[VT-VX] VS - VY Series 2 Inlet Manifold Gasket Replacement 6hr+ (Includes Pics)

[turbovich]

I don't suppose you know what the O ring sizes are? I can never remember.

Here you go..

 

[losh1971]

Burson sell them in a kit for about $5 - $7. Bugger of a thing is you can't buy a Buick kit, like you can an Eco, so have to buy a couple of different sizes from bearing supplier and use the best fit.

 

[Bill Burford]

I did not disconnect the fuel lines but tied the upper plenum chamber to the driver's side bonnet strut. Mine is dual fuel so I had another layer of things to do. I am pasting my notes here. Bill

VALLEY GASKET REPLACEMENT ON DUAL FUEL INJECTED 3.8 VX COMMODORE.

This is covered in a number of YouTube vids but here are a few of my ideas on a VX Commodore dual fuel with injected LPG .

Take photos of everything before you work on it so you can put things back in the right place!!

After removing the turtle cover remove the plate on top of the plenum chamber then before removing the top part of the plenum chamber remove the electrical connectors to the six petrol injectors using long nose pliers to avoid dropping the wire clips.

Remove the top part of the plenum chamber. I did not undo the fuel lines but simply tied the top part of the plenum chamber to the driver’s side bonnet strut.

There is a spring on the top of the inlet manifold exposed by removing the top plenum chamber. It holds the PCV valve. Extract the PCV and you should be able to blow through it one way but not the other, and it should rattle when you shake it. Give it a clean – see YouTube - or better still, replace it. They are not expensive.

The Throttle Body (TB) has two hoses, one towards the front connected to a port on the inlet manifold, and the other one is a purge hose going to a fitting on the back of the engine, driver’s side. This fitting has an electrical connector and another hose, and is rather hard to find. Detach it from this fitting and from the TB. There are two rather obvious electrical connectors to the TB, and two cables. The cable with the smaller plastic end is detached from the TB by bringing the ball joint on the TB backwards and the other larger metal one is a press on clip.

LPG injectors will depend on the type you have. On one side I had to detach the wiring to the module and of course you have to detach the hoses. Detach them from the modules rather than the manifold where they will have had more heat on them and might tear.

At the back of the manifold there is a clip holding reasonably major wiring harnesses which you have to unclip by lifting the harness up. Yours may be better clipped than mine were. Before lifting the inlet manifold, check the location of the purge hose from the TB to the back of the engine. It threads through the manifold pipes. (I did not pick that and when I lifted the manifold I had a plastic pipe about 300mm long with the hose connector to the TB on one end and no idea where the other end went. It was a bugger to get back when I had all the major parts reassembled and in the end I routed a longer hose round the front of the plenum chamber to connect the purge hose.)

Reassembly is covered on You Tube. Remember before replacing the alternator to put the plug leads and the alternator connector harness UNDER it, otherwise they will not fit!

Under the alternator are two hose connections to the heater tap. Use silicone RTV on the O rings which are best replaced. The bottom one which is about 190mm long and presses into the engine with nuts on two studs at each end, should fit easily. If you over tighten the nuts because it does not fit easily you can break the aluminium tang necessitating a trip to the wreckers.

Hope all this helps. Keep well.

 

[Rikls2]

Has any one changed these an ended up with a really bad missfire like its running on 5 cylinders afterwards ?? Trying to figure out where i went wrong

 

[ephect]

It may have had some water in the cylinder that it's clearing out.

Check to see if you have a vac leak, and the manifold bolts are tight after a heat cycle.

Worst case the gasket has move and its letting water in.

 

[Rikls2]

Is their any way to know if gasket moved will spark plugs tell me ? i did bump it out of place when placing manifold back on but lined it back up so was sitting snug (so i think) i did also arc alternator wire when putting that back on forgot to disconect batery

 

[Rikls2]

All sorted thanks guys a bit embarased to say but i had 3 and 2 spark plag leads around the wrong way

 

[Skylarking]

All sorted thanks guys a bit embarased to say but i had 3 and 2 spark plag leads around the wrong way

In my haste I’ve been there done that… we’re only human

Thanks for updating the thread with the cause and fix as it ties up your bit nicely…

PS: hopefully your electronics are ok after your spot welding attempt… always best to disconnect the battery when working on or near a car alternator... again, been there done that…

it’s especially important to avoid such mishaps in newer cars with a gazillion computers within… can get crazy expensive otherwise…

 

[Timmy B]

I am not a mechanic. Please only use this as a Guide. Take all necessary precautions when working on your car including gloves and eye wear protection. I undertook this repair with the help of a Gregorys Mechanic Book and generalised knowledge of my Ecotec Motor and components. If I could do it I am sure most others could as well. The repair by myself took a hard 6 hours of work. If you can't spare at least a day then I would leave this to a mechanic.

Things you will need:

Engine Oil, Oil flush (approx $35 bucks)
Coolant, coolant flush, new radiator cap (approx $50 bucks as I use genuine Castrol Coolant)
Thermostat, Thermostat Gasket (Ecotec Motor Tridon TTG46) (approx $24 bucks)
New Inlet Manifold Gasket Set, Instant Gasket Sealant RTV or equivalent (approx $140 bucks as I used a lifetime gasket set aluminium one)
A good set of Screw Drivers and Ratchets, a rubber mallet, Fuel Disconnect Tool
Turps/Petrol, Razor Blade tool

MONEY SAVED

I would guess this job would cost 4 hours labour in a mechanics shop, the current going rate is about $100 bucks an hour. Plus your guaranteed a mechanic would be using cheap coolant, oils, the cheap plastic gasket set, not quality products like I have used. So assuming this the mechanics price would be around $500 - $600 bucks, could be wrong though maybe someone can assist with this. So easily I've saved $200 - $300 bucks doing it myself and now I've got more of an understanding of my engine from doing it.

Step 1

Turn engine on. Open bonnet and remove Fuel Relay Fuse from Fuse boxs in engine bay. Check your diagram to confirm which fuse it is. Wait until engine stalls. Attempt to crank at least 10 times to try and reduce fuel in fuel lines and injector fuel rails.

Step 2

Remove Battery. This is to prevent any unintended sparks from hitting a Positive lead in the Engine Bay which could potentially damage components or computer hardware.

Step 3

Time to get dirty. Start by removing the air box and piping to the plenum. Don't forget to remove the Air Box Sensor and the MAF sensor.

Step 4

Remove the Throttle Bracket which is attached by three bolts on the rear. Pry off the throttle cable from the nob with a screw driver or similar. If you have Cruise control there will be a second cable and nob to pry off. (Not %100 percent sure as I don't have Cruise Control).

Step 5

Unbolt the EGR (Only for VT-VY). As I am aware VS does not have a EGR.

Step 6

Remove your Engine belt. Unbolt your alternator. Theres two screws plus a ground screw underneath. Theres also a support bracket which needs to be unscrewed. At the rear is a another ground i think which is surrounded by rubber. Don't forget to unplug the clip at the rear of the alternator. If all bolts remove the alternator should slide up and out of the supporting metal brackets.

Step 7

Ok now is the time to remove the coolant from the system. Undo the bottom radiator hose allowing coolant to come out. Have a tray underneath to catch the coolant to dispose of it. Remember Environment and dispose of coolant correctly. Remove the top radiator hose. Allow as much of the coolant to drain and then remove the thermostat housing by undoing the two bolts. Attached to the bottom of the housing will be the old paper gasket. Scrap this off using a razar or petrol/turps. Remove the thermostat, Discard if you have a new one. If reusing make sure thermostat still works. Test in boiling water. It should open up in Boiling water and close when cold.

Step 8

Unplug all the injectors and fuel rail lines that enter the body on the drivers side using the fuel disconnect tool. Undo all the vacuum lines from the rear of the plenum. Not all of them need to be removed as one or to goes to the fuel lines which you disconnect which can go with the hole plenum when pulled off.

Step 9

Time to remove the Tensior Pulley Assembly. undo bolts underneath. Undo the heater radiator pipes that connect to the metal pipe. Once all bolts undo slowly slide the metal cylinder out from the tensior pulley assembly and remove the whole assembly.

Step 10

Attempt to remove any coolant left in the lower manifold. After this make a quick check around the engine bay making sure no bolts or cables are in the way for when you remove the plenum/lower manifold.

Step 11

Remove the 12 bolts that attach the lower manifold to the engine. When reassembling the Torque range is between 12 - 16 NM which is quite weak. You may notice when undoing these bolts some will be extremely loose.

Step 12

Ok if you have removed everything correctly the whole plenum/TPS/ICA and lower manifold should come free revealing the intake manifold gasket. This is were I could see I had a small leak near cylidner 1 - 3. Also a small leak at the rear of the block.

Step 13

You need to clean the matting surfaces from which the gasket was sitting on. Do so using a razor, turps and or fuel until clean. Do the same on the bottom of the lower manifold. Be careful not to disturb the injector nozzels which poke through. While doing this step cover the engine compartment to prevent foreign objects getting into it. If you suspect anything has fallen in you need to flush your oil and replace the oil ASAP.

Step 14

Once you are satisfied both matting surfaces are clean position the new gaskets. Place RTV Sealant or equivalent in the four corners to provide a seal and stop leaks. Apply librally as it won't hurt as long as you get it in the right place. RTV Sets in 10 minutes so be quick to replace the plenum/lower manifold back on the engine.

Step 15

Bolt up 12 bolts on manifold to 12 - 16 NM Torque and let set for 2 hrs or longer if you have to spare.

Step 16

Reverse of Steps 1 to 12 making sure you set thermostat correctly with new gasket. (I put in a cooler Thermostat the 81 Degrees one, The car runs cooler during highway driving and doesn't heat up as quickly during city stop and go, not really necessary as long as your cooling system is in A1 condition.)

Step 17

Put in fresh coolant with correct water/coolant ratio 33% - 50%. Double check all plugs/wires/bolts are re attached and correct. Replace fuse relay and battery.

Step 18

If you are satisfied everything is correct and back together start engine. Check for leaks in coolant system. and around manifold gaskets. After a week replace oil and coolant to remove any foreign objects. Then you are done.

I know this is an old post, but thanks so much for ging to the trouble of writing all of this and including photos. Ended up doing it myself, and it took ages, but well worth it. I made the mistake of using cheap o-rings in the pulley tensioner bracket first time around - leaked like a sieve. All sorted after buying genuine o-rings.
Thanks again.