90 q45t Knocking Problem

[Katarnn]

Hey everyone, id like to say that q45.org and Nico has helped me out in the past alot with my Q and i hope you guys got some ideas about this frustrating problem i have now! ill explain...

I was driving back on the highway and slowed down to an exit and i started hearing loud knocking noise from the engine, we took off the front to look at the chain guides and they were backed by metal, no problems in there everything fine... then flushed the oil and added cleaner to try and clean out the lifters.. The noise still presists, somone told my mechanic that one of the hydrolic lifters may have went bad and that i need to replace it.. This is alot of work on a whim, anyone have any other opinions??

If you start up the car it sounds loud, and as it idles it goes away a little only coming back if you rev it a little. any help would rock....

[burijon]

If you really love the car it would be worth your time and money to go to T3 in Atlanta. They could probably scope it to pinpoint where the sound is coming from. Maybe you could do it on a long weekend.

http://www.t3auto.com

http://maps.google.com/maps?f=...&om=1

Another old post:zerothread?id=102790
Modified by burijon at 3:41 PM 9/10/2007

[96Qowner]

Can you give us some more info? Mileage and maintenance history? It has updated guides, so someone took good care of it at some point in its life. We can recommend some pretty harsh cleaners, if you want to try to unstick the HLA, if that's what it is.

zerothread?id=239012

zerothread?id=98972

[Q45tech]

Replacing a HLA requires the head be removed from engine and the head oven heated to expand the HLA socket......................not easy like on a valley cammed pushrod engine.

We usually start with an accurate oil pressure reading and a valve cover removal to have a look see.

With a Consult you can kill injection/ignition to single cylinders to note changes in sound.

Crank rod bearings are the usual first to fail after years of abuse.

[Katarnn]

I have some history of it, it only had 1 owner before me, took very good of the car, in the garage for most of its 120k life... Was out in dry new mexico weather most of its life then drove it to florida... Its had updated oil changes except for the last one, which went over a bit ( not to my choice) somone was barrowing the car and did not get the change when specified....

I used standard engine cleaner with 2x flushes, it did get a little better.. So im going to suggest to my mechanic that we use the GOOD stuff, as recommended on the site, i hope this works i dont want to have to replace the lifters... it sounds expensive and like alot of work..

[devonl]

I'm the guy looking at the car described above. In my earlier investigation, I took off the timing cover and the passenger valve cover. Now I'm trying to take of the driver's side valve cover to look at the HLA's on that side to see if they are sticking. I've run into a bit of a problem. The EGR pipe wraps around the back of the head and bends over top of the valve cover in such a way that there is no clearance to take the valve cover off. I can barely see where the EGR pipe connects to the exhaust manifold. Any of you that have taken an EGR pipe off know that it is usually rusted into place and is a *****. It does not appear that I have the room to put anything on the connecting nut or and if I could I would not be able to put leverage on it. This is all assuming that I do not have to heat the nut where it screws into the manifold.

Does anyone have any suggestions besides pulling the engine as to how I go about removing the driver's side valve cover?

[maxnix]

Decouple the EGR pipe at the exhaust while the car is on a lift.

[96Qowner]

I'm trying to take of the driver's side valve cover to look at the HLA's on that side to see if they are sticking. I've run into a bit of a problem. The EGR pipe wraps around the back of the head and bends over top of the valve cover in such a way that there is no clearance to take the valve cover off. I can barely see where the EGR pipe connects to the exhaust manifold. Any of you that have taken an EGR pipe off know that it is usually rusted into place and is a *****. It does not appear that I have the room to put anything on the connecting nut or and if I could I would not be able to put leverage on it. This is all assuming that I do not have to heat the nut where it screws into the manifold.

Read through these threads:

zerothread?id=107690

zerothread?id=51371

I searched in "post bodies" in Infiniti General "archived". There will be more in Q45 and Infiniti Online Mechanic forums.

[devonl]

I have the car on a lift. I still don't see a reasonable means of decoupling the EGR pipe. The exhaust manifold bolts are inexcessible without dropping the frame and I'm not going to do that. So, I can't remove the manifold. There is really no angle to put a wrench on the EGR pipe nut. Is there a special wrench for this?

[Q45tech]

There are literally hundreds of thousands dollars worth of specialty automotive tools................generally one need only a few thousand worth of tools to remove an entire engine.

The passenger side will tell you about as much as the drivers side [examing for sludge, varnish, and wear].

We use a wrench to fit the nut and bend it SLIGHTLY CAREFULLY out of the way an inch.

Common proceedure as the valve cover gaskets on every Q leak every 6 years and need replacing.

I assume you have removed the cover, coils, and plugs before proceeding to egr?

[devonl]

I got it. As it turns out, the last person to work on the car did not tighten the EGR nut down all the way. It was pretty loose. I still think the location and angle are a horrible design feature. If I have to put leverage on that nut, it would have been exceedingly difficult.

Yes, I know about specialty tools. I have a bunch for Honda and some for Toyota. You still have to know what you are asking for. I prefer not to bend my tools to work on a car.

I don't see anything immediately wrong with the HLA's on either side.