Story of rebuilding my Q's engine - really long

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forecast
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A few people have asked about my experiences in rebuilding the engine in my 90 Q.

look for photos after 7 EST today at http://www.q4sale.com/rebuild

I did all this work before discovering NICO. If I had know about NICO, I wouldn't have bothered, but just bought palmerwnd's engine. I never took any notes, or wrote down micrometer readings, partly because I really didn't think I'd ever be talking to anyone about it in depth. I took a few photos for my dad, but that's all

Now everyone knows a Q engine can't be rebuilt to factory spec by mere mortals, but I did my best.

The service history on my car - I bought it last August with 130K. Two weeks later I changed the guides. They were broken to bits and I had to drop the pan to clean them out. In the pan I found some odd needle type roller bearings. I pulled a valve cover at random and got lucky - a rocker arm was broken causing a dead intake valve. I replaced the camshaft, rocker arm and lifter. I assumed the engine would now be bullet proof through 250K.

The story starts in early January. A missionary friend of mine called me up complaining his Honda shook really bad. Some investigation revealed a burn exhaust valve (apply air pressure down the spark plug hole and monitor where the air comes out) A local shop asked $1600 for a head job. My friend (being a poor missionary) blanched at the thought and asked me for help. I'm the director of Info Tech at a small non-profit. I asked my boss for a week of paid leave to do some pro-bono auto work for the missionary. He said sure, but only if I carried my cell phone at all times.

The job went without hitch, just as predicted a burnt/chipped exhaust valve. But on the last day my wife calls. She says the Q started making a terrible noise on the highway. Like a screeching and loud thunk thunk thunk at idle. I'm thinking - Why! Why God am I carrying the cell phone - she probably drove it home before calling me and the whole thing is toast! I say something like - "well I'm glad you are ok, so uh... how long did you drive it that way?"

Amy must have heard something in my voice because the defensive shields go up "Honey, you have the cell phone, I wasn't going to just pull over on the highway and flag someone down."

"How Long?!"

"About 20 ... 25 minutes at the most" Ohhh! My heart makes a sideways knife like motion trying to deal with all the sudden adrenaline. After a few minutes my vision clears.

We tow the car to a local shop. The tech starts the car and shuts it off in about 10 seconds. "You need a new engine" His prognosis was exactly the same as mine - connecting rod bearing failure. We buy an older Mitsubishi Gallant for $1000 - basic transportation to get us around while we decide what to do with the Q

A friend who works at an Infiniti dealership in Lexington asks the master tech there for advice and got the following “Connecting rod bearing failure at 146K? That doesn’t happen to Q45’s”

After weighing my options. My $2700 book value car has depreciated 90% in 24 hours. The $2900 left on the auto loan has not. I decide if I can repair the Q for under $2000 I'll be better off than buying another car, and having to pad a new loan by $2900.

Now, Techs and shop owners will be lining up say that a Q engine can't be rebuilt to factory spec, at least not in the USA. That's true. I was aware of that going in. My goal isn't to return the car to factory spec. There are no 90 Q45’s with factory spec engines to found anyway. I'll be happy with the level of performance the car had in 1995 and that the engine goes another 150K. The first engine I rebuilt in high school went 90K before the van was T-boned by another driver running a red light. A critical factor in the rebuilding of an engine is dirt - a clean shop will make a lot difference, and I decided I was going to be anal about that.

Dropping the engine took three days. Mostly me and a friend worked at night after I left the office. Even though I was indoors, the shop wasn’t heated except when we fired up the kerosene heater. The skin at the tips of my fingers got frostbit and kept peeling off.

Baggies - 100's of little sandwich baggies and a permanent marker made re-assembly about 100x easier. I called my friend "Jack the stripper" he’d get under the car and stream of bolts would come flying out. I'd start hollering to slow down and start labeling baggies. Things like "AC compressor to bracket - 4 bolts" would be written on the baggie, sealed and thrown in a big box.

Once the engine was up on the stand the fun began. Tearing the engine down took about two days. I broke a hex socket getting the head bolts out. They must have been over 400 lbs; A three foot bar and everything I had was required to get them loose. The urge to use the impact wrench on them was almost uncontrollable. Another 2 dozen baggies in the bog box. What remained of the bad bearing was paper thin. I loaded everything in boxes and drove to the machine shop.

The machine shop owner took a special interest in my car. They get very few amateur guys anymore and besides this was a special engine. He noticed details like snap rings on the pistons and the fillet roll on the crankshaft and commented this engine was designed with love. He tentatively suggests that perhaps I ran it low on oil. I explain it had a known oil leak. Every time gas goes in the tank, the hood comes up and the dipstick pulled. It was never allowed to be low on oil.

The first thing we mic'ed was the crank. Amazingly it wasn't egg shaped after a 20 min beating on the highway. It was however worn beyond the point of the largest oversize bearing available. All of the other lands were still within spec and only needed a very light polish. Apparently the "little oil filter that could" had saved the rest of the engine.

The machinist talked me through the options for the crank. I could buy a new crank - $900 or he could weld a thin layer on old land and turn it down to spec $200. The risk of the welding method was two fold - the fillet roll would be gone, no machine shop in America could recreate that, and the crank metallurgy might be weakened by the heat of the process. He explained they could create a radius at the edge and test the crank for strength after welding, but I would have to pay for the work even if the crank was ruined. I choose the weld method because it was the only way to keep the rebuild under $2K.

Looking at the pistons was a surprise. Both the machinist and I expected to see one or more out of round or worn beyond spec. Amazingly not a single one was. The pistons did show signs of heat stress at some point in their lives - fine scratches at the base of the skirt from over-expansion. That had never happened during my ownership, but I suspect at some point in the past a hose or something ruptured, overheating the pistons and aging the bearings. One connecting rod didn't make the grade and had to be replaced - $80.

Today I wish I had written down the numbers from the micrometer for the cylinder walls. At 146K miles it would have been helpful to plot a wear line on them. The only important thing was really they could withstand a honing and still be okay.

Another machinist did the heads. They also passed the micrometer test on all points. He kept all the parts sorted so that I could put the lifters back into the original positions. No valves needed replaced. This wasn't my call. I told the machine shop I trusted their measurements and experience and would replace anything they said was out of spec. The intakes did need cleaned to remove some deposits.

After two weeks the machine shop got everything done and $1700 lighter, I was back at the shop, everything wrapped in plastic. I had trouble finding o-rings for the lifters. The old ones were completely flat and cracking like old plastic. At Infiniti they don’t sell the o-ring separate from the lifter itself ($50 each) I showed the dealership’s Master Tech one of the lifters with the old o-ring. He held up the light and rolled it around before giving it back to me. “I’d just put them back in like that”.

“Like this!?” I said poking at the brittle band with my fingernail until it chipped and a large curve fell out on to the floor.

“Well … not now.”

He went on to caution me to be sure and bleed air from the lifter before installation. His description of how to to that assured that while his heart was in the right place, they don't rebuild engines at the dealership.

I spent some time investigating exactly how the whole thing functioned and determined the o-ring was pretty critical to normal operation. I mic’ed what the o-ring should have been. At a shop where they rebuilt industrial hydraulic equipment I bought 40 vitron o-rings for $12.

I cleaned everything. Some things needed to be pressure washed with solvent at the machine shop others like the timing covers needed several cans brake parts cleaner. I scrubbed the chains until I could see the special colored links used in setting the timing. Again – not a single visible defect on the chains.

The oil pump was a small concern. It was serviceable, but under good practices should be replaced no matter how good it measures. I ended up re-using it, but I should replace it after another 50K I think.

After that re-assembly went quickly. I was eager to get the whole engine closed and sealed in as short as possible. The less time dirt could land on the open engine the better. This became 3 12 hour days. When I wasn’t working on I kept it wrapped in plastic. I used two full tubes of a special engine rebuilding oil. I coated every sliding surface with the thick red stuff. It was designed to dissolve in engine oil but provide lubrication through the first startup.

The lifters were the last great concern. The lifter is a two piece telescoping unit (it can't be disassembled). Under high pressure it shortens to compensate for heat lengthened valve stems. They all had to be individually bled and tested. I drilled a hole in a block just a bit bigger in diameter than the lifter. With compressed air I blew out the hole and flushed it with oil. Then one at a time I dropped the lifters in the oil, and used a plastic reed to release the check valve and pumped them full of oil. Then lickedee-spilt I installed them in the head. One lifter wouldn’t hold pressure and had to be replaced.

I noticed that when bolted together the lifters actually opened the valves just a crack even with the cam was rolled away. This was a huge area of concern for me; until I learned that when running the lifters would fade back under the pressure of the de to the correct height and let the valves fully close.

Finally the timing chains; once in place I triple checked and counted links to ensure accuracy. I installed the covers and slept for three days. It’s not easy to work a full time job and spend another 40 hours a week at the shop. I had to wait three days for external hoses to arrive from Scottsdale.

The installation went well with no major surprises. I spent two hours crawling over the car looking for disconnected cables, wires hoses etc. It started on the first try (after cranking without the fuel pump until the oil light went out). I took the car out and hit the gas hard in 1st to set the rings. The cylinders need to be shaped down to the crystal level to match microscopic features of the rings. This is the only time a rebuilt engine should see > 4000 RPMs before the 1000 mile mark.

2000 miles later I did a compression test. This was a cool engine (100 degree head). No cylinder was at the 185 factory spec. Not a real surprise. The highest was 172 and the lowest 159. No two adjacent cylinders were off more than 8 points.

One valve lifter makes a bit of clatter. You need the hood up to hear it, but it's there.

As for drivability - seems fine, loads of power. A hair light on power in 1000 - 1600 RPM range which seems strange, this may be an injector issue. The engine definately finds its legs at 2200 rpm and hitting the gas there shots the car forward like a slingshot with huge power up through 6000 RPM.


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AZhitman
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What a spectacular writeup!

Thanks forcast - I enjoyed that!

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DAEDALUS
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Wonderful write-up. Much appreciated, and will go in the archives. The machinist who recognizes an engine designed with love would get my business as well.

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PalmerWMD
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Great write-up Dan!

We really appreciate it.We will put it into Infiniti articles section soon.

Fred...:)

forecast
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photos of the tear down are up:

http://www.q4sale.com/rebuild.htm

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DAEDALUS
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Man, the sight of that crankshaft makes my stomach turn. I've watched autopsies that have had less of an effect. How exactly did you support the car high enough to get the engine out?

forecast
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Good question about the lifting.

I've edited the site to include two more pictures at the bottom.

For the mechanic without a quality powered device to lift the car - this was THE scarry part. I did hand jack it all the way up, but later I got smart and just used the kubota tractor attached by chain to the crossmember.

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DAEDALUS
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Good Lord! (Stomach's still turning!)

maxnix
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To go where no gaijin has gone before! Spectacular!

Quote »...when running the lifters would fade back under the pressure of the de to the correct height and let the valves fully close.[/quote]I guess I am dumb, but what is the "de"?

The master tech must have been a great help for consultation. Glad you got new viton o rings. The oil pump is probably not long for this world if it was pumping all those metal shards.

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Wow... forecast! That's one heck of a job! Glad to hear that it had a happy ending... Did you replace the fan? If not, the parts label on the fan blade makes me think the fan may have flown apart due to stress cracks at some point prior to you buying the car - possibly damaging the radiator and causing your suspected overheat!

Heath

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Which rod and bearing was it?

130k, just goes to prove that an owner can destroy anything.

I get to look at lots [may 25] of Q cams and followers and such as I try to examine many of the engines undergoing valve cover reseals- most look pretty good except for some of the HLA o ring.

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maxnix wrote:I guess I am dumb, but what is the "de"?


Huge typo - actually several words are missing but I didn't catch it until the 30 min edit window closed.

should read:

I noticed that when bolted together the lifters actually opened the valves just a crack even with the cam rolled away. This was a huge area of concern for me; how would the engine even start if the valves didn't seal. The opening was about 2mm. The lifters were fully seated and I stopped work until I learned that when running the lifters would fade back under the pressure of the compressing gas against the valves. They would telescope down to the correct height and let the valves fully close. Even after I closed the engine up, I still worried about it, until I slowly turned the crank several times and was absolutely satisfied the pistons weren't touching the partially open valves.

With the lifter, rockers and cams installed in the head 50lbs of pressure applied against a lifter would not cause it to telescope at all. I assume the high pressure chamber must vent oil when hundreds of pounds of force is applies. The one lifter that needed replaced would always give under about 40 pounds, I think it had a worn check ball.
Q451990 wrote:the parts label on the fan blade makes me think the fan may have flown apart due to stress cracks at some point prior to you buying the car - possibly damaging the radiator and causing your suspected overheat!


I did not the replace the fan. The previous owner did, however he claimed it was changed due to a cracked blade discovered during an oil change. My pet theory on the over heating is: A rad hose broke on the highway and the fluid and steam vented underneath the car - the owner didn't notice for a few miles, but when the gauge moved up by steam from coolant boiling in the block, he saw the temp and pulled over. I don't think this would cause a bearing failure as much as poor maintainence would though.
Q451990 wrote:Which rod and bearing was it?


The failed bearing was the rear section of the second land from the back. If memory serves, this would piston 6 (RH second from back)

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Jesda
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So what kind of poor maintenance causes this? Lack of oil changes?

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I think two or three causes contributed, both of which were invisible to me before it happened.

Since buying the car, I was impecable with the engine matainence; changed to sythentic oil, flushed the rad, and always checked the oil when putting in gas.

Suggested cause 1: Lack of proper oil changes and monitoring. Likely the oil would leak down between long changes to where at idle the pump would be sucking a mixture of air and oil which would compress and not create enough pressure to properly lube. The bearing starts to wear very slowly just at idle.

True story: The local Lexus dealership in louisville gave free use of a new SUV to the U of L basketball coach. In 25,000 miles he never brought the car in for an oil change (these were included for free). Around 28,000 he brought it in complaining of generic loud noises under the hood. The oil was still in there like pudding and and a cam was ruined from running dry. The dealership replaced the head and now has it sitting on the lot for sale!

Suggested cause 2: Overheating. The machine shop mentioned the pistons shows signs of overheating. During the rebuild I pulled the radiator out with both hoses attached and never touched it, a few weeks later the upper hose popped loose. Strange since I'd never even touched the clamp in question. The rad to hose connection shows signs of having been hit by a loose battery in the past. The rad neck was chipped. I surmise that at some point the battery was replaced and not tied down (it wasn't when I bought it), a hard turn to the right and the battery hit the rad neck and broke the hose loose. The engine lost coolant, but the driver didn't notice for some time, engine overheats and ages the bearing. (Since the rad overall looked very good, I expoyed a new hose on the rad and haven't had a problem since.)

#3. Hard winter driving. The car was originally sold in Chicago. I find it unlikely it wasn't garaged, but who knows. Perhaps the owner was in the habit of starting it and quickly pealing out, heavily loading the engine before the oil warmed up.

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GREAT POST,,,,,,,,DID AN ADMIRABLE JOB ON THAT REBUILD. WILL KEEP YOU IN MY ROLLADEX,,,,,,JUST IN CASE!!!!!!!! JEFF

Q45tech
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#6 conn rod bearing has been the culprit in 3 other failures. [that I have seen].......guess one has to be the first to fail.At least we know which one to check first.

Every day at 250,620 now I expect to start hearing a rod knock considering I really exercise the engine.......maybe the Mobil 1 for the last 170,000 bought me some time.

Did you ever calculate the total hours expended? Sounds like hundreds..............we calculated that the cost might be around $10,000 to do a complete rebuild.

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This was definately a case of me having more time than money.

There was also a certain desire to do because it sounded fun. The process (except for the bitter cold) was enjoyable, however I doubt I'd do it strictly as a hobby.

In terms of man hours let me figure out loud:

engine pull > 25tear down > 15rebuild > 35reinstall & reconnect > 25finishing > 10

total greater than 110 hours.

That should be tempered with the understanding that I've been working with automobiles since I was 14, but I have no professional training. I got degrees in theology and work as a computer networking specialist. I did the work because it seemed cost effective from an out-of-pocket point of view

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110 x 68= $7500 plus $3500 in parts =$11,000

We estimated about 50 hours for tear down, testing reassembly and about $1,000 per head for simple R&R............I'll bet to get it closer to spec would need new valve springs and HLA.

See why we buy used take out engines for $1500-$1,800 [delivered] and just do the guides and hoses and sensors and reseals........we end up with a workable engine for around $4,000.....then the $2,000 for removal swapping and reinstall............but alas $6,000 is too much for most to pay.

I could probably get the techs to work for me for $35 an hour cash on the weekends..........it would still cost me $4500 to do a swap.

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Resurrecting an oldi but goodie to ME ....

Kudos to the ONE they call Forecast!

Hope I can email you, as I begin this journey. I too have more TIME per say than $7,500 +


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