loosing antifreeze
 

My 2002 Chevy Silverado 4.3L 63k miles is loosing antifreeze somewhere. :confused:
Don't see it on the ground, on the engine - or smell it. Oil looks fine - no milk or foam.

Not loosing much - less than a half gallon in 6 months.

My one friend said it's probable a leaking intake manifold gasket - and the antifreeze is going into the intake - out the exhaust :eek: but there is no visible smoke. :confused:

How serious is this?? Another friend said just forget it - add some antifreeze when low keep driving.

Should I take it to the dealer?
If it is a intake gasket - it's too big a job for me - how much am I looking at?
Any ideas would be appreciated.

Thanks!

At that rate it can be leaking into the engine oil and not show milky. It will however show on a oil sample sent to a lab. Our S-blazer was leaking around that mileage and showed on the oil sample but did not discolor the oil.

Lower intake manifold (LIM)gaskets are so common on GM engines I almost consider them a maintenance item. It should be a 5-6hr job at a shop, more if the find other items needing service.

It can be very serious if the gasket has a major failure while driving. Many engines have been wrecked when the gasket fails while driving and dumps the coolant into the oil.

I just replaced LIM gaskets and a UIM(upper intake manifold) for a co-worker who just kept refilling all summer long. Time will tell if he did any long term damage.

Also check the bottom of the water pump real closely. There is a small 1/8" hole that is a weap hole and if you see any residue from coolant/water then replace it.

Change oil light came on - changed the oil today.
This oil was in it all summer - it looked fine.

Go to your local Amsoil dealer and give him a sample of your oil.
He'll send it off to get it annualized. They'll tell ya if there is any significant amount of antifreeze in it It's a free service from Amsoil

No offense but they are your dice so roll them as often as you want.

Was not aware that Amsoil offers that service for free, I use Blackstone labs. Just sent out a sample for my 6.5TD with 2300 miles and 7 months on the oil and requested a TAN reading as well.

Can't see any anti-freeze in the drain oil I took out Saturday.

So I'm sending a sample off to Blackstone labs.

Glad to hear your taking this seriously. Anti-freeze should not just go down like that.

What I'm not sure is how your results are gonna read now. Your supposed to warm the engine then take a sample mid-stream from the draining oil a few seconds after pulling the plug.

If there is anti-freeze - it will be at the bottom of the container holding the used oil - that's where I'm drawing the sample from. It's the best I can do now.

Be sure to come back and let us know what your findings are

Just mailed the oil out today - it'll be awhile.

is the truck making white smoke?

It doesn't have to make white smoke while burning coolant in small amounts but will still damage the O2 sensors and catalytic converter. Same with small internal leaks, not always visually noticeable. I've replaced many leaking intake gaskets that didn't show any signs except loss of coolant.

Recently I bought a Olds with a 3800 and 100k on it. Before I even tore it down I gave it a visual and noticed the OE upper intake manifold. Then I ordered new LIM gaskets and a UIM and replaced them before even driving the car, and yes they were showing signs of leakage and would have failed completely in time.

I have also had problems with the intake manifold gaskets. I had to change one on my 87 Dodge Dakota 2.2L, as well as my 80 Ford F-150 4.9L.

The report just came back from Blackstone and was very good. TAN levels plenty low so I should be able to keep the oil in for 1yr intervals.