Head gasket or intake?

Well I have been reading a lot about head gasket problems on here lately and am wondering. I know that the Grand Prixs are well known for the lower intakes going seeming like a possible head gasket problem. What I am wondering, Is there anyway to determine whether the problem I am having is head gasket, intake or both? I really dont want to get into a head gasket replacement if I can avoid it but if I have to I have to I suppose. Here are the symptoms involved which you may have read a hundred times. I am losing my heat every 2 or 3 days which invloves coolant loss from the rad. I replace the coolant and have heat again for a little while then it starts again whithin a few days. I do have the old milkshake oil dipstick now and then, I say now and then because sometimes it is and sometimes its looking good. But almost always showing over full for the oil which I am pretty sure is coolant in the oil. Again sometimes I have the thick shake like brown mixture on my stick and sometimes I dont, Sometimes the heat works great and sometimes I have none. It also seems to be a bit of oil in the rad or at least discoloration (Brownish but no milk shake substance). ut it is always after a few days going down on coolant. I do have a bit of steam from the tail pipe but not a whole lot. I have stuck my hand under the exhaust for a minute then smell my hand only to smell that sweet coolant smell on it. I know I have a leak of some sorts becaus I have had it pressure tested at a local garage through the rad cap and opened the cap for the valve cover and actually heard the hiss coming through as we applied pressure into the rad. Now what I need to know is this, is there a sure fire way to say whether this is for sure a Head gasket or an intake manifold leakage. I would much rather change the intake then the whole 9 yards but hey, what ya gotta do is what ya gotta do. I have priced everything I will need for a head or intake replacement but dont really want to only do an intake then find out it WAS the head causing the problem. BTW, I am losing no power as of yet, no sputters or stalling or anything of that nature. I have a haynes manual on the way within the next few days so I am getting ready to tackle what I have to. Just wondering, AGAIN, if there is a way to determine if this is for sure a head or an intake or possibly both. Thanks in advance for any and all replies, they are greatly welcome and appreciated.

Well I have been reading a lot about head gasket problems on here lately and am wondering. I know that the Grand Prixs are well known for the lower intakes going seeming like a possible head gasket problem. What I am wondering, Is there anyway to determine whether the problem I am having is head gasket, intake or both? I really dont want to get into a head gasket replacement if I can avoid it but if I have to I have to I suppose. Here are the symptoms involved which you may have read a hundred times. I am losing my heat every 2 or 3 days which invloves coolant loss from the rad. I replace the coolant and have heat again for a little while then it starts again whithin a few days. I do have the old milkshake oil dipstick now and then, I say now and then because sometimes it is and sometimes its looking good. But almost always showing over full for the oil which I am pretty sure is coolant in the oil. Again sometimes I have the thick shake like brown mixture on my stick and sometimes I dont, Sometimes the heat works great and sometimes I have none. It also seems to be a bit of oil in the rad or at least discoloration (Brownish but no milk shake substance). ut it is always after a few days going down on coolant. I do have a bit of steam from the tail pipe but not a whole lot. I have stuck my hand under the exhaust for a minute then smell my hand only to smell that sweet coolant smell on it. I know I have a leak of some sorts becaus I have had it pressure tested at a local garage through the rad cap and opened the cap for the valve cover and actually heard the hiss coming through as we applied pressure into the rad. Now what I need to know is this, is there a sure fire way to say whether this is for sure a Head gasket or an intake manifold leakage. I would much rather change the intake then the whole 9 yards but hey, what ya gotta do is what ya gotta do. I have priced everything I will need for a head or intake replacement but dont really want to only do an intake then find out it WAS the head causing the problem. BTW, I am losing no power as of yet, no sputters or stalling or anything of that nature. I have a haynes manual on the way within the next few days so I am getting ready to tackle what I have to. Just wondering, AGAIN, if there is a way to determine if this is for sure a head or an intake or possibly both. Thanks in advance for any and all replies, they are greatly welcome and appreciated.

For what its worth, the few g.p.s that i saw leaking were leaking from the intake in the front (front of the car) of the engine and could physically see it leaking and smell it. i dont remember how the oil was though cuz i took mine in and had it fixed right away,and they changed the oil. that was a 3.1 in a 99.

I'm no expert but I'd say if you keep driving it in this condition it won't be long before you know what the problem is because it will probably ruin the whole engine and leave you on the side of the road. Water in the oil is never good.

I'll second that. ^^^^

IMO the best DIY test for a possible head gasket is to run a cylinder compression test.

What year Grand Prix and engine size?

If it is a 97 - 98 model with 3800 NA its probably just the UIM/Plenum and gasket. If a 3.1 or 3.4 the lower intake manifold gasket.

I'll second that. ^^^^

IMO the best DIY test for a possible head gasket is to run a cylinder compression test.

What year Grand Prix and engine size?

If it is a 97 - 98 model with 3800 NA its probably just the UIM/Plenum and gasket. If a 3.1 or 3.4 the lower intake manifold gasket.
To add to Bob's suggestion ,a second option for diagnostics is a leak down test, this allows more time to hear pressure loss between the cylinders or into the cooling system.

To add to Bob's suggestion ,a second option for diagnostics is a leak down test, this allows more time to hear pressure loss between the cylinders or into the cooling system.

Whats up Max? Yeah, I carry a leak down tester/fixture in my back pocket...lol. :lol:

Seriously here is a good basic compression testing and troubleshooting procedure:



Engine Compression Test

A compression pressure test of the engine cylinders determines the condition of the rings, the valves, and the head gasket.

Important: Disable the Powertrain Control Module (PCM) by removing PCM fuse.

Disable the ignition-PCM. (remove PCM fuse).
Disable the fuel systems. (remove fuel pump fuse).
Remove the spark plugs from all the cylinders.
Remove the air duct from the throttle body.
Block the throttle plate in the open position.

Measure the engine compression, using the following procedure:

Firmly install the compression gauge to the spark plug hole.

Have an assistant crank the engine through at least 4 compression strokes in the testing cylinder.

Record the readings on the gauge at each stroke.

Disconnect the gauge.

Repeat the compression test for each cylinder. Record the compression readings from all of the cylinders. The lowest reading should not be less than 70 percent of the highest reading.

No cylinder reading should be less than 689 kPa (100 psi)


The following list contains examples of the possible measurements:

When the compression measurement is normal, the compression builds up quickly and evenly to the specified compression on each cylinder.

When the compression is low on the first stroke and tends to build up on the following strokes, but does not reach the normal compression, the piston rings may be the cause.

If the compression improves considerably with the addition of three squirts of oil, the piston rings may be the cause.

When the compression is low on the first stroke and does not build up in the following strokes. the valves may be the cause.

The addition of oil does not affect the compression, the valves may be the cause.

When the compression is low on two adjacent cylinders, or coolant is present in the crankcase, the head gasket may be the cause.

Remove the block from the throttle plate.
Install the air duct to the throttle body.
Install the spark plugs.
Install the Powertrain Control Module (PCM) fuse.
Install fuel pump fuse.

I got one in my hand right now, used to use it on my 426 to determine re- ring intervals, best static seal I had was 3% using .043 SS dykes pressure seal rings, Love the staging deal!! I found lots more info available with leak tester, of course you need a constant 100 psi shop air supply. Car looks like a Duster? I had one early on in Pro Gas, mild Hemi 4 link car, ran 9.80's @ 136, slow these days!

Love the staging deal!! Car looks like a Duster? I had one early on in Pro Gas, mild Hemi 4 link car, ran 9.80's @ 136, slow these days!

Yeah, I though you'd like that. Looks like a Plymouth Duster to me too but it could be a Dodge Demon. Either way I'd like to get one for a project car or an old '67 - '69 Camaro. Brings back good memories of the old days. Of course, I still see staging lights every year with my GTP. Old drag racers never die they just get older. :lol:

Well guys/Gals, thanks a lot for all the fast and smart replies, got me started in the right direction at least, been years since i tackled one of these. I am so hoping it is only an intake. I now have the haynes manual and was quite blown away after reading the procedure, times are a changing..lol. BTW to answer an earlier question I have a 1994 Grand Prix SE with a 3100 in her. I plan on starting what I have to start on Thursday. Anything else I should change or check while I have her torn apart? Any tips of the trade to make it a smoother go. I am going to order the new head bolts tomorrow morning, I also heard you need to replace the intake bolts new also but then I heard you dont as they are or are not tourqe to yield, can someone shed some light on this area? I will pick up the intake gasket and or head gaskets and any other parts I may need as needed as they are all in stock here locally. I will also have to buy a tourque wrench i suppose, ah well , always wanted one..lol. Thanks again for the replies and help, keep em coming and I will keep you posted on how things go. I am getting the compression testing kit tomorrow afternoon also.

They say to replace the intake bolts, because the new GM ones come with threadlock already applied. IF you take a wire wheel and clean the old bolt threads, apply new loc-tite and you'll be fine. While you have it down, there is an oil pump drive (basically a distributor with the top cut off) that has a o-ring that is famous for leaking oil. It is located on the drivers side of the engine in the center of the "V" under the throttle body. It is very simple to change while you have the intake off. The fel-pro part number is 70800 for the o-ring, and I always put a small block chevy distributor gasket (fel-pro 70194) between the top of the block and the shaft as added insurance. Fel-pro also offers a new improved design intake gasket kit (ms98004t) that does away with the plastic/rubber failure prone OEM gasket and replaces it with a steel/rubber design. That kit also comes with the valve cover gaskets.