Question about 1989 Cadillac Sedan DeVille

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Heating system replaced all cooling system parts, compression is good, coolant system pressure check is good. it heats good going down the road then cools down when you slow down. totally stumped on this one.

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  • todd_vogel54 Jan 29, 2009

    the heat in the cabin cools almost to the temp outside, the system seems to be cycling properly the fans come on when engine is at temp and turn off when cool enough.

  • Joe Prete May 11, 2010

    this calls for more information. What do you mean cools down, this is, most time a good thing, Is the engine cooling down too fast or are you not getting enough cabin heat? If so you must have a pressure or poor ciculation problem. Joefish

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Heater core has a restriction inside of it replace heater core and it will heat all of the time

Posted on May 19, 2009

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Will an air pocket in the coolant system cause it to overheat or over pressurize on a 2001 Nissan Sentra ?


1. The radiator cap if working correctly it will release pressure in the system provided the cap you have is the correct pressure setting. If you are having a problem with pressure then replace the cap with a new radiator cap with the correct pressure setting. Do not use a cap with a pressure setting other than the original equipment pressure spec. So you do not go to the parts store and buy any radiator cap on the shelf that fits because they come with different pressure ratings and some of these will be totally unsuitable for your car.

2. If the pressure valve is stuck in the "old" cap the pressure release system will not work.

3. Overheating
Air pockets in the cooling system can definitely cause overheating and can retard coolant flow through the system. If you are draining the radiator to replace the coolant or replacing the radiator you need to follow the correct procedures for bleeding air out of the system for that particular engine after coolant refilling. Some engines have bleeder screws on the cooling system to assist in the air bleeding procedure and some don't.

There are various causes for overheating so don't assume it will necessarily be solved by bleeding any remaining air from the cooling system and replacing the radiator cap with one that works.

Other causes can be...........
1. Faulty cooling system thermostat. (Replace the Thermostat)
2. Faulty water pump, especially if the impellers have corroded away or have disintegrated in the case of those design genius water pumps with plastic impellers. (Replace the water pump)

3. Cooling fans not working and if so the cause needs to be tracked. Check that your fans are kicking in. If the engine is overheating the fans should be running because they will switch on when the coolant reaches a specific temp and well before the coolant gets excessively hot.

4. A partial blockage in the coolant passages inside the engine but not in the radiator if you have a new one. If the coolant is not changed at the required intervals(frequently the case with many owners) or is over diluted with water you can get a build up of debris. If products like stop leak have been used in the system this can create similar problems with partial blockages inside the engine coolant passages.

5. A compression leak into the cooling system.
If you have bled air from the system and have continuous air bubbles in the cooling system I would suspect a compression leak. In that event a basic leak down test will show if you have compression gasses leaking into the cooling system and from which cylinder(s). The spark plug is removed and compressed air is forced into the cylinder via the spark plug fitting and air bubbles will show up in the coolant of there is a leak into the cooling system.
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Have the problem with overheating addressed immediately. Running the engine with an overheat condition will cause expensive engine damage many times the cost of fixing the overheating issue.

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Dec 29, 2015 | Nissan Cars & Trucks

1 Answer

87 pathfinder overheating replaced thermostat hoses are good resevoir has cracks in it though could this cause over heat ?


possible --if there is a pressure cap on it --if not then n you haven't mentioned when it over heats so here are a few answers
if it over heats all the time regardless have a compression test done--- have a flow test done on the radiator --check the radiator cap
if it over heats at lights ,in slow traffic or when the vehicle is goin slow with high rpms ( hilly work) but cools down when a road speed is achieved then replace the viscous fan hub or check operation of the electric fans
If the engine over heats but the temp gauge reads normal then bleed the air lock out of the cooling system
if it over heats at high speed then check the core fins are no falling off or there is nothing in front of the radiator preventing air flow,or check hat it is engaging overdrive,

May 29, 2015 | 1987 Nissan Pathfinder

1 Answer

1990 s10 blazwe heats up to over 210 degrees when driving down the road


have a pressure test done on the coolant system. have a compression test done to check for head gasket or cracks . have a flow test done on the radiator to check for blocked cores. IF blocked replace radiator as flushing is a waste of money.

Jan 13, 2014 | Cars & Trucks

1 Answer

Overheating


Doesn't sound like it ran hot enough or long enough to crack or warp the head. If there is a crack, the engine will continue to overheat. If a warped head, car would probably run rough, the affected cylinders would likely have little or no compression, there would be a noticeable miss, and overheating would continue.
Why the low coolant? It's a sealed system, so should never have to add coolant, other than a small loss from evaporation in the overflow tank. Monitor the level closely for the next few days. Note the level in the overflow tank to see if it drops over time. Leaks can be external anywhere in the coolant system-engine, radiator, hoses, heater core- or internal in the engine-head gasket failures can cause coolant in the cylinders (white smoke out the exhaust), or coolant in the oil (oil will have a milky brown look to it), or oil in the coolant (will see traces of oil in the radiator).
A couple of tests may be called for. A pressure test of the coolant system will check if the system holds pressure as it should-about 15 psi. If pressure does not hold, there is a leak somewhere. Water pumps usually leak through the weep hole when they fail. A radiator leak would show up when pressure is applied. If pressure does hold, check if you have a good radiator cap-the cap is what seals the system so pressure will maintain. Coolant under pressure raises it's boiling point by about 10 degrees, so is critical to keep the system under pressure.
If you suspect further problems-losing coolant or continued overheating-then have the chemical test done to check for exhaust gasses in the coolant. Basically a check if the head gasket is good, a simple test done at the radiator cap opening with a special fluid that changes color if hydrocarbons are present in the cooling system.
Or you could have a compression test of the cylinders to check the internal mechanical condition-not only tells you if head gasket is good, also tells you a lot about engine condition-even,. balanced, good compression in all cylinders translates into good power output-rings are good, valves are sealing good, all systems go.
The cooling system: water pump, thermostat, radiator, hoses, heater core and hoses, radiator cap, overflow tank, and the cooling fans and associated wiring. Make sure everything is working right and you'll be good to go.

Sep 17, 2013 | 1994 Toyota Camry

1 Answer

Why my motor over heat


There could be several problems with it overheating. 1. Low coolant level. Top off with recommended coolant. 2. Have the radiator cap pressure tested. A cap that cannot hold proper pressure can allow fluid to leak. 3. Spent coolant. When coolant breaks down, it cannot keep the engine cool properly. A coolant flush would be recommended. 4. A stuck thermostat. A stuck thermostat can impede the flow of coolant through the system. 5. Coolant leaks. It could be the radiator, water pump, thermostat housing, hoses, or freeze plugs. Have a pressure check done on the system. 6. Blown head gasket. When a vehicle overheats, it puts a strain on the engine and gaskets. Have a compression check done on each cylinder. These are some steps to take toward getting this issue resolved. Good luck.

Oct 16, 2010 | Ford E-150 Cars & Trucks

1 Answer

98 pontiac firebird v6 3.8 liter, keeps overheating and i replace all cooling sytem parts.


When you said you replaced all the cooling system parts, you mean the raditor, the hoses, the water pump,the therostate, the raditor fan and it's relays and sensers. If you've done all of this and you correctly purged all the air out of the system then The engine can be making too much heat another way. The coolant temperture senser can say that the engine is cooler than it really is ( makes a rich mixture, to warm the engine) The therostate may be installed unside down or is open all the time or is missing. ( the therostate needs to make the car get up to 200degrees F or the raditior may not get hot enough to remove enough haet to cool the engine. ( hot is good too hot or too cold is bad). Let's say all the cooling system work is good and you did'nt mix more than one kind of antifrezze ( they jel up and not cool.) The exhaust can be stopped up ( causes low performance too) Take out the oxagen senser and connect a pressure gauge ( leave the snser plugged in and grounded) If the pressure goes any higher than 5 Lbs. reving it or anytime then you looking for a clog. A good system revved up and heald staedy should show a vacume. The timing can be wrong ( low performance too) The timing chain can skip time and the measureed compression will be lower that 150 LBS. With the chain skipped the ingtion timing will be slow and that will cause overheating all by it'self. The engine may need an oil change, Gas in the oil from short trips and running too cold sometime. Overheating will rurine the mototr oil and it being bad will make the engine heat. The engine turning hard ( turning the engine by hand you should feel 3 compression shrocks per turn and it should turn easy except as it pressureizes each cyclinder, ( they should all feel the same) the oil should look clear and black, not brown. If it's some other color, coolant may be getting in the oil, The exhaust should'nt smell sweet ( antifreeze leaking into the combustion ) with the car running and the cooling system full with the cap off it shouldn't bubble or steam come out ( it tells their is a leak in the engine to the coolant and it'll blow bubbles in the coolant and the hot exhaust will heat the coolant more than the raditor will remove. It certainly should'nt bubble at all started cold and full.

Sep 28, 2010 | 1998 Pontiac Firebird

3 Answers

What is the coolent reserve tank for???? IF broke does it need to be fixed immedatley? Mine is busted and I was wondering if my car is going to overheat now. THANKS


The coolant reserve tank is a medium for the radiator to breathe. Water passes from the radiator to the coolant reserve tank and fort.

The car might not necessarily over-heat if the coolant reserve tank is broken, but it is advisable that you replace it to enable it serve its purpose within the operations of the car engine.

Good luck.

May 27, 2010 | 2004 Toyota Avalon

3 Answers

Would the heater control valve malfunctioning make the engine overheat blowing hot air out the heater one moment,then not blowing the hot air, temp gage spikes 225 plus. The motor takes awhile to heat up...


Heater control valve malfunction will not cause engine to overheat unless coolant is leaking externally...Overheating going down the road can be the result of a few different things...Partly clogged radiator...Insufficient air flow due to possible fan problem...External coolant leak...Make sure fans are operting properly and have cooling system pressure tested for leaks...Gaining and losing heat on the inside of the vehicle usually means system is low on coolant but you must find out where coolant is going

Jan 06, 2010 | 2004 Chevrolet Impala

4 Answers

No heat when engine is at low rpm or idle.


if engine temp. is good. i would rec. good flush of the heater core disconnect both heater hoses and flush core in both directions. (pressure washer works good)

Nov 21, 2008 | 2005 Nissan Altima

1 Answer

Overheating


Who did the replacement of the parts? Was it done at a shop or at home? Do you know if the cooling system was "burped" after the parts were installed and the coolant was refilled? If you're not sure, burp the radiator. This is easy to do. Jack up the vehicle so that the thermostat is angled upward. Start the car and let it idle until it's 3/4 of the way to overheating, then shut it off and allow it to cool down somewhat. Then pop the cap, let the coolant drain down, and refill it. Restart the vehicle and repeat the process, until the coolant level doesn't drop anymore.

What you're doing is this - anytime the cooling system is opened up, especially when the fluid is drained and parts are replaced, air gets into the system. When you reassemble and refill with coolant, you trap air bubbles in the system. Since the system is sealed, it operates under pressure. As the car runs, the coolant and the air bubbles are circulated. The bubbles get caught behind the thermostat (if you have it angled upward) and keep it from opening. This causes the engine to heat up to the point of overheating. You want to allow it to get about 3/4 of the way to an overheat so that you know the air bubbles are blocking the thermostat. Shutting down the car stops it from heating up to the point of damage, and allows the system time to cool off so that when you pop the cap, you don't get an explosion of coolant in your face. Once it's cool enough to open the system, you open it and release the pressure. This allows the thermostat to open and bleed the bubbles upward to the open cap, where they "burp" into the air. The space they took up fills with coolant, which is why your coolant level drains down. You top it off and repeat to make sure that all the bubbles are out. You'll know you're in good shape when you let it run and it gets to operating temperature and doesn't overheat anymore. Let it cool that final time, open the cap, and since you have no air pockets left in the system, nothing will burp out and your coolant level won't decrease. Then you should be good to go - put the cap back on and drive away happy.

Sep 27, 2008 | 1996 Jeep Grand Cherokee

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