

Another 2-3 hrs of buttoning up and cleaning tools and done.

Sorry for running up panic flag quickly, but I was totally stumped for about 1 hr.

Regards

 

TH,

I am glad you posted on your problems, because it shows that you are human. I learned most of what I know from your posts on the old cordclub.com site that is now gone.