specialk Posted January 20, 2007 Share Posted January 20, 2007 I'm doing an engine swap into an 86NA and whilst going through the donor engine I removed the plugs to check compression (engine has sat for 2 years). Two plugs came out very quickly and when I try to reinsert them (or the compression tester) they stop too fast also. A normal plug takes approx. 10 turns from engagement of the threads until seated, these take less than three. Anyway, does anybody have any really good ideas for fixing these threads without removing the heads? Quote Link to comment Share on other sites More sharing options...
zcarnut Posted January 21, 2007 Share Posted January 21, 2007 First, get a 14mm spark plug chaser, not a tap. A chaser will not remove metal (like a tap). Spark plug threads tend to collect carbon over time and the chaser will cut through it. You might get lucky. If the treads are really stripped then you can install a “spark plug insert kit”. It’s like a Heli-coil but you get a special tap in the kit that you run down the old plug hole. This tap enlarges the hole and puts threads in for the insert. The insert then screws into the hole and it is threaded for a 14mm spark plug. Yes, you can you this without pulling the head. It’s a pain on the Z31 because of the location of the spark plug, but it can be done. Just first cram an oil soaked rag into the cylinder through the spark plug hole to collect all the metal shavings. Tip: Do not use the crappy glue that comes with the kit. Use JB Weld instead. Otherwise, the insert will back out. Quote Link to comment Share on other sites More sharing options...
specialk Posted January 21, 2007 Author Share Posted January 21, 2007 Anyway, I've already got both heads off and the back two pistons on the drivers side have debris marks on them. BIG debris marks. LOTS of BIG debris marks (OK, not exactly lots, maybe 20 per piston). Not like a bolt, but like the tip of a screwdriver fell into each of them and left a bunch of marks on the piston (and then exited the cylinder). This is a pain in the keester, but I'm going to leave that bit as is -- cause I'm sure not removing/replacing the pistons Quote Link to comment Share on other sites More sharing options...
Guest TeamNissan Posted January 21, 2007 Share Posted January 21, 2007 Anyway, I've already got both heads off and the back two pistons on the drivers side have debris marks on them. BIG debris marks. LOTS of BIG debris marks (OK, not exactly lots, maybe 20 per piston). Not like a bolt, but like the tip of a screwdriver fell into each of them and left a bunch of marks on the piston (and then exited the cylinder). This is a pain in the keester, but I'm going to leave that bit as is -- cause I'm sure not removing/replacing the pistons You mite as well though man, then you get the peace of mind knowing the bearings and rings are new. Used and undamaged pistons rings and bearings are really cheap for that too. You could do the job yourself with a manual. Quote Link to comment Share on other sites More sharing options...
specialk Posted January 21, 2007 Author Share Posted January 21, 2007 Really cheap? Where? All the rebuild kits I see are multiple hundreds of dollars. Quote Link to comment Share on other sites More sharing options...
Guest TeamNissan Posted January 21, 2007 Share Posted January 21, 2007 I dont have a nice easy internet source for you ( although I'm sure someone in here can help you out with that. But I recent rebuild a 85 n/a for a friend and bearings, rings and a master gasket kit came out to 350 bucks from my local parts place. Oil and water pump was another 200. But thats a small price to pay in my opinion. Quote Link to comment Share on other sites More sharing options...
specialk Posted January 21, 2007 Author Share Posted January 21, 2007 Not for a car I don't expect to keep for too long. This is a daily beater that I just need to have run -- and not forever Quote Link to comment Share on other sites More sharing options...
Guest TeamNissan Posted January 21, 2007 Share Posted January 21, 2007 ah well screw it then i guess lol, that a piece of info that should be included you know . Quote Link to comment Share on other sites More sharing options...
specialk Posted January 21, 2007 Author Share Posted January 21, 2007 I 'intimated' it, just by claiming I wasn't going to go through the whole engine, but I do appreciate the help One other query though: The haynes mentions "all the different lengths" of bolts in the lifter and head bolts. I found all the lift bolts to be the same length and only 2 lengths in the head bolts. Do you recollect if that is what you've found too? Oops, one more question: I see exhaust gaskets listed that appear to be for one port at a time. I assume I just buy six of them, is that correct? Quote Link to comment Share on other sites More sharing options...
Guest TeamNissan Posted January 21, 2007 Share Posted January 21, 2007 I never messed with the heads on that engine so I cant say about the lifters but ya there are 2 dif lengths for the head bolts. Maybe its just being general about all the bold being dif but not just about the lifters. Ya you buys six of them, I have seen them come as singles and in 3's though not sure if thats by year or option. Quote Link to comment Share on other sites More sharing options...
specialk Posted January 21, 2007 Author Share Posted January 21, 2007 thanks very much! Quote Link to comment Share on other sites More sharing options...
specialk Posted January 21, 2007 Author Share Posted January 21, 2007 Anybody have experience with ebay seller partsdinosaur? He sells gasket kits for cheap and I'm wanting to get this thing running! Quote Link to comment Share on other sites More sharing options...
mtcookson Posted January 21, 2007 Share Posted January 21, 2007 Parts Dinosaur is awesome. I've bought the head gasket kit from him twice, one for my boosted Maxima and one for my turbo Z31. First time I got them for my Maxima one of the head gaskets got damaged in shipping so I emailed him and he sent me out a good head gasket right away. Definitely a good seller. I was worried about quality of the kit but the head gaskets are just like stock and they've held up just fine on my Maxima (replaced all of the upper gaskets). I haven't driven the Z much but I'm sure that one will hold up just the same. Quote Link to comment Share on other sites More sharing options...
specialk Posted January 21, 2007 Author Share Posted January 21, 2007 Thanks for the input (if you have a second, any input on the picture above?) Quote Link to comment Share on other sites More sharing options...
mtcookson Posted January 21, 2007 Share Posted January 21, 2007 On the pistons, as long as there aren't any gouges in the cylinder walls it should run pretty decent. Being a temporary daily driver, it should be fine. I actually have a VG30ET that looked similar but it was in even worse shape having 90 psi compression in four cylinders and 50 psi in two. Some of the pistons were actually missing metal on the edges. It was bad. Here's a picture of one of them, on the right side. http://www.machzracing.com/pictures/vginternals6.jpg That one is actually one of the better looking ones. The engine was absolutely abused (I think major detonation and such). Quote Link to comment Share on other sites More sharing options...
specialk Posted January 22, 2007 Author Share Posted January 22, 2007 My heads look like the mirror of the pistons (no surprise). The cylinder walls in all 6 cylinders look fantastic, but I'm so conflicted now I have 2 86na engines, each with manuals; the one you've seen here and another in the car, with a frozen cam. I also have an 87na with a toasted automatic. My plan was to take the 87 engine and stick it in the 86, and stick the engine you've seen here (and it's xmission) in the 87. Divest myself of the 87 and keep the 86 (I like it's looks more). Now, I'm thinking stick the 86 xmission in the 87 and work (over time) to get the frozen 86 engine running again. Yuck. Quote Link to comment Share on other sites More sharing options...
mtcookson Posted January 22, 2007 Share Posted January 22, 2007 If repairing that engine take much money I would just look at getting another VG. There are so many out there in decent shape that you can pick one up in good condition for very cheap. It sounds like you're getting everything planned out pretty well though. Good luck with everything! Quote Link to comment Share on other sites More sharing options...
specialk Posted January 22, 2007 Author Share Posted January 22, 2007 Seems a better idea (the 'other VG', that is). That's my leaning now. Quote Link to comment Share on other sites More sharing options...
Alex_V Posted January 26, 2007 Share Posted January 26, 2007 Thats detonation damage. Clean off all the carbon thats collected on the cyl heads and pistons, or run 89 octane or back off the base ignition timing 2-3 degrees. That will eventually damage the pistons and kill the engine, but it wont kill an NA engine that easy. As you can see though its well on its way to becoming the engine MTcookson had to replace. ~Alex Quote Link to comment Share on other sites More sharing options...
specialk Posted January 26, 2007 Author Share Posted January 26, 2007 Detonation on 2 cylinders only? Quote Link to comment Share on other sites More sharing options...
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