Overheating - Head Gasket?

[danw77]

OK guys, new to the forum. 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?

[Kep]

I agree with your skepticism.

Could be bad thermostat, bad fan, bad hose, bad water pump. If you're just seeing a high temp gauge it could be a bad sensor or gauge. Put a regular temp gauge on the engine and determine if it really is overheating.

Kep

[ghettosled]

you are thinking correctly. his mechanic is wrong. i would start off by checking if you can get heat through the vents. if not, then there is either a blockage or the thermostat is bad. personally, not to throw parts randomly at a car before knowing what the problem is, i would replace the thermostat and flush the system then check if it starts over heating.

im still wondering about his "mechanic" friend. ive always thought overheating cars can cause head gaskets to fail, but never failed head gaskets will cause the cars to overheat! especially with no signs of fluids mixing, steam, or bubbles in the coolent.

[Dave's]

First let me state I am not a professional mechanic (not for vehicles anyway) so if I'm incorrect then sorry. However, I'm pretty sure a bad head gasket is indicated by one of about four things. Oil in the coolant (with engine cold, remove rad cap and check, oil floats so you should see an oily film if there's a problem), coolant in the oil (remove dipstick and check for milky droplets clinging to it), coolant into a cylinder (white smoke out the exhaust which doesn't go away after engine warms up) (guess there could be bluish smoke from oil but that could be rings or other things), or loss of compression (checked by a compression tester). This too could be other things including a bad ring(s). I think OBDII wasn't required until '96 and I doubt OBDI or even II would actually tell you there's a blown head gasket.

[danw77]

thanks for your input on this guys. when i looked at the car, i didn't have the key so i didn't get to run it. in speaking with my friend further, he indicated that most of the cooling system had been replaced within the last couple years (t-stat, radiator, hoses). he hasn't had the water pump done though.

from what he said, it starts overheating about 10-15 minutes into a drive, sometimes longer. i forgot to ask him if he noticed any coolant loss, but when i looked at the car, the overflow was at the full mark. and he had never thought to check the heating vents.

as i said, i will look at it further this weekend and post my findings.

[danw77]

Here's where I am with this.... I noticed that the cooling fans weren't coming on at all, so I replaced the fan sensor switch in the radiator. Still overheating and no fans. Checking around, I noticed that the bottom of the radiator was cool, and also the lower radiator hose. I replaced the t-stat hoping that was the problem, and no go. Still overheating, lower hose still cold, and no fans. I'm thinking water pump, but I don't want to throw any more parts at this. I checked the heater vents for hot air, and when I drove it about a week ago there was hot air, but today it is cold (no heat). Am I on the right track with the water pump? I was going to try to flush the system, but not really sure the best way to do it. I was thinking of pulling all the rad hoses and t-stat, and shooting water down them. not sure if a flush kit will work since i can't really run this for very long.

[danw77]

I pulled off all the hoses and the t-stat and ran water through everything until it was clear. i think i've narrowed it down to either the water pump or head gasket. any way to tell before i do the water pump? and how long should expect the water pump to take? i'm guessing at least a day, maybe two.

[ghettosled]

i doubt its the head gasket. i dont know if this is possible, but if you disconnect a radiator hose and start the car, coolent should rush out when the engine runs, but not if the water pump isnt working. this is just a guess, i could very well be wrong.

the water pump is less than a day job. its basically a timing belt job.

[danw77]

there is no movement in the coolant at all. so yeah, it looks like i'm doing the water pump. any tips to make it easier? i have the factory service manual, but it seems like there's an aweful lot to pull off. is all that really necessary? sorry, but i'm used to working on domestic trucks, where a water pump is a 30 min job.

[ghettosled]

nope, water pump is buried and runs off the timing belt. get a new belt while you are at it.

i miss my old '79 suburban when it comes to things like this. i was able to replace water pumps in about a half hour as well, and thats with stopping to drink a beer half way through.

[danw77]

I started a new thread on this (http://www.toyotanation.com/forum/sh...53#post2358353) since my problems seems to have changed a bit.