My apologies in advance. I posted this in another thread, but it's buried so deep on page 2 that I don't think it will get seen. If anyone needs tech help with MG's, 5.0 Fox Mustangs, 65-69 Mustangs, or pre '55 Harleys, I'll be glad to help out. With gas at $3, an overcammed 347 stroker Mustang, a 454 3/4 ton Suburban and a supercharged Poncho GTP don't even combine to get 30mpg so I need to get the Nissan on the road....
I recently bought an immaculate, and obviously well maintained '97 base pickup with 5spd and 126k miles for almost free (traded for about 4 hours worth of grading with my tractor), that also came with a "free" noise that sounds a bit like a rod knock above 1800 whether under load or free revving. Engine also overheats after running or idling for 15 minutes, but the owner (a neighbor) said it never boiled over, and I know that he parked the truck the day it started giving him problems and bought a new 4wd. It would have sat in the shed forever if I hadn't asked him about it and made the offer myself . I was willing to also part with some cash, even after he told me what had happened so he had no reason to hide anything. The temp gage only gets a bit more than halfway between N and H but it's definitely hotter than indicated (my guess is 220-230*). I pulled the tstat, but that didn't change anything. Waterpump is fine, and so is the timing, and there aren't any vacuum leaks that I could find using propne.
I've pulled and grounded all the plug wires one at a time to vet out a bad rod bearing/wristpin, but noise remains exactly the same which leads me to suspect that its "all in my head..." I also checked to make sure that the cam gear/shiny link and crank are all matched at TDC and all valves appear to be opening and closing fully.
Number 1 cyl has 70# dry/80# wet and 2/3/4 have about 170, so one way or the other the head is coming off. I I had already pumped the cooling system up to 10 psi and it didn't leak down at all after 30 minutes. This afternoon I did a leakdown test, and there is a huge leak into the crankcase. Takes less than 30 seconds to go from 100psi to 0. Since there's no indication of oil in water or water in oil, and it's not smoking at all, I'm betting (hoping...) on a bad gasket, and (praying) against a cracked head.
This thing also has a REALLY bad chain rattle at startup - machine guns for 3-4 seconds, not just the routine 1 to 1.5 second loud clatter that my son's pickup has. I noticed that depending on exactly where the engine stops, the timing chain is either very loose on both sides, or fairly tight, but it needs to be replaced because most of the rollers are pretty loose, and the guides and upper gear show more than a little wear. I tried replacing the oil filter using one with an anti drainback valve but it doesn't help.
Since the clattering noise doesn't come on until 1800, I'm wondering if it could it be a failing lifter? I remember that I had to get a full set for a Hardbody that I rebuilt for a neighbor about 10 years ago because a number of them were clattering but it's been so long, I don't remember what they sounded like, although I do remember that the bad lifters also made a lot of noise just off idle.
Some questions:
1. Has anyone had the oil-pressure activated tensioner go bad, or is it just the rubbing block that wears out?
2. Where does the most common headgasket failure occur on these motors? Anything to watch out for before re-assembling?
3. Does anyone know what the normal oil pressure range is? Before I tear it down and spend any money, I want to hook up a direct reading gage to make sure the engine is basically sound, and that the noise really isn't a spun bearing....
4. Would a failing lifter make noise above 1800 but not at idle?
5. Any leads on best-priced parts appreciated.
My apologies in advance. I posted this in another thread, but it's buried so deep on page 2 that I don't think it will get seen. If anyone needs tech help with MG's, 5.0 Fox Mustangs, 65-69 Mustangs, or pre '55 Harleys, I'll be glad to help out. With gas at $3, an overcammed 347 stroker Mustang, a 454 3/4 ton Suburban and a supercharged Poncho GTP don't even combine to get 30mpg so I need to get the Nissan on the road....
I recently bought an immaculate, and obviously well maintained '97 base pickup with 5spd and 126k miles for almost free (traded for about 4 hours worth of grading with my tractor), that also came with a "free" noise that sounds a bit like a rod knock above 1800 whether under load or free revving. Engine also overheats after running or idling for 15 minutes, but the owner (a neighbor) said it never boiled over, and I know that he parked the truck the day it started giving him problems and bought a new 4wd. It would have sat in the shed forever if I hadn't asked him about it and made the offer myself . I was willing to also part with some cash, even after he told me what had happened so he had no reason to hide anything. The temp gage only gets a bit more than halfway between N and H but it's definitely hotter than indicated (my guess is 220-230*). I pulled the tstat, but that didn't change anything. Waterpump is fine, and so is the timing, and there aren't any vacuum leaks that I could find using propne.
I've pulled and grounded all the plug wires one at a time to vet out a bad rod bearing/wristpin, but noise remains exactly the same which leads me to suspect that its "all in my head..." I also checked to make sure that the cam gear/shiny link and crank are all matched at TDC and all valves appear to be opening and closing fully.
Number 1 cyl has 70# dry/80# wet and 2/3/4 have about 170, so one way or the other the head is coming off. I I had already pumped the cooling system up to 10 psi and it didn't leak down at all after 30 minutes. This afternoon I did a leakdown test, and there is a huge leak into the crankcase. Takes less than 30 seconds to go from 100psi to 0. Since there's no indication of oil in water or water in oil, and it's not smoking at all, I'm betting (hoping...) on a bad gasket, and (praying) against a cracked head.
This thing also has a REALLY bad chain rattle at startup - machine guns for 3-4 seconds, not just the routine 1 to 1.5 second loud clatter that my son's pickup has. I noticed that depending on exactly where the engine stops, the timing chain is either very loose on both sides, or fairly tight, but it needs to be replaced because most of the rollers are pretty loose, and the guides and upper gear show more than a little wear. I tried replacing the oil filter using one with an anti drainback valve but it doesn't help.
Since the clattering noise doesn't come on until 1800, I'm wondering if it could it be a failing lifter? I remember that I had to get a full set for a Hardbody that I rebuilt for a neighbor about 10 years ago because a number of them were clattering but it's been so long, I don't remember what they sounded like, although I do remember that the bad lifters also made a lot of noise just off idle.
Some questions:
1. Has anyone had the oil-pressure activated tensioner go bad, or is it just the rubbing block that wears out?
2. Where does the most common headgasket failure occur on these motors? Anything to watch out for before re-assembling?
3. Does anyone know what the normal oil pressure range is? Before I tear it down and spend any money, I want to hook up a direct reading gage to make sure the engine is basically sound, and that the noise really isn't a spun bearing....
4. Would a failing lifter make noise above 1800 but not at idle?
5. Any leads on best-priced parts appreciated.
Sounds to me that it likly had a lack of oil changes. leting the oil go on thes babys is bad news. First the hydraulic lash adjusters colapse then sedement builds up and clogs the ports to the chain tensioner. the tentioner then basicly floats with the chain so that two rattles there. Then the oil starts to pudle in the top of the engine and bakes all over the valve train. Head overheats and just keeps on destroying more parts. sounds like a complete overhaul. Do take a close look at the timing cover thes engines are bad about the chain cuting through the cover into the water pump cavity when the tensioner fails.
__________________ It's much easier to travel through a maze when you have a map!
Spat
Former Nissan Tech
14yrs ASE all but AT it's a bitXX!
New career - HandyMan/Electrician - Freedom at last!!
86.5 Nissan HB D21 234K Miles
94 Nissan Altima GXE ? Miles
97 Dodge Grand Caravan 3.8L 132K Miles
64 Chrysler 300-K 2-door Convertible 63K Miles
1. Has anyone had the oil-pressure activated tensioner go bad, or is it just the rubbing block that wears out?
I had some wear out and some break.
2. Where does the most common headgasket failure occur on these motors? Anything to watch out for before re-assembling?
I'd say between the cylinders or the outside cylinders (edge).
3. Does anyone know what the normal oil pressure range is? Before I tear it down and spend any money, I want to hook up a direct reading gage to make sure the engine is basically sound, and that the noise really isn't a spun bearing....
25+ at idle and about 60 for 2k rpm. Depends on weight of oil.
4. Would a failing lifter make noise above 1800 but not at idle?
I've been away from my home computer for a couple of weeks, but I really appreciate the feedback. The block crank and head are at a machine shop being cleaned up. Some of the rod inserts were badly eroded from a mixture of antifreeze droplets and a whole lot of micro slivers of that @%$!NG silver silicone that was used by a NISSAN DEALERSHIP when the chain and tensioner were changed by the prev. owner last November. I was in the cooling system as well.
The crank and bores miked out to standard with zero out of rounds, and amazingly the crank journals don't have a trace of finger-nailable scores. These motors are tough as nails!!!! The oil control rings were seized, and the gas ports were all blocked, but the compression rings were clean, snug and still had good end gaps, and it didn't burn any oil. Just had some blowby from #1 cyl and I'm fairly certain that was from the early stages of headgasket failure (I didn't see any trace of leakage, but there was a tiny erosion in the block, right inside the #1 cyl sealing ring area, facing towards the front of the engine.
Oil Pressure was only 45psi at 1800, and I was concerned to rev any higher until I found the source of the knock. I had pulled the plugs one at a time and started the engine to eliminate a rod knock, and had previously pulled a couple of Main and Rod caps (and saw no damage at all on the two that I pulled - glad I didn't button it up believing that the head was the source...) I shaved the oil pump cap to get it back to nominal clearance, so with the new bearings, I should be good to go pressure wise. The pump is only a year old, and there were no traces of metal in the pan or in the pump. I did find a bunch of trash including some casting support pins and a 1" long 1/4" diameter cylinder of core sand that had turned to glass and was stuck in the channel between cyls 3 and 4 just inside the freeze plug.
ZENO- Thanks for the tech info.
Hey SPAT- your observations were right-on. I found a 1/2" wide, 1/16" deep spot on the top of the block where a previous chainguide/tensioner? failure had sawed a pretty good chunk away, and I found the remains of 2 complete guides in the bottom of the pan. But no damage at all to the cover. The head hardly ahd any carbon buildup in the comb chambers, but lots of flaky carbon residue was in the oil passages, including in the oil grooves in the main inserts. This truck had faithful oil changes using Penzoil 10w30 every 3000 miles from day one and it only overheated once, but the inside of the motor looks like it came out of a beater Yugo on reclaimed oil....
Block and head will be back on Tuesday next; any reassembly suggestions/tips/trade tricks are welcome.
Thanks again
Seems like you have it all covered and these are rather simple engines. Try a VQ30DE now that will drive you nuts! yeah these nissans are tuff as hell. I haven't miced a nissan cylinder bore yet that was over .004 of wear.
My first Nissan was a 84 maxima with the strait 6 at 213k I rebuilt the engine as my shop project in school. It realy didn't need it but I was planning to go work for nissan so I figured what the heck. Well the highest reading I got on it was .003 wear. I sunk $1200 in that think and a month later some drunk, legaly blind, uninsured jerk slamed into the back of it with his truck while it was parked in a parking lot. It was completely totaled.
I have an 86 hardbody now and it a tuff one as well I plan to get a different truck for work next year and want to do a custom engine swap on it. Extend the front end and drop a strait 6 in it and make a flat bed with wood rails then chrome it out. Just for kicks!!
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