Well kids, I hate my life...

[jimbyjimb]

I spent this morning pulling the ABS unit and the A/C hoses off. That bracket for electrical connectors is all that stands in my way for removing the right valve cover. Getting to the bolts there is nigh impossible, so I'm just pulling the plenum. All the rubber is hard and brittle anyway, so here comes all new hoses, harnesses, plugs, knock sensors and going to ohm the injectors. Also putting on new timing chains since the covers will be off. Any input is appreciated, very open to advice on parts/anything in general!

Max-you'll be ahppy to know I'm also pulling the pan. No sense in doing a couple weeks work to lose 'er to a plugged oil pickup. New tension rods too.

[jimbyjimb]

Update-Blowby. Oil in the intake, pooled behind the throttle body. I'm going to check the PCV, see if that's sucking it. The entire inside of the intake is coated. I'm hoping it isn't blowby but right now that's what it looks like. I'm beating around a re-ring. Any particulars on what else could cause this?
Modified by jimbyjimb at 5:27 PM 4/19/2008

[jimbyjimb]

I'm not sure this could be blow by. The thing passed emissions with stellar results. I'll have to check the plugs out. Grr...

[goody90q45]

A small amount of oil behind the TB is to be expected. Notice that both of the 1" rubber tubes (crankcase ventilation) entering the air tube vent oil vapors directly off the valve cover. I've pulled TB and plenums off 5 Q's and every one has had some amount of oil pooled in the same area. The inside of the entire plenum and at least the backside of the TB are probably also coated in a darker but dry oil buildup. Wait until you see your lower runners.

The EGR passage being plugged is a sign that your Q may have not been well maintained for a number of years. A poor running engine (bad injectors/cracked emission hoses/vacuum leaks) will eventually plug the EGR system on most any car.

Carry on. IMHO what you're seeing so far is normal.

[jimbyjimb]

I checked on the service record at the local dealer and know it has been maintained to a certain extent. Glad to know the oil issue. Found a bunch of oil in the plug holes. Probably leaky cam covers. Thanks for the input!

[maxnix]

Ah, the Sirens of the VH45DE are calling you. At least you are doing the job right. Do it all now and be done with it for 100K or ten years.

Probably do not need hew chains for the camshaft unless they have been gouging the block. .25" stretch in 250K miles is abouot all that happens. More robust than almost anything else out there. Oil pump chain is commonly replaced as are the timing chain tensioners.

http://www.infinitipartsusa.com

Joe is your friend.

[Q45tech]

10 years might be optimistic as over 318k, I've replaced all hoses twice including fuel hoses.

As to PVC I clean it every 15k now or once per year due to blowby.

The engine smokes a little for 1-2 minutes on a COLD ovenight winter start but that doesn't seem to affect power..........the 50-80 times have actually improved at 300k vs 100k by 0.1 seconds indicating about a 10 lb/ft improvement [ring wear lower friction].

Once you really clean plenum and runners with brushes down to spotless ONCE it will be easy to keep them that way with a fogging after TB manual clean.

In town, idling with mild acceleration and cruising really are not this engines clean mode. It needs to be reved and stressed once per week to keep clean.

Obviously you must balance fogging with ringwear [don't fog every year/15k] but frequent BG44k [more than 4 per year/15k] don't seem to be a problem even with basic conventional oils].

Checking very hot idle oil pressure with an accurate gauge is a good annual exercise.

BE SURE TO CHECK at lowest rpm in drive ac on worst case situation because most engines spend at lot of time in that situation. WITH BRAND new oil and filter again worst case.

[jimbyjimb]

The only reason I'm going to do the chains is that they mistakenly charged and sent them to me, so I may as well since I have them. Today I'll have the plenum off and I'll re-time/install new chains and reseal the covers. If all goes well. It's been kind cold out here lately, like snowing in April. I Pulled a plug and it was clean, and in good shape even though all 8 are getting canned since I don't want to take this apart again for a while. The plug hole was filled with oil, probably leaking in from the cam cover. This simple chain guide job sure got ugly quick.

[maxnix]

IOS will take the timing chains back if they are still sealed.

The Sirens of Infiniti are calling you, dig deeper, dig deeper.....

You'll be amazed when you are finished with the suspension also.

[jimbyjimb]

The sirens of Infiniti are deafening me! turn them down...haha. Anywho, just got the messy plenum off. Any reccomendations on parts to order? Have checked past threads and have seen Joe's under-plenum hose kit. Any other reccomendations besides plugs, ohming and general cleanup? I think I will send those chains back, the originals are beautiful and the left side barely wore into anything at all, which is amazing.

[jimbyjimb]

Has anyone ever tried spraying rubber preservatives under plenum to help preserve these hoses? It would take some time and a whole spray-bottle, but it could be worth it. That'd be a trick.

[AZhitman]

Don't know about preservative, but I'd be temptd to wrap ALL of them in a heat shielding if I ever tear down another VH.

[maxnix]

Has anyone ever tried spraying rubber preservatives under plenum to help preserve these hoses?

Usually, the hoses fail from the inside out. You could try some Wurth on the insides I suppose.

[Q45tech]

The center coolant hoses and a few formed hoses fail first so why worry and just change them all every 6-7 years or 100k.

From experience I predict that 80% of current NICO early 90-93 Q owners won't own their Q in 7 years!..

The 10 of us remaining will be happy to change the parts.