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|Overhauling the Cooling System
on the FZJ80
|For this project, I inititally sourced the following parts....
For the cooling system overhaul, I purchased new heater and cooling hoses from C-dan on ih8mud.com as well as a new starter, fan clutch, several
gaskets, and other parts.
For the PHH, I purchased the silicone hose kit from www.1FZFEPHH.com This kit used impressive constant torque clamps and I decided to
purchase more of these clamps from NAPA to be used throughout the cooling system.
As the project progressed many more parts would be needed.
|In April, 2008 I embarked on a major overhaul of the entire cooling and heater system in the Land Cruiser.
The project initially started out with just the intention of replacing the famous PHH (pesky heater hose) before it
eventually fails. But evolved into a massive overhaul and replacement of most parts of the engine cooling system.
At the time of the overhaul, the vehicle was 13 years old and had about 96,000 miles on it. I have not experienced
any major cooling issues that I was aware of and most of these parts would have probably lasted much longer. But
the cooling system on the FZJ80 is more critical than on other engines for several reasons.
The 1FZ runs extremely hot inside the tight 80 series engine bay. 1FZ also has a history of head gasket failure usually
at higher mileage, due to defective head gasket design and materials in the early days after asbestos was banned.
Keeping the cooling system in top notch condition can potentially help prolong head gasket life.
And finally, an expedition vehicle that sees some duty in extreme Eastern Oregon desert temperatures needs the
highest quality cooling system available.
When finished, I replaced, all cooling and most heater hoses, thermostat and water pump. I upgrade the fan clutch
and I replaced the '95 Toyota 2 row aluminum radiator with a slightly larger 3 row brass radiator designed for the
|As I started by tear down, I realized that the more I removed, the easier it would be access parts of the vehicle. Since this was not my daily driver, I
could go a couple of weeks without driving it and decided to do everything as well as possible.
While not originally planned, I decided to remove the radiator to allow easy access the front of the engine and for parts removal and installing the
new alternator. But just to remove the radiator turned out be more challenging that I figured. I had to remove the front grill and both headlights to
access the proper bolts. The main battery and tray also had to be removed, which was fine since I wanted it out to create more room for the
|Fan and fan clutch
|Photos left to right: The old clutch (left) and new clutch attached to the plastic fan (right).....The two clutches, blue hub indicates the new
design....blue hub fan and clutch on the engine.
One of the first things to come out was the fan, clutch and fan shroud. Despite my best efforts, I ended up breaking the fan shroud. But it's an easy
repair with some liquid plastic welder.
While preparing to overhaul the cooling system, I thought about the fan clutch. Typically, the clutch lasts a long time, but they can get old and oil
inside can break down causing the fan to be less affective or not work at all. My fan clutch appeared to still be working, but what made me change it
out was finding out that Toyota had an upgraded version that improved cooling efficiency. It was differentiated from the original fan clutch, with a blue
painted hub. As mine was original, I ordered a new blue fan clutch from C-dan. Once the fan and clutch are removed as one piece, the plastic fan
can be easily unbolted and bolted to the new clutch. If only the rest of this project could be so easy.
Tip: The fan and should be removed together.
|Photo: 2 of the 3 new radiator hoses.
The 1FZ has three main radiator hoses. The upper hose is a single hose that leads to an aluminum tube, which bolts to the engine directly under
the distributor. The lower hoses are two piece, with the first piece leaving the radiator and entering a 90 degree pipe, which connects to another
hose that connects to the thermostat housing on the passenger front side of the motor.
All three were replaced. The hoses were difficult to remove and I ended up cutting all three off. When reinstalled, I used special stainless steel
constant torque clamps.
Tip: I unbolted the lower radiator pipe and pre installed the hoses to make it a little easier.
|Photos left to right: Old thermostat in the background. Brand new Toyota thermostat in the foreground....thermostat housing on the engine (lower left)
The thermostat is located on the passenger front side of the block. The housing is held in place by 3 nuts on 3 studs. Thermostats eventually wear
out and do one of two things. They either get stuck open, which causes the engine to run too cool, especially during cold weather, or they get stuck
closed or partly closed, which causes the engine to overheat.
They are very cheap and a good idea to replace at some point. I figure approaching 100K miles and almost 13 years, was good enough for the stock
unit and bought a new one. Install was easy. With the housing removed, the old one pops out. My original one was a little stuck, but be careful not
to scar the sealing surface when removing. The thermostat has an O-ring with a groove that wraps around the edge of the disk.
Tip: Make sure the O-ring is properly positioned around the edge of the thermostat, not in front of or behind it and make sure the air valve (loose
hanging thing) is pointed straight up. There's actually a little notch on the outside housing to show you where to align it. It can, however, be off by as
much as 15 degree to the right or left, just in case it moves on you during installation.
|The 1FZ radiator is bolted to a radiator frame, which then bolts into the body in four places. There are various ways to remove the radiator. Some
people remove the radiator and leave the frame, while others remove frame and radiator as one piece and still others remove one side frame and
leave the other. The reason is the radiator bolts are not very easy to get too.
The lower bolts are undernieth the battery trays and the front bolts are behind the headlights. I elected to remove the main battery tray anyway, which
made getting that bolt out easier. The passenger lower bolt can be gotten too with a box wrench. I went ahead and removed both headlights to
access the front bolts. The radiator then simply lifts out.
Tip: Don't forget to undo the transmission cooler lines and plug them. Only a little fluid came out of mine.
|Heater Hose Description
|Photo: Toyota parts diagram showing the main FZJ80 heater hoses (upper half photo) and rear heater hose system (lower half photo)
Also shown are photos of the brand new heater hoses and some of their locations using the below numbers.
The 1FZ and Land Cruiser 80 has a rather extensive heater hose system on the fire wall. One major reason for this is the rear heater system. The
Toyota Land Cruiser 80 has two heater cores. A standard front core and a rear core, which is located under the front passenger seat.
Here is my detailed description of the heater hose system. Numbered heater hoses do not include the rear heater hose system, which is only sold
by Toyota as a one piece kit, including pipes and hoses.
The coolent, destined for the heaters, leaves the engine via the block on the lower rear driver's side and enters the short PHH hose (heater hose no.
1) before going through a steel tube to the top rear of the motor. Here, (hose no. 2) connects to the heater valve, which is controlled by the climate
controls on the dash. Coolent exits the valve through (hose no. 3) and enters a horseshoe pipe, then (hose no. 4) which connects to a 3 way pipe.
This pipe feeds both the front heater core via the fire wall (hose no. 5) and the rear heater core.
Coolent exits the front heater core on the passenger side firewall near the rear of the engine (hose no. 6) and enters a 3 way metal T. The rear
heater coolent also enters this T from the bottom and both front and rear coolant exit the T via (hose no. 7) to a metal pipe just above the exhaust.
On later models, this pipe is one piece and bolts directly to the thermostat housing. On earlier models, this pipe has another heater hose in the
middle. (hose no. 8 - '93-94 models only)
The rear heater hose system leaves the driver's side T (hose no. 1) and connects to a pipe which goes behind the engine and connects to (hose no.
2) then enters another long pipe, which connects to (hose no. 3) connecting to the heater core through the passenger side floor board. The coolent
then exits the floorboard (hose no. 4) and follows the original pipe back to behind the engine (hose no. 5) and then up to the passenger side T (hose
The weakness in the rear heater hose system is actually not so much the hoses, but the metal pipes. They are located directly above the catylatic
converters and get extremely hot. This wears away the paint and the lines will rust and leak in areas that are otherwise prone to rust.
In total, there are 13 individual heater hoses. (14 for earlier 1FZs) The most common heater hose to fail and leak is the one that is that is the
hardest to reach. The PHH (known an hose no. 1 in my description). The problem with this hose is that the coolent is the hottest when entering
this hose and the hose is located right next to part of the hot exhaust EGR system. Typically this hose fails at somewhere just north of 100K miles.
Other potential failure points are the short hoses that connect to the firewall, and the hoses on the passenger side close the exhaust system.
|Heater Hose Replacement
|Photo: Board laying over engine to make accessing the rear hoses easier, giving me something to rest on.
I started out the project intending to replace every single heater hose on the vehicle. I then considered by passing the rear heater system
completely, since I rarely use it and cannot easily source individual parts (Toyota only sells the entire rear heater line system as one kit). I changed
my mind when I realized the rear heater hoses looked to be in good condition and appeared to be made of a thicker hose material for long life.
However, I did set about to replace every single other heater hose on the vehicle. As it would turn out, most were in decent shape, but these are not
easy items to repair in the field, so it will be yet another thing I will not have to worry about for at least another decade.
Toyota sells 3 formed heater hoses. The rest are straight hoses that can be cut to length. The formed hoses are (refer to description) heater hose
no. 2, no. 6 and no. 7. It's a good idea to replace formed hoses with new formed hoses. The reason being that the hoses are formed to keep
stress on the hoses and metal pipes minimal as the engine vibrates and moves independent of the firewall and other pipes.
Because the rest of the hoses are straight, you can use any 5/8" heater hose you want. Some heavy duty possibilities are Toyota's own heater hose,
Gates Green Stripe or some form of silicone heater hose. The Silicone heater hose is popular to use to replace the PHH, since the silicone hose is
the most heat resistent and longest lasting hose and most people only want to replace the PHH once....and forever.
What I decided to do was using Silicone for the PHH (hose no. 1), Toyota's formed hoses where required, and use Toyota's straight hoses for the
rest of the applications. I tried to use the thicker Gates hose on some of the applications, but found it nearly impossible to get it to fit and found that
the stock Toyota hose was more flexible and easier to wrestle on. So, every heater hose, except for the PHH, is a Toyota OEM heater hose.
Hopefully, I will never have to think or worry about my heater hose system again, with the exception of the rear heater system, which I will keep an eye
on in the future, as needed.
The heater hoses were very difficult to access and remove. Here's some tips.
Toyota used two types of hose clamps. Claw clamps, which are easy to remove and can be used again, although they do lose tension over time
and cotter pin clamps. The cotter pin clamps are one time use clamps and should not be reused. Pull the pins out and the clamps will come
undone or carefully cut them off with a dremel.
Cut the hoses off. Don't risk damaging the pipes by trying to wrench them off. But be careful not to scar the pipes as you cut.
To access the rear firewall hoses, lay a board over the engine to lay on (be very careful not to damage whatever the board is resting on). This will
allow you to work directly over the hoses and trust me, its much easier and more comfortable to reach the hoses this way.
I used Sil-Glyde as a lubricant which made installing all of the hoses much easier.
|Fan Belt idler pulleys
|Photo left to right: The new AC idler pulley (top) and old pulley disassembled in order from left to right (bottom).....the alternator fixed idler pulley.
The 1FZ has two engine belt systems. A double belt runs the alternator, water pump and engine fan. These belts run against a fixed idler pulley
and are adjusted via the alternator lower mount. The AC compression has its own single belt which is adjusted via a seperate adjustable idler
pulley. Both of these pulleys have internal bearings which eventually fail. Usually a pulley bearing that is failing will make noise long before it
siezes. But once it siezes, the potential for belt failure is not far behind. Both of these pulleys are easily replaceable from Toyota.
Usually idler pulleys can be rebuilt by simply replacing the bearings. The metal parts should last the life of the engine. However, the alternator idler
pulley is built with two halves assembled and rivited with the bearing in the middle. It's not possible to replace just the bearing. The AC idler
pulley's bearing can be removed and replaced if you can find the right size bearing.
I chose to go ahead and replace both idler pulleys from Toyota as a PM. As it would turn out neither one showed any signs of bearing wear at all
and worked perfectly, but since I had already purchased new units, I put them on and kept the old ones as spares.
Tip: The alternator idler pulley simply unbolts off. Very easy. The AC idler pulley needs to be taken apart to be removed from the vehicle. There are
several pieces that need to go back in order when putting the new one on. See above picture.
|Pictures left to right....old pump (upper) verses new pump (lower)....view of the water pump housing with the pump removed...new pump installed.
I never intended to replace the water pump when I got started on this project, but once I removed the fan and inspected the pump, the bearing felt
rough and appeared to make a creaking noise. Being right there and easy to replace, I figured better safe than sorry and ordered a new Toyota
pump. When I went to replace, I removed the old pump and inspected it further. After playing with the bearing seal a little bit, the noise stopped and
the original pump felt just fine. I realized that the 1FZ pump is a very heavy duty unit and probably was designed to last a very long time, if not the life
of the motor. My original pump, probably would have lasted much longer, but I didn't have confidence in the bearing seal and since I had a new
pump ready to go, I went ahead and replaced it. Unfortunately, this is the most expensive water pump I've ever purchased. Almost twice the water
the pumps I've purchased for other Toyotas and Subarus.
Tip: Toyota supplies its new pumps with gaskets. Be sure not to over torque the pump bolts. The torque specs are not very high at all.
Around 15 ft/bls as I recall, but always double check your FSM.
|Toyota Part Numbers
|The following are at least some part numbers for the parts that I sourced.
For heater hose part numbers scroll down and refer to the heater hose parts photo.
Blue Hub Fan Clutch: 16210-66020 (Fits '93-'97)
Thermostat (82c): 90916-03117 (Fits '93-'97)
Water Pump: 16100-69325 (Fits '93-'97)
Alternator Fan Belts: 90916-02353-83
AC Fan Belt: 99332-10910-83
1993-1994 FZJ80 Brass 3 row Radiator: 16400-66040 (will fit '95-'97 also)
1995-1997 FZJ80 2 row aluminum radiator: 16400-66081 (for reference)
|Photo: Sludge on top of the radiator.
Toyota produced two types of the radiators for the 1FZ. For the original 1FZ equipped FZJ80s, model year 1993 and 1994, Toyota produced a 3 row
brass radiator. In 1995, along with a few other changes to the FZJ80, Toyota changed the design of the radiator to a 2 row aluminum radiator.
Obstensively, the design change was made to save weight. About 10lbs. The 2 row radiator has larger rows than the 3 row earlier design, but over
all the earlier brass radiator is slightly larger. It's said to offer the advantage of cooling better, but there's some controversy about this.
However, the '93-'94 radiator is at least slightly cheaper than the newer aluminum version, so because it likely offers better cooling and is cheaper,
it's a popular upgrade when a replacement is needed. It should be noted that the metal type only refers to the core and fins. The upper and lower
tanks are made of plastic on both versions.
Radiator failure occurs in several ways. Typically, the radiator gets corroded or plugged up with corrosion or sludge over time. Sometimes this can
be cleaned out with a process called rodding that requires disassembly of the radiator. The tubes of the core can also get damaged and leak or
leak from corrosion. Generally, the Toyota radiators are very good and should last a long time, if not the life of the vehicle, but the 1FZ have been
known to produce a sludge of an unknown type or source.
Sludge is typically grey in color and can vary in amount from very little to completely plugging up the entire radiator. What causes it is a mystery.
Some attribute it to mixing of Toyota red and green coolants or using the wrong type coolant in the 1FZ or leaving it in too long and attribute the
sludge to additives in the coolant. Others believe that the sludge is corroded aluminum. Still others believe it's left over block casting sand. One
thing is clear, the sludge has been found in engines that were meticulously maintained using only Toyota red coolant from day one.
When I pulled my radiator out, I did not intend to replace it. But after it was drained, I looked into the fill hole and could clearly see what appeared to
be a significant amount of grey sludge. The only way to know for sure was to remove the tank. After prying up the tabs, I was able to lift the plastic
tank off. What I found was a serious amount of sludged that had settled on the passenger side of the top radiator and blocking several tubes. The
rest of the radiator appeared to be OK, although still showing some wear. The sludge combined with the fact that I damaged one tube when pulling
out the alternator, motivated me to go ahead and order a brand new '93-'94 brass radiator from C-dan on www.ih8mud.com.
|PHH replacement (Pesky Heater Hose)
|Photo left to right:
View of the original heater hose. Actually not in bad shape, at least from the outside.
I used a dremel to remove rear PHH clamp and plyers to remove the front claw clamp
Then used a razer blade to cut the hose off
Here's the biggest problem with the PHH. The two ends of the pipe are this close together which makes it very hard to install the new hose.
|Photos from left to right:
Photo of the old cut hose (left) compared to the new Silicone hose (right)
Looking down at the top of the pipe that the PHH connects to, with the upper heater hose removed. A bolt just below this pipe can be undone, which
allows the pipe to be manuvered around and pivoted on another bolt mount, which is impossible to get to, to unbolt.
View of the pipe pulled back, allowing more room to install the hose.
New hose installed, but the clamps not cinched down just yet.
|Old verses new...or is it new verses old? The original radiator is actually the newer aluminum style and the new radiator is the older style.
Photos: Left photo shows the new '93/94 brass radiator (black) compared to the old '95 aluminum radiator. Right photo show the top of the brand
new brass radiator.
The new radiator weighed in at 30lbs. The old aluminum radiator weighed in at 20lbs. Which one cools better? There's debate about this, but
many believe the older style is better. It's suppose to have better cooling properties with its brass tubes, larger area and more tubes. This isn't to
say the stock aluminum radiator doesn't do its job. But add the fact that the older style is cheaper and is a direct bolt in...the choice for replacement
is pretty easy.
|This project could easily be branded as overkill. Parts were replaced that weren't technically worn out or needed immediately servicing. But the
justification for replacing them is that some of these parts can fail without warning. Replacing them in the comfort of my garage, while I had the
available down time, was much easier than if I was 100 miles from the nearest civilization or a few days prior to leaving on a long trip. And these are
parts that I won't have to worry or think about for many years to come.
In the end, my operating temps have come down. Where I averaged about 185-195 in winter ambient temps, I'm now seeing 179-181 in spring
ambient temps. I imagine the improvement will be just as noticeable during the hot weather of the coming summer. The key is not so much lower
temps under normal operating conditions, but controlling the temps better during extreme conditions and most importantly overall system reliability.
In the end, it was well worth it.