Intake Manifold Gasket
Newfie Hauler:
TheRealNewfieAztek,
I was thinking about this a little more last evening. You have a couple options to try and determine if it is a lower intake gasket vs. a head gasket. The head gasket is crucial to maintaining engine compression. An engine compression test might yield a "blown cylinder head gasket" (not that test's only function). If it where a complete failure, meaning that there was a gap in the seal between the cylinder head and the block that travelled from the cylinder to the outside of the block, you would lose compression. A simple compression test might find a bad leak. A cylinder leak down test might also provide similar information as well, however, it might be able to find more minor leak. Combine those with a coolant pressure test and you may even be able to narrow it down as to which area of the gasket may have failed, but also if it is a coolant or an oil leak.
These tests are not necessarily for the novice. However, if you take the Aztek to a shop, they will most likely preform one, two or all three of them and perhaps a dye test (adding dye to the coolant to check for leaks - although it may have enough residual dye from the factory).
When I mentioned in my previous post that you might be able to visually see a leak, it would most likely have to be a leak in one of these gaskets that goes almost all the way through. The usual point where you can see the lower intake gasket leak is if you find the upper radiator hose. Follow it back to the engine. You will see the aluminum housing that it fits into the engine. Look at that side of the engine (actually the rear of the 3400 engine). You should be able to see where the upper intake meets the lower intake and where the lower intake meets the front (left) cylinder head and the engine block. The joint where the head, block and lower intake come together is where the leak usually appears. You should see the leading edge of the gasket between the lower intake and the cylinder head (see Chameleon-Kat's pics attached to this post). If it is wet or if it has dirt stuck to it, it may have failed. What happens is that when it leaks, the coolant vaporizes. It leaves behind a sticky residue that attracts dirt under the hood. That way it may not look like a current leak, but it is. Because it vaporizes you may never actually see anything on the ground and may only occassionally catch a wiff of the sweet-smelling coolant every now and then.
Best of luck getting this repaired. If you have any further questions, please let me know.
Newfie Hauler
TheRealNewfieAztek:
Quote from: Newfie Hauler on April 10, 2006, 05:37:03 AM
What kind of symptoms is your Tek having? Loss of coolant, oil or both? Any white milky substance on the underside of the oil fill cap or dipstick? Does the coolant reservoir fluid look like a milkshake? Loss of power? White exhaust plume present even when engine warms up? Loss of heat in cabin? Rough idle?
Sorry it took so long to get back to you on this. I have a slight loss of coolant, although if I loosen the rad cap (just slightly to the point where you have to press down to turn further), there appears to be no visible loss of coolant. Most trips now are less than 25km, and I would say I go through 8-12 oz of diluted antifreeze in a week. I don't see any white milky substance on the dipstick, although there is on the oil fill cap (and I cleaned it the other day just to confirm and it was milky after a short drive). The reservoir is somewhat milky, although where I was probably low for some time, it could be due to sludge. Lots of heat, runs smooth, and I haven't noticed white exhaust after it warms up.
Newfie Hauler:
RealNewfieAztek,
It does sound like you have an internal engine coolant leak. I am basing this rough diagnosis on your description of the amount of coolant being lost and the white milky substance on the underside of the oil fill cap and in the reservoir. That is water mixing with the oil. Some really short driving at cold temperatures (well below 32 degress F/0 degrees C) will cause some moisture to form, but that should only be under the oil fill cap at best. None should be appearing in the reservoir.
Typically, the lower intake gasket causes an external leak. However, I have heard of one or two that are so bad as to cause an internal leak. I am suspected though that you may have a bad head gasket instead of a bad lower intake gasket. A coolant pressure test, compression test and cylinder leak down test should help pinpoint the problem.
Having coolant in the combustion chamber is not a good thing. It is in there if it is mixing with the oil. The good part (if there is one) is that you mentioned that there is no white exhaust plume once it warms up. If that had started to appear it means that water/coolant mixture is trying to be burned in the combustion process. The water/coolant mixture is very hard on the internals of the catalytic converter and the oxygen sensor. Because of that, I would get it test and have any problems corrected as soon as possible. The longer you wait, the great the chance more damage could occur.
TheRealNewfieAztek:
Good News :mellow:
Put it into the dealer this morning and I have it back this afternoon at a cost of $100 plus taxes. Turned out to be the infamous Lower Intake Manifold Gasket. Done as a GMPP Goodwill Warranty (not that it matters to me, as long as it was done for a very reasonable cost).
Essentially, when I bought the machine from a dealer in another province, it had a GMPP until Feb 27/06 or 140km. I noticed a problem with coolant loss 3 weeks after warranty expired, and when my dealer checked, it turned out that the selling dealer had not switched over the GMPP into my name, even though my dealer was told by them in Oct '04 they were going to switch it over. I'm not sure if that had anything to do with it, but it's done and that's all that really matters.
Invoice shows $386 for parts, and 4.6 hours labour (labour seems low compared to what others have reported).
Thanks for everyone's help on this.
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