Over Heating? (2 Viewers)

[koszowskima]

Hey all,

Two days ago I did about a 40 min drive (30 min highway) in my 87 FJ60. The outside temp was like 35 F. The highway drive was at like 50-60 MPH. About five minutes from my exit on the highway I saw the Temp gauge was barely below (I mean barely) the RED H. The car seemed to be driving fine, and maybe a slight smell but hard to be sure. I completed the drive with about 10 min of normal city driving and the Temp gauge settled at like halfway up the gauge. It never has an issue with 40 min drive nonhighway.

I am trying to figure out the best way to test out my cooling system without actually overheating the truck. First, was it probably fine and the gauge was off? Can I test the cooling system piece by piece? Not familiar at all with the cooling system

The truck has never overheated but that was one of the longer/fastest drives I have done in a while.

Thoughts?

 

[Gimme a 60]

I don’t have much experience working on cars, and I have only had a cruiser for 4 months. (So don’t rely on my word) But check your Thermostat, it may be old and possibly worn and opening and closing when it shouldn’t? My 62 did the exact same thing you are describing on the highway. So I just bought a thermostat anyways because they are cheap.

Good luck!

 

[sodafeld1]

how clean and fresh is your fluid? ph coolant tester strip? thermostat? leave internal heater on if a problem, for extra fluid circulation.

if that is all good , it maybe the earth which it shares with fuel gauge which also rises in unison with temp. If temp rose with fuel then it is the dirty earth, old cars... This happened to me recently, so I am putting in an aftermarket temp gauge, either from hose above thermostat or from the head. The original tojo gauges are not the best.

 

[kevin in okinawa]

replace thermostat and observe

 

[OSS]

My bet it’s an electrical malfunction in the temperature gauge. It’s very common.

There’s nothing mechanical that would cause the coolant to suddenly get super hot while cruising on the freeway in 30 degree weather.
Thermostats don’t suddenly shut when up to temperature.
Water pumps don’t suddenly stop spinning then spin fine a little later.
Radiators don’t suddenly stop working.
And coolant will continue flowing if it hasn’t leaked out.

If the coolant really did get super hot, the fan clutch would engage at speed and roar, and if you put your hand in front of the air vent in the cab with the heater on, you wouldn’t be able to - you’d burn yourself (trick to remember on the future).

If no coolant leaked out - my guess is an electrical malfunction to the temp gauge.
Mine used to do it occasionally too. Kinda unnerving.

 

[CruiserTrash]

Next time it happens see if your fuel gauge spikes at the same time as the temp gauge. That's a known electrical issue and at least one person on Mud is working on a solution. Just one thing to keep in mind with the FJ60 cooling system - obviously there are many other factors.

 

[TheElegantFox]

One note if and when you do replace the coolant, not properly burping the coolant system can lead to the truck overheating in a kinda mystery sense. I had that happen to my 62 after a coolant flush.

 

[DFXR]

If you’re in the testing mood, get a coolant analyzer kit from your local auto parts store or online. You’ll just be testing your coolant for the presence of engine oil. Kits are cheap.

Hopefully it comes down to one of the quirks listed in the posts above. But - and sorry to be Barry Bummer here - a blown HG can take many forms and isn’t always a super obvious disaster of white fog. I had a spike like yours, in a very similar driving situation. Back to normal for a few days and then suddenly, a rough idle started while sitting at a stoplight near home. Pulled plug wires to isolate it, followed up with a compression check, and had the common leak between cyl 3 and 4. The good news was that I never had a catastrophic failure, and the head itself was ok as well as the bottom end. The bad news was that I still needed to replace the HG.

I am thinking that by mentioning this here, I am exorcising any HG demons for you.

 

[ChaserFJ60]

I agree with @OSS. I had very strange temp fluxuations where my temp would spike at the max H then go to the bottom level ice cold in less than 2 seconds, which unless you drop your truck in liquid nitrogen is entirely impossible. I would verify the temp with an outside thermometer

 

[2mbb]

I agree with the electrical-related diagnosis. I used to have a VW Rabbit that had this same problem. Looking at the FSM you test both gauges by disconnecting them from their respective senders and measuring the voltage sent from the gauge to the sender. In both cases the correct voltage is 3.5V. This indicates (to me) there is a voltage regulator integrated into the combination meter circuit board.

 

[koszowskima]

Thanks all,

I did recently fill up the truck with a full tank, however, the temperature gauge did go up gradually, and then went back down slowly and stayed at halfway once off the highway. I drove it again today for about 20 min on the highway and the temp gauge sat at about 1/3 of the way up. Today was warmer out and I actually hit a higher speed (60-65 MPH I was flying haha). So not sure if the gauge was acting up yesterday or what.

Lastly, I did have the heat on yesterday and the air was warm but not scalding.

The only part that concerns me is the gauge usually seems to work well. Starts below C and usually crawls up as the drive goes on. I have never had huge quick fluctuations.

When i first got the truck (like a year ago) the coolant hose had a small hole in it so it was just peeing antifreeze into the fan and spraying it everywhere. I switched that out and I think I filled it up with enough coolant but I will double check.

I will check coolant, try to test the thermostat, and do one more "hot drive", and report back

Lastly, any advice for burping the coolant system?

 

[sodafeld1]

strangely enough, i have had no burping trouble even after replacing radiator. Once I have reinstalled radiator, or even internal heater radiator (gotta remove the whole dash for that) and refilled with fresh coolant, start her up, take the rad cap off and top up whilst running.
maybe because my driveway is not flat, front sits elevated when parked.

 

[CruiserTrash]

@koszowskima When my gauges do the electrical problem thing, it's not like they suddenly and immediately jump. You can see the needle moving, but it's more of a sweep and then they hold real high. Sometimes it's for 30 seconds, sometimes it's 30 minutes. It can go a couple months without happening or happen multiple times in a day. It seems to happen on the highway more often. That's the temp and fuel gauges for me.

Also, I noticed your in Denver too. What part of town are you in and which 60 do you drive?

 

[Michael Hanson]

Check all hoses for leaks

 

[pithicus]

Mine does this weird thing too. Out of nowhere the gauge quickly creeps up to near the red mark , then quickly drops to under half. It's quite fast, about a minute from where the gauge starts moving up to back again. I paniced the first time. Now It doesn't bother me. Happens in cold weather too. I put it down to a thermostat sticking issue.

 

[koszowskima]

@koszowskima When my gauges do the electrical problem thing, it's not like they suddenly and immediately jump. You can see the needle moving, but it's more of a sweep and then they hold real high. Sometimes it's for 30 seconds, sometimes it's 30 minutes. It can go a couple months without happening or happen multiple times in a day. It seems to happen on the highway more often. That's the temp and fuel gauges for me.

Also, I noticed your in Denver too. What part of town are you in and which 60 do you drive?

My gauge is not presenting like that, but good to watch out for.

I am in the Cap Hill area. I have an fj60 87... I am new to the world of working on cars but have repaired a lot and learned a lot.

 

[batthewmrown]

Thanks all,

I did recently fill up the truck with a full tank, however, the temperature gauge did go up gradually, and then went back down slowly and stayed at halfway once off the highway. I drove it again today for about 20 min on the highway and the temp gauge sat at about 1/3 of the way up. Today was warmer out and I actually hit a higher speed (60-65 MPH I was flying haha). So not sure if the gauge was acting up yesterday or what.

Lastly, I did have the heat on yesterday and the air was warm but not scalding.

The only part that concerns me is the gauge usually seems to work well. Starts below C and usually crawls up as the drive goes on. I have never had huge quick fluctuations.

When i first got the truck (like a year ago) the coolant hose had a small hole in it so it was just peeing antifreeze into the fan and spraying it everywhere. I switched that out and I think I filled it up with enough coolant but I will double check.

I will check coolant, try to test the thermostat, and do one more "hot drive", and report back

Lastly, any advice for burping the coolant system?

Burping is easy. Park on an incline, run the truck up to temp, squeeze the top hose to get any air that's trapped out. Some people say it isn't necessary, some swear by it. Can't hurt.

I know parking in Cap Hill is a nightmare. I'm down in Wash Park with off-street flat space, manuals, tools, and a decent bit of experience if you need.

 

[4runner2FJ60]

In the FAQ section there is a sticky about the temperature sending unit and all of its quirks. I had issues with mine when I first got the cruiser and by process of elimination finally got it straight. I replaced the sender, as much of the wire from the sender to the firewall as i could get, removed the cluster and cleaned the contacts on the back, swapped a cluster with a very nice Mud member that mailed me his extra, tested the fuel sender......nothing would do it. Then one day I replaced all my fluid, water pump, fan clutch and thermostat, radiator, and boom! It has worked perfectly ever since. It is not the most exacting gauge in the world and you will notice it is tightly tied to the fuel gauge. If I stop somewhere and jump back in within a reasonable time, when I start her up, the temp is higher and fuel is lower, as she runs for the first ten seconds both gauges move slowly the opposite direction. Cooler then more fuel. My normal temp reading is just below half way up.

 

[koszowskima]

Burping is easy. Park on an incline, run the truck up to temp, squeeze the top hose to get any air that's trapped out. Some people say it isn't necessary, some swear by it. Can't hurt.

I know parking in Cap Hill is a nightmare. I'm down in Wash Park with off-street flat space, manuals, tools, and a decent bit of experience if you need.

Parking is really tough. Thanks Ill be sure to reach out