I've been doing a tune up on a 96 3.4l z34 monte carlo i bought a few months ago. (car would take off fine from complete stops, had no issue leaving a little rubber behind, but once i made it up to 30+ mph car would lose power and not accelarate quickly and it's been getting terrible fuel economy)

I pulled the upper intake/upper plenum along with the throttle body (along with a few two coolant hoses and various vacuum lines) so i could pull the back spark plugs and put new ones in along with the new wires, after i put everything back together and started up the car it had a really hard time starting and began to dump/spray coolant from the gasket inbetween the throttle body and intake leading to the plentum.

White smoke is also coming from the exhuast but there is no coolant in the oil.

I'm no Master mechanic, simply a diy'er so i'm lost as to where to go from here.

it seems as almost as if the coolant is coming from around the throttle body and doesn't appear to be coming from anywhere else.

Any assistance it greatly appreciated.

(this is the first time i've ever change spark plugs on even a chevy, this was insanely hard to do compared to my eclipse that i had...)

 

its still probably the intake manifold gaskets, the lowers, did you pull them off?? are they plastic still?? if they are go buy the felpro kit or even the new dorman kit(615-205, its cheaper than felpro, but comes with more stuff, and just as good)

i would wager my guess that thats still the problem

if your good i would buy that kit, and 2 head gaskets and just do everything, and you'll find the problem

 

Yea, i'm leaning toward the LIM gasket, or head gaskets.

 

I haven't touched the lowers, all i pulled was the upper intake plenum and throttle body, i believe that part is still plastic, but i'm not entirely sure where it is, if you could post a diagram that shows where it is that would be great and i honestly don't see how pulling the upper plenum could result in this happening.

I'm believing that i may have cracked the coolant area attached to the intake just behind the throttle body becuase when i was pulling it i had to use a rubber mallet to knock it loose, is this a possibility? its really the only way i can see this happening? the car had no issues with coolant previously that i'm aware of.

 

i'm not really a mechanic, i just sell the parts, but i do know the common stuff, and when someone says coolant leak on a 3.1 or a 3.4 its ALWAYS the lower intake and possibly head gaskets, i can probably get you a picture of the parts @ work tomorrow, or you can just go to this site

www.dormanproducts.com and type in dorman part # 615-205 and it will show you everything in the kit

hopefully you didn't crack the actual manifold itself..but take a look @ that, i wager a guess as to that will fix the problem

 

I pulled the throttle body off and it turns out where it looked like the coolant was coming from was a broken gasket on the throttle body... so basically just a simple 3-6 dollar part... i'll be installing it tomorrow since i had to order it.

Does anyone have a good suggestion as to getting all the coolant out of the upper intake? since it's kind of pooled there and i imagine since it's blowing white smoke there may be some in there too.

 

Thanks again for all the assistance too by the way.

 

You may want to pull the plenum again and clean it out good. Next time you have it out, just unbolt the TB extension arm from the plenum itself. Its alot easier than removing the throttle body and all the coolant and vacuum lines. Also, when you changed the plugs, did you gap them to .045? The emissions sticker says .060 and they come pregapped from the parts store at .060 but this is WRONG! They need to be gapped to .045 or your car will not run right. It has the correct gap in the owners manual for the LQ1. I dont know why they have the misprint on the emissions sticker.

 

I left them pre gapped at .060, but i'm going to pull the plugs again anyways so i can clean them and take the air compressor and blow out any possible coolant in the motor.

I'm just waiting on autozone to call me to tell me they have the part.

 

Yeah the reason you had a hard time starting it is because the gaps were wrong. If you did get it running your CEL would have started flashing I almost bet you. I had to pull everything apart and put it back together 3 times the first time I changed the plugs because I had the wrong gap on them.