Coolant on Top of Right Cyl. Bank

[LanceGT4]

I checked this morning to see where the excess green rain water was coming from on my '99 C4 with about 96000 miles on the engine.

I have a pool of coolant on top the block under the oil cooler area. sigh!
With an inspection camera I can't see any obvious leaks from the cooler connections to the block. Or, on the surface of the cooler.

What are the chances that the seals have perished and I can put new O-rings in? If the seals fail am I looking an oil water intermix or one or the other all over the engine?
Thanks for any info you have.

I'm really can't afford a new cooler just before Christmas. the $10K over the last 2 years on other parts and maint. has me hoping for a simple fix this time.

[JFP in PA]

The orings for the cooler are very cheap, couple bucks at most. There are only four bolts holding the cooler down, so the orings are easy to change. Major issue is that you need to drain the cooling system in order to change the orings (good time to put in fresh coolant/distilled water mix), and do any other cooling system updates (e.g.: water pump, t-stat, etc.).

[LanceGT4]

Leak is fixed, it was the O-rings.
What a tight. patience testing job.
on my 99 with a 2002? replacement engine I needed 2 X 999-707-409-40-M17 and 2 X 999-707-389-40-M17 O-rings. Buy new gaskets for the intake to head runners 997-110-247-00-M30 and I should have bought one for the throttle body to intake, also. I also bought a liter of Pentosin CHF 11 S and replaced the steering fluid I sucked out.
When the exchanger is popped loose from the block I don't see any way to avoid some water / oil contamination.
Plan on an oil change. If I did this again I drop the oil pan plan and check for water. Loctite 5900 to seal it according to our host.

I had to cheap out and reuse my coolant. Wonder of wonders! On the refill and start up I didn't have any purging problems.

Draft a helper with long skinny arms, some of the reaches are tight to say the least. The factory manual did not mention a fuel circuit on one of the A/C coolant pipes in the back of the compressor. Before you remove these hoses cogitate on how the heck you're going to re-connect them.

one of 2 fuel lines you have to reconnect!

I hope this is a repair that you never have to do with the eng. in :-)
Lance