Cooling Issues on 1989 FJ62 (1 Viewer)

[fabiodaddy]

I have an interesting problem that just started on my rig.
1989 FJ62 190K+, stock engine upgraded H55 trans.
I noticed the coolant level down a bit and some coolant dripping down the front of the engine a while back. Decided it was time to tackle the dreaded water pump on Rusty. Ordered up the Aisin WP, clutch and fan blade from Kurt, as the fan blade had taken a hit from when the alternator bolt backed out and damaged it.

Anyway, after several evenings of work and a lot of swearing I got the WP, clutch and fan replaced. Testing after revealed no leaks and things seemed good. Drove it to work a couple (short 10 mile commute) times and found no issues.

Loaded the rig up for the Memorial Day camping trip and made it about 20 miles and the thing started to heat up. I figured I must have not gotten all the air out when I refilled the coolant so I pulled over and proceeded to burp the thing again. Idling, the thing never goes passed normal temp on the gauge. It is only when you put a load on it that it starts to heat up. I repeated the burping process 3 different times and I still could not remedy the cooling issue. Turned the thing around and went home and used my Tundra instead. Rusty brought shame to the family on that trip.

Anyway, I took another look at it last night and decided to try burping the air out again since I didn't have a funnel to assist me while out on the road. I was able to get some additional air out this time and thought I had fixed it. I took another run and it still wants to overheat. Not sure what is going on.

So here are the things that I know.
1. Never had cooling issues before changing out the WP. Only changed it because it was leaking.
2. WP, fan and clutch all Aisin and brand new so they should not have any issues.
3. Thermostat was changed a few years ago and it seems unlikely that it would 'just go bad' during the WP service. But it's possible.

Possible causes and next steps.
1. I am thinking to remove the thermostat and see if that makes a difference. If so, I'll change that out again.
2. Is it possible that I got some debris in the system from changing out the WP? I can do a flush on the system, although it looks clean without any rust in it.
3. Not sure what else to try. Any suggestions?

 

[Kmonty66]

sub'd having same stage issue. When I replaced my tranny to the 5spd, i had no heating issue as a matter of fact it ran cooler, for sure going up hills. Lately it had been starting to heat up again going up hills. I did a visual check didn't see any problems, then the other morning I smelt coolest and figured for sure that it was my heater core, nope turns out the rad was leaking form the inside bottom tank, not enough to visually though the previous week. I had the rad replaced last week, but Im still having the same problems/almost as you...

 

[rrv333]

Try researching a thread by Output Shaft. He had a very informative thread about some cooling issues with his LC. I believe his is a 60, don't know if that makes a difference, I wouldn't think so.

 

[SteveH]

Brand new or not, is your fan clutch working as it should? Do you hear the school bus 'roar' sound at times?

 

[Kmonty66]

Brand new or not, is your fan clutch working as it should? Do you hear the school bus 'roar' sound at times?

I'm guessing since the way you described the sound...No although my engine compartment fan works, Ive heard it on before. I'll do a search on the fan clutch.

Thank you.

 

[fabiodaddy]

Good point @SteveH. I'll have to verify that it's working. It is spinning at idle, not sure what its doing while driving.
I burped it one more time last night with the front end up, both heater valves open and topped off funnel in the radiator. Still got some air out.

Idled at normal temps for 30 minutes. I used a IR thermo and checked top of radiator once up to temp and it was at 195*-200* range. Decided to go for a drive and took thermo with me. Once it started to heat up I pulled into parking lot and took another reading. Top of radiator was 225*, so gauge seems to be working as it was about the top white mark...not quite to the red. I then turned on both heaters/fans and headed home. With both heaters on I was able to make the run home with the temp hovering around second white mark and nearly normal once I made it back home (mostly down hill).

So with just a little more heat removal (both heaters on) the temp stays close to normal. Kind of sounds like my Rad is not quite doing it's job. Wonder if it is plugged up? I have not had any cooling issues in the past, since getting radiator repaired right after purchase of the rig 6 years ago.
I suppose I could have knocked some crud loose when I replaced WP. Sound like a good flush might be the next step.

Any thoughts???

 

[SteveH]

225 on the radiator top seems very hot, but I would aim your IR temp gun at the head, as well - it will likely read even hotter. Also check the lower radiator hose to see how hot it is, to see if your radiator is rejecting heat.

I agree that it sounds like your radiator isn't up to the task. When my FJ40 radiator was clogged, the truck would run cool under most circumstances, but would overheat at 60 mph. When driving at 60, you can be sure the fan clutch isn't an issue, so that was what clued me in to the radiator being clogged (and it was). Most modern 'flush' products are worthless, and won't get much out of the radiator (in my experience). The acid-based ones are long gone. You may find it easier/cheaper to replace the radiator.

 

[Michael Hanson]

Hi, My bet is the thermostat and its o ring. Burp with front of cruiser going up hill ,turn rear heaters on to fill lines. Also old hoses will collapse from the INSIDE. Mike

 

[houstonfj40]

Sounds like rad. Runs normal with no load, then heats up on hwy or load. Restrictions in Rad my thought.

 

[LAMBCRUSHER]

I had the at-speed-under-load runaway temp thing. Put in a new napa AISIN clutch which did NOTHING. I put in a used fj80 aqua hub clutch with a new 50% mix of 7 and 15 csk fluid and retimed it to start opening at about 100 and full open at 140....my rig runs hotter when its cooler now (tops out just under halfway mark)- when it gets warm enough to start the clutch, the temp DROPS (to just above lower mark) and stays low til the clutch stops...Central California and I run my 3FE at 69 mph at 3450 rpm in 4th gear (h42) down the freeway with r12 blowing cold in my face. I think I could get slightly better overall mileage if I set it a bit higher, but keeping the motor cool is kinda like an investment to me...If you can't hear your fan, chuck the clutch and get another one...after you make sure there is decent airflow past your condenser and radiator...


all that said, @houstonfj40 may be onto something...In my understanding of things, there are 3 things to cause excessive heat: runaway heat load (mechanical), lack of pressure (leaks or air pockets), or lack of flow (both coolant AND air). If your radiator hasn't been serviced in a while, and it has become restricted, there would be greater back pressure on things like, say, oh, maybe the water pump? which might have been the factor pushing it to loose its seal...as well, if the radiator weren't flowing, you could have cool spots that could affect an otherwise functional fan clutch from operation. They open based upon AIR TEMP over their coils...


if you have decent air flow thru your cores in front of the clutch, and the radiator flows well, you should hear the fan run when temps increase, if the clutch is doing its job....If you got a cheap napa AISIN clutch, then go rebuild your old OEM with thicker fluid...and get the radiator boiled and pressure tested...

 

[fabiodaddy]

I guess I'm a little confused about the fan clutch operation then. My fan turns all the time regardless of the temperature. The old one did as well, although you could stop it if you held it.
From some of the posts it sounds like it should only work at a certain temp? So what is the clutch's normal operation?
WP, clutch and fan are all Aisin brand and came from Kurt so I'm assuming it should be of good quality. Doesn't mean that it couldn't have a problem though.

My guess right now is that I have a partially plugged radiator.

 

[FJ60Seth]

If all you changed was the fan, fan clutch & water pump then I'd start with fan clutch. Get up to operating temp, roll up a newspaper like you'd use to swat a big fly with, and gently feed it into the fan blades. It should stop the fan but make you think "I'm glad that's not my fingers". You could also put your old fan clutch back on.

I've heard many times that the fan doesn't do much at highway speeds, but that wasn't my experience. My symptoms were the same as yours and the fan clutch was the culprit.

 

[mattressking]

Fan clutch functionality is normally prevalent at cold startup, listen for the roar for the first few minutes at most, then you should hear it wind down and idle change due to load no longer being present. The newspaper check is a good one, give that a shot and let us know but since you replaced all with new Aisin units, I can confidently say it isn't your problem.

Fan clutch issues appear after load is on truck and when slowing down and at a stop, the temps rise. Once moving again, the temps drop back down. If this occurs, fan clutch is almost always the culprit.

Heating up on highway is most likely blockage in rad. Fan isn't relevant at highway speeds, airflow through the radiator core is what is doing a majority of the cooling.

Another quick test is to run the truck then when it gets hot, turn the heat on full blast, front and rear. If it gets nice and warm inside your thermostat is functioning and seal is present.

 

[fabiodaddy]

Heaters work well. In fact if I run both heaters on high the temps are almost normal. Thermo is new since I got the rig as I replaced it. It was missing the o ring on the top so no heat. After I replaced thermostat and oring....wala....heat.

 

[LAMBCRUSHER]

Fan will always spin, but only has power when clutch engages( which will chop your finger off). Both heaters on and maintaining temps? Sounds like blockage at this point. Which can prevent the clutch from engaging, complicating the issue...

 

[fabiodaddy]

Well, I have a bit of an update. It's not a good one either.
I didn't have time to do the cooling flush so I took it to a local radiator shop. Asked them to do a test/flush and that way they could repair the radiator if need be.
Their tests show a bad head gasket. They said it is just starting to leak and it is putting a lot of pressure into the cooling system. If that is the case that would explain some of the coolant leak and water pump issues and the intermittent over heating. That had crossed my mind, but I didn't see any sign of coolant in the oil (no milky mess). But if it is not leaking much a visual wouldn't show that.
Does that sound like a reasonable diagnosis?
Well, I guess I'll have to change out a head gasket. Fun times!!!

 

[Kmonty66]

They tested for carbon/emissions in the radiator/oil?

 

[fabiodaddy]

That's what they said.
I told them that I used the same pan to drain oil and coolant (I clean it out well before using, but never get it all). Could your test have detected some residual oil from that? He said 'NO' that they detect the gas from the opening of the radiator.

Bummer.

 

[Kmonty66]

Indeed.

 

[LAMBCRUSHER]

sounds like a possibility...lack of pressure/leak...get the rad boiled and tested outside of the rig while you're doing the head gasket.