96 Riv. Burning coolent

I have a 96 Buick Riv. 3.8L series 2 with 105K miles, recently I have noticed that I have been loosing coolent, starting to slowly overheat but no signs of leaks on the ground or around the engine.

Once in a while the car will blow a lot of white smoke, that smells sweet out the tail pipe,(mainly on turns?) but not all the time? It must be burning. I have no signs of coolent in the trans fluid or oil.

I am assuming head gasket or a cracked head but I am wondering If there are any other possible causes. Like can the lower intake gasket break and cause same symthoms? My cooling system is not bubbling over and once filled it will run fine for 100 miles until it runs low on coolent again. Then starts running rough and blowing smoke on sharper turns while accelerating.

Thanks in advance

Zbird

Sounds like a bad upper intake, remove the throttle body and look for signs of coolant in the plenum and/or deterioration of the manifold between the egr and throttle body coolant passages, common issue. If you replace the upper intake consider doing the lower intake gaskets with the aluminum frame type by Felpro.

I wouldn't have thought that coolent even went through the upper intake. there are not coolent hoses going to the throttle body or upper intake. Looking through the PCV valve in the upper intake, there are signs of coolent. I will remove the throttle body and upper intake tomorrow and repost.

Kind of makes sense, Thank you very much

The coolant is directed thru a passage in the intake into the throttlebody

Max you were right, the upper intake right next to the EGR inlet melted and was pooring coolent into the upper intake and throttle body.

Cost me about $160 and 4 hours.

Thanks Again

Zbird

Max you were right, the upper intake right next to the EGR inlet melted and was pooring coolent into the upper intake and throttle body.

Cost me about $160 and 4 hours.

Thanks Again

Zbird Good deal!!

Hi,

Reading this post with interest.. and believe it has to do with coolant changes, or lack of coolant change. I had the same service done on the 97 Riv only it cost 8 times as much. From the invoice, the parts installed were:
Manifold - $165.19
Manifold - 405.02
Gasket - 43.15
Gasket - 72.59
Pipe Assy - 16.93
Seal Drv - 3.20
Pipe Assy - 16.93
Thermostat & Gasket
Hey.. why two pipe assys?

Recently (like last week) my mechanic popped off the plastic engine cover and commented "the plenum was updated" and he tapped on it with finger. It DID look like a new plenum. Does that make sense?

This may (or may not) have happened because the coolant (Dex-cool) wasn't changed every 48 - 60 months. I never changed it from 1997, actually the car was built in 96, till 2007 or 10 years later. THEN in 2009 the intake gasket cracked and/or manifold metal became damaged/corroded. The EGR stem, pipe or valve is located there in the back of the motor too, yes? The understanding is.. the mating surfaces were so old and "crudded up" including heat from the EGR (sound right?) and corrosion, that basically it was all replaced?

Do you think lack of coolant service was a factor? or are these known to fail? I had a failure in a 79 Olds intake gasket because it was aluminum, or something like that years ago.

-Ed

I have read a lot of posts here on problems with the lower intake gaskets, on the 3.8......

I have not really run into this problem.....when I have removed the lower intake, have not seen any gasket problem......however, it could possibly happen, if you have a situation where you are losing coolant and you continue to run the vehicle just by adding coolant to the system.... then you get crudded up coolant ports caused by dexcool making contact with air pockets....and the engine overheating....

I remember when the upper plenum problem first came out, GM wanted you to replace not only the upper plenum, but also the lower plenum, which had a smaller diameter EGR pipe.....that's why you have two manifold's listed in your repair.......

This is a good article that may help clarify some of the misconceptions concerning gaskets, coolant & manifolds.

Closing The Gap on Intake Manifold Gaskets: Engine Builder (http://www.enginebuildermag.com/Article/75823/closing_the_gap_on_intake_manifold_gaskets.aspx)

Good article, HotZ28! A must read for all techs...

Several things that stand out......especially on the GM 3.1 and 3.4 gaskets......

What good is doing an intake job, if the sealing surfaces are pitted? They may initially seal, but with vibration and expansion/contraction, it's just a matter of time......cars that come back within a year to a couple of years for an intake leak, more often than not are caused by this problem....I must admit, I have done a few that were "marginal" in my time......

In such cases, I would be leaning towards the aftermarket felpro gaskets....the backup sealing area may cover some of the pitting.....

Most important, follow prescribed procedures.....if it calls for new bolts, get new bolts......tighten in sequence.....and definitely use a torque wrench.......I have seen guys zip these things together with air tools, without regard for sequence or torque.....when you see that, you have to wonder about other aspects of the job....

Just as an aside, I am a stickler for a clean engine, when the job is done......when you clean an engine, it reflects not only on your capability as a tech, but it also shows the customer that you have fixed their problem, when they go and check to see if that leak is gone, a clean engine with no leaks, is your own personal advertising campaign.....is it any wonder, that some techs in a shop, are "requested" over others?.....pride in your work is good for you AND the shop you work for.....