white smoke/consuming coolant

Hi my name is Sammy and im new to this forum, i bought a 99 Gran Prix sedan about 4 months ago, it alway had a lil stumble on the highway at about 55-60 and between 1800-2200 RPM, i just thought is needed some plugs no big deal. One very cold morning the car wouldnt turn over, kinda like the motor was locked, eventually it turned over and started but ran rough and smoked ike it blew a head gasket, drove it home checked it over and really didnt see much just refilled coolant took it for a ride and has been good only with a occassional sent of coolant but it would only last for about a minute. well yesterday it did it again but it wouldnt start, i removed the plugs(changed them while i was at it) to see if i could spin the motor freely and it did, reinstall plugs and it fired up. my question is , it sounds like a bad head gasket but only does it on occassions, and also think it can be in the intake. just need help deciding what to do, the intake job i can do but the head gasket job i rather not do in this cold weather. thanx


sammy

Since you are consuming the coolant by ingesting it into the intake tract my best guess is that it is an intake gasket.

Typically a blown head gasket will overheat by boiling off the coolant.

However, my recommendation is to go ahead and do both jobs at once.

Reason: suppose you change the lower intake gaskets and are wrong. Then you get to buy another set of parts and do the lower intake gaskets *again* plus the head gaskets. Way too much risk in my thinking not to go a little farther into the engine and know for sure that you have the issue resolved for many more miles.

it would help if you posted what model GP you have, and what motor.

3800's arnt really known for blowing head gaskets, however if you have an SE with the 3100, I'm willing to bet that you have a blown head gasket...

Consuming coolant is not typically caused by a blow Lower intake gasket

but instead by a warped Upper Intake Manifold.

My money is that this motor is a Natually Aspirated 3800 and the motor is hydrolocking because when you fill the radiator your are also filling the combustion chambors.

WHen you took the old plugs out, what did they look like?

BTW, if you continue to run and drive a motor that is hydrolocking, you could cause serious damage up to and including bent rods/push rods, and ultimatly could break a rod and throw it right through the side of the block.

My advice would be to properly diagnose and take appropriate action before the motor is ran again.

Consuming coolant is not typically caused by a blow Lower intake gasket

but instead by a warped Upper Intake Manifold.

My money is that this motor is a Natually Aspirated 3800 and the motor is hydrolocking because when you fill the radiator your are also filling the combustion chambors.

WHen you took the old plugs out, what did they look like?

BTW, if you continue to run and drive a motor that is hydrolocking, you could cause serious damage up to and including bent rods/push rods, and ultimatly could break a rod and throw it right through the side of the block.

My advice would be to properly diagnose and take appropriate action before the motor is ran again.
yes it is a N/A 3800. the more i read up on this site the more i think youre right about it being intake related. thanx for the info

sammy

best thing to do is remove the upper intake plenum and have a look. Its not very hard.

best thing to do is remove the upper intake plenum and have a look. Its not very hard. well i replaced the lower intake gaskets and replaced the plastic upper intake but now the car wont start trys to but just wont now. went over everything and i dont think i missed any plugs or anything. the car keeps fouling the plugs bad, checked for spark and it looked weak so i decided to replace ign module and all 3 coils while i was at it, it fired up for like a second then just died , cranked it over a few times only to pull the plugs and find them all soaked with fuel again :frown: . im lost the only thing that i notice that i missed but dont think its my problem but i could be wrong, i didnt replace the EGR tube with the one that came with the replacement intake. im losing my head with this car. by the way it a 99 gran prix sedan with a NA 3.8

sammy

My guess is you have the plug wires wrong. 1-3-5 are on the front/close to the radiator, 1 is on the accessory drive end.

2-4-6 are on the rear, 2 is on the accessory drive end. 6 is closest to the manifold's O2 sensor.

The wires may cross each other in the triple-clip harness. I suspect 2 and 4 are crossed as they go to the rear of the engine.

Make sure the plug boots are seated on the plugs...easy to miss...you need an audible "click" as the clip engages the spherical form on the end of the plug. Buy a tube of dielectric grease, put a dab in each boot on both ends and swab it around with a pocket screwdriver to make sure the ID of the boot is coated. This will ease assembly and help keep water out.

Also, you could presumably return to your original set of ignition hardware...you were only leaking coolant before.

Good suggestion by crazyhorst. I actually had this same issue, replaced plugs and wires on a 3800 only to have the car not start. I was so used to the 3100 that I didnt realize the 3800 cylinder numbers were different. When I realized my mistake, car started and ran great.

Your old upper intake, was it warped near the throttle body?

Plugs are soaked, so your getting fuel. Have you tried to swap the plugs out? Maybe you fouled them all out.

Do you have a compression tester? Maybe its a good time to check compression on all cylinders since your car may have been hydrolocked.