1999 Oldsmobile Intrigue overheating 3.5

Those dealer mechanics were complete idiots and probably just wanted to take your money.

Every dealer knows these motors are prone to head gasket failure because the factory thermostats that were originally installed were causing these motors to run way hotter than they were designed to.

They know this because the manufacturer issued a TSB years ago, and almost every one of these engines that didn't have these replaced ended up blowing the head gasket.

Also, it's easier to check for a blown head gasket than it is to replace any one of the parts you've already replaced.

All you need to do is pop the top of the overflow tank (While engine is cool). Then start your engine. While you have someone push the accelerator, look inside the coolant.

As the engine revs up to about 1,500 rpms, you'll see large bubbles coming up in the coolant.

And don't bother putting another dime into that engine. You money will be better spent finding a used engine with 50,000 miles on it and having it installed.

WARNING:
Make sure you trust the mechanic and he/she tests the used motor to make sure it doesn't have any pre-existing problems.

Also, make sure to put the thermostat in that GM recommends or you'll blow that head gasket also.

Wish I would have waited took car to pontiac september 8, pressure tested it, no leaks throughout system, it looks to them to be the thermostat, when I got there it also could be a restriction in the system, just brought it home was flushing it just now. When I finish I am going to check what you said, then get back to you. Thank you very much.
The dealer wanted 300 more to find the restriction and possibly more if they had to go deeper into it.
Did what you said, its no large bubbles in reservoir. Took to a mechanic, he took off the reservoir cap and did the same thing when engine was hot then saw large bubbles in reservoir. Also anti-freeze bubbled over reservoir and spilled, he said it was a leak in head gasket because the bubbles and spilling of anti-freeze. With no pressure it shouldn't even spill.

I had the coolant system pressure tested again, no interal/external leaks, replaced radiator and oem thermostat. Followed these steps in order. Ant exactly and all the burping procedures this did not solve the overheating problem. THE FIX: I started from square one again which a few changes to the filling procedure: 1: drained the coolant you will get approximately 5 litres out of the pee cock(don't forget to open the rad bleed valve) 2:disconnect the top rad hose from the engine. 3:I cut the top heater hose(near the fire wall) and installed a "y" flushing adapter inline 4:I also connected a drain hose to the engine outlet (where I disconnected the top rad hose) I did this so as to not make a mess. 5:I connected a garden hose to the "y" flushing adapter I also used a ball cock valve to control the water flow. 6:I kept the cap on the surge tank. 7:turn on the water and watch the surge tank the water will start to rise you will be able to contol the level by regulating the flow from the hose.

8:You will probably see the water coming out in spurts or bubbles WHEN IT COMES OUT IN A CONTINEUS FLOW ALL THE AIRS OUT, you need the hose pressure toget the air out the water pump just cannot do it! Thats why this is such a common problem for the DIY guy. 9:also run the water until it is clean so as to get the right coolant mixture. FILLING: 10: you will need to get 4.75 litres of anti freeze in the system for 50/50 mixture which can be a challenge. 11:shut the water off but do not disconnect, with the rad bleed open and the rad peecock closed add coolant thru top rad hose until it comes out of the bleed valve, you will probably get about 3 1/4 liters in the rad. Close the bleed valve(I made a tool to open and close the bleeder. I ground 4 driving slots in a socket so I could use a ratchet wrench ) 12: I added the balance of the antifreeze to the surge tank.

NOTE! The top rad hose is not connected to the engine so as you added antifreeze it will push out water this is what you want you need to add about 1 1/2 litre this way, you are adding a total of 4.75 litres of antifreeze to the system. CONNECT THE TOP RAD HOSE. The level in the surge tank will be below the cold level proceed as follows: 13:The garden hose should still be connected to the "y" flush adapter slowly add water to the system and watch the surge tank level when the fluid level reaches the cold level shut the water off and disconnect the hose. Seal the "y" adapter with the plug that comes with it: 14:ALL DONE run the engine a few cycles to mix the coolant and drive, drive, drive, problem free.

I just did this today, drove for approximately 15 - 20 min, let car idle for approximately 35 - 40 min, I am going to drive it now until monday and will post what happens, don't know if its fixed but I sure hope so. Trying to help as much as I can. The reason I am posting this is because I couldn't let the car idle for more than 10 min without it getting. Thank you for your help, Ernest.

July 10 2016, I recently started having the same issues. I am not sure what happen in between the time this became a huge problem was driving my car around and replacing small parts crossing my fingers hoping it will solve the issue, so I replaced these one by one and was still overheating. Water pump, thermostsat and flushed the radiator hose because it was still overheating and couldnt figure out why. However when I replaced the waterpump it worked fine for about a week then started to overheat again. Car has been sitting in the driveway close to a month now. Had a similar issue with a different car but resolved the issue. From my experience all I can tell the rest of you make sure your oils and coolant are always topped off and start the process of elimination, #1oil does not look milky #2 compression check with tools at home if possible #3 check your spark plugs! And see if they are wet. They should not be wet at all. You want to do these 3 steps before replacing parts & start assuming its something else save time and money.I just discovered my spark plugs had coolant. Need to pull them out now. So again guys check your oil and spark plugs for signs of water/ coolant compression check why pay a mechanic when all u need is a few tools in the garage. Anyway cars stil in the driveway and taking my heads apart from this twin cam engine. Should have learned the 1st time.

Forgot to mention wet sparkplugs may be a result in blown heads, gaskets etc. Hope this helps