Chevy & GMC Vans

Hey everyone, been a member of the Astro and Safari Community for about 8 years or so now and love it. Here is my specs. 1998 GMC Safari with a 2003 4.3 from a sonoma. I did the engine swap myself 5 years ago and know what I am doing as far as that goes, used all the astro stuff on the sonoma block. Motor has 75000 miles on it. For over the past year I have been losing water somewhere and couldnt find it. NO SMOKE OUT OF THE EXHAUST AT ALL. I keep current on my oil changes and never noticed anything before, but last week I did and oil change and noticed water dripping out of the drain plug when the oil was already drained. My question is where is it coming from. I have 3 theories if they are all possible, not sure?

1) Intake Gasket. When I did the motor swap 5 years ago I did the intake gaskets myself cause i had the manifolds off of the motor to put it in the van, then put on the intake manifold.

2) Head Gasket. I hope this isnt the issue.

3) Radiator cracked where the oil cooler lines are. Not sure if this is possible but this would be the best case scenario as far as I can see. Is it possible that the radiatior is leaking into the oil cooler lines?

It seems as I am using much more water these days than a year ago. Anyone got any ideas before I go and buy a radiator tomorrow? Thanks!

All of the things you mention are certainly possible. Have you done a compression test? That would confirm the head gasket problem....or not a head gasket problem. The oil cooler leaking is extremely rare if it happens at all. I personally have never heard of it. So...that leaves the intake gaskets. My Safari did exactly the same as yours. Lots of water useage without any visible signs. So, I did the intake gaskets. And what do you know, there was water in the intake valley. That's my guess if the compression test is OK.

My $ is on the intake ....... had it happen on mine. Eventually causing main bearing failure at 140,000 miles

I appreciate all the replies. If it is Intake Gaskets there will be noticable signs when I pull the intake correct?

Here is a test you could try.Take off the rad cap and allow the thermostat to open.Look down inside the rad neck and if you see a steady steam of bubbles it very likely a blown head gasket or cracked head.What you are seeing is the compression leaking into the coolant system.

Matt, mind did show easily seen signs. Where the front and side met.

When you say "water" coming out of the oil drain plug do you actually mean anti-freeze? If it is clear water it is probably just condensation if the engine isn't running hot enough and long enough. If there was water in the engine, the oil would be milky.

If the oil cooler sprung a leak, you would see oil in the radiator. Cooling system is at 16 psi and engine oil runs at 40 psi+.

I am not sure of the routing of the coolant through the heads (steel or aluminum) but i had an aluminum head in a BMW that leaked the coolant into the oil. NOT into the cylinders or anything else. But yes.. If it is coolant in the oil the oil would look frothy and probably would have crud on the oil filler cap and such..


Hmmm

Defiantly a frustrating puzzle

It looked like just water and ive been losing water somewhere so when its not freezing out im just putting water in the radiator. Ive had this van like this for 5 years and have never had a problem like this, I always do my own oil changes. Did a Radiator leakdown test today and it started at 14 psi and after 10 minutes or so it was down to 10 psi without any visible leaks to the radiator or coolant lines. There was antifreeze puddling up on the tranny that looked like it was coming from the passenger side rear of the engine. Checked all visible freeze plugs and looked good. Going to pull the doghouse tomorrow and see if I can find anything. When I pull the doghouse I am expecting to see coolant leak from the passenger rear of the intake manifold. We will see. Thanks for the replies and keep the info coming, taking it all into consideration!

does this van have the rear heat. Could be coming out of one of those lines??? BUt wouldn't explain it being in the oil...


Hmmm...

No rear heat, its a cargo van

Matt-do the bubble test I suggested in the post.

leadtrombone wrote:BUt wouldn't explain it being in the oil...

I don't think there is an internal problem...water in oil would be milky looking.

If there is water/coolant leaking on the trans housing, you have a leaking intake manifold gasket.

Did the radiator bubble test and everything was just fine. Going to tear into it tomorrow and see what I can find out. Thanks

Cool Matt.I think then you can eliminate the head gasket/cracked heads from your list.I suggest you follow the path of looking for a intake gasket issue as it was suggested.Keep us updated.