Intake Manifold Gasket May Leak Coolant or Engine Oil on Buick Rendezvous

Problem Description and Possible Solution

The intake manifold gasket may develop and external engine oil or coolant leak. In some cases, an internal coolant leak may occur causing coolant to mix with the engine oil. Running the engine with a coolant/oil mix may result in engine damage. Replacing the intake manifold gasket should correct this issue.

Problem Data
RepairPal Verified
Average mileage: 120,022 (17,735–200,000)
Engines affected: 3.4L V6, 3.6L V6
6 model years affected: 2002, 2003, 2004, 2005, more2006, 2007
65 people reported this problem
Viewing 1 - 20 of 24 comments
Was driving home from work and surprised by the "High Coolant Temp" light and chime. Temperature gage was pegged on H(ot). I turned the AC off and saw the temp needle move down some. Continued the ride home with the needle oscillating between medium and hot.

When I got home, I noticed the coolant bottle was still filled, suggesting that I still had coolant. Checked the oil level the next morning and noticed coolant mixed with oil. Had vehicle towed to local mechanice where it is having the lower intake manifold and head gasket manifold replaced. Mechanic recommended refilling with a non-dexcool coolant. Repair bill estimated at $1700.
I was driving one morning when check engine light started to flash. suddenly the check engine went solid and engine started to overheat and producing thick white smoke. The engine was diagnose head and intake gasket failure. I had to replace the engine. their was no symptoms or warnings before failure begin.
Engine began to loose power and was reading major intake malfunction or misfire. Has been leaking coolant at an alarming rate. Overheating and now will not even run for five minutes before engine completely overheats and shuts down. Looking at replacing whole upper intake manifold but don't know what that cost will be very nervous to find out.
noticed milky looking antifreeze in overflow and low level.......of course G.M, knew about this problem and did nothing it was changed , now leaking again at 110,000 miles.....
Small hose on to of motor was busted. Replaced it still some oil in water.So far so good motor sill runs fine.
engine oil leaking into the coolant and coolant leaking out of the intake gasket, engine is ruin and extended warranty won't cover it. So right now it sits.
small leak on garage floor mechanic said it was intake gasket. Haven't done it yet wondering if it could be waterpump since it was similar small spot when past waterpumps were 'weeping". It's been so cold haven't gotten in and looked closely. Will this weekend tho. It's been sitting in garage not driving it. Do a radiator pressure test and confirm source.
Vehicle was running fine it still does however when I checked the oil it was all milky on the top and the stick had water droplets at the top not dure if I should repair or ride to the wheels fall off
I was having battery issues where my car battery was dying over night. I found that if I unplugged the battery at night it would not die. One day when I was revving the engine to charge the battery I noticed a water leak under my car. I touched it and it felt like water was leaking mixed with oil. I took it to my mechanic and he told me it was the manifold intake gasket had to be replaced. He quoted me $730 for the job. After he was done with the job he found that the radiator was clogged and that was another $$337.00 to replace the radiator. car is running fine now but I still have a battery issue where if I leave the battery plugged in over night it will die. I put a switch on the positive side of the battery where I just lift the switch whenever I leave the car for long periods of time without turning it on and so far so good :D
This is a common GM issue with this engine. Happened to a Pontiac I had also. GM will deal with you on this to defray cost. You may have to bypass dealer who gets lower payment from GM to do work. Big fight with Buick dealer. Actually would not call GM. I did it myself since Pontiac was done before by my really nice Pontiac dealer. No questions asked in their case.
First the car became hard to start. Next, started running rough + high temperature. On checking the coolant reservoir was empty and saw water in the oil. It's at the repair shop with an estimated bill of $1650 to tear apart the engine, replace the gasket and fix whatever other problems this may have caused. We're lucky to have a great repair shop.
during a spark plug change on a 2003 rondavous i noticed quite a bit of oil in the lifter valley, reading another post, this happens in 2000-2005 models 0f the 3.4 in particular since thats what i have. looks like a new gasket replacement of the upper half is in order. and thats where i stand today with it.
this has happen twice in less then five years had it fixed two times already last time march2015 last time mileage was 154000 can not remember what the mileage was first time