RIP 94Q...LOUD Engine Knock, Oil Light On

[goody90q45]

A quick summary if you don't care to read my ramblings* Oil light on and engine has a loud knock.* How do I diagnose what went wrong?* Based on symptoms, diagnosis may be futile since repairs may be too expensive.* My willingness (and abilities) to do this type of DIY repair are limited but part-out is an option since I was thinking of selling one of my Q's anyways.

I think she's dead but I'm looking for advice on whether to do expensive and maybe futile exploratory surgery, or a caropsy looking for the cause of death as I part her out.

I started a few days vacation Wednesday morning by waving goodby to the wife as she drove off to work in the 94Q. She'd been driving it all week since her Accord needed new tires which was the honey-do at the top of my "enjoy your vacation while I work" list. Thirty five years at the same job does have its priviliges (lots of vacation).

Five minutes later I get a call from the wife saying the oil light came on and the engine has a loud knock. My main reason for standing on the porch to wave goodby was not to throw kisses at the wife but to listen to the Q as it drove away. Everything sounded normal as she idled in the driveway and drove off. She made it about 2 miles before having problems.

I followed her route expecting to find a trail of oil leading to the Q and there was none. Oil level was full (and clean) but the knock is constant and sounds like it's coming from both heads as well as both sides of the bottom end. It's so loud I really can't pinpoint the source. There's also a smell of fuel but no white exhaust (injector o-ring).

I took the wife home and let her take the 90Q to work (I'm a risk taker). I dropped off the wife's car for tires, had breakfast close by to mull my options while I waited and then went and had the Q towed home to the "Driveway of Doom" (3 other Q's have been parted out there) while I decide what to do next.

I'm really heartbroken over this because this Q is in excellent condition mechanically and cosmetically. I've spent about $7000 over the last 4.5 years getting it this way. I just fixed the transmission and it was finally shifting properly. Right now I'm undecided whether to spend a lot of time and money to find and fix the problem (exploratory) or start parting it out with the idea of looking for what might have broken (caropsy). I'm hesitent about spending $$ on diagnosis because I can't imagine that an engine knocking this loudly can be quieted without major work. I'm also sitting on a 90Q that runs great and was considering selling one or the other anyway so this may be a blessing in disguise.

What I've done so far is change the oil and filter looking for metal chunks. There were none. I plugged in the Consult and there were no ECU codes except for my one dead KS. All the engine functions (including timing) are normal except the injector duty cycle and another injector function I can't think of right now. The oil light remains on and the knocking is still very loud. The engine starts up and runs like nothing's happened.

It seems odd for a 94 engine to blow and I'm looking for opinions on what could have gone wrong. Throw a rod? Camshaft break? Oil pump failure? Oil flow blockage? Since I had a couple of hydrolock issues a few years ago I'd lean toward that and a bent rod but wonder why there's no white exhaust smoke. I was also going to check compression, remove the valve covers to inspect cams/lifters, and measure oil pressure if it can be done in my driveway. Is there anything else I should be considering or is this all a waste of time since the damage to the engine is already done and the knocking will never go away. Installing another engine is not an option.

And yes, I am accepting condolences and welcome cash and meal offerings to get me through these hard times and to help defray the cost of burial.

[elwesso]

Obviously some sort of loss of oil pressure caused this..

Regardless, you're probably going to be looking at a new crankshaft and fresh bearings, and that may be all it needs... Not an impossible task, and probably worth it considering that JDM engines are increasingly getting hard to find in good shape.. The engine has to come out either way.. Which really isnt that impossible of a task once you get a cherry picker (or some other rig to lift the engine)...

Chances are it is simply a spun rod bearing the question remains is how to find out why it happened... IN either case, if you decide to fix it or not, it would be a good idea IMO to figure out what happened.. Oil pump chain/guide comes to mind, ive heard rumors that the 94s got the upgraded timing chain guides but not the oil pump guide? Also the oil pump chains still tend to stretch so that could be an issue too?

If it still runs OK i wouldnt even bother thinking anything on the top end.

[dsagers]

Hi Mike

Please post or send pics of the 1994. Interior & exterior.

Thanks

[Q45tech]

I always measure my hot idle oil pressure at least once per year to see if there is any decline and how much.

Longway between 14 psi oem minimum and the 2-3 psi necessary to turn oil light off.

[3Q Jay]

damn Mike--so sorry to hear.do you have your old oil? might be worth sending to blackstone for an analysis. even if no chunks came out, there might be high levels of aluminum (oil pump case). or lead/copper (bearing).

you've never taken your balancer off (270 lb-ft on crank bolt) right?

[Mint Q45A]

You mentioned that you finally got the transmission to shift properly. Out of curiosity, what did you do to it? ....assuming you didn't simply replace it...

Tks!

[Jesda]

[Q451990]

This thread sucks... I'm sorry to hear this Mike.

[Q45denver]

Sorry to hear that. At least you have a spare. Worn rod bearings appear to be a weak point on these engines hastened by OCI, overheating, hydrolocking, high revs etc. . However, 160K + miles is pretty good for a high performance engine. Keep/part any new/good parts and look for a low mile replacement.

[Q451990]

However, 160K + miles is pretty good for a high performance engine.

Not the VH! I will be livid if I don't get to see at least 200K.

Of course at my current driving rate that will be sometime after 2020, so that may not be realistic. Probably won't be able to afford gasoline by then!

Heath

[Q45tech]

We know for a fact that engine bearings don't wear out unless abused in 19.5 years and 323,000 miles just hit 7,000 rpm twice yesterday in monthly equipment test.

Obviously ring and bore wear will eventually leave an engine blue smoking and less than smooth [idle] to drive especially in the first 10 minutes of a winter crank..............low compression on some cylinders.

When they get old you have to check their pulse and BP daily............fluid levels and oil pressure. It becomes LIKE a 2nd or 3rd job.

As a side note I have only been driving Q every other day and then maybe only 25-30 miles so I've noticed that the battery [14 months old] never gets a full charge..................by measuring bat voltage before a crank precisely.......................12.3>12.4 volts not 12.8 volts.

7 year old [120k] remanned alternator may be tiring but I have 2 spares.

The only thing not replaced is vacuum booster, ps pump and rack, IAC, fuel damper and regular, coils, and internals, cats [4], TPS, TB, viscous clutch.

Easier to say what hasn't that what has by now.

.

[mxr662]

Sorry to hear about your car.

if it has a solid knock and the oil light is on, checking the oil pressure is probably a waste of time.

Motor Swap?

[goody90q45]

Thanks everyone for your condolences and comments. I came out of mourning yesterday afternoon long enough to pull the active sway bar, Jeff Williams FSTB and NICO ECU. Go away vultures.....They'll all be installed on the 90Q. I couldn't work up the nerve to start parting her out and the one time I thought about it and reached for a 12mm wrench my entire arm started shaking uncontrolably.

I'm reluctant to put in the time, effort and storage space needed to part this car out and can't afford a professional repair or engine replacement at the moment. It's probably going to be listed soon on Craigslist for dirt cheap just of get it out of my driveway. Any NICOnauts close by (or far away) who want to take this on? Any tax people know the latest laws on donating to a non-profit?

However, 160K + miles is pretty good for a high performance engine. Keep/part any new/good parts and look for a low mile replacement.

It wasn't long ago that if a car had 100k miles it was ready for the junkyard. I'm always impressed by the high mileage most of us have on our engines . I had a 90 Dodge caravan that was a bucket of bolts at 80k miles and died at 130k miles. My 90Q has 245k miles and runs like new.

You mentioned that you finally got the transmission to shift properly. Out of curiosity, what did you do to it? ....assuming you didn't simply replace it.......

transmission shifted great but it randomly would not shift out of 1st gear. I replaced the revolution sensor (ohming way high) and it shifts like new. It helps that in the last 4 years I've done two transmission flushes and drained and refilled the Mobil 1 ATF multiple times.

damn Mike--so sorry to hear.do you have your old oil? might be worth sending to blackstone for an analysis....you've never taken your balancer off (270 lb-ft on crank bolt) right?

Oops. Blended with used transmission fluid into two gallon containers. I've never touched the balancer or crank pulley. Except for the knocking the engine is still idling very smooth.

[Infinitiguy19]

I thought you were coming back to us with good news.

[Q451990]

Too bad you don't have room to park her and wait until you have the time and funds to replace the engine. One of those brand new short blocks that were floating around on ebay a couple of years ago would have been nice...

[nismotuner82]

I have a guy here in Florida that is looking to sell a VH45 for cheap. I think it is complete minus trans and ECU. He is a friend of mine, and im trying to find the CL add for you as we speak....

Cory

.......just spoke to him and he sold it yesterday, drats!
Modified by nismotuner82 at 8:20 PM 10/4/2009

[mxr662]

Any updates Mike?

[goody90q45]

I haven't done any more diagnostics. She's been sitting in my driveway for a few weeks now. I listed on Craigslist for $1100 and no calls. Lowered it to $900 and got a couple of emails and 2 calls but no one's come by to look. I'm getting ready to relist at $700 and will take $500. If I can't sell her I'll probably pull $500 worth of parts and call the Infiniti salvage yard to come and get her.

[MinisterofDOOM]

Sorry to hear it, Mike.

[Q45tech]

Why I seem/act so harsh on many VIP's and newbees, if the basic engine is not in good shape what do you really have.

The only way you can tell in a used Q is to pull valve covers, pull front cover, drop oil pan and examine the bearings/rods.

We had a discussion yesterday about all the blow Q engines we sent to scrap with working injectors.Just think hundreds of injectors in rails that could be swapped today. We threw away $5,000 worth [at $50] that could have been removed for $1,000 worth of work max. Same with precats, coils, crank pullies, sensors, TB, IAC, etc.We just didn't have space and who knew.

Over the years we were offered dozens of BEYOND pristine JDM engines cheap, some really were brand new [you cannot clean them up enough to have soft hoses or spotless interiors.

[Q451990]

some really were brand new [you cannot clean them up enough to have soft hoses or spotless interiors.

You're killing me... not that I have the place to store one either, but wow... that would be worth building a shed.

Heath

[CINNALOCKS]

Wow sorry to learn of your problem Mike. I hope you get it sold soon for what you had in mind. Good luck on your next one.

[goody90q45]

....you've never taken your balancer off (270 lb-ft on crank bolt) right?

I didn't understand why you asked this until Ozzie emailed me and asked the same thing. If the pulley comes loose so does the oil pump gear, chain, and oil pressure since its all driven by the crankshaft and held together by the torque of the main bolt. After I got Ozzie's email I couldn't wait to get home from work and check it but sorry to say that the pulley is still on very tight.

UPDATE- It looks like I have a buyer for the complete car, not from my Craigslist ad but from an infrequent NICO member about 80 miles north in Chico who happened to see this thread. Marv (don't know his screen name) owns 2 Q's already and gets a great parts car for $500 and I get my driveway back and don't have to deal with the pain of parting out this Q. He's working on borrowing a trailer and should pick it up in a week or so.

Thanks everyone for all the nice words.

[goody90q45]

FINAL UPDATE- The Q is gone. Picked up by Marv yesterday and trailered 80 miles north to Chico. It may reappear some day with a repaired or new engine or its bones and organs may get used in the other two Q's that Marv owns.

It was a great car but the 90Q is just as nice. It'll get a lot more attention now that Q1 is gone.

[jmorasch]

hey mike sorry to hear about the bad situation you encountered......

[lino]

I was away from the Q45 forum for a while and missed this thread. I can't believe this happened to you Mike. I feel horrible . Well at least now you got it away from you so that you don't have to stare at it all day. That would be more painful. The great thing is that you still have one great Q to enjoy. May she serve you well .