1985 FJ62 Overheats (1 Viewer)

[Johno]

I would like some help diagnosing the problem. My 1985 FJ62 with 3F motor has recently started to overheat.

Here is what I've done so far:
Thermostat - Checks out OK and for now I have left it out.
Fan Fluid Hub - This was suspect so for now it is replaced
with a fixed hub.
Radiator - Removed and reverse flushed - seems OK
Engine Block - Flushed through top radiator hose to bottom hose.
Water Pump - Disconnected top radiator hose and started engine
most water pumped out in a few seconds.
Head Gasket - No sign of water in oil or exiting exhaust. No
significant amount of bubbling at radiator cap.

Problem - Engine overheats to the point of boiling after about
15 kilometers (10 miles)

Any suggestions appreciated

 

[60wag]

Hmmm... you've hit all the usual suspects.

Does the heater put out significant heat before it overheats? This would confirm that coolant is actually circulating - that there isn't a blockage somewhere.

Is there a shrould around the fan on radiator?

Can you measure the temp of the rad with an infrared probe? This might show cold spots in the rad indicating insufficient flow.

 

[kevinmrowland]

Yeah, I like what he said, and do you really have a 1985 FJ62? With a 3F not a 3FE? Where are you located? Show us a pic of your truck, if it really is a 3F I would love to see a photo of the engine compartment.
Welcome.

 

[prairie wolf]

you said you left the thermostat out for now.

if driven without one temp would probably rise.

thermostats hold water in radiator to cool it.

then it gets released back into motor when cool enough.

Are there a ton of bugs on the front of the radiator?

Belts tight enough?

most people know more than i do but just my thoughts.

life is good.

 

[import silvia]

you said you left the thermostat out for now.

if driven without one temp would probably rise.

thermostats hold water in radiator to cool it.

then it gets released back into motor when cool enough.

Are there a ton of bugs on the front of the radiator?

Belts tight enough?

most people know more than i do but just my thoughts.

life is good.

That is a bad little myth that has long been proven false. The thermostat keeps the engine at the correct temp by only letting in enough of the cooled water to maintain the correct temp it does not hold out radiator water until it has cooled enough. If that were the case an overheating engine would never open its thermostat.

If you are overheating while under way then you either have an airflow issue or a system cooling capacity issue (clogged radiator). Start your truck from a cold system and feel the radiator to see if it heats up uniformly or if you can feel any cool spots.

 

[Johno]

1985 FJ62 with 3F motor overheating

Yes it is 1985 FJ62 with 3F motor.
In Australia 4WD's were given a bit of a delay in needing to comply
with some emmission controls. It doesn't have catalytic converter
or air pumps that you guys have to put up with.

Thanks import silvia. I did reverse flush the radiator and flushed the
engine block but I will have another go with a radiator flush product
and see if that shifts more gunk.

Thanks 60wag. Yes both the front and rear heaters are working. In
fact with both heaters on full it keeps the temperature down enough
to use so long as it isn't worked hard. The fan has a shroud. I've had
the FJ62 since 1986 and its stock standard. I don't have an
infrared probe but will follow up on making sure the radiator is clear.
Somebody told me adding a pint of vinegar running it till hot and
flushing it is as good as anything.

Thanks for your posts.

 

[bigbrowndog]

Yes it is 1985 FJ62 with 3F motor.
In Australia 4WD's were given a bit of a delay in needing to comply
with some emmission controls. It doesn't have catalytic converter
or air pumps that you guys have to put up with.

Thanks import silvia. I did reverse flush the radiator and flushed the
engine block but I will have another go with a radiator flush product
and see if that shifts more gunk.

Thanks 60wag. Yes both the front and rear heaters are working. In
fact with both heaters on full it keeps the temperature down enough
to use so long as it isn't worked hard. The fan has a shroud. I've had
the FJ62 since 1986 and its stock standard. I don't have an
infrared probe but will follow up on making sure the radiator is clear.
Somebody told me adding a pint of vinegar running it till hot and
flushing it is as good as anything.

Thanks for your posts.

Did you measure the coolant in to make sure you never put less in because of an airlock, common on the 2H. Might pay to look at the pump under pressure also some of the radiator core could be blocked.Always pays to stay with toyota genuine thermostats and radiator caps. Check your timing and fuel mix as the 3F will tend to overheat if run lean same for 3FE.
My 1990 80 series has a 3F also the 3F is in the FJ75.

 

[Johno]

Thanks bigbrowndog,
I run the motor and then add more water as I have had the air lock
problem before.
I now have a bottle of Wynnes radiator flush and will give that a go
tomorrow morning.
I do use genuine radiator cap (just fitted a new one) and thermostat
although for now have left that out to aid flushing and elliminate it
as a possible problem.
I keep thinking it must be a head gasket problem or even a cracked
head but I can't find any evidence that this is the case.

 

[Johno]

Thanks BigBrownDog for the PM.
I have now used the Wynes radiator flush but it didn't do much
and the problem remains.
There is no sign of any water leaks including the water pump.
I have now once again removed the radiator and this time the
water pump as well. No sign of any water pump problem.
I have flushed the radiator again this time leaving it sit for a couple
of hours filled with dilute Phosphoric Acid.
I will refit the water pump and radiator tomorrow but don't expect
things will be any different.
As I said before I can't find any evidence of a problem with the
head gasket or head but I am running out of ideas

 

[60wag]

Get the rad flow tested by a radiator shop while its out of the truck.

 

[Johno]

Thanks 60Wag for your post and BigBrownDog for your PM.

The engine runs fine with no noticeable reduction in power.

It seems that my problem is the radiator. I don't have a good
radiator repair shop near me but I have tried using several products
to clean it out. Of those I have found a very strong industrial
detergent did the best job. Others I tried with little effect are
Wynnes Radiator Flush, Dilute Phosphoric Acid, Vinegar 50/50 with
hot water, and CLR Calcium Lime Rust remover.

Anyway what I did is with the radiator lying horizontal with the
inlet and outlet up scour the radiator in the same way as they scour
water supply mains. That is with compressed air and water.
To reverse scour I connected the garden hose to the lower radiator
outlet using a rubber bung to seal it and turned the tap on full.
I then connected my air compressor line to the radiator drain
connection with the compressor set to 100 PSI. This seems to scour
out the radiator very effectively. I did this many (maybe 50) times.
To forward scour I connected the hose to the top radiator inlet and
applied the compressed air to the radiator overflow pipe with my
hand held on the radiator cap inlet.

Now having put everything back together I drove my test run to the
end of my road and back (15 kms = 10 miles) and the temperature
only got up to normal. Previously I would have had to stop along
the way to avoid it boiling.

Thanks guys for your assistance.

One other thing. I would like to add to the things that should be
bought from Toyota (the thermostat and radiator cap) the fan
hub. I have recently bought an after market fan hub that was
OK at first but failed after 2 months. It was replaced free of
charge by another after market hub that failed straight away.

I am now running a second hand fan hub that seems OK but not as
good as it should be. I will get a new Toyota fan hub.

 

[bigbrowndog]

Good to hear Johno. Good trick the compressed air , LOL bit of Tassie know how.
Yes, the cleaners only work when it is a mild case if cores are blocked the cleaner will not go through only follow the easy path and clean that.I think the toyota fan is the only way to go also especially with a diesel the petrol motor is more forgiving.Did you pull your old toyota fan apart and check it, perhaps the oil level was low.

 

[3F62]

Before you replace your fan hub $$$$$$, crack it open & add some silicone oil Toyota part No.08816-10001 its 18ml tube about $15 Aust made the world of difference to mine.......

Cheers

 

[Johno]

Thanks BigBrownDog and 3F62,
My original fan hub has a problem with its valve driven by the
bi-metal coil in front. I have two other fan hubs, one after market
that I don't trust and another second hand one. I will try to get
the silicone oil and add it to the second hand fan hub and see how
that goes.
Thanks for the tip

 

[bigbrowndog]

Thanks BigBrownDog and 3F62,
My original fan hub has a problem with its valve driven by the
bi-metal coil in front. I have two other fan hubs, one after market
that I don't trust and another second hand one. I will try to get
the silicone oil and add it to the second hand fan hub and see how
that goes.
Thanks for the tip

With the one that is nackered you can stick some small bolts or self tappers in it works ok up here but may not be great in a Tassie winter. Is the spring ok on the other see if it has disconnected or has broken. If you hold a hair dryer or heat gun near but not on it you will see if it is working properly or not.
https://forum.ih8mud.com/showthread.php?t=79661
Some pics here. cheers.

 

[Johno]

Thanks bigbrowndog,
I have already put some grub screws inside the buggered fan hub.
I ran this a few days but found the noise running at 110 kph a bit
much. It did provide heaps of cooling though. Still without a
thermostat I couldn't get the temp gauge to move up the scale any
more than about the width of the needle.
I bought a tube of the silicone oil from Toyota and added that to the
"seems OK" fan hub and am now running that.
The weather here in Tassie is still fairly cool (although spring is now
here) so I will have to wait until the weather warms up and I am
towing a heavy loaded trailer to see how the fan hub now performs.

Thanks again for your advice.

 

[Beck's Bier]

Something that I did for a "jig-rig" on my overheating toyota P/U was install an electric fan on the opposite side of the radiator (if you can find one that fits) with an on/off switch wire from the battery to the dash. This was just a quick fix when I was low on money and had nothing else to drive.

Good luck anyways and I hope you dont get screwed by the radiator shop if you decide to go there.

 

[Dynosoar]

1.Water Pump

2.Replace hoses they may be colapsing undr load (restricting flow)

Good luck you Tasmanian Devil

Dynosoar

 

[Johno]

1985 FJ62 Cooling System now OK

Thanks everybody, my cooling system is now working properly.
The scouring of the radiator did the trick and saved me the cost
of a new one or at least the cost of a major radiator repair.

A couple of tips:

When removing the radiator.
To avoid having to remove the air conditioner condenser use an
angle grinder with a 1mm thick disc and cut screwdriver slots in the
ends of the two horizontal bolts that hold the top of the radiator.
Using a screwdiver to hold the bolt you can then with an open
ended spanner remove the square special nuts.

I fitted a length (about a foot) of a ladies stocking inside the top of
the radiator held in place by the top hose. This caught an amazing
amount of muck that no amount of flushing had got out.
Be careful about leaving the stocking there permanently as it seems
to act as a wick and a small amount of water seems to find its way
out.

Thanks again for all the advice.

 

[rpm1982]

i have the same problem with my 1992 80 series 3F so i hope this helps me