Help me diagnose this please: High temp gauge, low/no heat inside (1 Viewer)

[Pappa Bear]

I've got a 1985 FJ60. It's my teenage daughter's daily driver (yes, I spoil her). I drive it a couple of times a week, because I love it, and also because I want to keep an eye on it (I'm trying to teach her how to 'listen' to cars, keep an eye on gauges, etc. but still like to know our family cars myself, just in case my wife and kids miss things - and they do).

Anyhoo, during an easy drive a couple days ago, I noticed that the temp gauge was climbing, and so I pulled over to check things like the coolant level (fine), oil level (fine), etc.

So I drove home slowly, and kept an on the temperature gauge, which never pegged, but it got close.

I tried the old trick of blasting the heater at high to pull some heat off the motor, but it wouldn't blow hot air, and so it did nothing for the engine temp.

Thoughts? And thanks in advance.

 

[morgan85]

It sounds like you have a thermostat that is stuck closed.

 

[Gumby]

Low coolant or air in the system can cause this. You also have a heater valve, IIRC, in the heater hose. If its not opening that's your no cabin heat problem. If that's it you have different problem with the overheat.

Is the upper rad hose getting hot? Are both heater hoses getting hot?

 

[Gumby]

It sounds like you have a thermostat that is stuck closed.

I think that would cause more than just getting close to overheating and he should still have cabin heat.

 

[Pappa Bear]

That's what I was thinking, based on previous experience

It sounds like you have a thermostat that is stuck closed.

with other vehicles, but I'm not very handy, and so hearing from others is helpful, so thank you.

 

[Pappa Bear]

Coolant level is fine, but there might be air in the system.

Low coolant or air in the system can cause this. You also have a heater valve, IIRC, in the heater hose. If its not opening that's your no cabin heat problem. If that's it you have different problem with the overheat.

Is the upper rad hose getting hot? Are both heater hoses getting hot?

I'll check those hoses later when the motor's hot.

Thanks for the input.

 

[Elbert]

don't know why all of a sudden you would have air in the system...any work done recently?

did you check the heater control valve on the firewall...for operation.. are the heater hoses hot on both sides of the heater core when engine is hot?

I don't trust the factory temp gauge ... the thermostat is a logical place to look, espcially the magic rubber gasket that sits on top of the thermostat that everyone seems to forget about.

hot temps and no heater don't add up...is coolant full?

 

[Gumby]

don't know why all of a sudden you would have air in the system.?

Very bad words. We won't say them out loud until we get more info, but 80 guys are terrified of it. Rhymes with dead basket.

 

[Pappa Bear]

Very bad words. We won't say them out loud until we get more info, but 80 guys are terrified of it. Rhymes with dead basket.

LOL bite your tongue!

 

[Elbert]

Very bad words. We won't say them out loud until we get more info, but 80 guys are terrified of it. Rhymes with dead basket.

Yes...but assume there would be other symptoms in play too if so. I agree that could be the bottom line issue, hopefully not.

 

[FJ40Jim]

Yes...but assume there would be other symptoms in play too if so. I agree that could be the bottom line issue, hopefully not.

No, no other symptoms required. These engines are not mandatory "coolant in oil" symptoms in the event of dead basket or fracked bed. It can just draw down coolant level & bleed air into cooling system. Which leads to no cabin heat and high temp gage reading.

Try filling the cooling system and burping it thoroughly, then drive again. If gage still reads high, then it's time to verify the gage reading w/ a temporary mechanical gage installation.

 

[EOE_overland]

Very bad words. We won't say them out loud until we get more info, but 80 guys are terrified of it. Rhymes with dead basket.

Wow did that make me laugh!

No need to jump off the cliff yet ? Still need to hear about hose temps, heater valve, etc. Probably thermostat or gauge sender for the first line of diagnosiseses?

 

[Randy88FJ62]

Let's start with your cabin heater. The heater core is infamous for getting clogged / corroded. This leads to no hot air in the cabin and should be unrelated to the overheating issue. A quick search and you'll find that people flush the core via the inlet and exit hoses as a first attempt then actually take apart their dash to ge to the core if needed.

Next is your gauge; the temp gauge on these rigs are no more than dummy lights. They tell you when the truck overheats and that's it. A lot of people on this site recommend installing your own mechanical temp gauge.

Your Overheating Issue:

How old is the radiator? If it's got corrosion and other gunk in it then it's capacity may be poor.

Look for leaks in the engine bay and under the truck where the coolant lines reach the rear heater. A leak could cause your system not to hold pressure and would result in hotter temps.

Fan Clutch: Do you hear your machanical fan come on ever? Try getting the engine hot over a normal long drive and turn off the truck. When you turn it back on you should hear the fan engage immediately as it knows it's hot.

Depending on your free time and how long you plan on owning the truck a new water pump, radiator, thermostat, and new belts can be done over a weekend and give you peace of mind.

Be careful of air in your system as FZJ80 guys will ask you to burp the car as they treat theirs like little babies.

 

[FJ60Seth]

I think "no cabin heat" and "gauge high" are unrelated. Focus first on possible overheating. Overheating is caused by either a cooling defect or a leak.

Is the fan belt that turns the water pump tight?

Confirm the coolant temp is high. The easiest way is with an IR thermometer. Aim it at the thermostat housing as the motor warms up. When the temp levels off, the thermostat has opened. Note the temperature.

Aim it at various spots on the radiator. The temp should decrease from top to bottom. Note the temperatures.

Check the fan clutch. Get the engine hot and leave it running. Take a rolled up piece of news paper like you'd use to hit a house fly or annoying neighbor kid, and slowly feed it into the fan blades. The fan should shred a couple inches of paper and not stop easily. If you think to yourself "I'm glad that wasn't my finger" then your fan clutch is working.

Next check for leaks. If your budget permits, I'm a huge advocate of buying a coolant-system pressure tester.

Hopefully at this point you've found the problem. If not, there is somewhere else that could be leaking.

 

[TobyB]

"coolant-system pressure tester"

That's one of the quickest ways I've found to test for dead basket compression leak into the cooling system.

t

 

[lifes a beach]

I have had the same issue in my FJ62 recently - temp gauge runing high, flushed radiator and put in new coolant and new thermostat. Still have same issue. Find coolant low about every week with no signs of a leak. Sometimes gauge will spike to High and then go down to normal withing a minute or two. I did turn the heat on and it blew really hot until last night ... no hot air either. Could there be a connection with it running hot and heater coil? I some times heard a "gurgling" sound when i first started it and hit the gas...

 

[gregnash]

Gurgling sound, some also describe as mice scrambling on newpaper, behind the dash is usually an indicator or air in your system from what I have read, which means system needs to be burped. Think most of the guys here have answered the next necessary steps from easiest to hardest (most costly). I would start slowly ticking things off the list and see where it leads you.

 

[lifes a beach]

Thanks... I was reading all the forums and threads regarding "burping" and think I will try that first...