High mileage service

[Qxx4]

Hello,i need help so after tommorw im doing a major service like changing the pcv valve and tighting the power valve screws so what do u recommend doing as long as im disassembling the top part of the engine so i need to know what parts needs to be cleaned from carbon or changed.

P.s fuel filter and spark plugs done 8 months ago

[00pathyse]

cleaned the maf and throttle body? Not much else needs to be cleaned unless something is wrong.

[atraudes]

Check to see if there are any puddles or dampness around any of the injectors. If you see any, you have an excellent opportunity to replace the injector gaskets. They're pretty cheap and not horribly difficult to replace, so maybe do it regardless?

Replacing the PCV and crossover hoses is probably a good idea too. Both of them were pretty rotted on mine. The crossover is a hose that runs between the valve covers so that a PCV valve isn't needed on either side. The crossover is molded, so your best bet is to buy an exact replacement, but I used bulk hose without too much trouble. Sorry, no idea what size the hoses are.

I also replaced all of the hoses on the vacuum gallery the same day I pulled the intake runners off, though you can really do that anytime.

You know to replace the intake gaskets when you pull the runners, right? Fel-Pro makes a great gasket kit if you don't have one already. Also, immediately plug the intake manifold with rags or paper towels or something so you don't accidentally drop a nut or bolt down the intake manifold. One of the other members here did that not too long ago and is still posting updates on his adventure getting the metal bit out.

Another note while I'm thinking of it: on my 2001 I needed a slightly longer 10mm wrench to access one of the bolts on the backside of the intake. The one I had was just slightly not long enough.

What year is your QX4? I had an 01+ in mind when I responded, but the ideas are probably applicable to previous years.

Good luck! That's a fun weekend project

[attofarad]

If you are taking off enough anyway that it is easy to remove/replace the "water control valve", do that while you are in there. If you are not familiar with the part, it is a second thermostat, which sits between the engine and the firewall. My wife's water control valve was found to have failed at 187k miles, while in there replacing a coolant leak in the crossover tube gasket.

[Qxx4]

Check to see if there are any puddles or dampness around any of the injectors. If you see any, you have an excellent opportunity to replace the injector gaskets. They're pretty cheap and not horribly difficult to replace, so maybe do it regardless?

Replacing the PCV and crossover hoses is probably a good idea too. Both of them were pretty rotted on mine. The crossover is a hose that runs between the valve covers so that a PCV valve isn't needed on either side. The crossover is molded, so your best bet is to buy an exact replacement, but I used bulk hose without too much trouble. Sorry, no idea what size the hoses are.

I also replaced all of the hoses on the vacuum gallery the same day I pulled the intake runners off, though you can really do that anytime.

You know to replace the intake gaskets when you pull the runners, right? Fel-Pro makes a great gasket kit if you don't have one already. Also, immediately plug the intake manifold with rags or paper towels or something so you don't accidentally drop a nut or bolt down the intake manifold. One of the other members here did that not too long ago and is still posting updates on his adventure getting the metal bit out.

Another note while I'm thinking of it: on my 2001 I needed a slightly longer 10mm wrench to access one of the bolts on the backside of the intake. The one I had was just slightly not long enough.

What year is your QX4? I had an 01+ in mind when I responded, but the ideas are probably applicable to previous years.

Good luck! That's a fun weekend project

Sorry forgot to mention it's a 2003 and another question is the pcv valve on the 03's threaded or non-threaded and does it make it different if it's GCC specification,not US bcuz I live in dubai.

Thanks for your time and help

[atraudes]

Looks like yours is threaded:

post6275283.html

No ideas on GCC/US.

No problem!

[Qxx4]

I have another question well as I said I live in Dubai and I cannot find maf cleaner but I have found carb cleaner will it do the job or I need another alternative

[atraudes]

From what I've gathered, no, it's probably not safe. It may work for now, but it could eat at the element. If you're going to substitute, rubbing alcohol and a q-tip or CRC QD Electronic Cleaner are the safest alternatives.

http://www.bobistheoilguy.com/forums/ub ... er=1528722

[Qxx4]

So guys today I was planing to change the Pcv valve but things went the wrong ways I took the first part of the manifold and I saw 3 plates of the power valves were missing and found out that 2 of them were stuck on the last which this caused gates to get stuck closed so only 3 gates the engine took air so I was expecting to find the last plate on the second manifold but I didn't so to took the injectors pipes out and broke the pipe between the cylinder heads but not a problem I took out the third manifold and found the last plate and I changed the Pcv but it dosent end here when I took the third manifold I found that the gates were stuck open because of the carbon built up with 2 cans of carb cleaner I clean it and I got them unstuck and their is a lot of carbon built up also on the valves any ways to clean these out and I'm saying a lot of carbon built up and I will post some pics now it took me 5 hours dissembling it and I will be finishing it on Saturday. But what a great engine air was only going to 3 pistons and was running fine I was shocked