What are all the possible causes of a loss of coolant? on 1999 Buick Regal

The coolant level drops slowly, but no coolant appears on the ground beneath the car. Radiator pressure test does not maintain pressure; and a mist appears to spray out of lower right (when viewed from rear) side of engine until pressure is released at the tool. Coolant in radiator is normal color. No codes or check engine light are displayed.

by in Herndon, VA on February 11, 2014
2 answers 4 comments
ANSWER by on February 11, 2014
Lots of possibilities!! Have you had it checked while hoisted? May need an inspection mirror or video scope to pinpoint the leak, no way we can help beyond this!
COMMENT by on February 11, 2014
Thanks for your response, pushrod. However, both my radiator pressure test results (as I listed in the problem details) and a confirmed solution previously posted on this site (Leaking Water Pump Housing, the Plastic elbow from Manifold to WP Housing)have convinced me that this plastic elbow part, between the intake manifold and the belt tensioner, is the cause of the leak. I am going to have it replaced, and then monitor the system going forward. Thanks for your assistance.
COMMENT by on February 11, 2014
That may have been my posted answer, if so i usually suggest the revised metal 90°'s rather than the plastic! Available @ NAPA. Wait a bit and i will post the part #....6601942 that's the part # for the metal replacements, they are actually called heater hose connectors!
COMMENT by on February 11, 2014
Thanks again for your reminder to use the aluminum metal part!
ANSWER by on February 11, 2014
have cooling system pressure tested to determine source of leak
COMMENT by on February 11, 2014
Thanks for your response. However, both my radiator pressure test results (as I listed in the problem details) and a confirmed solution previously posted on this site (Leaking Water Pump Housing, the Plastic elbow from Manifold to WP Housing)have convinced me that this plastic elbow part, between the intake manifold and the belt tensioner, is the cause of the leak. I am going to have it replaced, and then monitor the system going forward. Thanks for your assistance.
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