Page updated on 04-22-2018

how to change intake manifold gasket

06-10-2004, 04:26 PM
im new to the pontiac cars so i dont know much bout them, my neighbor asked me if i can change her intake manifold gasket on her 1999 grand prix. i was wondering if u guy can help me out and tell me how to change it or a link to where i can find info on how to change the gasket.
tia for the help guys.

06-10-2004, 06:31 PM
It is not difficult to change an intake manifold gasket but it will take you several hours. First you must disconnect the battery. Drain the coolant from the radiator and remove the engine cover if equipped. If not remove the air cleaner tube from the throttle body. You will need to remove the top radiator hose from the engine. It may be a good idea to replace the thermostat so disconnect the hose where it connects to the top of the manifold. Now you will need to remove such items as the coils, spark plug wires. It is best to number them so you can get them back on the right plug. Now you will need to remove the associated hardware that will prevent removal. Take the belt off, remove the alternator if it is attached to the manifold either directly or by a bracket. Remove the fuel line from the fuel rail after you release the fuel pressure. Be very careful not to damage the rails or the threads when you remove the fuel line. If there are any other hoses or lines connected to the manifold you will need to remove them as well. Disconnect the throttle cable, kick down and other associated connections to the throttle body. Now gently remove the wires from the injectors, there may be a clip that must be removed. Mark each one as to the number and location. Use a piece of tape to mark them.
Once everything is loose take a socket of the appropriate size and loosen the manifold bolts. Start in the center and work your way in a cris-cross pattern going toward the outside of the engine. Once everything is loose remove the bolts and place them in a bag or tray so you don't lose them.
Now, gently pry the manifold loose from the front of the engine. Use a screw driver and gently pry until the manifold comes loose. Once loose remove from the engine and place aside. Place paper towels in each port and lay a shop towel or two in the lifter galley. This will prevent any gasket or other material from dropping in the ports or galley that could damage the engine. Scrape the gasket surface with a gasket scraper to remove the old gasket. Wipe the surfaces clean and get ready to put everything back together.
Remove the towels being careful not to drop anything in the ports and make absolutely sure you do not forget to remove one! Place the new gaskets in place, there should be retainers with the set or locating pins on the heads. At the end of the manifold where it contacts the block there will be an area that has some type of silicone sealant. Remove the old sealant and replace it with a sensor safe silicone material. Most good gasket kits come with this in a tube. Put a healthy bead, not too much and allow for a curing time of about 30 minutes. Replace the manifold by placing it straight down. Don't twist it or move it excessively as you may dislocate the gaskets and cause a leak.
Replace the bolts and torque to specification in a pattern designated by the manufacturer. Hook up everything you disconnected and fill the radiator with coolant. Reconnect the battery and you should be able to start the car. Run it up to operating temperature and check for leaks.
I told you this will take time. I would also invest in a Chiltons manual before attempting to do this job.
If the car is a GTP forget the whole thing if you are a novice and have her take it to a repair shop. Good Luck!
By the way! Just how good looking is this neighbor anyway!!!

06-11-2004, 10:08 AM
who needs Chiltons after a response like that, nice work GTP DAD. one more thing i like to do is glass bead everything before i reassemble it. it makes the job go easier when everything is clean.

06-11-2004, 12:56 PM
thanks for the info guys. hopefully i can attempt this thing.

10-08-2004, 07:00 AM
I know this post is pretty old but was wondering how your manifold change went? And was there any product line ( gasket set) that is of higher quality.

I am changing out my son's 1998 manifold gasket this weekend. Thanbks for th detailed instructions. His is a not the GTP version just a straight up 3.8 V6. Any additional advice would be welcome


10-08-2004, 09:58 AM
Actually the non-supercharges 3.8 is much easier to change than the supercharged one. Just be very careful with torquing the manifold. Don't overdo it because it will crack. These manifolds are very brittle and if you go wild with a wrench you will have to replace it. In fact most are composite material. Be sure to change the oil and refill the coolant when done. Good Luck!

10-08-2004, 10:02 AM
Thanks for the advice. Of course I am doing the uppper and lower manifold. But it looks more like that it is leaking from the upper manifold only because the indentations in the lower manifold are filled with Antifreeze. I would think if it was the lower one there would be more on the ground. The engine runs great and there is no sign of coolant in the oil Anyway maybe I should just change both to be safe

Just to be sure I get all the required gaskets I'll ask one other question.. Does anyone make a complete kit for this task I am about to undertake? If not other than the obvious upper and lower gaskets, is there any trick ones that I should have on hand also?


10-09-2004, 09:32 AM
Just to give you guys an idea of what you are saving on this job. I just had the same thing completed at the dealer on my 97 GT. Upper and lower intake gasket, new intake, and the misc that goes with it. in all 1644.64.

Also check for coolant in the plugs from teh leak, that is how mine was discovered and it fouled the plugs, this left my wife stranded.

10-09-2004, 09:47 AM
GTP Dad,
How long did that take to type? I'm alittle better then "hunt and peck". I figure a week to 10 days?
Great job.

10-09-2004, 02:59 PM
Only about 10 minutes. I have a lot of experience changing manifold gaskets for some reason!

Anovib, you should be able to get a complete kit to do this job if you purchase the kit for the lower intake manifold gasket replacement. Since you have to remove the upper manifold first, the gaskets should come with the kit. Remember, take your time, label everything properly and you shouldn't have any problems. Let us know how it turns out.

10-09-2004, 08:10 PM
Hey all.. !!!

I started at 9 am labeled everything like GTP Dad suggested. Ran down to the Autoparts store got the gasket set. Cleaned everything.
Also Re- O ringed the Injectors. Even changed the spark plugs. That turned out to be the toughest job of all.

Had lunch and started the engine at 2 PM. Like you all said. Easy Job time consuming yes but it does help to have air tools. Done in 5 hours. Took it for a test drive racking up around 40 miles round trip. Not a leak in site.

Thanks to everyone


10-11-2004, 10:06 AM
IF it's a 3800, it's more likely the upper intake is cracked than a bad intake gasket. They make aftermarket replacement upper intakes that come with the intake gasket for around $150. If you don't replace the upper intake now, you will be shortly, as they all crack sooner or later in the coolant passage behind the throttle body.

02-12-2005, 01:55 PM
Anyone know where I can find the torque specs for the UIM? (97 Grand Prix GT)

02-12-2005, 07:20 PM
Intake manifold to the cylinder heads is 132 inch pounds. Per the Haynes Manual.

02-13-2005, 03:02 AM
The last couple weeks, my wife's 2001 GpGT 3800 sounds like the coolant fan is on (at max speed) all time. In fact, the fan-like noise is coming from the upper intake manifold. It sounded either air blowing inside or water gashing inside.

There is not external leaks visibly on the car. The coolant level is same. RPM is normal and the car is not losing power. Do I need to replace the UIM and/or the gasket? Thanks,

02-13-2005, 03:07 PM
I would pull the manifold off and check it just to be safe. Replacing the gaskets is not difficult just time consuming. If you hear that loud a sound then something is going on. Before pulling anything off, I would check for a vacuum leak, as you could have a hose that is cracked or has fallen off.

02-14-2005, 06:59 PM
Dad, same torque for the upper plenum?

Anyone have any experience with the upper plenum from these guys? only $150

The local dealer wants $235 for the upper and $47 for the gasket!!!

Dad, I saw something on the net where there was a kit that changed out the EGR tube (smaller tube with a sleeve). What do you think about that? Or just change the upper and the gasket to fix a very small coolent leak from under the right side.


Intake manifold to the cylinder heads is 132 inch pounds. Per the Haynes Manual.

02-15-2005, 05:40 AM
I looked at the link and the price seems quite good. It also offers several advantages over the stock one. I would go with it. Also it has improved EGR characteristics so I wouldn't worry about changing the EGR tube if you change to the new plenum. The book did not specify the torque for the plenum but it sounds about right. If you purchase a new plenum they will probably supply you with the torque specs. If I was going to do this job I would certainly replace the plenum with a new one due to the possibility of a crack or warpage in the old one that is causing your problem. I would also change the lower intake manifold gasket while I had it torn apart. Not much more money and you already have it torn apart anyway. Good Luck!

01-11-2010, 10:36 PM
Dad, know its been awhile since original post but are you still on here? Was thinking about taking this task on with a 1995 grand am gt... Am a high school senior but went to tech school for automotive mechanic last year so im pretty good with my hands and tools... Procedure abouit the same?

01-12-2010, 08:24 PM
Dad, know its been awhile since original post but are you still on here? Was thinking about taking this task on with a 1995 grand am gt... Am a high school senior but went to tech school for automotive mechanic last year so im pretty good with my hands and tools... Procedure abouit the same?

Welcome to AF.

Please post at the Grand Am forum. This thread has been closed due to no relevance and/or applicability due to make of car and engine.

Add your comment to this topic!