Coolant leaking near radiator cap

Bertimus

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Buick Ownership
2005 Buick Lesabre Custom, 1988 Buick Reatta
Just bought a 2005 LeSabre with 50k original miles. It's been sitting for almost 4 days (been checking every day for any type of leak) and just today I noticed a few drops under it. It's coolant and I traced the leak to be coming from the radiator cap or somewhere near it. The engine starts/ sounds/smells great. The oil is fine (no milkiness). No smoke from the tailpipe. No check engine light. When I first opened the radiator cap it was almost overflowing. The coolant reservoir levels are on point. Could it be a bad cap?
 
Last edited:

2007LucerneCXL

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Illinois
Buick Ownership
2007 Lucerne CXL. and 1995 Lesabre currently, past 1973 Riviera, 1968 Riviera
Besides the cap the overflow tank and hose should be looked at but lack of details it's guessing about the source.
 

sightcrr

Member
44
8
8
Buick Ownership
2004 LeSabre Custom, 2005 LeSabre Limited
I borrowed a pressure tester from Auto Zone with $245 deposit and none of the 25 or so caps would make a good seal. Bought a new 15psi cap from gm for about 10 bucks to make sure I had the right pressure and good seal. My leak was from a broken antifz fill kit.
______________________________
 

sightcrr

Member
44
8
8
Buick Ownership
2004 LeSabre Custom, 2005 LeSabre Limited
The first thing I would have done or do is replace coolant elbows and if you want the easy way the idler pulley and bracket.
 

BuickGirlFromMars

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Buick Ownership
1999 Buick Park Avenue Ultra (Supercharged)
is your radiator cap part of the radiator, the body of the end tank and the snout you put the cap on, made of plastic?



THIS MAy be relevant if its an older lesabre radiator or its refurb

Bulletin No.: 00-06-02-001
File In Section: 06 Engine/Propulsion System
Date: January, 2000
Subject:
Engine Running Hot, Overheating and/or Loss of Coolant (Polish Radiator Filler Neck and Replace Radiator Cap)
Models:
1999-2000 Passenger Cars and Trucks with Composite Radiator End Tank
Condition
Some customers may comment on one or more of the following conditions:
^ Engine running hot or
^ Engine overheating, and/or
^ Loss of coolant/low coolant message
Cause
The radiator filler neck may have an imperfection in the sealing surface.
Correction
Important: DO NOT REPLACE THE RADIATOR.
Using a piece of 400 grit wet/dry sandpaper backed with a flat piece of wood, polish the filler neck sealing surface using a circular motion.
Replace the radiator pressure cap
 
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