Replaced Valve Cover Gaskets, What did I do wrong??

[Jeff Williams]

Decided to do the valve cover gasket replacement myself (didn't have the extra $500 to $750 for labor).

I did the passenger side today. I unplugged everything, and tried not to remove the fuel lines, but eventually had to. The front one, from the filter was a snap, but the rear one was under pressure, and I had to plug it, to keep it from draining the tank. I dripped some fuel into the engine, while getting to rocker cover off, but it was aver little ammount, and I didn't think it was a big deal, really.

Finally got the cover out of the engine bay, and cleaned it up, and put on the new gasket. I then took a brake to eat lunch. I plugged everything back in, and did a test run, before doing the driver's side.

I started the car, but had forgot to re-plug the MAF. I plugged it in and re-started the car. It seems to be running rough. Like may be the even cylinders weren't firing.

I checked all the connections of hoses, and wires, and they all seem fine. I unplugged and re-plugged the Fuel Injector wires, and there was no change.

I drove the car around the block, and it seem like I have a 1.8 litre engine. It barely moves.

I disconnected the battery for about 20 seconds, to see if that would reset the ECU. (I really don't knkow much about the ECU).

I am planning to do the driver's side, tomorrow, when my headache is better.

I have spent the last hour on this site, doing searches, but have found no help.

I recall a mention of the fuel pressure, and a thread with someone having the same driveability problems.

I do not have a manual, and do not know how to check the ECU cotdes, so a little help there would be nice, too.

I feel like it is something simple, but don't know where to start.

Can you guys give me some ideas?

Thanks for the help!:help :help :help :help

I really am a good DIY mechanic, but this enigne is not your normal engine. I will master the Q, eventually.

[Q451990]

Did you re-check the coil connections? My guess it's an electrical connection somewhere. Drink some beer, watch some football, and re-check everything tomorrow... you'll find it eventually. Just bleeding down the fuel pressure shouldn't cause a problem.

FIY, pull the fuel pump fuse and run the car 'til it shuts off... you'll get most of the pressure out of the lines.

Heath

[Jeff Williams]

That's what I forgot to do! Pull the fuse, and run out the fuel, before I started.

I let the car sit for a couple of hours, and re-checked the wiring harness connections. I am not sure, but I almost felt the one to the coil packs move a MM or so.

I started the car, and backed out to the street. It seemed like its old self. I drove around the block. The normal power was back, but I still have a rough idle.

Tomorrow, I will replace the fuel filter, flush the coolant, clean the MAF, and put on my secondary K&N filter, when I am replacing the driver's side gasket.

I will pull the black cover off the coil packs, and re-check their connections, as well.

Thanks for the info.

Anyone else that knows what I might have done wrong, or what I need to check, please chime in.

[elwesso]

Im not sure what the deal is...... Does the idle seem like it did when one of your plugs went bad??

So its back to normal power, but still rough.....?

Im getting ready to do the covers soon, how did the job go?? Once the plugs are out, is it pretty easy???

[Q45tech]

Every time you [we/T3] do a valve cover reseal we insist upon new plugs, so we can clean the spark plug bore holes out. Look at the piston crowns with a light, etc. Gauge what's happening in the engine.

All the techs are now equipt with digital compression gauges [ebay $50-$75-$100] with a hold feature so one can do the tests without a helper.

Pretty amazing you would do the reseal job without a FSM, even I forget where things go and refer to the FSM at least twice a day and keep 2-3 at home for reference.

Things I forget are the large air hose that connects under the main air hose to TB. The system [PCV] is closed loop and any air leak will probably cause the engine to not start or run very badly depending on magnitude of air leak..........because the MAF may not see all the air going into engine and read below the 1.1-1.2 normal voltage.

We have seen reversed fuel lines [but then it won't start/run], reversed throttle cables, unplugged ignitors, misplaced coisl [the front ones are diffferent]. broken coil to plug extensions.

[rover3l]

I can't offer any special tips but yesterday I started a spark plug change. I am a poor to average DIY mechanic so I decided to get my son to video the dismantling procedure. I decided just to do the drivers side yesterday and today I will do the passenger side. I must admit I was concerned with how stiff the wiring to the ignition coils is an the possibility of breaking something.

Apart from this concern I am not sure what might have gone wrong and would suggest just carefully retracing your steps and making sure all connections are secure and all pipes are connected

[Jeff Williams]

Thanks for the info.

I retraced my steps, and found coil pack on cylinder #6 was about a MM out. I put it back together, and replaced the fuel filter, cleaned the Throttle Body and butterfly, cleaned the MAF, and flushed the radiator. I had a small leak, on the filler cap, & had to recaulk the housing.

Once I got it back together, it ran fine. There was a little hesitation, but I think that was from the fuel filter replacement.

It is amazing how much fluid will sit on the top of the engine. I degreased the motor, and used an air hose to blow the water off. I had to use a shop vac, to suck all the water out of the valley under the plenym. I got 4 cups of nasty drity water!

I decided the driver's side was not possible, without a plenum removal, or a magic wand, (or the FSM). Now I know why the dealerships charge $700.00 to replace the $11 gaskets.

Actually, the plugs don't have to be removed, to get the covers off. Just everything else.

Dennis is right, do it all at the same time, to reduce bloody knuckles. Then you can clean everything at the same time. I would plan on the plenum removal, and replacing the KS as well.

Definitely take lots of digital pictures.

I have re-wired many cars, and built a few wiring harnesses. I am not intimidated by the spagetti of wiring. I just don't want to do a bone-head mistake, that costs me more money.

I am so cheap, I don't want to buy the FSM. I guess I will ask for it for Christmas.

It took about 1.5 hours to remove the cover, .5 hours to clean everything. 2 hours for lunch, and a nap, then about 1 hour to re-install. I hour to search NICO for help, then about 1 additional hour to diagnose my problems.

I am going to tackle the driver's side when I have more time.

Right now, it is drying out from the cleaning.

[Q451990]

I decided the driver's side was not possible, without a plenum removal, or a magic wand, (or the FSM).

...I am so cheap, I don't want to buy the FSM. I guess I will ask for it for Christmas.

You don't have to remove the plenum... just the throttle body and possibly the EGR valve. Spring for the $20 subscription to http://www.nissan-techinfo.com/infiniti - it'll be the best $$ you've spent on your Q in a long time. The 1994 FSM and all of the G50 series TSBs are waiting for you there...

Heath

[Jeff Williams]

You don't have to remove the plenum... just the throttle body and possibly the EGR valve.

Heath

Thanks. I was not in the mood to remove the TB, and didn't have the gaskets.

I need the bushings for the rear sway bar, and i will get the gaskets at the same time.

The car ran perfectly last night, and this morning. I love how smooth the idle is, when I clean the MAF & TB. I am starting to think I should do this every oil change.

Thanks for the info on the FSM. & TSB's. I got a disc, with some of that on it. I guess I need to just print out what I have, before I decide what I need. It always seems I don't have my laptop, when I decide to work on the car.

[GEOFF]

You don't have to remove the plenum... just the throttle body and possibly the EGR valve. Spring for the $20 subscription to http://www.nissan-techinfo.com/infiniti - it'll be the best $$ you've spent on your Q in a long time. The 1994 FSM and all of the G50 series TSBs are waiting for you there...

Heath

Does FSM mean full service manual? Is that more detailed than the serivice manual in the trunk? Infiniti of Scottsdale said I did not have to remove the throttle body...is that possible?

[DAEDALUS]

It's the same Factory Service Manual, just that later years did not come with them. Not sure if it's possible or not with the TB there, but it would sure be easier at least with it out of the way.

[GEOFF]

Thanks for clearing that up. I think I can squeeze the cover under the TB. I looked underhood and I prob need to remove EGR Valve. Is that a actual gasket or liquid gasket?

[elwesso]

I doubt it.... I had the plenum off, and its night and day.... You need to remove the whole tube assy (EGR).... I dont think id try it without removing the TB....

Should I have done the passenger side while the plenum was off??? I looked at it, and I dont really think the plenum gets in the way.....

[GEOFF]

I think the techs may knuckle bust the drivers side cover w/out removing TB. You dont need to remove plenum to do either side, especially the passnger side. I have another car to drive, so I will start removing things until I can get the cover off. Is the EGR tube assy hard to remove at the bottom? It sure looks like it.

[elwesso]

just unbolt it from the plenum and keep pulling on it until it frees itself... Keep playing with it until its REALLY loose, and then reach down and unscrew the bolt... Thats how I did it......

[GEOFF]

It was a little tricky, but I got the Driver's side cover off w/out removing or even loosening the plenum. I noticed evidence of a liquid gasket around the head near the front of the car. It is a 95 Q with the rubber gasket so not sure about the additional sealant. Can someone tell me the torque specs on the Thottle Body? Not sure why valve cover was leaking...old gasket didnt look that worn or different from new one.

[elwesso]

I dont know either, mine looked just fine. It was brittle in some places, but came out fine for the most part and mostly intact......

[DAEDALUS]

I assume the rubber compresses and maintains a good seal until it hardens and loses its springiness. You can tighten the bolts a little more, but eventually the cover will flex enough between the bolts that this won't do any good.

[elwesso]

Robert.... You are correct, and I checked the torque on my passenger side covers, and I got as much as about 10 ft/lbs (spec is 9).. I guess its just a matter of time!!!

[DAEDALUS]

The TB bolts should be tightened in 2 steps. Do the upper left bolt, then lower right, then upper right, then lower left. Tighten to 6.5-8.0 ft-lbs. Then repeat, with final torque of 13-16 ft-lbs.

[GEOFF]

Thanks guys...Anyone put an additiona liquid sealant on any part of the rubber gasket?

[elwesso]

It does actually say to do that in the manual.... but we attribute to it as a misprint.... maybe the covers have been resealed at some point and they followed the FSM??

[GEOFF]

I think it is factory or at least would assume since the Q has only 65K miles on it. I know the 90-93 has liquid gasket. The liquid was only added to parts of the front and back of the cover where it has the curves downward and the dips in the back. I added just a little to those areas.

[Q451990]

Ahh - the "half moons" - yep, those should be sealed with RTV.

Heath

[GEOFF]

Ahhh...thanks, I was waiting for some reassurance on that. It sure seamed to be factory done. Glad someone had a good name the those "half moons"

[elwesso]

I dont think you need to use RTV on the Half moons... my car didnt have it on there.....

[Q451990]

Are the half moons incorporated into the rocker cover gasket? My truck uses a rubber gasket with separate "half moons" but if I remember correctly the Q gasket incorporates the half moons. In either case I'm sure they should be sealed with RTV.

Heath

[elwesso]

The gasket it one piece and goes around the entire thing, half moons included.....!

[Q451990]

Wes - the "half moons" definately need the RTV. Q2 was leaking there, and we discovered that they hadn't been sealed at it's dealership reseal a couple of years earlier.

Heath

[elwesso]

So that needs to be done even with the rubber gasket that covers them!!! I see no logic in that, as mine was just fine after 125k... Mine was leaking out the bottom, and all the rest was just fine!!!