90 Q: Just bought....no service history....advice?

[gr8ful]

I recently bought a 90 Q45 with a bad fuel pump at an auction for $800. Interior is in great shape, a few scratches on the doors and it has high miles (220,000). It appears to have been decently maintained.

My local Infiniti dealers could not find a service history on the vehicle in their systems or on Nissan.net. I know the #1 priority is whether the chain guides have been replaced. Questions:1) Is there a way to tell if they have been replaced without a major engine tear down? 2) Is this something my Infiniti dealer could verify in a bumper to bumper inspection?3) Is it safe to “assume” the guides have been replaced given the mileage?4) If problems are uncovered by the inspection, what type of problems should I absolutely have only the Infiniti dealer fix, rather than my mechanic or doing it myself?5) What effect will using a lower octane than 91 have on the performance &/or engine?

I’m obviously hesitant about putting a ton of money into a high mileage vehicle and I’m developing real appreciation for the Q45, especially the 97-99 Q45t (Falk, your 98 is definitely one nice ride). I am now seriously considering making as small an investment in my 90 Q as possible and saving my dollars for a nicely maintained, low mileage 97-99 Q45t.

Thanks, any and all advice welcomed.

[maxnix]

My local Infiniti dealers could not find a service history on the vehicle in their systems or on Nissan.net.

1) Is there a way to tell if they have been replaced without a major engine tear down? 2) Is this something my Infiniti dealer could verify in a bumper to bumper inspection?3) Is it safe to “assume” the guides have been replaced given the mileage?4) If problems are uncovered by the inspection, what type of problems should I absolutely have only the Infiniti dealer fix, rather than my mechanic or doing it myself?5) What effect will using a lower octane than 91 have on the performance &/or engine?

The Infiniti dealer performed service history is archived at Infiniti. The dealer can get it.

1.) No, the front covers have to come off.

2.) No.

3.) No.

4.) Infiniti specific ones. No way to tell your independent technician's level of competence with the information you supplied.

5.) It will severely reduced it's longevity and can compuond other problems like poor cooling. If you can't afford Premium, look at Hondas or Cadillacs.

[redmanfx]

Never assume that the guides have been done even if you have a high mileage Q. Premium gas is a must or you will ruin the engine and the exhaust system with continued use of octane below 91. Even the FSM states that if you "have" to use gas with octane level below 91 to mix it if possible. Full throttle driving should never be done if you don't have 91 octane or higher in the tank. The VH45DE engine can last forever if properly maintained and lubbricated, which is one of the greatest features of the Early Q's. My Q has 275K and runs so quite you can't hear it running since I've replaced the pulley bearing.

Pulling the front cover off the motor is supposed to be easier then dropping the oil pan to check for chain guide pieces and almost everything can be done by you if you have the time and inclination.

Falk's Q is indeed a cherry and I look forward to one day parking mine next to it just to hear it whimper!!

If you ever want to sell the Q I'll give you $500 cash for it as is. I love the G50!

[bullittandy]

The Infiniti dealer performed service history is archived at Infiniti. The dealer can get it.

1.) No, the front covers have to come off.

2.) No.

3.) No.

4.) Infiniti specific ones. No way to tell your independent technician's level of competence with the information you supplied.

5.) It will severely reduced it's longevity and can compuond other problems like poor cooling. If you can't afford Premium, look at Hondas or Cadillacs.

Regarding #3- When do guides fail? Has anybody made it that long on the original guides??Regarding #5. What in the world are the knock sensors for then?? They "listen" for detonation and retard the timing. They don't "know" if you have 93 Octane in Arizona heat or 87 Octane in New England coolness. In addition, driving habits influence pinging/detonation as much as anything. Only cars without knock sensors runs hot because of incorrect timing.

P.S. Nice job on insulting the new member.

[Rex]

Regarding #3- When do guides fail? Has anybody made it that long on the original guides??Regarding #5. What in the world are the knock sensors for then?? They "listen" for detonation and retard the timing. They don't "know" if you have 93 Octane in Arizona heat or 87 Octane in New England coolness. In addition, driving habits influence pinging/detonation as much as anything. Only cars without knock sensors runs hot because of incorrect timing.

P.S. Nice job on insulting the new member.

Regarding #3, we've seen motors completely lost <70k, and I recall jesda eeking out >185k, and they found the guides were brekaing, but no missing parts.

[gr8ful]

Never assume that the guides have been done even if you have a high mileage Q. Premium gas is a must or you will ruin the engine and the exhaust system with continued use of octane below 91. Even the FSM states that if you "have" to use gas with octane level below 91 to mix it if possible. Full throttle driving should never be done if you don't have 91 octane or higher in the tank. The VH45DE engine can last forever if properly maintained and lubbricated, which is one of the greatest features of the Early Q's. My Q has 275K and runs so quite you can't hear it running since I've replaced the pulley bearing.

Pulling the front cover off the motor is supposed to be easier then dropping the oil pan to check for chain guide pieces and almost everything can be done by you if you have the time and inclination.

Falk's Q is indeed a cherry and I look forward to one day parking mine next to it just to hear it whimper!!

If you ever want to sell the Q I'll give you $500 cash for it as is. I love the G50!

Thanks for the thorough answer about the octane, just wanted to know if this was just a recommendation for optimum performance or could it cause real damage.

I see that I definitely need to check the chain guides, so where would I get an FSM or instructions for pulling the motor cover? I'd love to do as much of my own work as possible and as long as I have a good set of instructions, I have all the patience in the world.

I'll keep your purchase offer in mind, but I will get the maintenance caught up and see how much I enjoy the Q. Unless I come across a deal on a 97-99 Q45t that I just can't pass up.

[gr8ful]

I found several FSMs on CD on ebay motors. I would imagine that the CD version is as complete as a hardcopy, true?

[Rex]

I found several FSMs on CD on ebay motors. I would imagine that the CD version is as complete as a hardcopy, true?

Be aware some of the ebay CD versions are no better than a random stack of xerox pageshttp://forums.nicoclub.com/zerothread/196270

[gr8ful]

Thanks Rex, I'll keep searching for a hardcopy version of the FSM.

Also, my local Infiniti dealer and several mechanics are warning me not to replace the transmission fluid since I have no history of regular transmission services. They say, if it has not been changed regularly, it is best not to flush and replace the fluid as this often stirs up things and causes problems. The transmission does not appear to have any issues, shifts smoothly with no slippage.

Have any of you found this to be true? I do have 220K miles on the car, but I don't know if this is the original transmission or not.

[FDR Dippin]

Not an expert opinion, but I would certainly change it, I wouldn't pressure flush it, but I'd replace it and filter. Same with the engine. Don't forget gear oil in rear axle, it's a simple job but I suspect often overlooked.

[maxnix]

Read a few more of the posts, especially all by Q45tech. All your questions will be answered.

Be wary of following advice from newbie members who are too lazy to do the reading and research!

[bullittandy]

Read a few more of the posts, especially all by Q45tech. All your questions will be answered.

Be wary of following advice from newbie members who are too lazy to do the reading and research!

In order to not sound rude I've edited this post. I think you're wrong about low octane "severly reducing" longevity. Maxnix, please explain how using octane lower than 91 will severly reduce the longevity of the engine.
Modified by bullittandy at 9:29 AM 9/16/2006

[bullittandy]

Thanks Rex, I'll keep searching for a hardcopy version of the FSM.

Also, my local Infiniti dealer and several mechanics are warning me not to replace the transmission fluid since I have no history of regular transmission services. They say, if it has not been changed regularly, it is best not to flush and replace the fluid as this often stirs up things and causes problems. The transmission does not appear to have any issues, shifts smoothly with no slippage.

Have any of you found this to be true? I do have 220K miles on the car, but I don't know if this is the original transmission or not.

I've heard this also but I don't have any evidence to prove it. I think it would be bad to aggressively clean either the transmission or engine (strong flushes) which would certainly dislodge some deposits. However, I would (and have) drain and refill the transmission fluid a couple of times over the couse of several thousand miles which would get new fluid in but not too quickly.

[93 Q45]

FOR 800.00 I WOULD BUY A FUEL PUMP AND DRIVE IT TILL IT DIES

THEN PART IT OUT THE 90 IS A GREAT CAR AND IN MY OPINION MUCH CAN BE DONE FOR VERY LITTLE IF YOU CAN TINKER

MY FUEL PUMP COST ME 80.00 DOLLARS AND 1 HOUR TO PUTT IT IN

PS I LOVE JUNK YARDS FOR INTERIOR PIECES THE GUIDES WELL

IVE HAD MINE FOR A COUPLE YEARS AND IVE SEEN THE PRICES OF THE

PARTS MENTIONED AND YOU CAN SOURCE A JDM MOTOR

FOR ABOUT THE SAME COST SO DO WHAT YOU WILL. WHEN MY 93 DIESI WILL ALSO BE AFTER A 97

[maxnix]

I think you're wrong about low octane "severly reducing" longevity. Maxnix, please explain how using octane lower than 91 will severly reduce the longevity of the engine.

Maybe I am, but please read Q45tech's posts before you decide.

The knock sensors are there to limit engine destruction until the offending failure can be corrected as soon as possible. They are not there to allow running on kerosens or even 87 or 89 octane gasoline, or what no passes for such these days. That is why the Owner's Manual and other OEM publications for the G50 require 91 or higher octane. Remember also, the gasoline was better 15 years ago.

Engineering design in an analog system requires conditons remain as near as possible to the designed mean of the parameters. The more variance, the sooner failure will occur.

[bullittandy]

1.Maybe I am, but please read Q45tech's posts before you decide.

2.The knock sensors are there to limit engine destruction until the offending failure can be corrected as soon as possible. They are not there to allow running on kerosens or even 87 or 89 octane gasoline, or what no passes for such these days. That is why the Owner's Manual and other OEM publications for the G50 require 91 or higher octane. Remember also, the gasoline was better 15 years ago.

3.Engineering design in an analog system requires conditons remain as near as possible to the designed mean of the parameters. The more variance, the sooner failure will occur.

1. Are you serious? I have to read several thousand posts before I can tell you that you're wrong?!? Get real. I have my own brain and experience from which to base my answer-you might try that sometime.

2. From this answer-it is clear to me that you don't understand what knock sensors do. They "listen" for pinging/detonation and retard ignition timing until the pinging/detonation disappears. They don't "know" if you have 93 octane and are climbing a steep hill in Arizona in the Summer with a full trunk and back seat. They also don't know if you have 87 octane in Maine in the Fall and are gently cruising at 55 MPH. All they know is that the engine is detonating and adjust accordingly. Now if the car was pinging due to low octane or whatever other reason, AND the engine did not have a means of retarding the timing-THEN engine damage would occur.

3. This is silly and an obvious attempt to impress others.

[96Qowner]

Here the thing about knock sensors:

They're just little microphones. They don't prevent knocking; they just listen for it. First, your engine knocks, THEN the sensors detect it, THEN the ECU retards timing. So, using low octane fuel WILL cause knocking until the KS hear it and timing is retarded. Knocking is bad for your engine.

Here's an explanation from Dennis:

zerothread?id=125199

If this is really all about saving a buck or two each fillup, then just forget it and use the octane recommended for the engine - not worth the savings.

[bullittandy]

Thanks for clarifying that the ECU retards the timing not the K/S.

We should also clarify that that knocking and pinging are different types of pre-ignition with knocking being very bad for the engine and pinging being possibly bad for the engine. If you've driven a car that was knocking you'd see why its bad- it makes a gas engine feel and sound like a diesel. Its not a guarantee that the engine will be damaged by occasional pinging

It's important to note that its not whether lower octane is in the engine's best interest- it is not. But that is not the only consideration, the other is time, money, piece of mind and knowing what will ACTUALLY happen if 87,89,90 octane is used- not much.

An analogy might be- Are fast food hamburgers as good for you as baked salmon? No. Will a fast food hamburger have immediate, long term and airreversible impact on your health? No. Do I recommend fast food hamburgers every day? No. Will I tell you to visit a cardiologist if you eat Wendy's twice this week? No.

[redmanfx]

Let's not forget the Q runs rich which is not typical compared to other cars. This car was over-engineered 15 years ago, now you have the wear and tear of age to boot. Besides, I believe we're answering someone's question and not trying to show each other up. Beware 10% ethanol fuel as well,... it seems to kill our injectors.

Search Tangalora's post about changing the chain guides out and her epic adventure dropping the oil pan and then finding she didn't have to, but being glad she did to remove the guide pieces. Ahh, it should be required reading. Ozzie also recently did his guides, so there's a ton of info here on the matter. Plus there's too much love here to do a tit for tat....

[Q45tech]

The problem with the marketing posted octane number on the pumps is it may not be real...............there are no federal or state requirements that octane must be really octane............Premium is just that premium, the best they made that day, the liquid that contains the highest percentage of cleaning additives and maybe has close enough octane AVERAGE to not be totally unethical in charging 5-6 cents more for it.........how the refineries 5-6 cents more per gallon becomes 20-25-30 cents more at the pump is another story.

[Q45tech]

Paying $800 for a 220k 90 Q is just the begining.......the opportunity to pay another $10,000 [in labor and newish parts] to get it functioning as brand new......obviously most don't love the concept that much.

By the time I accumulated 220k [2001] I had spent $30,000+ in rehabiltation and over the next 5 years spent $12,000 [at my discount parts and labor] to get another 90,000 miles................hope you can do as well $2400 per year x 5 = $12k.Obviously a transmission or diff or driveshaft or injectors or KS/hoses can make for a bad year.

[bullittandy]

[QUOTE=redmanfx]Let's not forget the Q runs rich which is not typical compared to other cars. Besides, I believe we're answering someone's question and not trying to show each other up. QUOTE]

Running rich would decrease pinging/knocking.

I'm not trying to show anybody up. I'm providing contrasting information that is based on my experience and knowledge as opposed to Maxnix's obvious ignorance about the topic of octane.

[bullittandy]

[QUOTE=bullittandy]

I'm not trying to show anybody up. [/QUOTE]

This actually isn't true. I'm testing to see how much Maxnix likes a taste of his own medicine. Judging by his silence-not much!

[Q451990]

Not to jump into the middle of this urinating contest .... but I think the issue with knock sensors and octane is that the ECU doesn't have an unlimited ability to retard the timing advance! It can only do so much - so giving it crappier (than premium) fuel only compounds the problem.

Is the engine robust enough to stand the abuse? The answer is probably "yes" in most situations. This is one of the most robust engines ever made (except for the timing chain guides). I guess it depends on your expectations. Do you want it to last 100k, 150k, 200k?

For the extra $.20/gallon or 8% premium over regular unleaded it's cheap insurance in my book.

Heath