steelsoldiers Posted March 5, 2004 Report Share Posted March 5, 2004 I have posted on this board and the previous one the saga of my '92 Deville. I got the car from my Granddad who only put 34k miles on it in 11 years. It currently has 34,505 miles. Here's a quick recap for those who didn't see the thread. About two months ago my car started losing its heat from time to time and shortly thereafter it would overheat. At first, it only happened when going up a long hill on the way home from work. Then, it became more and more frequent of a problem. Lots of things were suggested on this forum including a bad water pump, thermostat, hoses, blown head gasket, etc.... Now, here I am again. I just picked my car up from the shop after having the water pump replaced, thermostat replaced, and cooling system flushed. Driving it home on the 4-lane, it was overheating worse than ever. This probably has something to do with the warm temps too. But, it now has a new pump, thermo, upper/lower hoses, heater hoses, and 50/50 and it is still overheating and the heater goes cold on me! That doesn't make any %%$#ing sense!! If it is overheating, the heater should be scaulding hot and my shoes should be flaming, but no, it's ice cold!! One day when it was doing the usual crap I popped the hood and felt the top hose. It was hot, but easily pinched together so I'm thinking no flow from pump or thermo. Then, I touched the heater hoses and they were cold even though I had it turned on all the way home! What the heck is going on here guys?? I am about ready to set fire to it and shove it over the hill. Actually, a guy at work wants to buy it, but I can't sell it like this! Please help! Link to comment Share on other sites More sharing options...
JasonA Posted March 5, 2004 Report Share Posted March 5, 2004 I have posted on this board and the previous one the saga of my '92 Deville. I got the car from my Granddad who only put 34k miles on it in 11 years. That's probably your problem right there. Letting cars sit for a while doesn't do them any good. Just after taking a cursory look at your symptoms, it sure seems to me like the problem is with the heater core circuit. Either the core itself is plugged, lines are plugged, something. That would explain the no heat and it MAY explain the occassional overheating (I'm not too sure on how much the 4.9L engine relies on that for proper coolant circulation). With the old style coolant (the green stuff), it can gel if it sits for too long without any circulation. It sounds like that may be a problem? Also...don't flush the cooling system any more -- that may have just loosened something up to clog a water jacket, or some contamination may have been introduced from a flushing machine if they used that. I'd check your heater circuit (the cold hoses hint that it's out of the loop for some reason). Again, I'm not intimately familiar with the 4.9L engines, so I can't suggest individual things to check...like maybe something freak like the thermostat installed backwards or something. Sounds like the heater core circuit is at least part of your problem. Good luck. Hopefully, someone else will give some more or better advice. Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
steelsoldiers Posted March 5, 2004 Author Report Share Posted March 5, 2004 That makes sense to me, but sometime the heat works just fine, but only for a little while and then it dies off again. I can only remember a couple of time when the heat would come on and stay on for the whole trip. Then the next time I would run it, it would quit heating and overheat again. It's just so weird how it does that. I have spent all winter freezing my buns off on cold leather while the dang car overheated! I have never owned anything like this before. Is there some kind of control valve that could be sticking shut? I looked in the manual, but couldn't find anything for sure. Thanks for the quick reply Jadcock Link to comment Share on other sites More sharing options...
PAUL T Posted March 5, 2004 Report Share Posted March 5, 2004 Are you sure the shop did what they said they did? I would take it back to the shop and see what they say. Have you checked to see if your cooling fans are working? I agree with jadcock that something could be clogged up. Take your heater hoses off and hook a water hose up to one of them and see if there is a restriction in the heater core. Also check to see if the shop topped off the antifreeze by looking in the radiator and see if the level is to the top. When a car sits as long as yours did there will be a few problems pop up from time to time but be patient and tackle them one at a time and you will get a lot more happy years of driving out of her. I had mine for 10 years before things started to happen, but I have almost got them whipped. Your better off fixing what you got than go out and buy a pig in a poke. Link to comment Share on other sites More sharing options...
steelsoldiers Posted March 5, 2004 Author Report Share Posted March 5, 2004 I trust the shop completely. They have always done me and my family right. The cooling fans are really cranking. I can hear them from inside the car when I stop. When I got out tonight and popped the hood, the were roaring along. That sucker was hot! The top hose was hot and real hard to squeeze. The coolant jug was bubbling mightily. I'll let it cool overnight and then check the level in the jug. When you flush out the heater core, do you just take the hoses off down at the bottom of the engine and at the "T" on top? Thanks guys, I'm feeling a little better now that I have vented Link to comment Share on other sites More sharing options...
PAUL T Posted March 5, 2004 Report Share Posted March 5, 2004 Thats were I would unhook them. Be careful where the hoses are pointing when you hook the water hose up or you could get water where you do not want it. When you unhook the hoses you might get antifreeze everywhere so I would pull the lower hose first and drain what comes out into a bucket or something. Be careful not to leave a bucket of antifreeze out where any animals can drink it or you will be minus an animal real quick. Also do not rely on the overflow jug to determine if the radiator is full. Open the radiator up cold and check it there. Link to comment Share on other sites More sharing options...
steelsoldiers Posted March 5, 2004 Author Report Share Posted March 5, 2004 Hmmm, I got to thinking about what you guys suggested about the heater circuit. If even 30% of the engine coolant circulates through the heater core and the core is partially to fully blocked it could cause some serious overheating. So maybe the core is full of crud, but flows enough the build a little heat sometimes, but there is more crud circulating in the system which plugs the core further causing the no heat/overheat situation. I will try to pull the hoses and flush the core both ways. I read on hear once that you should flush with water and then fill the core and lines with a CLR mixture, let it soak, and then flush until clear again. Is that still advisable? Thanks. Link to comment Share on other sites More sharing options...
Ranger Posted March 5, 2004 Report Share Posted March 5, 2004 I don't think the heater curcuit being plugged should cause any overheating. It certainly would cause no cabin heat and flushing it would be a good idea. What sounds more ominous to me is the overflow tank "bubbling mightily". That sounds like a blown head gasket pressurizing the cooling system. Link to comment Share on other sites More sharing options...
98Concours Posted March 5, 2004 Report Share Posted March 5, 2004 I think that's about it. I flushed the heater core on my 90Seville and used limeAway. Just filled it up, let it sit a while, then flushed it out with water both ways. Jeff Jeff 98 Concours 90 Seville 04 Corvette Link to comment Share on other sites More sharing options...
steelsoldiers Posted March 5, 2004 Author Report Share Posted March 5, 2004 What sounds more ominous to me is the overflow tank "bubbling mightily". That sounds like a blown head gasket pressurizing the cooling system. Yep, I thought about that too. Maybe it's a combination of a blown head gasket and a plugged heater core. That's be just my luck Link to comment Share on other sites More sharing options...
Ranger Posted March 5, 2004 Report Share Posted March 5, 2004 Yea, kinda sounds like 2 seperate issues. Being '92 with green coolant it should be on it's 6th coolant change by now. Do you know how many it has had? That might be a clue. Link to comment Share on other sites More sharing options...
mike98c Posted March 5, 2004 Report Share Posted March 5, 2004 Hmm, I had a Taurus with the 3.8l engine that had the head gasket go bad. The heater core plugged up (apparently when one of the hoses started to disinegrate internally) and the car started to overheat I replaced the hose and flushed the core and the temps. went back down. A couple days later the car started to blow coolant out and sure enough the head gasket was gone BUT I found out later that engine will blow a head gasket almost every time if it overheats. I still think however the heater core plugging up caused the problem. The passages in the head were clear. Link to comment Share on other sites More sharing options...
Ranger Posted March 5, 2004 Report Share Posted March 5, 2004 Sure sounds like it's worth a shot. Flush the core and see what happens. Nothing to loose. Link to comment Share on other sites More sharing options...
steelsoldiers Posted March 5, 2004 Author Report Share Posted March 5, 2004 The strange thing is how the two seem linked together. I never lose heat without an overheat and vice versa. Sometimes the heat would be working and then slowly get cooler and cooler so I would shut it off. It wouldn't be 30 seconds later and the hot coolant light would come on and the fans would be cranking. Sometimes the heat will come back on during the trip, sometimes not. If the car was icy, I could go start it and turn the defrost on and most of the time it would warm up and defrost the windshield, but as soon as I start driving for a little bit the heat would be gone again. Weird..... Link to comment Share on other sites More sharing options...
Ranger Posted March 5, 2004 Report Share Posted March 5, 2004 OK, I may be way off base but here's my theory FWIW. At hight RPM you pump more combustion gas into the cooling system (perhaps none at idle). That "air" gets trapped in the heater core (highest point in the system maybe?) so the core cools and there is no heat. All the while the exhaust gasses are circulating in the water jacket causing the cooling system to loose efficiency. Make sense or am I blowing hot exhaust gases? Link to comment Share on other sites More sharing options...
steelsoldiers Posted March 5, 2004 Author Report Share Posted March 5, 2004 Well, that might be a possibility Larry. I wonder why the upper radiator hose could be squished together sometimes and other times it would be tight? Also, why would the heater hoses be cool to the touch? No flow I guess... Where can you buy a test kit to check for hydrocarbons in the coolant? I think that would be a good start too. Maybe I could buy one of those cooling system pressure testers too. Link to comment Share on other sites More sharing options...
tjtjwdad Posted March 5, 2004 Report Share Posted March 5, 2004 Larry Grandolfo Posted on Mar 4 2004, 06:36 PM I don't think the heater curcuit being plugged should cause any overheating. It certainly would cause no cabin heat and flushing it would be a good idea. What sounds more ominous to me is the overflow tank "bubbling mightily". That sounds like a blown head gasket pressurizing the cooling system. My thoughts exactly. Jim White Link to comment Share on other sites More sharing options...
steelsoldiers Posted March 5, 2004 Author Report Share Posted March 5, 2004 Here's an update for you. I went out this morning and checked the fluid levels. The tank was right on cold full and the radiator was about an inch below the filler neck. I left the cap off and started the car. As soon as I started it it dropped another inch in the radiator. Then, if I revved the engine up it would suck the level down another 3-4inches in the radiator. As soon as I let off the gas, it would rise back up to the original level or a little higher. Is that normal? I wuld think that if the engine and hoses are full of coolant that the level shouldn't drop in the tank when revving because the water pump couldn't pump the coolant anywhere. It almost sounds like the engine is full of air or combustion gasses:angry: and the water pump can displace that gas with coolant when revving, but then it surges back higher because the blown head gasket is allowing more and more gas in to raise the level. Does that make any sense? The coolant color had a little rust to it and it smelled funny which brings a head gasket to mind again. I have got to get that coolant tested somehow. Link to comment Share on other sites More sharing options...
JasonA Posted March 5, 2004 Report Share Posted March 5, 2004 Here's an update for you. I went out this morning and checked the fluid levels. The tank was right on cold full and the radiator was about an inch below the filler neck. I left the cap off and started the car. As soon as I started it it dropped another inch in the radiator. Then, if I revved the engine up it would suck the level down another 3-4inches in the radiator. As soon as I let off the gas, it would rise back up to the original level or a little higher. Is that normal? Yeah, I think that's pretty much normal. Pretty much reflects the momentum of the coolant in the system I think. Theoretically, if it were plumb full, you don't think you'd see any movement -- the effluent would equal the influent and the level would stay constant, but I think in any system, there's going to be some movement of water. I think you have nothing to loose by replacing the heater core and hoses at this point. Also, conventionally, there is a heater control valve that controls flow to the heater circuit. However, I don't think there's one on the Northstar (flow through the core is constant) and there may not be one on the 4.9L engines either. But traditionally, that's something to check if you're not getting any heat. Also...it sounds like the engine has fully overheated a few times by now, so you may have to do the head gaskets anyway at this point. Have your mechanic pressure test each cylinder to see if the heat gasket is compromised in one or more cylinders. It sounds like the coolant was at full boil a few times, and assuming a proper 50/50 coolant/water mix and the correct radiator pressure cap, that coolant was HOT HOT HOT (like, 260-270 degrees or more). Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
steelsoldiers Posted March 5, 2004 Author Report Share Posted March 5, 2004 I read the chapter in the manual about replacing the heater core and it doesn't look too bad(famous last words ) The only thing that looks tough is getting the clamps off of the hoses at the core. There is no room there to get pliers in on the clamps. How have you guys got them off before? Also, have any of you guys replaced head gaskets on the 4.9L before. I have done a lot of rebuilds and engine swaps before, but I am always wary of working on something new. Any tips? Thanks. Link to comment Share on other sites More sharing options...
KHE Posted March 5, 2004 Report Share Posted March 5, 2004 I wouldn't automatically jump to the conclusion that the head gaskets are bad without thouroughly troubleshooting the system. Have you verified that the coolant concentration is 50:50? Very easy to do with a $5 tester from Meijers or WalMart. The tee in the heater hose that is about one foot from the thermostat housing may have been replaced with a standard tee without an orifice. The leg of the tee away from the thermostat, towards the front of the engine, should have the orifice. You can flush the heater core with a garden hose - flush in both directions and then purge the flush water from the core. I'd be hesitant to use any type of chemical in the heater core. Checking the operation of the thermostat would be in order too - place it in a pan of boiling water and verify that it opens fully. You can also rent a cooling system pressure tester and pressurize the cooling system to 15psi and look for leaks. It does help to drain the coolant before pressurizing as any leaks will be more apt to leak the air vs. coolant. To test the headgaskets, take an old spark plug and remove the porcelain and electrode. Braze on an air compressor fitting and use it to pressurize each cylinder to 120 psi. Make sure the cylinder is held at top-dead-center (both valves closed) and look for bubbles in the radiator. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
steelsoldiers Posted March 5, 2004 Author Report Share Posted March 5, 2004 I wouldn't automatically jump to the conclusion that the head gaskets are bad without thouroughly troubleshooting the system. Have you verified that the coolant concentration is 50:50? Very easy to do with a $5 tester from Meijers or WalMart. The tee in the heater hose that is about one foot from the thermostat housing may have been replaced with a standard tee without an orifice. The leg of the tee away from the thermostat, towards the front of the engine, should have the orifice. You can flush the heater core with a garden hose - flush in both directions and then purge the flush water from the core. I'd be hesitant to use any type of chemical in the heater core. Checking the operation of the thermostat would be in order too - place it in a pan of boiling water and verify that it opens fully. You can also rent a cooling system pressure tester and pressurize the cooling system to 15psi and look for leaks. It does help to drain the coolant before pressurizing as any leaks will be more apt to leak the air vs. coolant. To test the headgaskets, take an old spark plug and remove the porcelain and electrode. Braze on an air compressor fitting and use it to pressurize each cylinder to 120 psi. Make sure the cylinder is held at top-dead-center (both valves closed) and look for bubbles in the radiator. Thanks for the good tips Kevin. I will definitely check all those things before tearing into the engine. It's going to be a fun weekend Link to comment Share on other sites More sharing options...
KHE Posted March 5, 2004 Report Share Posted March 5, 2004 Glad to help out. Post back your findings. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
steelsoldiers Posted March 5, 2004 Author Report Share Posted March 5, 2004 I will. My brother is coming in for a visit this weekend and I'll put him to work on this thing too. Hopefully between the two of us we can run all the little checks and cleaning procedures and get this thing figured out. I get so pissed off at the car, but on the other hand I miss driving the big land barge too Link to comment Share on other sites More sharing options...
Lawrence Posted March 5, 2004 Report Share Posted March 5, 2004 Two things I would also check. One is the vacume storage cannister that works the blend doors. Around it somewhere is a check valve. The purpose of this valve is to mantain adequate vacume to the system when the motor is producing low vacume (such as long accelerations, uphill, etc.). this little check valve only cost a couple of dollars. I am not famialir with this car so I couldn't say where it is but you should be able to find it. Second is an obstruction of the heater core. Below is a link to someones post on this. http://www.cadillacforums.com/forums/showt...ght=heater+core Of course neither of these would have anything to do with the overheating, but may help with the heat. It seems you have two isolated problems. Link to comment Share on other sites More sharing options...
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