Hi - I was loosing coolant and had to top up the rad. Checked my oil and at first couldn't tell if antifreeze was mixed in as it wasn't particularly milky at all. Did a pressure test on the cooling systems and found that the coolant was leaking from the intake - front driver's side corner. Assumed a leaky intake gasket. Before removing the intake Idrained all the coolant from rad and it did not show any evidence of oil presence - just normal coolant appearance. Next I removed the intake manifoldand did find coolant in the valley - but again not any milky or foaming appearance just relatively clean. Next I drained the oil and then it was more apparent that anti freeze was present - but again it appeared clearerversus milky looking (a little bit sludgey at times). My questionis - based on my information - is it reasonable that the intake gasket is the only culprit or did I make a rookie mistake and not rule out the head gaskets made doing more thorough checks.
Appreciate Your Feedback!

 

Yep. Intake manifold. The amount of milkiness depends on how bad the leak was. If you were leaking predominantly to the outside of the motor, you may not see it all that much in the oil.

 

Thanks Kyle - in follow up I'm about toput the intake back on. I noticed a bit of pitting around one of the coolant ports should I or shouldn't I put a small dab of the permatek silicon on it and razor it off flush before putting on the gasket. On some articles it says to do it and others say don't - your opinion? Also when siliconing up onto the head portion (approx 1/2 inch up) from the blockdo you run this bead before or after you put on the intake gaskets? Last question- aside from putting on removable thread lock onto the manifold bolts - do you need to put any of the permatek near the head of the bolt to seal it?

Thanks again.

 

I had a small amount of pitting at the rear coolant passage in the heads on my old 2000 Bravada. I left it be with a dry gasket. It all depends on the extent of the pitting and your feeling. If you want to, just smear on a thin coat. No need to scrape it with a razor, just smooth it out with your finger.

As far as the bead at the lifter valley rails, I run the bead before I put the gaskets down on and then dab a bit more silicone on the corners of the gasket to tie it back into the previous bead.

I also did not use anything on the manifold bolts. I believe they have a small amount of sealer on them from the factory, but it is not a silicone type sealer. More like pipe thread sealant. Something that does not harden up all that much.

 

Thanks again - I'll be putting it on tonight. Hopefully it will be up and running by Saturday as I'll give it a day to cure then reassemble. In the mean time I'll repair my leaky oil lines & put newplugs in.

Take Care!

 

Just an update - it's been almost 3 weeks, no coolant loss or contaminated oil.Installed new lower intake gaskets, oil cooler lines, transmission dip stick, spark plugs and wires, thermostat, and flushed coolant and oil. Vehicle is running very well and got rid of all the common bugs. Just wanted to say thank you for the correspondance and articles provided in this forum. The were very helpful.