[small reward] SOHC sounds like a diesel. Few quick questions.

[acgourley]

So I replaced the timing guides on my SOHC a couple weeks ago, the engine sounded like a diesel ever since. Imagine the sound of an old truck pulling up to you.


Few things:

-700 miles later, the problem persists. Perhaps there is a drop in power, I can't say that for sure.

-My timing is "about" right, it it where it was pre-diesel at TDC 0. However - the spindle between the dist. and the oil pump isn't necessarily in the same spot. I couldn't find all the marks people talk about, so i just installed it such that my dist. is how it used to be.

-Idle is fine.

-Plenty of oil, but when starting the engine, usually when its cold, the oil lamp blips for a very short period, periodically, until the car heats up.

-No obvious vacuume or electrical problems, but then again my eye for these isn't great.

-ECU Code 55 (no problems recorded).


Questions!

Could this be from my timing chain? At one point it was 2 teeth off when looking at the cam gear, but I didnt check while i had the crank gear visible. Anyway to check this without taking off the front cover? Mirror + stick? Would this cause the diesel sound? I didn't move the chain on the gears, I DO NOT see how changing the timing guides could have made the chain jump teeth. If they're off.. they probably have been for a while and can't be the culprit.

Could this be a fuel injector? How should I check? Wouldn't the ECU throw an error code in this case?

I've heard people say this happened from their manifold being loose, but i didn't touch it, and it looks fine w/o taking the heat shield off.

I appreciate the help, I'll try to respond in as much detail as I can, and keep this post up to date. Please ask for any clarifications details you need.

If you directly lead to the solution, I'll paypal you 10 bucks. Not much, but I'm pretty far in student loans/CC debt since i'm just finishing school :P

[gotta240]

If your oil light is bliping, dont run the car. I wish i could give you further insight to the problem, but i will tell you not to run w/ the light on at all.

I once used a crankcase cleaner and it loosened a lot of debree. That debree got into my oil pump. The light went on just for a couple seconds on start-up. I turned it off and had it towed...after the oil pump was cleaned/cleared i got a rod knock a week later..... just a heads up

[acgourley]

Hrmm. Thanks for the warning. I actually have ran it about 700 miles since i did the work on it last. (Long drive home for the holidays) The light thing seems to be recent, since i got back. So hopefully that means its not debris in my pump.

[big_schaf]

sounds like its time to take a trip to the wreakers fro a replacement motor...or a de or a sr..or if your a baller a rb

[Walperstyle]

SOHC = valve issue

SOHC engines are known for making a ticking noise that follows with the throttle response.

solution

http://www.northwestnissans.com/board/showthread.php?t=50073

[Blackhat]

On the more hopefull side of things. A vacuum leak will generate the same type of "diesel-truck" sound. Happened to my 240 when I removed the EGR and didn't get the hole plugged all the way. There's a pretty good loss of power when that happens though. Might want to double check any vacuum lines you may have moved around when doing your work.

I'll hope for you that it's just a vacuum leak but that oil pres. light doesn't sound too good.

[acgourley]

big_schaf: new engine isn't an option right now. if this car breaks i'm out of a ride for a while haha.

walperstyle i'll check it out

Blackhat, I'll check the EGR. My only question is, wouldn't that throw a code?

[Blackhat]

I didn't necessarily mean the egr, I just mean check any vacuum lines you may have worked near (and maybe gotten loose). The EGR reference was something I did that created a vacuum leak.

[acgourley]

A vacuum leak would make a lot of sense, it's just hard to find those hehe. None of them in the area i worked are incorrect, but I could have pulled/cracked a tube down the line easily. I suppose i'll find the vacuum diagram and follow each line one by one...

[acgourley]

one more thing, if it helps - my gas milage is fine. But it sort of smells like my emissions...wouldn't pass smog. It's not super strong though.

[Blackhat]

Any smoke?

Does the oil pressure light always come on on coldstart? You said it was blinking, don't suppose there's excessive vibrations in the engine?

[Densetsu Motorsports]

Try to take off the upper tensioner.

[BOROSUN]

mixed sparkplug wires?

clogged cat or exhaust?

[acgourley]

Update:


I think the oil light was just the car *slightly* low on oil. It was leaking in a few spots I had not tightened enough. (I need a small torque wrench, I guess on everything that isn't 1/2 inch drive) After adding oil, the light doesn't blink on or off the 2 times i tried starting it up.


I traced about half the vacuum lines, which look okay. One to the EGR solenoid was a bit loose, but it didn't change anything. The rest are all underneath my injectors/throttle body area, and I can't really see them.

The sound remains! It is hard to describe, but i'll try: part of the normal engine sound is louded and sharper than usual. Maybe you'd consider that 'tapping' maybe you'd consider it the raspier sound of a diesel. When I listen around with a wrench, no part is explicitly tapping. The top of the valve covers just make a whooshing sound, like everywhere else.


Densetsu Motorsports: It's a sohc

BOROSUN: never moved them from their spots, never messed with the exaust. This all happened after fixing my timing chain guides.

blackhat: no smoke


Thanks for the help so far guys...

[acgourley]

Oh and just to vent, i bought some aluminum pulley on ebay ... guess what, didn't fit.

Great. So i file it out a bit, it goes on halfway this time. Me, being bright, decide to just use the bolt to force it on. Totally demolishes the pulley. Luckily everything else on my motor is fine, the pulley was weak and gave easy.

Sigh, oh well. At least it didn't cost much.

[ViZion Zs]

check to make sure your firing on all cylinders, go through and unplug each wire and see if it make a difference or no difference if there is a difference decide if its spark or fuel. most likely you need to reset your chain.. or you blew your headgasket.. check your oill is it oil or yoohoo?

[DOHC20sr]

i had a funny noise kinda like that on my sr...dont know if its the same or not, but i ended up haveing a colapsed lifter

[acgourley]

Vizion Zs: I'm firing on all 4. The oil is also fine.

As I mentioned...maybe its my chain being off a few teeth. I'd be VERY curious how it moved teeth while all I did was adjust the guides..but shit maybe the slack hung down and it moved over the crank shaft gear a little bit?

[acgourley]

i had a funny noise kinda like that on my sr...dont know if its the same or not, but i ended up haveing a colapsed lifter



yeah, this sounds like the next step for me. I need to either check my chain or check my lifters.

I have a big question now ... how bad can either of these problems be for my motor?

If either is real bad, i'll get to work asap. But this is a really bad time for me to sweat this stuff too much, i have finals and then am moving 2-3 times in the next couple months.

[BOROSUN]

yeah, why dont you do a power balance test first.

also why dont you double check your exhuast manifold and gaskets

[acgourley]

Yeah, i did the balance check, its not that. Besides, when one cyl isn't firing, the engine shakes pretty bad, and that is not happening.

I should check the exhaust manifold. I'm gona go take off the heatshield...then just manually inspect for cracks? I tried search but couldn't find much info on this.


edit: Its damn hard to take OFF the shield, huh? Well I looked all around it, didn't see any gap between the manifold and the head, and the manifold, while rusty as shit, seems to be without noticable cracks.

[acgourley]

Update

If anyone is following this, I just had a mechanic look at it for a short while. He was sort of puzzled as well, but he said that because my idle was fine, it probably wasn't vacuum or timing chain problems.

He also told me the misfiring was due to the valves, which was probably due to the lifters. We both agreed it was strange for my lifters to go while i wasn't even working on them.


In the end, it looks like I can drive on it for a while, and my motor isn't going to explode. Thats good.


Anyway, no one here *really* answered my question, but Walperstyle did lead me to lifter thread. If that turns out to be it, i'll revive this thread and pay up to him or donate to the forums or something.


sidenote: i wanted to take a poll, who else ran into this issue, or hasn't? how many miles? Did you get your lifters replaced ever? Just curious.