I35GEEK

I have a 2003 Infiniti I35 with 175,000 miles. It has been given me years of faithful service since I purchased it in 2006 from a grandmother. The car only had 15,000 miles in 2006 which was almost brand new. Like many others on this forum, I am a DYI person and we hate stealerships. A couple of months ago, I started to hear an engine rattle. After some diagnosis, I determined that it was the main timing chain tensioner and guide which require replacing. Like so many others during this pandemic, I lost my job. But the good news is that I had time to tackle this project. Since I was going to work on the car, I decided to also go ahead and do the following services which I have been putting off:

1. Passenger CV Axle (torn boot) replacement
2. Swap out new brake pads and rotors for the front (brakes pulsate on highway)
3. Engine oil cooler gasket (oil leak)
4. Fix lower oil pan gasket leaking

The above was the easy part :-)

I spent hours dismantling the side engine cover to access the timing chain tensioner and guide. But I eventually did it! Someone on the forum said it is a project from hell & I totally agree!. I decided to also replace the water pump and thermostat since I had everything pulled apart anyways. I bought a timing chain kit but I took the advice of those on this forum and not replace the timing chain. But I thought I would replace the other timing guides (large top one & smaller one near water pump). I also took someone else's advice and marked the timing chain in relationship to the sprockets before I touched anything. So far so good. I was able to replace the side tensioner and main guide.

Here is where I started to run into trouble. When I disconnected the top guide, the timing chain popped out of the main sprockets and teeth. I can no longer put the chain back onto the sprockets and lined up to my original markings. It is off by a couple of links. I did not put my timing chain at TDC prior to removing my tensioner and guide because I was not going to replace the chains. I decided that I now need to put the chain back on and follow TDC procedure to make sure that everything is perfect before I put the everything back together. I do not want to do this again. Hell, no.

I released the tension on the new tensioner. Chain seems to be tight. Great. I started to rotate the crankshaft to move the 2 main sprockets from its current 9 & 11 O'clock position to the TDC position of 11 & 1 O'clock. I was able to rotate the crankshaft clockwise a couple of turns using breaker bar and the sprockets began to rotate. But after a couple of turns, the crankshaft is stuck and I no longer turn it even with a break bar. I read that you can break valves if you over do it. I tried rotating it in reverse - counter clockwise. That worked but again after a couple of turns, I am meeting resistance and can no longer turn the crankshaft. When it does move, I can actually feel and hear the pistons moving. So now I am stuck and not sure exactly what to do from here.

I tried taking out the spark plugs (#2, 4, 6) from the front valve cover. I heard that the vacuum from the pistons could be creating resistance and removing the spark plugs will make it easier to turn the crankshaft. But after removing the front 3 spark plugs, I still have the same problem - crankshaft turns a couple of turns and then stops. I prefer not to have to remove the back #1, #3, #5 sparkplugs because I need to remove the manifold. But I will if that is the only way to do this. I definitely do not want to remove the front and back valve covers to access camshafts etc.like I've seen in some youtube videos.

I know this is an advanced project from hell. So there is not much information on the internet about this. But I am hoping someone experienced on this forum can let me know why I can't turn my crankshaft enough turns to rotate the sprockets to TDC. Any advice on what to do next? I am stuck and I need my car back. Your wisdom will be greatly appreciated.

Reality sucks

iTrader: (3)

First things first, Make sure nothing fell into the engine, or spark plug holes you have out.

This is what you need to Do.

Take the main chain off, you will need to remove the rear plug #1.
Back the crankshaft back a few teeth so that all pistons are mid level in the bore. you can then roatate the cams freely.
set the Cam sprocket marks to the small **** on the inner cover, and then rotate the crank back to its tdc mark. Then Install the chain. #done

#Simple.

I35GEEK

Thanks @Reality sucks for the quick reply. Just to clarify, do I follow your steps exactly as you stated?. Remove rear plug #!, take main chain off first, then rotate crankshaft back a few notches (with chain off), rotate cams to marks, put crankshaft back to TDC mark, reinstall chain?

Question - why is it necessary to remove rear plug #1? If I need to, I will certainly do it. I have changed spark plugs before and it requires removing manifold etc? I am just trying to learn because I am getting to an area outside of my knowledge even though I worked on cars DYI for years. Many thanks.

Reality sucks

iTrader: (3)

@I35GEEK The Real reason you want to remove plug #1, I find it easier with a long dowl of some kind down in the #1hole so that i can clearly see it move and to be 100% sure #1 is at tdc, and that the mark on the Oil Pump is correct.. The chain marks are somewhat irrelevant, Align the components to there marks and roll on.

I35GEEK

Hi @Reality sucks I have put the #2, 4, 6, spark plugs back loosely in the holes to make sure that nothing falls into the engine since your first posting. So thanks very much for your advice.

Your explanation of why I need to remove #1 spark plug makes sense. I think I will try a long clean plastic straw. I will report back in a few days upon completion. You are an angel and a blessing.

I35GEEK

Hi @Reality sucks . I am about to tackle TDC project today. Based on your instructions, I think I know the answer to my final question. But I will ask it just to double check. Is it OK to rotate the Camshafts sprockets and Crankshaft independently (with timing chain off)? All the instructions that I've found only talks about rotating the Camshafts sprockets and Crankshaft with the chain on and therefore, everything rotates in unison together.

DougR

The answer is yes, if you follow Reality's instructions. I added three comments in parenthesis to Reality's instructions ...

Take the main chain off, you will need to remove the rear plug #1.

Back the crankshaft back a few teeth so that all pistons are mid level in the bore. (Valves cannot hit pistons when pistons are mid-level in the cylinder bores. Use your clean soda straw to verify that 3 pistons on the forward bank are mid-level.)

You can then rotate the cams freely (because all pistons are at mid level in the cylinder bores. Obviously, if you reach a point where one or both cams do not rotate then do not force against a hard stop.)

Set the Cam sprocket marks to the small **** on the inner cover, and then rotate the crank back to its tdc mark.

Then Install the chain. (Double and triple check that all marks line up before installing timing chain cover. Rotate engine 360 degrees twice to verify it turns freely. It will be easier to do this with all spark plugs removed. Cover exposed holes with shop rags. Put spark plugs back in after free rotation is verified.)

#done

I35GEEK

Thank you @DougR . Your explanation helped me to understand rationale for the steps as outlined by @Reality sucks . You both are great teachers! I feel brave enough and confident enough to tackle the final steps of this project from hell.

I35GEEK

I wanted to report back from my project from hell and share learnings from doing timing chain tensioner and guide via timing chain cover removal. I nervously started the engine after I bolted everything back together.. Praise God, it started on first try. Here is what I have learnt for those who are thinking about this job:

1. Make sure you have plenty of time. It is not a job to rush. Even the pro's on this forum claim at least 10+ hours of work.
2. While you are there, you might as well change the water pump if it is still the original. Having done it with the cover off, I now understand why this is a major pain to do with the cover on. I also changed my original thermostat since I decide to take it off to give me some more room to work with.
3. I changed the main tensioner and guide but I went ahead and changed the other 2 guides (top and right side). The plastics on these guides were brittle probably due to their age (my car is 2003).
4. Take the advice of those much smarter than me (@reality sucks & @dougR) on how to set TDC. See above.
5. Practice putting the cover back without RTV. You need to know exactly how to maneuver the cover chain back in to minimize RTV smudging all over the place. Someone recommended putting a light coat of RTC also on the engine block in case the RTV rubs off the timing chain cover on the way in.
6. You will need to change the crankshaft gasket (the O ring gasket where the bolt goes through) to avoid oil leaks.
7. The plastic U piece gasket at the bottom of the timing case that goes on top of the upper oil pan, can come off. I put RTC at the top of the plastic as per FSM but I added a couple of drops of JB Weld Instant Adhesive at the bottom of the U to hold it against the timing case. This prevents it from moving during the timing case install.
8. When you start the engine the first time, do not be alarm at the engine noise. It will do so until the oil pressure builds up.
9. You will need more oil than a regular oil change because you have emptied the oil from the entire engine during this repair. In fact, I had to refill the oil a couple of times within 24 hours before all engine clicking noise went away.
10. Enjoy you new car!

After this project from hell, my car now runs smooth and quiet again. I am at 170,000 miles and I like to get another 50,000 miles out of it. Now if I can only find time and some bravery to tack my final project - rear main seal oil leak.

DougR

Thanks for the follow-up. Congratulations on a job well done! Very good list of suggestions too.