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94 Camry overheating
10-15-2011, 01:41 PM
I couldn't find this particular problem in the forum search so I'll post it. The radiator burst so I put on a new one. While trying to flush the engine (with both radiator hoses disconnected and a garden hose stuck in the lower hose), very little water came out the top hose and what did was more of a boil over gurgle than a smooth flow. I then replaced the water pump, timing belt, and thermostat. On a test drive, the engine now hits the red line temperature after driving three blocks. The upper hose gets too hot to touch but the bottom hose remains cool (room temperature cool) as if no coolant flow is occuring at all.
It just occurred to me to do a compression test to make sure the head gasket is okay but even with a damaged head gasket I would assume I'd get some flow. I'll check the compression and then update this post.
Engine: 4 cylinder, federal
The engine is starting and running fine so I haven't done the compression test yet. I have let the car sit and idle while the engine heats up and everything works fine: the bottom hose get hot from flow, the heater puts out hot air, the radiator fans come on, and the dash needle falls slightly when the fans kick in.
Then the next day I drive it around the neighborhood and it goes to red line. I pull over, turn off the engine, and feel the lower hose. It's cool and the radiator is cool except for the very top. Also strange that the heater blows out cool air. As I said above, I've changed the water pump and thermostat.
10-20-2011, 12:11 PM
No flow after a new thermostat usually means a busted water pump. But first check to see if you have an air bubble in the system and make sure the little jiggle valve in the thermostat is located at the top of the thermostat housing.
Park the car on a hill nose up and then let it cool. Also open the heater temp control to full hot. Then remove the cap, squeeze the upper radiator hose, and see if bubbles come out. Squeeze until no more bubbles appear, then refill with coolant. Start the car and recheck...if it starts to get hot again (gauge goes over 1/2 way), shut it off. Then suspect the pump.
Hope this helps!
10-22-2011, 04:00 PM
While test idling it this morning, the exhaust was very white. I did a compression test and the values were:
They are all a little high but the car has 240K miles. There was definately antifreeze in at least one chamber. Does this mean the head gasket is damaged? If so, I would have assumed that one chamber would have been low.
10-23-2011, 04:30 PM
If you have antifreeze in a cylinder, you have a bad head gasket, cracked head, or a cracked block, compression or no compression. As far as the overheating problem, check the thermostat in hot water and make sure it opens smoothly at 180 degrees as it should without sticking. Make sure you installed it correctly. That is the only point in the system that could impede flow like you describe.
Was your engine overheating before the radiator died?
10-23-2011, 06:00 PM
Hard to say if the engine was overheating before. It's my son's car. He didn't notice the engine going to redline in the first place so I doubt he noticed the temperature needle at other times.
I did check the new thermostat in hot water and it did open at 180F repeatedly.
The thermostat only fits in one direction. It doesn't have the jiggle valve but that is what AutoZone shows for this car.
Are there seperate tests to determine whether the head or the block is cracked.
10-24-2011, 07:54 AM
You're right - A cracked head is another possibility. Sorry, I don't know of a way of checking the block while it's still installed in the car. I think block leaks are usually in the cylinders. If you can eliminate the head gasket and cracked head, then I think the only other possibility is the block. If you have good compression, the most likely explanation is the crack is in the cylinder and far enough down in the bore to not substantially affect the compression.
The only way I know of testing the head gasket specifically is replacing it (you can possibly spot the leak in the gasket when it's been removed), and then checking the head for cracks while the head is off the car (dye penetrant test since you have an aluminum head).
You may be able to spot the leak in the head gasket once the heads been removed, but it's uncertain since you have good compression and that implies only a small leak.
You can try running some stop leak through your cooling system and hope that that seals the leak, but I haven't heard many people having much luck with that.
Did the old thermostat have a jiggle valve?
10-25-2011, 08:04 AM
Yes. The old thermostat had a jiggle valve.
Is the dye penetrant easy and foolproof enough to be done at home or is that for a shop? Can it be done without disassembling the head?
10-25-2011, 09:19 AM
First thing I'd do is replace the thermostat with one with a jiggle valve, then see how the engine behaves. It is there to allow the air in the system to escape and permit filling of the system without trapping air. This may not be the solution to your major problem, but it is the only one you can do cheaply. No matter what the problem is with your engine, you will have to replace the thermostat to maintain good coolant circulation. It might be time- and cost-efficient to price a used and assembled head at a salvage yard and just replace the head. Those engines are really common. It's a gamble. First, see what effect the thermostat with the jiggle valve has on the engine.
If replacing the thermostat doesn't solve your problem, replace the head gasket and while the head is off, inspect the head combustion chamber area and gasket visually to see if you can spot the problem.
You can do a dye penetrant inspection on the head yourself, but the head has to be clean and off the engine. Deposits in the combustion chamber and oil in general will hide cracks. You have to disassemble the head to get to the valve seat area and clean the head thoroughly. If you don't clean the head as a whole, then you are betting you can clean where the crack is. If you don't find one, you will be second-guessing your decision. If you find one, then you are golden. The most likely places to look for cracks are in the hottest area of the head, those being the combustion chamber and the exhaust valve area. However, the crack could possibly be the result of an impurity in the head metal and be almost anywhere....
11-07-2011, 08:01 AM
Progress report: I removed the head and there was standing anti-freeze in the cylinders. Cleaned and checked for cracks and all looked okay. I replaced the head gasket and installed the head. The instructions for reinstalling the camshafts say to "apply grease to the thrust portion of the camshaft". What/where is that? "Thrust portion" is singular so is there only one "thrust portion"?
Do they mean the head journals and the portions of the camshaft that sit in them?
11-07-2011, 08:41 AM
The thrust portion of the cam is any bearing surface facing to the front or rear, on the side. This is not the normal bearing surface that are circular around the outside of the cam. The normal bearing surfaces, both inserts and cam, should be coated with clean engine oil.
Don't forget to change the oil and filter to get rid of any antifreeze in the oil. If you didn't, check the head for warpage with a precision straight edge.
11-15-2011, 08:31 PM
Progress Report: I got it all back together and it runs great. I have an exhaust question but I'll start a new thread for it. Thanks for your help.
11-15-2011, 11:34 PM
02-04-2012, 07:19 PM
I have the same problem and also replaced the pump, belt and thermostat. How does a bad head prevent water flow?
02-06-2012, 02:04 AM
A bad head doesn't prevent water flow. The only restriction in the water jacket is the thermostat.
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