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92 VG30E Engine noise


Huck
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My poor Pathy started making an awful sound while I was on my way home from work the other day. It was keeping the engine from running right. Real bad miss. I couldn't keep it running without someone holding the throttle and running the engine about 1500 RPM. I've done some diagnosis to see what might be the problem:

 

Noise: Fairly intermittent, somewhat metallic. Doesn't sound like a connecting rod knock (heard a few Ford V8s with bad rods). No metal in oil.

 

ECU: No check engine light.

 

Timing: Was spot-on before the problem.

 

Compression test: 120-128 psi across all six. Side note: Driver's side bank a real b**** to get to....

 

Visual inspection of Valve Train from top shows all lifters and rockers in their proper place. Nothing bent broken or missing visible from top of heads.

 

The funny thing was, I was just in traffic. I wasn't (and hadn't) really worked her hard since the previous weekend (12 miles in on a logging road. Here ). I did have some belly scrapers. Could I have picked up a rock in the clutch? I did a clutch in my last Pathy with my dad about four years ago, but I can't remember if the bell housing is open at the bottom of this transmission. Any ideas???

 

BTW, this motor is a non-interference motor, so a valve would have to be mangled to strike the piston, right?

 

Huck

Edited by Huck
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BTW, this motor is a non-interference motor, so a valve would have to be mangled to strike the piston, right?

 

Wrong, this is an interference motor. If your timing belt jumped, you can be smacking valves. When is the last time the timing belt was replaced? 87-93 motors state 60k mile change intervals.

 

ECU: No check engine light.

Did you run the ecu codes? Explanation in the "Garage/How To" section

 

Timing: Was spot-on before the problem.

Have you checked it since?

 

Compression test: 120-128 psi across all six. Side note: Driver's side bank a real b**** to get to....

This was checked after the issue occurred? I don't know if you would get a full compression reading if the belt slipped a tooth or two...

 

I did a clutch in my last Pathy with my dad about four years ago, but I can't remember if the bell housing is open at the bottom of this transmission

No, it is not. I don't think that has anything to do with the issue.

 

First thing I would do is check the timing and the ECU for codes. Do you have a mechanic's stethoscope? A piece of tubing or metal rod can be used in a pinch...

 

B

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  • 2 weeks later...

Fixed it! The timing belt idler pulley loosened and allowed the belt to jump a tooth. I haven't started it yet, but I want my buddy mechanic to look it over before I close it all up to make sure it's timed right. I'll post again once I've done a compression test. The first indicator should have been how loose the belt felt when I first pulled the cover off.....

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Glad you found it and hopefully it did just jump 1 tooth and nothing was damaged. Since you are in there, you may want to consider replacing the belt and tensioner just to play it safe. Again, do you know when the last time it was changed? How many miles on the truck?

 

B

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I'll post again once I've done a compression test.

 

damn the compression check fire that bitch up...if you hit a valve you more than likely didnt hit 1 you hit at least 2 (being that 1 cylinder is exhausting when 1 is on the intake)...if it runs like ass and smells like raw fuel you some valves...no biggie go buy a gasket set and all new valves (dont want to take the risk of missing 1 bad one and having to buy a new gasket set and a valve spring compressor, lapping paste and valve lapping tool, torque wrench and a 10mm alan head socket

 

I completely broke a timing belt doing like 50ish and bent 3 valves (1 of which was over looked initially and discovered to be bent later but luckly we replaced all of them)...rebuilding the top end was my 1st major experience with the supervision of one of my ex gf's fathers who told me yea i've done this lots of times before (no he had only done it once in kwajalene (sp) on a civic) and told me after the fact but now knowing what i know and only doing this job once I could do it again in my sleep and I would tell a buddy the same thing to make them less nervous...3 days total...1 tear down and wait for parts....2 pick up parts and had 1 wrong valve so rebuilt what we could and then the next day threw it all back together

 

2nd from the left is a straight valve the rest are bent #1 exhaust and intake and #3 exhaust (the one tagged in red is the #1 exhaust and was found after the fact to be bent ever so slightly) another good tell tell sign of which 1 hit is look at the piston...i bet theres a smiley there...

 

20500780046_large.jpg

 

But all that said hope its only 1 tooth and you're sailing good...if not don't let the job intimidate you especially if you or your friends are mechanically inclined and you can save a boatload of $ doing it yourself and start building your tool collection if that's what suits you. This job would have cost me probably close to 1k @ a shop and we got out right around $250-300 which I then got lectured b/c he wouldnt let me pay for anything and i made him take the $ from me but he was being a great person helping out a broke ass college kid like someone had done him back in the day

Edited by unccpathfinder
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Glad you found it and hopefully it did just jump 1 tooth and nothing was damaged. Since you are in there, you may want to consider replacing the belt and tensioner just to play it safe. Again, do you know when the last time it was changed? How many miles on the truck?

B

 

Brand new belt on there. It was last changed at 175k and I've got 183k on there now. It's in good shape, not even worn. I'm tempted to change the tensioner. As far as I can tell, it just backed off a bit and let the belt loosen.

 

uncpathfinder: I think I'll play it safe, unless you have a spare set of pistons and valves laying around that I could have. I was just barely idling when it went, so I'm pretty sure I lucked out. I did my best not to run the engine too long or rev it at all because of the noise.

 

Once again, when I get the courage to do this job, which I think is just re-timing my valves (and a first for me), I'll post with details and maybe a how to and some pix.

 

Experience can be the best Teacher.

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Brand new belt on there. It was last changed at 175k and I've got 183k on there now. It's in good shape, not even worn. I'm tempted to change the tensioner. As far as I can tell, it just backed off a bit and let the belt loosen.

 

Ok, just looking out for you. A few summers ago 4 or 5 members had timing belt issues. A few with very ugly results. I just hate to see something so avoidable happen...

 

B

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uncpathfinder: I think I'll play it safe, unless you have a spare set of pistons and valves laying around that I could have. I was just barely idling when it went, so I'm pretty sure I lucked out. I did my best not to run the engine too long or rev it at all because of the noise.

 

if it comes to that I have 2 complete sets of heads laying around (one being the rebuilt set and the other off of an 86 maxima) and well yep i have a set of pistons out as well

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if it comes to that I have 2 complete sets of heads laying around (one being the rebuilt set and the other off of an 86 maxima) and well yep i have a set of pistons out as well

 

LOL! I was kinda joking, but in all seriousness, I might want to buy those from ya if it comes to that....

 

Right now though, the only reason I'm on a broadband connection and not a dialup is because my wife is still working. I'm waiting for the laborer's union and the company I'm starting with to get off their a$$eS and talk so that I can go to work and make some money. Unemplyment doesn't pay well.

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yea...i've been getting rid of crap b.c. its getting close to moving time again and I always hold on to stuff b/c theres somone that will need it sometime and if i throw it away then they're going to need it or i'm going to need it and have to spend a lot more $ than what they should.

 

 

ouch...yea i understand that completely...if I was closer I would offer some assistance but if it comes to that maybe there's someone in the area that could assist.

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yea...i've been getting rid of crap b.c. its getting close to moving time again and I always hold on to stuff b/c theres somone that will need it sometime and if i throw it away then they're going to need it or i'm going to need it and have to spend a lot more $ than what they should.

ouch...yea i understand that completely...if I was closer I would offer some assistance but if it comes to that maybe there's someone in the area that could assist.

Thanks man. In these times, we need more people like you. I'll pay it forward. There's the B.C. guys just across the border from me. After some quick research, there's a great junkyard across the border in Surrey too.

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  • 1 month later...

UPDATE!!!

Timing belt was a little loose. Went through the timing and re-timed the valves. Went by the book all the way. Rolled the engine through by hand and I'm still getting resistance randomly (never in the same crank position). My mechanic buddy said "All that leaves is your oil pump." I guess since I have the whole front end apart, putting a new oil pump on (at 183k miles) isn't so bad.

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Yes, all the spark plugs are out. I wasn't able to turn it through the compression stroke by hand with the sparkies in. The feeling is way different between the compression stroke and the firm stop I get from the oil pump.

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  • 3 months later...

Well, it's been a few months now. I re-timed the valves four times (fourth time with help from a guy who's done a couple). Note: there are three marks on the timing belt and they're all three very important, 'nuff said. It fixed the problem. The timing belt must've slacked enough to slip a cog. It passes the compression test on all six cylinders at 120psi (+/- 10psi). Now I have a lifter making a racket from sitting there without oil too long. Easy fix.

 

Got rain making mud out there right now. Wish I was at Portal Pit throwin' some around... Better not push my luck.

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Note: there are three marks on the timing belt and they're all three very important, 'nuff said.

 

not so much the marks on the belt but more importantly the # of teeth between cam to cam and cam to crank

 

glad to hear you didnt bend anything and only jumped a tooth or 2

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not so much the marks on the belt but more importantly the # of teeth between cam to cam and cam to crank

 

glad to hear you didnt bend anything and only jumped a tooth or 2

 

Yeah, I'm lucky for what happened. The sucky part is I have to take off all those damed hoses with the plenum because the lifter noise is on the driver's side.

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Now I have a lifter making a racket from sitting there without oil too long. Easy fix.

 

Try flushing the motor and changing the oil. I used to have a lifter tap at start up but after I did that it went away completely. :shrug:

 

B

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Try flushing the motor and changing the oil. I used to have a lifter tap at start up but after I did that it went away completely. :shrug:

 

B

 

 

Ahh, the cheap way. I like it! ;) Just sludge in the oil channels/lifters or something like that.

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Yeah, pretty much. I should be more clear though. The lifter only tapped at start up but pretty hard. I did an engine flush and replaced the oil filter with the cheapest I could find, put in the cheapest oil I could find, drove it for a week (100 miles), then replaced the oil with Castrol semi synthetic and a Bosch filter. A few weeks later I realized that I hadn't heard the tapping for a while... :shrug:

 

I'd definitely try flushing and replacing oil before tearing into the motor if it was me, but then I don't know how bad the lifter sounds...

 

B

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Yeah, pretty much. I should be more clear though. The lifter only tapped at start up but pretty hard. I did an engine flush and replaced the oil filter with the cheapest I could find, put in the cheapest oil I could find, drove it for a week (100 miles), then replaced the oil with Castrol semi synthetic and a Bosch filter. A few weeks later I realized that I hadn't heard the tapping for a while... :shrug:

 

I'd definitely try flushing and replacing oil before tearing into the motor if it was me, but then I don't know how bad the lifter sounds...

 

B

 

Good to know. Can't wait to start slingin' mud again.

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