The Nissan Path

This is a long post. Sorry. I'm long winded.

I finally found some time to dig into this task and I found out what was making the noise, and more problems. The noise was being caused by a broken timing chain tensioner spring on the secondary timing chain on the right side. The spring was broken about halfway down and it just coiled into itself. It's an easy enough fix but I also found a crack in the head starting from the forward most exhaust lifter area on the #5 cylinder. It won't be so easy to fix. I removed the head and took it to a machine shop but they aren't sure if it can be fixed yet. I'm doubting it can. I can't make out exactly where it ends up. Ill find out today. I'm pulling the second head off today also. If I have to rebuild/replace one side the other is going to get done also. Balance.

The lobes and bearings on the cams look great. No scorching. no noticeable defects. They look brand new. The engine has 180K miles so I was pleasantly surprised. Even with 2200 RPM cold starts (I'll never understand why, Nissan) nothing seems to be overly worn. In fact, the lifters tops look like mirrors. No grooves or scratching even. They literally look brand new.

I have some questions for the experts, though.

The piston tops have some carbon built up on them. Some of it appears to be flaking off. Should I clean the carbon off completely or just blow the flakes off with compressed air? It's not a bad build up but if the heads are going to be clean and sparkly?

What should I use to clean the timing chain covers? I use brake cleaner on most everything to clean up grease and oil but I wasn't sure if the aluminum covers would be able to take that chem. Maybe throttle body cleaner?

New head bolts. Threadlocker or no threadlocker for the Nissan? I don't see anything in the SM for threadlocker but I thought I should check.

Thanks, smj999smj, for all the help you give on the forums. We ST mechanics really appreciate it.

Well, if there was ever a time to clean the top of the pistons, now would be the time! Just don't use anything too abrasive. A fine or very fine grade of Scotch pad or even a rag wet with a solvent to soften the carbon up would work. Solvent could be WD40, brake cleaner, Simple green, for some examples. Then wipe it down with a soft rag or microfiber towel. If you have compressed air, you can do that, but be careful not to get anything into the engine.

For cleaning up the timing cover and parts, I used to clean them up in a parts cleaner and then use brake cleaner to clean the parts cleaner off of the parts. Brake cleaner won't hurt anything. Best would be one of those expensive spray wash cabinets or steam cleaners, but the average DIY'er doesn't have access to one of those.

Do not use thread-locker nor any kind of lubricant on the head bolts.

I can also give you some advice about the sealant you'll need on the timing cover and other parts. You're going to be laying down a lot of RTV sealant as you probably already know from cleaning up the parts. First suggestion, use the grey sealant, not the black. I used black sealant on my 2006 and now I have a couple of areas where there is oil seepage; not the case on my 2008 on which I used grey sealant. Second, if you are going to apply it using tubes, it's going to take forever and your fingers will hurt by the time you're done! Use either the sealant in the caulk tube with a caulk gun or use the pressurized cans. My suggestions are the following:

Permatex 82195 Ultra grey Rigid High-torque RTV (caulk tube style):

https://www.amazon.com/Permatex-82195-H ... 2862&psc=1

Permatex 85084 Ultra grey Rigid High-torque RTV (pressurized can style):

https://www.amazon.com/Permatex-85084-H ... 9142974131

Your local auto parts store should carry at least one of them.

I'm going to use the green scotch pads on the pistons. The blue isn't doing anything. The green takes it off in about 30 minutes per piston. I'm being as careful as I can but there is no way to keep it out of the coolant passages. I've got a metal tube just small enough to go into the passages. I'm going to hook it up to a shop vac and clean all the passages around the pistons with that. The pistons that I've cleaned have just a little bit of scuff on the tops but nothing major.