[sal98]

Hello all, this is my first post and also my first project build. Nothing fancy here at all, forced to do a rebuild of my QR25DE due to a precat failure and wanted to get some tips and feedback on things I should and should not do. Looking to go all stock but would like any suggestions or links to any worthwhile upgrades. I was looking to remove my balance shaft as this is an 05 altima, but didn't know if most guys just pull the whole thing or just remove the chain. Also I pulled the head and pulled out all the valves. Was burning oil for quite a while and had a lot of oil and carbon buildup on all the valves. looking to send the head out to be cleaned up and possibly decked, and then lapping the valves myself. I did not blow the headgasket but I think my rings are shot. I originally did a wet dry compression test and pulled a 190psi wet and a 65psi dry on all cylinders

Motor already pulled but bottom end hasn't been unassembled yet, had to purchase a special Torx bit called a Torx Plus to get the flywheel off

 

[sal98]

Also wondering if ther are any other specialty tools that will be needed to complete pulling the engine apart. The connecting rod cap ends bolts look a little weird to me in when looking at photos online. Can they be removed with basic tools?
As you can tell I am a newbee to these imports and would really appreciate any help out there.

 

[westner]

You are about to open a "Pandora's Box" because you will see ills associated with a damaged motor that you may not have anticipated. You may get away with a very mild cross-hatch honing of the cylinders to accommodate stock pistons, otherwise you will have to bore them either 0.5 or 1.0 mm over and get the corresponding pistons and rings. A good choice of pistons, rods and head bolts are the 07+ QR25DE versions. The pistons are slightly higher compression and the rods and head bolts are much stronger. You will not have to deck your head if you go that route. It is also a good idea to check out the condition of the main bearings at this time. I don't know the age of the motor or how much abuse it took, but you don't want to pull the engine again to replace them.

I am not a professional mechanic and I don't own a $20,000 tool set but I was able to do most of the work with tools I had. It wasn't a big deal to purchase a "specialty" tool when I came across that situation.

Good luck with your built.

 

[ArmoredSpecV]

head bolts are 10mm allens, the flywheel bolts are internal torx, the rods, mains, and balance shaft assy bolts are all external torx.

 

[sal98]

You are about to open a "Pandora's Box" because you will see ills associated with a damaged motor that you may not have anticipated. You may get away with a very mild cross-hatch honing of the cylinders to accommodate stock pistons, otherwise you will have to bore them either 0.5 or 1.0 mm over and get the corresponding pistons and rings. A good choice of pistons, rods and head bolts are the 07+ QR25DE versions. The pistons are slightly higher compression and the rods and head bolts are much stronger. You will not have to deck your head if you go that route. It is also a good idea to check out the condition of the main bearings at this time. I don't know the age of the motor or how much abuse it took, but you don't want to pull the engine again to replace them.

I am not a professional mechanic and I don't own a $20,000 tool set but I was able to do most of the work with tools I had. It wasn't a big deal to purchase a "specialty" tool when I came across that situation.

Good luck with your built.

I have the engines head off and I can see the piston walls which look pretty ok to me, but I'm no mechanic so I will have to leave it to the machine shop to tell me whats what. I actually have 194k miles on this engine so if I need a honing then it definitely deserves it. Thanks for the info on the 07 parts. Sounds like the route to take.

 

[sal98]

head bolts are 10mm allens, the flywheel bolts are internal torx, the rods, mains, and balance shaft assy bolts are all external torx.

Thanks for the info, would you happen to remember what size internal Torx to use on the rods and mains. Also I had to find a Torx Plus bit for the flywheel as my pics show. Are these internal torx bolt heads the same type?

 

[ArmoredSpecV]

i just bought a set of them from harbor freight. cheapo wholesale tool outfit. i dont know the size off the top of my head.

the rod, main, and balance shaft bolts are the opposite of the flywheel bolts. you need a socket that goes over a torx head. hope that helps.

also, on your cylinder walls check for the ring ridge towards the top where the head is. run your finger up the cylinder wall. if you have a noticeable ridge there you can either get a ridge reamer and take care of it yourself or buy .020-.040" over pistons and just do it the right way. but at the very least you would need a deglazing which wont cost much before you drop the new rings in.

 

[sal98]

Thanks Armored spec, I live in L.I New York and they not to long ago opened a harbor freight near me. I'm into model aircraft and all the guys at the field talk about this store so I think I will have to make a stop by them later today.

When you say ridge, what do you mean. I'm not quite understanding what this would look like. I know it would be better to go for the honing and then get over-sized 07 pistons and rings. It's just that this is my only ride right know and timing with money issues is really tight. I also have to read up on fitting new bearings or rather calculating which size bearings to buy.

 

[westner]

The rings don't travel all the way to the top of the cylinder. Over time they will wear down the cylinder but leave a lip where they stop. That's an indication that a standard size piston will be too small. Measure the cylinders with a bore gauge. If the diameter has worn down close to 0.5 mm over stock then you could remove the ridge and then hone the cylinders to the required size. As I stated earlier in this thread,

"You may get away with a very mild cross-hatch honing of the cylinders to accommodate stock pistons, otherwise you will have to bore them either 0.5 or 1.0 mm over and get the corresponding pistons and rings."
​

You will not be able to hone out more than a few thousands of an inch. A machine shop will have to bore them out.

 

[slyguy700]

For mpg, you can do a maxima final drive if you want to go crazy and get insane good gas mileage. really poor acceleration though if not turboed.

 

[ArmoredSpecV]

what andy said...lol

if money is an issue instead of buying the 07 pistons which cost around $230, just mill the head down and that will raise compression. you dont really need to buy all the 07 bottom end parts either, but it will definately smooth the car out a lot since they are balanced way better.

 

[sal98]

OK, Today I had a pretty full day, I did find and visited the Harbor Freight store in hemstead LI. I was able to pick up a set of reversed torx impact sockets from them for $9.99 which fit like a glove. They had tons of other cheapy tools but I wanted to see how this set held up first before buying anything else. Then I hit Autozone and Ace hardware to pick up a few things like bolts for the engine stand and a puller for the crankshaft pulley. Once I got back home I was able to break the engine down and pull one of the pistons. Besides being slightly burnt the piston, rings and cylinder walls look really good to me. I could barely feel a ridge with my fingernail at the top of the cylinder. I stuck the old rings back in the bore and pushed them down halfway with the piston to see what the ring gap was. Not sure on the specs, have to look through the fsm tomorrow and check, but will post pics soon.

 

[sal98]

Wanted to post a few pics on the progress so far. Here are some of the bottom end, I'm not quite sure on how good or pad these parts are. if any one can tell by the pics please chime in.

 

[sal98]

Wanted to post a few pics on the progress so far. Here are some of the bottom end, I'm not quite sure on how good or pad these parts are. if any one can tell by the pics please chime in.

 

[sal98]

Here are some of my pistons. Mind you like I said this engine has 194k miles on it so far.

 

[sal98]

This is were I think I can see a big problem. The fsm states ring gap should be max limit .54mm top ring and .67 2nd ring. I'm using a .6mm feeller gauge and its way more space than spec

 

[sal98]

I guess I'm going to have it bored out and then get new pistons and rings. I am still trying to understand the bearing selection thing. If I do not have any work done to the crank, can i just purchase the same bearings as the originals?

 

[westner]

This is were I thing i can see a big problem. The fsm states ring gap should be max limit .54mm top ring and .67 2nd ring. I'm using a .6mm feeller gauge and its way more space than spec

The reason the gap is so large is because your cylinders have worn down. You need to measure the cylinder diameter exactly at several depths. I have a feeling that they wore down very close to 0.5mm, in which case you won't need to bore the cylinders but get away with a good hone after you ream away the small ridge. The final pass with the hone should produce a 25-35° cross-hatch to facilitate ring seating. All you'll need is a set of 0.020" oversize pistons with a set of corresponding rings.

 

[slaya786]

I'm actually in a very similar boat as you.. I just started pulling apart my engine today, almost upto where you are. Just about ready to pull the piston's out and see the damage.

You're gonna have to bore and hone out your cylinders now, and get oversized pistons. Also, as far you're bearings are concerned technically if you aren't machining down your crank, you should be able to use the stock bearings. But measure to be sure, at the very least measure with plasticguage.

I'm also from LI (bayshore), and you just made my day by telling me we have a harbor freight out here ... must be new because there wasn't one here before.

What machine shop are you going to, I've hunted down about 15 around the area and found some really good prices, PM me if you want some details on that.

Good luck.

 

[sal98]

Great, someone to compare with. I never visited the harbor freight in bayshore, only the one in hemstead off peninsula blvd. That one should be new as well. There pretty big stores.
I have only visited 2 shops so far. One was S&K on route 109 near me, but they said they only do mega motors putting out at least 500 hp. The other one was in copaigue on sunrise hwy near bethpage rd. There asking 200 for a boil and bore of the block only. and 450 for the head. I have already removed the valves and keepers, as well as the buckets ( which I have labled to keep the same order). So I'm not sure what the price would be for the head know. My valves are really bad from carbon build up, I hope they can clean them as well,