Overheating, what would cause this???

[Sloan]

I drove my FJ60 down to Orange Co. today and then headed up to Burbank to pick up my daughter. It was in the 80s and I drove roughly 40 miles in some 65 mph and then some stop and go traffic. When I got into Burbank I stopped to get an iced tea and when I came out my radiator over flow had puked all over the ground. I wait 10 minutes or so and fire it up and then gauge needle screams toward the hot mark. I call AAA and when he gets there 25 minutes later I start it again to back it out of the parking space and the temp is acting normal. I had it towed home and when I started it a second ago it is acting normal. What would cause this? I did have the AC on low for the whole drive. Thanks for any thoughts.

 

[SAR_Squid79]

There are many things that *COULD* cause this. It could be something as simple as an air bubble in your radiator, a bad fan clutch, or you could have a cracked head, or blown head gasket.

You need to do some more troubleshooting. It could have been a complete fluke... My FJ62 did this once, almost 2 years ago, and has never done it again.

 

[roamingaz]

I had that happen to my Ford, it would only overheat if I drove it more then 20 miles or so, just around town it worked normal. Turned out to be a bad freeze plug.
Try doing a pressure test to determine if it's a head issue.

 

[obscurotron]

Start simple. First, pressure test the system. Then check the fan clutch. Next, flush the radiator - see if you get good flow OUT of it (i.e. coming out the bottom opening as fast as the water is going in. If all that checks OK, pull the t-stat and test it in some boiling water, but do several hot-cool-hot-cool cycles to make sure it opens and closes properly multiple times. If THAT checks OK, do a leakdown test and/or get a test kit to look for hydrocarbons in the coolant and check the oil for the presence of coolant.

 

[Schattenjager]

Start simple. First, pressure test the system. Then check the fan clutch. Next, flush the radiator - see if you get good flow OUT of it (i.e. coming out the bottom opening as fast as the water is going in. If all that checks OK, pull the t-stat and test it in some boiling water, but do several hot-cool-hot-cool cycles to make sure it opens and closes properly multiple times. If THAT checks OK, do a leakdown test and/or get a test kit to look for hydrocarbons in the coolant and check the oil for the presence of coolant.

This seems like very sound advice to me. If you're going to pull the t-stat - just replace it while you are in there. You can also test the quality of your coolant with an inexpensive float type gauge - even if it looks OK, it may have lost some of it's ability to wick and dissipate heat.

Here's hoping your solution is an easy - and cheap - one!
:elkgrin:

 

[SAR_Squid79]

According to the Factory Service Manual (FSM) this is the order that you should troubleshoot (FJ62):

Engine Overheating:

• Fan belt loose or missing - Adjust or replace belt
• Debris on radiator or condenser - clean / repair as necessary
• Hoses, water pump, thermostat housing, radiator, heater, core plugs, or head gasket leakage - Inspect and repair as necessary
• Thermostat Faulty - Check thermostat
• Ignition timing retarded - Set correct timing
• Fluid coupling faulty - Replace fluid coupling
• Radiator hose clogged or rotted - Inspect and replace hoses
• Water pump faulty - replace water pump
• Radiator clogged or cap faulty - Check radiator repair as necessary
• Cylinder head or block cracked or clogged - Repair as neccessary

 

[Sloan]

According to the Factory Service Manual (FSM) this is the order that you should troubleshoot (FJ62):

Engine Overheating:

• Fan belt loose or missing - Adjust or replace belt
• Debris on radiator or condenser - clean / repair as necessary
• Hoses, water pump, thermostat housing, radiator, heater, core plugs, or head gasket leakage - Inspect and repair as necessary
• Thermostat Faulty - Check thermostat
• Ignition timing retarded - Set correct timing
• Fluid coupling faulty - Replace fluid coupling
• Radiator hose clogged or rotted - Inspect and replace hoses
• Water pump faulty - replace water pump
• Radiator clogged or cap faulty - Check radiator repair as necessary
• Cylinder head or block cracked or clogged - Repair as neccessary

I ran it up the street to the radiator shop this morning and it was a faulty radiator cap. The rubber gasket had deformed in such a way that was allowing it to block the circulation of the coolant. New cap, problem solved. Thanks for all the input, what did we do before the internet? :victory:

 

[SAR_Squid79]

LOL - and according to the FSM, the Radiator Cap is the next-to-last thing you should check... YOU CHEATED!

...but I'm glad you got it sorted out, and I'm glad it was something easy and simple (and cheap)!

 

[KANZ]

Most of the time, things are very simple. In fact so simple that we tend to overlook them. I have a 84 FJ60 and experienced the same problem. I was under the impression that my radiator was always full, because my reservoir was at the right level. I was wrong. The small reservoir hose had developed a very small leak over time and prevented the radiator from recharging with coolant from the reservoir.
Glad that you have solved it.

Harald
www.kanzoutdoors.com

 

[subytoy]

My Subaru Impreza did the same thing when it was new. I replaced the cap with a new Suby one, same problem. I then bought a Stant cap and it's been fine for four years.