: coolant leak

12-28-07, 12:58 PM
Hi everyone, my daughter's Cat has a slow a-freeze leak. I replaced a hose and while that helped, it still has a slow leak from somewhere. I can't see any coolant leaks but after dropping her oil (which looked good) I opened her oil cap to fill the oil and saw a white sludgy mixture in the cap and spout. I wiped it out and now a week later it has come back although not as thick (yet). I have checked the dipstick and the oil looks clean. She still has the coolant leak. Could this be a head gasket going or maybe the oil cooler???? Also my stepson tried to do a pressure check on it but couldn't fit the unit to her coolant resevoir tank lid, is there an adapter for this? THANKS!!!!!

12-28-07, 01:00 PM
Change the heater bypass valve and use 50% synthetic oil.

12-28-07, 01:24 PM
HI and thanks for the FAST folwup. My stepson thought that it might be the head gasket starting to go and since he had never worked on a Cat engine he was a bit reluctant on getting into it. Could you tell me where the heater bypass is and how involved it would be? Also is that a common symptom ( milky sludge in oilcap/stem) for the heater bypass? This has been really frustrating. I was considering adding a coolant leak sealer to the coolant system but my stepson advised against it. Thanks

12-28-07, 02:31 PM
What kinda Cadillac is this? A Catera?

12-28-07, 02:51 PM

12-28-07, 03:02 PM

12-28-07, 03:17 PM
^^ wtf?

12-28-07, 03:20 PM
Why is this in the Lounge ?

12-28-07, 03:30 PM
Hi, I'm new to this and wasn't sure how/where to start a new thread. It is a 1997 Catera. Thanks

12-28-07, 03:59 PM
The HBV is a common problem. You can order it at gmpartsdirect.com (GM Part#90566947) The mayo sludge is from moisture, most commonly short trips. Take it for a long trip and it should clear up. Best to use semi-synthetic You can access the HBV if you remove the scuttle (plastic tray) beneath the wipers (remove wipers first). It'll be behind the plenum to the left with 3 hoses connecting to it. Full description here: http://www.omegaowners.com/forum/YaBB.pl?num=1193594464

12-28-07, 05:54 PM
Discussion has been moved to the dysfunctional cat section.


12-28-07, 06:01 PM
Yeah, I advised her not to buy it, but what do I know. I have learned that these Cateras are lemons and so has she. I guess that I should count my (her) blessings that these problems don't appear too serious (yet).

Po Pimp
12-28-07, 08:38 PM
Cateras are not lemons. They do however have some extremely expensive maintaince. The timing belt should be your main worry as far as "the lemon" part is concerned. I would suggest doing this every 40K miles. Not cheap either, do it yourself if your are mechanically inclined and understand the procedure.

White sludge. Most likely it is the oil cooler. I would suggest not driving the car until this is fixed. Coolant and oil together means no viscosity, severely wearing engine internals. May not be there yet but you never know. In freak cases with oil coolers the oil could siphon back in the cooling system leaving you with a bone dry engine. I went with an aftermarket oil cooler. It ran me around $40-50...some where around there it has been awhile.

12-29-07, 12:07 AM
Lemon huh? Bad enough we have to put up with crap from our so called cadillac bretheren but from a fellow Catera owner? Especially one looking for our advise and/or help? A little tact and outright flattery will serve you better. :annoyed::(

Mayo in the filler is either caused by condensation or a leaking oil cooler. Check the coolant tank. Oil? Leaking cooler. Bubbles (engine running) and an exhaust smell? Head gasket. Neither? Move to the filler cap. Clean out what mayo you see and go for a drive. Get her nice and hot and check again. No Mayo? No problem. Mayo? Oil cooler. Bubbles.........


12-29-07, 09:53 AM
I just spoke w/the cadillac dealer and he has informed me that the milky sludge in the oil cap/stem is normal for this vehicle when not driven everyday, as long as it's not in the oil or dipstick. I had dropped the oil and it looks clean as does the dipstick, so I'll keep my fingers crossed. My stepson and I will work on the MAF and some tuning today. Thanks for your input., Frank

12-29-07, 04:47 PM
Thanks for the help. I checked the HBV w/ my step son and saw no leak (even w/car running). He thinks that there might have been an air pocket in there from when we replaced a leaking hose a couple of weeks ago. I'll keep an eye on it and if it goes low again, I guess that I'll have to send it to the dealer so they can run a pressure check on it. My step son tried to run one but his connection to the res.neck wouldn't fit properly due to a lip on the inside edge of the filler mouth. Do you know if there is an adapter for this? Thanks again. Frank

12-29-07, 04:54 PM
I should appologize for the lemon remark, I'm just not accustomed to working on a foriegn engine. It seems that there are SOOOO many coolant hoses and everything is so expensive to reair/replace. Even a simple pressure test is proving more difficult due to the resevoir filler mouth having a lip on the inside edge preventing our tese from securing properly. Well other than what I've mentioned, the car does run very smooth and looks good. I guess that we'll have to live w/the costly repairs for now.

12-29-07, 08:36 PM
Warm up the engine. Cycle the HVAC from 60 degrees to 90 degrees. Check for HBV leaks at both extremes. It may only leak when the heater is on or when the AC is on.

12-30-07, 11:40 AM
Thanks for the tip. I checked it cold and it looked fine, but I'll recheck it tomorrow warmed up and w/the heater going. My daughter loves this Cat and it drives really good. I enjoyed driving it this weekend (1st time). I'm used to driving a 2007 Chevy Tahoe (which I love) but the Cat was a pleasant change. Nice handling, quiet and comfy, a real pleasure ( loaded w/leather,etc). I'll look at the coolant again tomorrow and as a last resort take it to the dealer. The milky sludge did go away after a short highway trip. What a relief, I really thought that it was a head gasket. Have a happy new year to all. Frank