MrMagoo Posted August 11, 2015 Report Share Posted August 11, 2015 I need to do a coolant change on my '95 DeVille 4.9L, and I've read where people have said you shouldn't flush the system with water because you might upset the 50/50 mix. Why are they saying that? Because... 1) The factory service manual I have (not Chilton or Haynes) says to flush with water (and I would be using distilled, not tap). 2) If you drain all the water out, how would there be any left to throw the mixture off? 3) The manual warns against "a solution of higher than 70/30 mixture of antifreeze to water", but it doesn't warn against an imbalance the other way. Is there something I'm missing? Link to comment Share on other sites More sharing options...
Cadillac Jim Posted August 11, 2015 Report Share Posted August 11, 2015 Yes, you should flush your system, because a lot stays behind if you just drain it. Refill with half your car's coolant capacity according to the owner's manual and top it off with distilled water, then check to make sure that it is between 50% and 70% antifreeze. Water/antifreeze mix has its best freezing point, AND boiling point, between 50% and 70% antifreeze. Outside that range, both suffer. If the boiling point comes down, steam pockets cab form in the head and the bubbles can confuse the thermostat and cause overheating. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
KHE Posted August 11, 2015 Report Share Posted August 11, 2015 If your engine does not have block drains (and I do not think it does) you will need to measure the amount of coolant you drain out. If it is less than 50% of the total capacity of the system, it will be very difficult to get the concentration of the new antifreeze to 50%. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
MrMagoo Posted August 14, 2015 Author Report Share Posted August 14, 2015 Sorry to take so long replying -- I've let myself get distracted by some other projects this week.I haven't crawled underneath the Caddy to see where it is, but the manual says the radiator does have a drain cock. Link to comment Share on other sites More sharing options...
KHE Posted August 15, 2015 Report Share Posted August 15, 2015 Yes - the radiator has a drain. I was referring to block drains. If the 4.9 engine has them they will be on the engine block down low - one each side. If it has block drains, you will be able to get all the coolant out. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
MrMagoo Posted August 16, 2015 Author Report Share Posted August 16, 2015 Ah, gotcha. Link to comment Share on other sites More sharing options...
MrMagoo Posted August 16, 2015 Author Report Share Posted August 16, 2015 I suppose I could go the expensive route and flush with 50/50. Only half-kidding... Link to comment Share on other sites More sharing options...
KHE Posted August 16, 2015 Report Share Posted August 16, 2015 Unless the cooling system is full of crud/plugged up, there is no need to flush it. Unless you can drain at least 50% of the coolant out, you will have trouble getting the concentation at 50/50. In the 4.9 engine, the use of the cooling system pellets is required due to the wet sleeve cylinders. You can buy them at any GM dealer or the Bars Leaks golden seal is the same stuff. Crush the pellets and add them to the radiator before filling with new coolant. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
MrMagoo Posted August 17, 2015 Author Report Share Posted August 17, 2015 I did get the pellets and Bars Leaks, but I appreciate knowing why they're needed. I might see how much I can drain out before I decide to flush or just replace. I could use the turkey baster trick. Link to comment Share on other sites More sharing options...
winterset Posted August 17, 2015 Report Share Posted August 17, 2015 great question!! And good for you getting the bars. I use the bars powder. Aluminum is porous and our block and heads are aluminum. Adding this "stop leak" is just a $4.99 insurance to stop nuisance leaks that might not be seen. Imo, these leaks can be internal or external. I have always added this as part of my 4 year fluid drain and fill on my '96. I never flushed. I also believe the stop lean keeps the dexcool out of the headbolt Threads. Btw, Make sure your radiator and surge tank have no cracks in it. Also make sure you stay 50/50, and keep an eye on the surge tank that it is full when coolant is 3" from the top. Do not fill the surge tank to the top. Link to comment Share on other sites More sharing options...
winterset Posted August 17, 2015 Report Share Posted August 17, 2015 Just saw you have the 4.9. Not sure if that is all aluminum. Either way if GM recommended it in '95, i would still use the bars. Link to comment Share on other sites More sharing options...
MrMagoo Posted August 17, 2015 Author Report Share Posted August 17, 2015 Well, well...while perusing a different part of the manual, I lighted upon a passage that says that every 2 years/30k the coolant should be drained and refilled. Nothing about flushing. My next question is, I want to replace the thermostat while I'm at it. I find 4 or 5 choices on Amazon, and I don't know which to get -- 192, 195, 180, or 160 degrees. http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=1995+cadillac+deville+thermostat+acdelco&rh=i%3Aaps%2Ck%3A1995+cadillac+deville+thermostat+acdelco Link to comment Share on other sites More sharing options...
KHE Posted August 17, 2015 Report Share Posted August 17, 2015 195° is the factory thermostat specification. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
MrMagoo Posted August 18, 2015 Author Report Share Posted August 18, 2015 Thanks! Link to comment Share on other sites More sharing options...
MrMagoo Posted August 19, 2015 Author Report Share Posted August 19, 2015 Out of sheer curiosity, what do the different thermostats allow for -- different driving styles or something? Link to comment Share on other sites More sharing options...
Göran W Posted August 19, 2015 Report Share Posted August 19, 2015 Mostly different climates. Link to comment Share on other sites More sharing options...
KHE Posted August 20, 2015 Report Share Posted August 20, 2015 Out of sheer curiosity, what do the different thermostats allow for -- different driving styles or something? I think it is for those who think they know more than the engineers that designed, developed and validated the engines... there are some that think a 160° thermostat will make their engine last longer... Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Cadillac Jim Posted August 20, 2015 Report Share Posted August 20, 2015 There are those who think that a good tune-up is to throw away the air cleaner element and the thermostat. "If you mow your lawn and find... a car, you might be a redneck." --Jeff Foxworthy -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
MrMagoo Posted August 23, 2015 Author Report Share Posted August 23, 2015 Since they're so inexpensive, I decided to go ahead and replace the heater core while I was at it -- hopefully do some preventive maintenance so the plastic doesn't break. I've found the threads on here to be very helpful with that, but there's one thing I don't know: the OEM number for the foam seals for the core. I've tried several places and can't even find where to look it up. Does anyone know the number, or know if this is something I can fabricate on my own? I'm working under the assumption that the original core is in the car, and the foam will be too shot to use again. I'll find out for sure tomorrow when I take it apart, but I'd like to order the seal ASAP so I can get this done. --- Also also, I decided to do the drain-replace method and get about half the coolant, and I might do another drain-replace in a few weeks to get even more of the old stuff out, then I won't have to touch it for a while. Opinions needed: should I put the GM sealant pellets in at this refill, or at the next one? Thanks! Link to comment Share on other sites More sharing options...
Bruce Nunnally Posted August 24, 2015 Report Share Posted August 24, 2015 Do you mean seal, heater core call out #13 in this diagram? Unfortunately that part is no longer available. I am uncertain if there is a generic substitute. SEAL. Heater Core. SEAL,HTR CORE TUBE(120.0 X 36.0 X 6.0MM)(09.262). SEAL,HTR CORE TUBE(120.0 X 36.0 X 6.0)(09.262). Stock Code 03058179 Manufacturer VPI Categories This product is no longer available. http://parts.nalleygmc.com/showAssembly.aspx?ukey_product=2990068&ukey_assembly=379782 Bruce 2023 Cadillac CT4-V Blackwing Follow me on: Twitter Instagram Youtube Link to comment Share on other sites More sharing options...
MrMagoo Posted August 24, 2015 Author Report Share Posted August 24, 2015 One of the threads I read said it was 4 pieces of foam; 7 and 8 in that diagram look like the most likely ones of anything. Link to comment Share on other sites More sharing options...
Bruce Nunnally Posted August 24, 2015 Report Share Posted August 24, 2015 7 SEAL. Heater Core. . Stock Code 52470751 ; 52469028 Manufacturer GM Categories This product is no longer available. 8 SEAL. Heater Core. . SEAL,HTR CORE CVR(198.5X9.0X4.0MM). SEAL,HTR CORE(198.5X9.0X4.0MM). SEAL,HTR CORE(USED W/MODE VLV 52468099)(FOR 2ND DES SEE 52470032)(198.5X9.0X4.0MM). Stock Code 03058154 Manufacturer VPI Categories This product is no longer available. Click to show all similar "SEAL. Heater Core. " products. Some sites like http://oemcats.com/oem-parts/52480246.html Give the appearance of helping track down new old stock but not sure if the listed sources actually have inventory or not Bruce 2023 Cadillac CT4-V Blackwing Follow me on: Twitter Instagram Youtube Link to comment Share on other sites More sharing options...
MrMagoo Posted August 24, 2015 Author Report Share Posted August 24, 2015 Wow -- thanks for that OEM site. I was trying to find something like that and didn't know where to look. When you were posting this, I was waiting for the local dealership to call me back, and he gave me the same numbers as above. Looking at the prices for the places that supposedly do have them...I think I'll end up making my own if I can. Yikes. Link to comment Share on other sites More sharing options...
Bruce Nunnally Posted August 24, 2015 Report Share Posted August 24, 2015 I think that is what I would suggest as well. Just be careful to select materials that can withstand the temps involved. KHE may have better advice tho. Bruce 2023 Cadillac CT4-V Blackwing Follow me on: Twitter Instagram Youtube Link to comment Share on other sites More sharing options...
winterset Posted August 24, 2015 Report Share Posted August 24, 2015 Is part #13 required to seal the system, or is it some kind of thermal seal for the heater core case? I never replaced my heater core, and it would really stink if there is a part that didn't last 19 years, and its no longer sold. Heater cores always seem like a PITA. I will say a prayer to the heater core gods tonight too after my prayer to the head gasket, half case, P0741, and rear knuckle gods... Link to comment Share on other sites More sharing options...
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