99 Express Van 5.7 Cooling Question

I've got a 99 Express Van 3500 with the 5.7 engine and about 56k on the clock. Truck has always been maintained well, oil changes, etc.
Using Dexcool Coolant....
Recently while checking fluids and such it was low on coolant, the overflow was empty and the rad was maybe 1/4 low.....I have never seen any obvious leaks and the truck never lost coolant before, at least not this fast....
Then I noticed an oily residue on the inside of the radiator cap, not alot, but it was there and looked like dirty oil....This is also a recent development....
What do these symptoms suggest to you guys ???
TIA
Jeff
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Leaking intake manifold gaskets.
Do the water pump right away also.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Arrggg....I thought that answer might be comin my way......Wouldn't bother me so much if it wasn't a van !!!! Anything crazy I should be aware of ????
I have a service manual and would use Quality parts, but sometimes a little extra wisdom goes a long way.
Thanks for your responses !!!
Jeff
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Ether buy the pre-mixed coolant, or use distilled water with straight dexcool. I find it just easier to use the pre-mixed stuff. its ok to use die grinder and scotch brite pads to clean the manifold its self because you can wash it when done, but don't use them on the heads. Of course this is all based on it being an intake manifold leaking. I think I be willing to spend a few dollars to find out for sure. aint no fun on a van.
Whitelightning
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Thanks WL,
Good tip on the premix...I did not know about it although thanks to this forum I have been using distilled water !
I also get your point about the head cleaning, would not want abrasive crud in there.
About the testing for an intake leak, is this something one could do by his self ??
If so, What is needed and how to do ??
If not, Who would I have do it....Dealer ???
Thanks, Jeff
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.