Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.

New Posts Contact us

Just Commodores Forum Community

It takes just a moment to join our fantastic community

Register

VT 3.8 Inlet Manifold Gasket Replacement - recommendations?

vtbob

New Member
Joined
Mar 29, 2009
Messages
17
Reaction score
0
Points
0
Members Ride
99 vt 3.8
I'm in the slow process of replacing the inlet manifold gaskets on my VT 3.8.

Are there any recommendations, such as putting sealant on the gaskets etc?

Noticed the end pieces had some black silicon on them - Is that a factory thing?
I bought the car ar 80k and it is now at 200k+.
Not been touched by me previously!

Anything else worth replacing or doing?

Noticed the valley is a pain to clean without dropping crap into the working!

Just going to have to do an early oil, filter & coolant replacement.

BTW, What is a good coolant to use?
Been using some $20 ready mixed stuff, but have noticed some corrosion around one of the coolant ports on the manifold, so maybe it just aint good enough.
 

Raging Bull

New Member
Joined
May 26, 2005
Messages
300
Reaction score
4
Points
0
Age
40
Location
Melbourne
Members Ride
VX S Pack L67
I'm in the slow process of replacing the inlet manifold gaskets on my VT 3.8.

Are there any recommendations, such as putting sealant on the gaskets etc?

Noticed the end pieces had some black silicon on them - Is that a factory thing?
I bought the car ar 80k and it is now at 200k+.
Not been touched by me previously!

Anything else worth replacing or doing?

Noticed the valley is a pain to clean without dropping crap into the working!

Just going to have to do an early oil, filter & coolant replacement.

BTW, What is a good coolant to use?
Been using some $20 ready mixed stuff, but have noticed some corrosion around one of the coolant ports on the manifold, so maybe it just aint good enough.
Yeah silicon is a must when putting on the red side rubber seals, you put the silicon on the side corners and yeah I'm pretty sure it is a factory thing since there was silicon when I took my ones apart.

As soon as you remove the injectors plug up the holes tight with some tissue pieces just don't plug them in too deep just enough to cover them so that you can easily take them out later. Once the manifold is removed get a big rag, preferably some kind of an old t-shirt and place it on top of the area so that no crap can get in there whilst you clean the place out.

Careful taking the manifold out once the screws are undone.

- There's an annoying bracket at the back of the manifold holding it in place, try to pry it back while taking the manifold out.

- Don't forget to disconnect everything before pulling it out, I forgot about the coolant temp sensor connector located on the passenger side edge of the manifold.

- Try not to damange any of the vacuume hoses that you have to disconnect when taking the thing apart.

- Theres a metal o ring at the front of the manifold(might be only on L67) if you damage it and put it back together again it will leak, so be careful when taking it out again.

- Give the manifold a nice clean once it's off and make sure to remove all the old gaskets etc from the top and bottom and if you have access to some sand paper, give it a good clean so it's nice and shiny and adheres to the new gaskets nicely. Buy some throttle/carby cleaner and go crazy with it.

- Use a torque wrench when torquing the manifold screws, make sure you get the correct torque. From memory it was only a weak 30Nm for the manifold.

- Clean out the throttle body, IAC and manifold with the throttle body cleaner, if your manifold is super grimy and black go to Safeway and pick up a bottle of Mr. Muscle oven cleaner for $3 it will take away the grime and bring back the original shine in no time.

- As you put the new gaskets in and bolt up the manifold, put the heater on hot and undo the bottom radiator hose, then get your garden hose and flush out the system through the top, wait until clean water is coming out from the bottom. Do the same thing by disconnecting the heater hose and forcing water through there until it's clean on the other end.

- Change the thermostat/gasket as well while you're at it, takes only a few minutes.

- Pick up the genuine Holden coolant concentrate and mix it with distilled/demineralised water. You'll fit about 5 litres of concentrate in the radiator and the rest has to be filled up with the water as you're bleeding the system and freeing up the air gaps.
 

vtbob

New Member
Joined
Mar 29, 2009
Messages
17
Reaction score
0
Points
0
Members Ride
99 vt 3.8
Thanks for all that info.
Only problem I already have it off so missed out on your initial tips.:)
Think I will have to get the vacuum cleaner on it to suck out any bits that have fell in.
I will have to try the oven cleaner because everything else I have tried, including carby cleaner didn't remove much of the grime.
Is it worth replacing injectors that have done over 200k?
The engine was running just fine prior to the strip.

Thanks again!
 

Raging Bull

New Member
Joined
May 26, 2005
Messages
300
Reaction score
4
Points
0
Age
40
Location
Melbourne
Members Ride
VX S Pack L67
Yeah get your injectors supersonic/overhauled cleaned or whatever it's called, it's worth it in my opinion. Mr. Muscle will smash the grime away and bring it back to the aluminum, it's a great product. Don't forget to bleed the cooling system properly.
 

vtbob

New Member
Joined
Mar 29, 2009
Messages
17
Reaction score
0
Points
0
Members Ride
99 vt 3.8
Job now done, Mr Muscle worked a treat.

Couple of tips.

Keep your valley end gasket pieces incase the ones you get in the kit are different.
The ones in the kit I had wouldn't fit at all!
Different profile!


Although you dont have to touch the throttle cable adjustment, be careful when tightening the 2 lock nuts. Mine were loose, and on tightening they easily sheared the outer sleeve.
A few cable ties fixed the problem.:whistling

As recommended, change your thermostat. Mine looked as grotty as hell!
 

Simonn

New Member
Joined
Sep 28, 2007
Messages
231
Reaction score
0
Points
0
Location
keilor down, vic
Members Ride
Vx S pack m5
sorry. But I suspect my car may have a leaking intake manifold gasket. If I was to put a radiator pressure testor onto the radiaor would it show a drop if the intake manifold gasket is leaking? if it does not show a drop would it mean 99% that my gasket is not buggered?
 

alien

New Member
Joined
Nov 5, 2008
Messages
913
Reaction score
17
Points
0
Location
Tullamarine, Vic
Members Ride
03 VY Supercharged 3.8L
Simonn, if you have a pressure tester then yes thta's the best way. Or you could check your oil for a milky appearance. In the sump and under the filler cap [or if you want remove the rocker covers and look too].
 

Simonn

New Member
Joined
Sep 28, 2007
Messages
231
Reaction score
0
Points
0
Location
keilor down, vic
Members Ride
Vx S pack m5
ok thanks would you happen to know what pressure to pump it up to? btw its on a vx 3.8
 

Simonn

New Member
Joined
Sep 28, 2007
Messages
231
Reaction score
0
Points
0
Location
keilor down, vic
Members Ride
Vx S pack m5
thanks. Anyone know how likley it is for vx engines to do head gaskets. The old man done a c02 test from the radiator and it gave a positive read which means exhuast gases are getting into the coolant somewhere. I'm praying it not from the head gasket.
I was thinking maybe there is a leak between the comustion chamber and coolant gallerys in the intake manifold with the engine having an EGR type system there may be a small amount of exhuast gasses in the combustion gasses and becuase of a possible leak between the combustion intake and coolant galleries some of the combustion gasses (with the exhuast gases in them from the EGR) may be getting into the coolant thus giving a positive reading. If anyone could commant on weather or not this is possible it would be great.
 
Top