4runner running hot!!!!!!!!!!!!

[fatboyparris]

My 1996 4runner has started to run hot......yet not losing any fluid???
I've replaced the clutch fan, waterpump, thermostat as well as having the radiator cleaned out and the compression appears to be ok (per the mechanic) also, I took the car to the Toyota dealership for a recall to fix a condition that may cause the vehicle to run hot....the car had started to run before the recall and continues to do so after the fix. Any suggestions would be greatly appreciated, I feel my mechanic may be at a loss!!!!!!!!

[Brian R.]

The engine will overheat if the head gasket is installed incorrectly.

The hose leading to the water pump may collapse internally when there is suction on it and restict flow.

Did you check the coolant level in the radiator?

Anything blocking airflow through the radiator?

Thermostat working correctly? Check opening temperature and valve lift with hot water and thermometer. Should open 176 - 183 degrees F and open 8.5 mm (0.335 inches) at 203 degrees.

[fatboyparris]

Thanks for your help.......I'll check the items that you suggested.

What do you think the chances are that Toyota installed the cylinder head gaskets incorrectly during the recall??????????

[Brian R.]

Low, but possible. If your overheating started at that time, I would say likely.

[fatboyparris]

Bad news, it appears that I have a cracked head....will advise as to $ to fix.

A new problem arose as I was dropping the 4runner off at the shop...the power antenea wouldn't go down however, you could hear the motor running...I can get it to go down by giving it a slight twist and gentle push. Any advice???

[Brian R.]

Who says you have a cracked head and how do they know?

[Doug Rodrigues]

Brian R. asked a good question: What did the shop tell you that they diagnosed a cracked head? Do you have diluted oil that looks creamy, or strange looking stuff in the radiator? Are you losing radiator coolant? Is the fan even turning on at the proper temperature? Stick a cooking thermometer into the radiator as the engine warms-up. At what temperature does the fan kick-in? What temperature is the fan supposed to kick-in?....probably around 185 degrees, on the average. Is one of the spark plugs looking vastly different than all other plugs? Was the recall work actually done?

**Opps...I forgot: The 4-Runner doesn't have an electric fan! Getting my cars mixed-up. Sorry.

[Brian R.]

There's been a recent discussion on antennas. Search this forum.

[fatboyparris]

Let me qualifly my last statement saying that it is a cracked head..what I should have said is that the shop is speculating that it is a cracked head at this point. After we were able to finally get the car to run hot..the mechanic did a flouro carbon test which tested positive. The first time this was tried was at a normal running temperature which revealed a negative result. They (shop) seem to think that it may be a crack since it only yields a positive carbon test when it is running hot? What is your opinion of this hypothosis? Also, I couldn't find the antenna reference that you suggested I check, but I will continue to look. Again, thanks for your input!

[Brian R.]

http://www.automotiveforums.com/vbul...d.php?t=249735

[trx125]

Stretched head bolts, improper torque spec, bad head gasket(or upside down), or cracked head can cause the motor to run hot. iwould check and retorque head. i once had broken head bolt and the water would leak out over time out the side of head and evaporate on manifold before i could find leak. just some suggestions before breaking down the motor again.

[Brian R.]

trx125 - How do these faults cause the engine to run hot? A slow leak or a warped head from bad torqueing shouldn't cause a temperature problem. I don't understand...???

If these are just observations, that's cool, not everything is explainable, but if you know, teach me.

[trx125]

Stretched headbolts, improper torque specs, and warped head will not allow the mating surfaces between the head and the block to seal properly when the engine heats up the metals expand causing variations in the head that the headgasket can not compensate for allowing hot gases from the cylinder to enter the water ports and superheats the water beyond the cooling system's ability to tranfer heat away from the engine causing it to run hot(sometimes very quickly) or water escapes externally causing overheating(no coolant) or enter the oil system causing lost of lubrication which leads to overheating or worse(damaged or blown engine). I hope this helps. if i can answer any others i will try

[Brian R.]

Sounds like the lead from the cylinder into the water jacket is the main culprit.