serafanas

Hello all,

I have an issue with my Maxima: This is the noise she makes. It's high-ish pitched metallic noise as is something is smacking a metal at about half the RPM.
After reading in the forum I now have two ideas - distributor gear worn out or timing belt loose.
Is there any way for me to know for sure without getting inside? I do know that distributor would need a new seal if I removed it, and where I live it would be kind of difficult to get just the seal. If someone had this, please chime in. Would be really appreciated. Trying to keep her alive a little longer

ac max 92

iTrader: (13)

Noise travels and could be difficult to say but have you put a stethoscope on it? Could be a worn gear or timing belt for sure or possible valve train.

chrome91

iTrader: (1)

is it the diesel ish clatter throughout the whole video thats the noise?

serafanas

Yes, it's the diesel-ish clatter. And it misses hard. Works like on 4 cylinders. Spark plug wires, distributor rotor and cap brand new (had a bright plasma show before). But changing them to new didn't solve the problem. Spark plugs all look perfectly fine.
Also, distributor rotor wiggles by ~2mm when I try moving it by hand.
Tried using the srewdriver method to listen for the source of the sound and listening around heads does not look like higher noise. Distributor looks like the source.

If it is belt or the distributor, what is the fastest way to check? Can't see a way to get to the belt without removing all the alternator/AC/etc belts to see if it's not tensioned correctly.
Is it safe to remove distributor and not replace the seal on it's stem?

ac max 92

iTrader: (13)

If your referring to the o ring you should be fine. It wouldn't dry rot that quickly if your just pulling the distributor to check the gear you'd just have to make sure you set the timing when you put it back in. If you have a timing gun/light it might not hurt to just check the timing.

chrome91

iTrader: (1)

rotor should move a smidge when moved by hand. its when you get alot of play somethings wrong

but yeah check the distributor if you think thats where the noise is coming from. otherwise it kinda sounds like maybe valve or lifter noise

serafanas

I will be taking distributor out tomorrow then. I do not have a timing gun yet.

Any way to confirm valve without taking the head/s of? Compression test I guess would be easiest? Do valves really fail on maxima's? Had this one a long time now and had a maxima before this for 14 years before this one...

chrome91

iTrader: (1)

not really, theyre interference engines so if the timing belt goes its likely taking a few valves with it. the fact that the noise doesnt really change with rev's is making me think its not a valve or lifter now

serafanas

Yes, the sound changes very slightly with RPM. But it's not linearly increasing/getting faster. Will take the distributor off today and see how it looks. Any way to check tension on the timing belt without disassembling half of the engine?

chrome91

iTrader: (1)

cant remember how hard it is to do but you would have to remove the timing cover or at least part of it

also before you remove the distributor mark where it sits now so you can at least get it back to how it was after removing it if the dis doesnt appear to be the issue

serafanas

I took the distributor out. And now I'm pretty sure it's this bad boy's fault. The gear is chowdered. Not broken, but very rough on all teeth. Metal is all scratched. The camshaft teeth look ok. After starting her back up I placed my ear directly on top of the distributor cover and it's definitely the source of the sound. So I guess some bearings inside the distributor are toast?

chrome91

iTrader: (1)

was the distributor bolted down tight? weird that the gears would be chewed unless its a bearing in it loose

serafanas

It was bolted down pretty tight. And it was pretty difficult to get it out after loosening it. So we'll see if a new distributor fixes this. If not, I'll need to disassemble much more to find the issue.

ac max 92

iTrader: (13)

Did you ever get another distributor? I have a used one if your interested? 45 + shipping. Pm me if you need it.

serafanas

Yep, got a new distrubutor... And it didn't help one bit. Now after it didn't solve the issue, I did what I should have done weeks ago - check injectors. One of them measured 4 Ohms. Got a new injector, it measures correct - 12.6 Ohms. But it doesn't fire. So, I guess wiring is shot somewhere down the line... Now waiting for some time to free up and I'll go down the rabbit hole to find where that injector's wire is broken.

I changed all 6 injectors to a set of new injectors 2 years ago (4 were dead), so that fooled me into thinking that "it surely is not the injectors" and it cost me quite a sum...

Tarzan

Diesel'ish chatter can be a sign of broken exhaust manifold studs. But by this age, I'd assume those should have failed long time ago and gotten replaced, should they not?

serafanas

Yep, exhaust studs were changed last summer. And I could tell that sound from any other sound in my sleep.

chrome91

iTrader: (1)

what octane gas is running in it? if its hot as ***** where you are and you have low octane fuel it can make a diesel noise. long shot out of it needing to be damn desert hot

serafanas

I'm in Europe, so it's 95 octane. And it's not hot there yet, so not the issue here. I'll report back when I find the time to troubleshoot the wiring of that injector

Tarzan

Well, technically by this age the combustion chamber may have quite a lot of carbon deposits (unless at some point the head was pulled and it and pistons/valve heads cleaned), which may start glowing and you get "premature detonation" known as knock.
But if you always hear this noise even when you start a cold engine, then of course yours is not from knocking.

serafanas

So, just returned from my garage. I am confused.
Pulled a known good injector's connection of to double check.

Bad injector:
Engine off
Left ---- Right
12V ---- 0V ( at first got a spike to 10v, but maybe it's my meter)
Engine idle:
Left ---- Right
14.2V -- 10.2V

Good injector:
Engine off
Left ---- Right
12V ---- 0V (no glitching)
Engine idle:
Left ---- Right
14.2V -- 0.4V

So is my ECU fried? Or is the wire shorted and it manifests just when the car is started?
Measurements were taken at the injector connector (wiring, not the injector itself). triple checked every measurement.
Now, if we come to the conclusion that the wire from connector to ECU is shorted... How do I change it? My only option is to make a new hole in the firewall, because I'm not disassembling that wiring "log" that is just behind the injectors.

Tarzan

Rather sounds like ground is bad from that injector, or am I out to lunch?
In Gen 3 ECU, are injector positives hot, or injector negatives? From your measurements it sounds like injectors positive is hot, and injector negative is too positive, so I feel it's a bad ground. Measure your "right" to the engine ground, if you do not get a short circuit around 0.1 Ohm, check ground connection. Hope I am making sense.

serafanas

Injectors are positive hot. Measured straight to engine intake, so only better ground would be to the battery, but I doubt it would be any different. I'll do the final check tomorrow. Find a long wire and ohm the lead that goes from ECU to injector connector.

serafanas

So, ECU is the problem there. Measured straight from main harness connector to 3 injectors (the back ones). All wires measure to 0.3 Ohm... Looking for an ECU in junkyards now.

ac max 92

iTrader: (13)

I'll have to take a look but I may still have another ecu left if your interested? I had a couple ecu's. I know I sold one just not sure if I sold both I had. If your interested pm me and I'll have a look.

serafanas

I am from Lithuania, so I imagine it would be very expensive to have it shipped from Canada. Thanks for the offer and all the help. Trying to source it locally now

Tarzan

If that fails, Poland has tons of formerly German old cars, if you can try calling around shops in Poland, they might have some.

serafanas

I'll try if the one from Latvia does not work. Waiting to have it delivered this week. I tried looking in this forum for info if the ECU's were any different one from another, but I found no useful info. I know that California definitely had some extra emissions stuff, but other than that - all of VG30E ECUs and parts for that matter are all the same throughout the years.

ac max 92

iTrader: (13)

Strangely enough I ordered a sensor for my Benz from Latvia and was actually more affordable both part and shipping wise then it would have been from U.S to Canada. If you wind up needing another ecu I could always get you a shipping quote if you like. I could let the ecu go for 50 usd + shipping or I could do both ecu and tcu go for 70 usd+ shipping.

serafanas

Yeah... Got my ECU today and it seems it's not the problem. Same cylinder misfiring. I did seal the injector correctly, so I guess now my only option is to tear down the intake AGAIN and try to see what in the hell is wrong with it.

Thanks for the offer, ac max 92. Latvian guy sent me TCU too, not sure why.

Tarzan

That sucks. So to continue down the troubleshooting path, can you measure resistance from the negative of the "bad" injector to the engine block, and post the Ohms here. We need to find out why you are seeing 10V there. The voltage drop on the injector remains to small to open it, obviously. If you had access to an oscilloscope, that would help as well.

Also, do you have the FSM? Look up the wiring diagram for the injectors and follow the negative wire. It could have shorted with something else receiving those Volts you are seeing. This is a very old car we are looking at, so insulation wear is a real possibility.

ac max 92

iTrader: (13)

Wouldn't hurt to check the ground by the intake manifold too and clean it up if need be and re attatch. Did you ohm test the injectors too? 10-14 ohm on each injector?

serafanas

So... I feel dumb now. I didn't have much time to check the junkyard ECU, so I just plugged it in and started her up. That same evening I remembered that I forgot to plug in all injectors. So I started her on 4 cylinders before. Just drove ~30km with her and it's all back to normal. I still have a slight miss on idle and in drive when standing still. No idea why I have that slight miss, but it's not bothering me much. It happens every 5-10 seconds and is barely feel-able. Not sure if I want to invest time into tracking it down as now I have brand new ignition system (except the transistor and coil). So either it's some ground or ???

Anyway, thanks to everyone for all the input

serafanas

Also, there still is a very strong gas smell when driving and opening a window. No idea where it's coming from as all the hoses are dry as they can be. Exhaust? but when smelling from exhaust tip it's smelling like fully burnt gas - no gas smell at all. I'm playing with this riddle for half a year now.

Tarzan

For gas smell, look for leaks around fuel lines. I had a leak in Winter from that short piece of fuel line which connected front and rear fuel rails. Was a beotch to reach for replacing, as it's under the intake manifold. Old fuel lines dry up and their clamps no longer hold gas pressure.

For a small miss, if it really repeats itself at regular intervals, it may be connected to gas smell. If you'll find and eliminate a leak, chances are your gas pressure at the injectors will increase and fix your rough idle.

ac max 92

iTrader: (13)

^ +1 I agree with this as it's a likely place and also common on these cars with the age. It's always a good idea for what it's worth to just change both small pieces on either side of the rail when doing your injectors being your already in there. If I'm not mistaken your fuel smell is probably more evident on a cold start and sometimes by the time you check you may not see it because the fuel evaporated quickly. If it was your exhaust you'd probably have more of a miss due to an injector not seated right or stuck open dumping fuel.

chrome91

iTrader: (1)

yep fuel smell on cold start/cold climate on 3rd gens is most often the fuel lines

CMax03

iTrader: (3)

I believe you have connector and injector issues...Best to replace all the injectors with Partsgeek GB injectors, and upgrade all your injector harness with new connector pigtails (weatherpack design) from ebay $25 for set of 6....

serafanas

The gas smell is not when starting the car, but driving it and opening any window. I can't locate the source my using my nose around the car. All the lines look in perfect condition and first I checked is the one that connects two fuel rails together. I'm a bit lost where it may be leaking that much and not be visible at all...

chrome91

iTrader: (1)

check the gas tank for any leaks maybe as well as the fuel filter