My 2002 Chevy Silverado 4.3L 63k miles is loosing antifreeze somewhere.
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 but there is no visible smoke.

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.