Intake Gasket failure -- what are the symptoms?

[Wubs]

OK, I've resigned myself to the fact that I may need to do this. But how do I know for sure?

I'm filling up the overflow monthly -- a leak, yes, but where? No puddles under vehicle.

I checked my oil dipstick -- oil is amazingly clear (change oil indicator says I have about 40% life left before changing it is due).

I checked the oil filler cap, don't see any grey sludge on the cap.

So. short of going to a mechanic to have him investigate, is there any thing (or things) I should look for?

Maybe I see a problem when I look at the oil filler cap, or inside where I pour the oil, but not knowing what to look for, I'm missing the obvious?

I'm asking here because I don't want to pay a mechanic for something I feel I should be able to determine myself. I'm willing to take pictures and post them here if that helps. I wanna learn how to do is much maintenance on my own vehicle as I possibly can.

Thanks in advance!

[GMMerlin]

Originally Posted by Wubs

OK, I've resigned myself to the fact that I may need to do this. But how do I know for sure?

I'm filling up the overflow monthly -- a leak, yes, but where? No puddles under vehicle.

I checked my oil dipstick -- oil is amazingly clear (change oil indicator says I have about 40% life left before changing it is due).

I checked the oil filler cap, don't see any grey sludge on the cap.

So. short of going to a mechanic to have him investigate, is there any thing (or things) I should look for?

Maybe I see a problem when I look at the oil filler cap, or inside where I pour the oil, but not knowing what to look for, I'm missing the obvious?

I'm asking here because I don't want to pay a mechanic for something I feel I should be able to determine myself. I'm willing to take pictures and post them here if that helps. I wanna learn how to do is much maintenance on my own vehicle as I possibly can.

Thanks in advance!

Its time to pressure test the system and look for leaks

[cdru]

A pressure test would be a very good starting point as GMMerlin pointed out. Basically it pressurizes the coolant system and then you can watch how the pressure reacts over time. It should be able to hold approximately 15 psi for more then a minute or two.

There is several places it can leak and it's hard to see from the top of the engine compartment. Common leaking points are under the throttle body in the valley between the two heads and around cylinder 1 (passenger side rear cylinder). Depending on where it is leaking, if it comes into contact with a hot surface, it likely can burn off quicker then it leaks. After a drive long enough to get the engine sufficiently hot, park the van and open the hood. If you smell a semi-sweet smell, then it's antifreeze burning off. You can even "spill" a few drops on purpose on the exhaust manifold to get accquainted with what you are looking (...make that smelling) for.

Absent of any obvious visual leaks or smell, you can get a small vial of UV dye that you add to your antifreeze. What the dye does is act as a tracer. Shine a black light on it (a real one, not one of the blue coated light bulbs) and it will glow. Even if it evaporates, it still leaves a trace of the dye.

Also don't exclude the idea that it could be a head gasket. If it was a slow leak into the cylinder, it would burn off and you really wouldn't have a trace of it. It also could be a leaking water pump (via the weep hole) or a coolant hose/clamp that is leaking.

As to not knowing what it looks like, it's hard to easily describe. Many people describe it as a light brown mayo-like consistancy. It won't be in huge globs, more like a think coating or film. It would be in the inside bottom of the oil cap and also on the inside of the valve cover. If you can take/post some good pictures of each of these places, we might be able to tell.

[Wubs]

Soon as the weather turns nice here (ie, no rain so I can use my camera outside), I'll take pix of the oil filler cap and the dipstick.

Anything else I should take a pic of?

[cdru]

Originally Posted by Wubs

Anything else I should take a pic of?

Well, do you have a hot wife/daughter/sister?

There isn't a whole lot more that is easily accessable. You may try to look at the valley between the heads directly under the throttlebody, and also the back half of the transmission. See if anything looks wet.

[Wubs]

Ok, here are the pictures.

#1. Oild dipstick:




#2. Oil filler cap:



I guess the only other thing left to do is stick my finger into the filler hole and see what colour the oil is, then I guess I have to shell out for a pressure test.

Thanks

[cdru]

For what it's worth, it doesn't appear that you have the "mayo", however it's hard to tell. My cap actually has a recessed center so it collected the stuff when mine when south.

One other place I forgot to check is the PCV valve. It too will accumulate the gunk over time. However it's fairly protected so you might not have anything there if you are early on in a leak and it hasn't had a chance to accumulate.

If you really want to know if it's leakingin your oil, send a oil sample to Blackstone Labs. They will look at it and tell you if any antifreeze was found. It's only $20 and will tell you definitively if you have a leak into your oil.

[Chameleon-kat]

Lets see if I can get pics to work, these are pics of a GM 3.4 engine (looking from drivers side front) First is what the gasket area should look like if its not leaking externaly:



Next is one with external leak:


Note the wide 'dirty' area in second pic. Hope this may help someone