Coolant leak

Well if they are saying it has a head or intake gasket leak, that would mean the coolant would be leaking into the motor and not onto the ground. Does your car puff smoke? If it is a white colored smoke then you are probably burning coolant. If the coolant is on the floor though that atleast is a good sign because it means the leak is external. Leaky gaskets letting coolant leak into the motor are not fun to replace and cost a lot if you take it to a shop.

The 2.8, 3.1, 3.4, 3.5 are of the same basic design. Examine the lower intake gasket at the front and back of each head carefully for traces of antifreeze. Check out the 3.4 pic:

You might want to buy, borrow , or rent a cooling system pressure tester. Run it up to about 15# and you should be able to see the leak better.

Thanks All. There is no smoke or steam from the tail pipe. No deposits on the oil filler cap. Only a small leak where the engine bolts to the transmission ( front driver's side) ,that is not where it leaks but where it drips off. The area above this is wet I'll try the pressure test with a strong light and mirrow and maybe see where it comes from. Ernie

Ernie,

The 3.1 is prone to leaking around the intake gasket. The small leak you have found IS the problem. get it repaired NOW or you will wish you did. Just did two of them this past week. One was leaking external (like yours it had a small wet spot that didn't seem like much, but the coolant evaporates fast on a hot engine) the other one had gone too far, it had an internal leak that destroyed the bearings in short order. That one got a shortblock, rebuilt the heads and sent it home. Would have put a crate engine in it but the owner didn't like the price even after I explained that the rebuilt would probably come close in price.

In your case if it isn't leaking internally you should be able to pull the intake, clean it up good and install the newer GM gasket and be OK.

Steve

I have not removed an intake manifold in close to 30 years. I am about 2/3 sure that is the problem I will take it to the dealer Monday and get an estimate and if reasonable let them fix it. I am not sure what reasonable is. Does anyone here know? Steve?? I found a manual online that you can rent. Week, month, year. The web site is not too hard to use and I think I could do the job.

Wild ass guess, Ernie...When our 1998 Buick ate the plastic plenum, the dealership suggested about $700-800. An independent mechanic (of impeccable reputation) offered to do it for $250...

In the long run, the Buick dealership offered $350 with coolant change, etc. We accepted, since we would have documentation in case GM ever decided to recognize their bastardization problems.

Now, the plenum is different from what you are facing. Yours may well be a little less. But you can extrapolate the probable region of cost.

I did the 3800 Plenum about 4 months ago on a 1994 Buick. Cost of Plenum was about 240.00 Took about 4 hours to replace but I never did one before. Total Cost with coolent, injector o rings and misc was about 275.00.

I did a 3.1 intake manifold about 6 years ago...not a lot of fun.... but needed to be done. Service shop wanted 750.00.... I did it for the gasket kit (cheap) and some bruised knuckles. Car had 85,000 miles on it and ran for another

hth

By the time we are done doing the job (we charge 98 dollars an hour), it's usually a 750-800 dollar job. The labour charge is about 6.0 hrs, but a good tech can easily do it in 2.0 hrs. I wrote up a detailed explanation of how to do this job a while back. I'll paste it below and you can do with it what you want. It should be pretty close to what you will encounter with your vehicle. It was written for a van, but the procedure is very similiar for your car. There will be some difference at the throttle body area and the fuel lines for the injector rail go way down under the exhaust. Don't bother trying to disconnect any fuel lines, simply remove the nut that holds the fuel lines against the rear head and then position the injector rain and lines up out of the way and bunjee cord it up to the hood. It's too much work to try and disconnect the fuel lines and then snake them out under the exhaust crossover pipe. You will see what I mean when you get there.

Ian

Ok, I'll go over the basic procedure for the van.

First step would be to drain the coolant. This year, you need a 1/4 inch square drive ratchet and preferably a short extension. Use the 1/4" ratchet to turn the drain c*ck counter clockwise about an 1/8 of turn, then you have to pull the drain c*ck out while turning it further.

Next...pull the rubber hood seal off at the front of the cowl area...then you can pull off that plastic piece that covers the wiper motor area (passenger side of the engine compartment.

Pull the air filter housing and snorkel..usually, I find it easier to remove the rubber section first, and then you have more room to remove the air filter cover and air filter. There are a couple of electrical connections on the snorkel and the MAF sensor, unplug them...and then follow that wire harness back and unplug everything else on it, except where it plugs into the coil pack ( oh yeah, I'm going to give you the "faster" version). So you should have a couple more sensors at the throttle body, a red connector at the evap solenoid and then a harness clip at the coil pack. You can position this harness back over the coil pack. Remove the front three spark plug wires at the coil pack. Unhook all the clips that hold those wires to the engine, but don't bother to take the wires off the front plugs, just lay the wires over the front of the rad support. Remove the vacuum booster hose at the upper plenum.

Remove the two bolts that secure the coil pack bracket to the upper intake plenum (10 mm head). Now you want to remove the MAP sensor which sits bolted to a small bracket on the upper plenum right in front of the coil pack. You will need a 7 mm socket or wrench to undo the two long screws that hold it in place. Then unhook the vacuum lines and the electrical connector and lay the sensor and vacuum lines somewhere. Now you can remove the upper plenum bolts. At the passenger rear side of the upper plenum, there is a small brace that goes from the alternator to one of the bolts in the upper plenum. Get that brace off and then you can take that one plenum bolt out.

Now go to the back of the engine, you need to find the EGR pipe that comes up to the upper plenum and EGR valve. The temptation is to remove the valve, but don't bother. Just remove the bolt that holds the flexible pipe to the upper plenum. There is also a small nut that holds the Transmission filler tube to a stud on the upper plenum. You need to remove that and push the filler tube off that stud. There is also one nut at the throttle body that holds a coolant pipe in place, remove that and disconnect the two small throttle body coolant hoses at the back of the engine there. At this point you should be able to remove the upper plenum. Do "not" bend the coil pack bracket up to give yourself clearance. This makes it very difficult to start those bolts properly later on. Just slide the upper plenum out from underneath it. You may notice that I said nothing about the cables to the throttle body. I do not disconnect them, just leave them on the plenum and flip the plenum upside down and off to the side. It will just sit there.

Next, you need to remove the fuel rail and injectors. There are two 10mm head bolts that hold the rail to the lower intake, and one that holds the fuel lines to a bracket at the rear of the rear head. Remove all three, carefully pry/pull the fuel injectors and rail out of the holes. Take a close look at the injectors once you have them out, any o-rings that have come off need to be retrieved from the intake manifold area. Sometimes they will just be loose, other times, they are stuck in the injector holes. Again, I don't disconnect the fuel lines, just position the rail and lines off to the side somewhere.

There is a heater pipe that goes into the lower intake at the rear of the engine. You need to simply loosen the nut that holds it to a stud at the rear of the rear head, and then you can pull the pipe out of the intake. Note: replace that o-ring seal.

There is also a heater pipe and bypass pipe assembly that runs along the front of the front valve cover. That is the same pipe that had the two small throttle body hoses connected to it. Remove it, and either move it off to the side, or disconnect the "quick connect" fitting (sometimes they aren't all the "quick" and so I just leave them).

Now you can remove the front valve cover, if you need room to get at the one bolt, remove the left engine strut and you can get a run at the bolt. Then loosen the two rear valve cover bolts that you can see. One will be under the alternator, the other is under the coil pack. In both cases, there is just enough room to completely loosen the two bolts.

Now you have to deal with the power steering pump. Remove the small plastic shield that sits right above the water pump pulley (this just give you a little more clearance for the ps pump pulley). Now, remove the serpentine belt. Then remove the three bolts that hold the pump to the engine, you can access them thru the bolts in the pulley. They are 13 mm bolts. Now, you must loosen the ps pressure hose fitting at the pump. Use a 5/8 wrench and just loosen it until the hose will be able to move. In other words, don't completely remove the hose. Now, reach your hand down the two ps hoses and you will find some plastic clips that the hoses are in. Pop the Pressure hose (left one as you look down at the two hoses) out of the plastic clip. Now, you should be able to pull the pump up and lay it down between the front of the engine and windshield washer bottle. You may need to fiddle with the rubber return hose, as there is a bracket in it's way, you can move the hose around the bracket.

At this point, remove the lower intake bolts (8 of them) and the upper rad hose from the lower intake. The intake should now slide out from under the rear valve cover. Trust me, it comes out. Now you have to loosen the rockers arms enough so that you can get the push rods out. The rear rocker arm bolts can be reached, even though the rear valve cover is in place. Just loosen each rocker arm just enough to be able to remove the push rods. Keep them in order, as it's important that you don't mix them up.

Clean up your gasket surfaces..etc. Then install your intake gaskets to the head first, then the push rods. Short pushrods to the intake valves, long to the exhaust valves. Be meticulous about cleaning the front and rear surfaces of the block and the intake manifold, as this is where the RTV sealer goes. Also clean the joint between the rear valve cover and the cylinder head and where the intake manifold will meet the two of them. Do not mess with the rear valve cover gasket, just make sure it stays up in it's groove. Before you install the intake, make sure you have a nice bead of RTV on the front and rear mating surfaces, and put a dab of RTV in that corner where the rear v/c and head and intake will meet. From there, it's pretty well just the reverse of the removal procedure. Don't bother trying to tighten those two rear valve cover bolts until you have torqued down the intake manifold. Then they will just slide right in. Also, when you install the upper plenum, you are going to slide it back under the coil pack, and then engage the EGR pipe and the throttle body coolant hoses. Take your time here, and make sure everything is where it should be before tightening down the intake bolts.

Hope this helps, and all goes well. The procedure for the Century will be almost identical, other then the Trans dipstick tube.

Ian

I just had the intake manifold gasket replaced last week on my 3.1. It was leaking near the thermostat housing.

The 3.1 and 3.4 engines are from the same family and have the same reputation for intake manifold gasket leaks. My bet is that you are one of hundreds of thousands of people who are having just that problem.

John

Ernie, Mine is doing the same thing, and it sure sounds like a leaking intake manifold gasket. The manifold to cylinder head joint is directly above where the coolant is pooling up on the transmission in my case. Personally, I would be carefull with the pressure test as you don't want to force coolant into the engine. Howard

The leak can either be to the exterior (not so bad) or into the engine oil (very bad!).

Anyone with one of these engines is well advised to have a used engine oil analysis done at least once per year to catch contamination before it gets bad enough to completely trash the motor. Many places offer used oil analysis services for around $20. The one I use is:

They caught the problem on my '02 Olds at about 40,000 miles. Luckily it was still under GM's extended warranty at the time. I keep checking it every other oil change to see if it comes back.

John

re. coolant leak .it leaks into the oil. cost me $1100.00 for new gasket,labour ,etc... on a 2000 Impalla. GM makes garbage autos, their quality sucks.

they have just about recalled every new 2006 models that they have produced.

re. coolant leak .it leaks into the oil. cost me $1100.00 for new gasket,labour ,etc... on a 2000 Impalla. GM makes garbage autos, their quality sucks.

they have just about recalled every new 2006 models that they have produced.

How do you explain what? If enough antifreeze leaks out then gravity will eventually pull it to the ground.