Overheating - Please help!

[danw77]

OK guys, new to the forum, so if this isn't the right place to post this type of question, please help me out.

I am trying to help a friend diagnose an overheating problem in his 94 Camry (4 cyl w/ 250k). I know my way around engines pretty well (mostly Jeeps and GM), but I'm not so experienced with Toyotas.

It had started to overheat, so he took it to a mechanic who is a friend of a friend (his, not mine). The mechanic said he needed a new head gasket, at a cost of $1500. A couple of things don't sound right about this to me, beside the ridiculous cost.

First off, the mechanic said he hooked it up to his computer, and the codes indicated it was the head gasket. Secondly, the mechanic said it had been going for some time, and has now finally worn completely. As far as I know, there is no computer in the world that can diagnose a blown head gasket, esp on an OBDI, which I'm assuming this is(?). The only symptoms are overheating. I checked the oil for coolant/water and found none. There is no steam/smoke coming from the exhaust. I have not had a chance to look at the car thouroughly , but I intend to this weekend.

I'm thinking this might just be a water pump. I really don't have anything to base that on, but something in my gut just says that this isn't a head gasket. What should I be looking for specifically. Are there any simple tests that I can do to rule out a head gasket? If it's the water pump I assume that there would be no heat through the heater vents and/or the upper hose would not heat up. Anything else I should be looking for? Lastly, if it's not the head gasket or the water pump, what else do I look at? Thermostat? Rad cap?

[DressUpYourPet]

if the head gasket is blown there are always indications, the temp gauge quickly pegs out and stays there. also if you pull out the spark plugs some of them might have water or signs of water, or even rust on them.
Some other causes of overheating: clogged radiator, clogged fins in radiator. Defective or worn out radiator cap not holding pressure. Coolant leaks. Thermostat stuck shut.

To check for the blown head gasket, remove the radiator cap, idle the engine and watch it overheat but not for too long. Sniff the fumes coming out of the radiator hole, you may see alot of bubbles and smell exhaust fumes, if you do then his head gasket is blown alright.
If it turns out the gasket is in fact blown, if you swap out the cylinder head for a remanufactured one yourself you could shave that $1500 price in half or more.

[toyomoho]

Not up any codes for this engine (or ODBII) that point directly to a head gasket. Was the check engine light on when you took the car to the shop? If not curious as to where these codes come from?

Other then the computer what other methods did the shop use to diagnosis the problem. The engine typically does not blow head gaskets unless severely overheated or hot rodded.

When does the engine overheat: at idle, stop and go traffic, on the freeway? Does turning on the heater full blast have any effect on the overheating? Is coolant disappearing from the overflow tank (and no radiator or hose leaks, etc)? Overall how does the engine run, lots of power, idle OK, etc? Are the cooling fans kicking when the engine overheats. Do the fans turn on with the A/C compressor?

As DressUpYourPet states overheating on this engine can be caused by a number of problems. Water pump failure, T-stat, partially plugged radiator, radiator fan temp switch failure, etc.

You can do coolant test for exhaust gases, auto parts stores have kits for around $40 or have someone do it. There is also compression and cylinder leak down tests, coolant system pressure tests. Might pull the plugs (very easy to on this engine) and check for constant electrode color of gray/whitish. Typically water in the cylinder acts to steam clean them. Look around the head gasket for leaking water, oil, etc.