Overheating hzj73

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

samreilly

samreilly

Joined
May 17, 2020
Threads
14
Messages
38
Location
melbourne, australia
Over heating issue
Fj73 with 1hz-T in it, after installing a 80 series brake booster and master cylinder from a wreckers and changing all my oils the water temp is reaching 100 c on a normal freeway drive that would never normally happen and egts are getting up to 500-550c. Radiator is 2 years old after it was recored. Brakes have been bleed multiple times after the install.
Where should I be looking for the reason of this because I’m lost cheers.
 
None of the activities mentioned should directly impact the engine temp and cooling.
Recheck your engine oil level.
Check your coolant level and -system for leaks.
How old is your engine and coolant? Possibly any gunk in it ?
Bring it to temperature and check:
Fan engaging?
Radiator: Is the main hose pressurized? If not, the thermostat is not opening. If pressurized, it might however still not open fully.
Is the radiator warm all over the surface? If not, some cores might be blocked.
If the fan / fan clutch is fine, my next suspect would be the thermostat. You could pull it and check for mechanical blockage. Sometimes stain builds up, blocking the valve plate to move freely. You could also put it in a pot of water, with a kitchen thermometer in it, heat it and check operation.
Good luck Ralf
 
sodafeld1 said:
How are you measuring your temp? Don't think brakes shall do much to temp.
Click to expand...
Temp gauges and only theory behind brakes is the previous drive I had to pull over due to the same issue but the brakes were smoking and since they’ve been bled again but still think they make be stuck slight on
 
Felde said:
None of the activities mentioned should directly impact the engine temp and cooling.
Recheck your engine oil level.
Check your coolant level and -system for leaks.
How old is your engine and coolant? Possibly any gunk in it ?
Bring it to temperature and check:
Fan engaging?
Radiator: Is the main hose pressurized? If not, the thermostat is not opening. If pressurized, it might however still not open fully.
Is the radiator warm all over the surface? If not, some cores might be blocked.
If the fan / fan clutch is fine, my next suspect would be the thermostat. You could pull it and check for mechanical blockage. Sometimes stain builds up, blocking the valve plate to move freely. You could also put it in a pot of water, with a kitchen thermometer in it, heat it and check operation.
Good luck Ralf
Click to expand...
Engine oil just below full, no visible leaks after cleaning underbody and radiator. Levels all up to standard was put in early this year and pretty sure around the 2000s. Shouldn’t be any gunk but it’ll be worth flushing the radiator.
Fans engaging,
Is testing for it to be pressurised by it being firm to squeeze because it’s pretty soft once warm.
Radiators is warm all over
I’ll test the thermostat tomorrow as I’m leaning towards that as well.
My main theory with it having to do with the brakes is as mentioned above and the pedal being quite firm and as if the brakes are constantly slightly on and the engine is fighting that, let me know what you think ? Maybe seized callipers ?
 
Sounds like two separate problems.

So like an after market temp gauge from coolant or thermocouple to block. As Felde said for engine cooling system. Give it a good reverse flush, even run some citric acid through the system, including inboard heater radiator fully open.

Thermostat (I keep 82c spares, cheap insurance), fan clutch, fresh coolant, I like the 8year penrite green..Hot radiator tube at the top and cooler at the lower tube? It should be, if radiator works.

I got a cheap supercrap radiator tester, it is ok for checking if the coolant system holds coolant pressure, especially radiator and the radiator cap (cheap insurance too). Does your overflow bottle over fill or get empty?

I also have the blue dye tester from warren and brown which tests if you have a head gasket leak, it is good test, quick and easy for an unfortunate major fix. It tells you if you have engine gasses in your coolant. Hope not. If the other suggestions doesn't work you are welcome to give my dye test a go.

I too recently had some temp changes from Melbourne to Sydney and back.
So, now, after a new injector diaphragm and fan clutch I just came from a bush run. The thermocouple was reading a bit hotter than usual but still within spec. I use to run a bit cooler. Thankfully the fan clutch kicks in at 85c like clockwork going a long uphill. But still thinking ahead to summer..a copper adrad radiator is about $600aud.

Smoking (disc assuming) brakes would be unrelated to engine besides vacuum booster, which is altenator oil pump on the 2h. Something is binding there, sounds like. Perhaps a seized piston on the caliper? I installed new calipers but had to pump the pistons fully closed from fully open using thin shim plywood instead of the disc pads. Caliper pistons can seize when new or stored on the shelf for awhile. The pistons can bind and do not travel fully without freeing them fully open and closed. I got a pair of new calipers from onlineauto for a pretty good price a few months back.
Hope you didn't warp your discs.
 
sodafeld1 said:
Sounds like two separate problems.

So like an after market temp gauge from coolant or thermocouple to block. As Felde said for engine cooling system. Give it a good reverse flush, even run some citric acid through the system, including inboard heater radiator fully open.

Thermostat (I keep 82c spares, cheap insurance), fan clutch, fresh coolant, I like the 8year penrite green..Hot radiator tube at the top and cooler at the lower tube? It should be, if radiator works.

I got a cheap supercrap radiator tester, it is ok for checking if the coolant system holds coolant pressure, especially radiator and the radiator cap (cheap insurance too). Does your overflow bottle over fill or get empty?

I also have the blue dye tester from warren and brown which tests if you have a head gasket leak, it is good test, quick and easy for an unfortunate major fix. It tells you if you have engine gasses in your coolant. Hope not. If the other suggestions doesn't work you are welcome to give my dye test a go.

I too recently had some temp changes from Melbourne to Sydney and back.
So, now, after a new injector diaphragm and fan clutch I just came from a bush run. The thermocouple was reading a bit hotter than usual but still within spec. I use to run a bit cooler. Thankfully the fan clutch kicks in at 85c like clockwork going a long uphill. But still thinking ahead to summer..a copper adrad radiator is about $600aud.

Smoking (disc assuming) brakes would be unrelated to engine besides vacuum booster, which is altenator oil pump on the 2h. Something is binding there, sounds like. Perhaps a seized piston on the caliper? I installed new calipers but had to pump the pistons fully closed from fully open using thin shim plywood instead of the disc pads. Caliper pistons can seize when new or stored on the shelf for awhile. The pistons can bind and do not travel fully without freeing them fully open and closed. I got a pair of new calipers from onlineauto for a pretty good price a few months back.
Hope you didn't warp your discs.
Click to expand...
The problem only came about after I had installed the 80 series booster and master cylinder.
Yeah aftermarket, I’ve reverse flush the heater core but definitely worth doing the radiator too. I’ll have a look at the pressure tester too might be worthwhile.
Yeah it’s front discs and looking like that might be the case I’ll give that a go
 
samreilly said:
Temp gauges and only theory behind brakes is the previous drive I had to pull over due to the same issue but the brakes were smoking and since they’ve been bled again but still think they make be stuck slight on
Click to expand...
That for sure indicates a different problem with your brakes.
You first need to check that the new brake booster does not apply force to the brakes when brake pedal is not depressed. I understood you put a 80s into your J7. Not sure about what the dimensions of the 80s are, but probably the dimension of the engaging piston are different or not well adjusted.
- Check the manual: Procedure to check on pedal travel and booster tobe behavior is described there.
- Jack it up, tranny in neutral, hub locks free (if fitted), and try to rotate each wheel manually: None should bind / almost no grinding noise.
- With brake pedal not engaged and engine running, there should be only very little discharge of brake fluid from the bleeder when opened like for bleeding brakes, as the system is supposed to be pressure-free when not braking.
- You probably can also check for the vakuum valve in the booster to shut properly, but I have no idea on how to test that.
(Can all be done only if your brake pads and disks have not been destroyed by the incident. If the brakes overheated, you nee to take it all apart and carefully inspect. Probably get an expert involved).
The new booster probably had pushed a piston to an corroded area it has never been before and now got stuck there. But its unlikely this happens to multiple wheels. I understood all brakes or all front brakes got hot? Then I'll recon the booster to be the culprit.

Dragging brakes do require the engine to work harder, but I doubt this would cause overheating. You would notice the smell of burned brakes well before.
I recommend to address one issue at a time. First get the brakes right and then do another shake down run and monitor the engin temp then.
Good luck Ralf
 
x2 can't see how brakes are over heating engine.
Coolant issues can happen any time. I just replaced the water pump which was probably unnecessary, they work as long as they spin.
Don't even think twice about replacing thermostat, it is just a wax mechanism which makes it open. They can get stuck. They are cheap. Fresh coolant, anytime.
For me, the fan clutch was probably due. Easy job. Going up a long steep hill and watching the fan clutch kick in and definite temp drop is what I wanted to see. So I can try to do the refilling of the special oil into the old fan clutch on a rainy day now.

Changing to 80 series booster maybe pushing caliper pistons more too, which is a separate issue. I think some folks have done the swap here from memory, bigger booster = better brakes. But changing from stock can lead to other issues, only the brave. Hopefully it is just a stuck caliper piston, caliper piston rubber kits are not too far off the price for a whole new caliper last I looked locally.
Also, I think the motive power bleeder is a superior way of brake bleeding, It doesn't mess with the master piston. When you push the peddle to bleed, the master piston pushes further than what it normally would during braking operation. So on a used master, the piston maybe corroded at the far end peddle push where it normally never goes, which can open another can of worms. Brake fluid being ultra corrosive. Don't need help to pump the brake peddle either with the power bleeder.

Makes me wonder if you had a look inside the cylinder? How was the piston and seals if it was a used unit? Sometimes the master needs to bleed separately too when installing. Newly installed master cylinders are notorious for holding air.

Sometimes I momentarily regret over fiddlin, but when I get out there after nailing it, it is worth it!
 
coldtaco said:
There’s an adjustment on the brake booster, it’s a real pain to do, if I remember correctly you will need a 7mm wrench. Sounds like it needs to be loosened up. You have to loosen the booster from the firewall enough to be able to access the adjustment.
Click to expand...
So on the rear of the booster ? Where about’s is it
 
Yes Coldtaco s right about adjusting the brake booster gap.
I did it but cant recall the details.
This was in addition to installing an extra long push rod between pedal and booster.

You could test for brake drag as Felde suggests.
 
Flushed the coolant fully and no bad signs there as well as the thermostat doing its job properly, finally got it on jack stands and definitely resistance on both wheels with the car in neutral so off they came and this is where I’m at now. After a couple pumps of the brakes the pistons on the right goes out fully and stays there left is a bit more even but brake pads on the left side had a lot more wear on the out brake pad, am I looking at new callipers or is this fixable?

1DE9C4D3-A73D-4A49-8903-F92002318FBA.jpeg


1962FF60-96E1-4A0F-8CC0-D2603DFE6B16.jpeg


6305D320-7EC9-48F7-860C-281D60460023.jpeg
 
This is fixable. There are rebuild kits available for the piston seals and rubber boots and stuff.
I did it on mine (which looked worse than yours): Post in thread 'What did you do on your 70 series today?' WDYD - What did you do on your 70 series today? - https://forum.ih8mud.com/threads/what-did-you-do-on-your-70-series-today.804784/post-13727078
In most cases it's just a bit of corrosion from old, moist brake fluid. Once cleaned, they'll do just fine.
Getting the pistons out may be a PITA. Don't use pliers. Either use compressed air or leave the caliper attached to the brake system, move it away from rotor, and press them out using the brake force. A little sketchy either way.
You will need a pair of flat nose circlip pliers to get the metal rings on that hold the boots.
Good luck Ralf
 
Felde said:
This is fixable. There are rebuild kits available for the piston seals and rubber boots and stuff.
I did it on mine (which looked worse than yours): Post in thread 'What did you do on your 70 series today?' WDYD - What did you do on your 70 series today? - https://forum.ih8mud.com/threads/what-did-you-do-on-your-70-series-today.804784/post-13727078
In most cases it's just a bit of corrosion from old, moist brake fluid. Once cleaned, they'll do just fine.
Getting the pistons out may be a PITA. Don't use pliers. Either use compressed air or leave the caliper attached to the brake system, move it away from rotor, and press them out using the brake force. A little sketchy either way.
You will need a pair of flat nose circlip pliers to get the metal rings on that hold the boots.
Good luck Ralf
Click to expand...
Ahhh thank you I’ll give it a crack tomorrow
 
I installed calipers for a 1990 4runner. A little bigger than stock but bolted right in (after dust shield trimming as Coldtaco wrote.)
 
You must log in or register to reply here.

Similar threads

HZJ73 Cruiser
Hello All! 1994 HZJ73
Replies
9
Views
957
dubyahard
dubyahard
dosequisrex
"New" HZJ73 - Maintaining and Improving
2
Replies
39
Views
3K
dosequisrex
dosequisrex
Mountainjnky75
HZJ73 runs rough on cold mornings
2
Replies
33
Views
2K
Mountainjnky75
Mountainjnky75
AK101
HZJ73 front diff plug options?
Replies
3
Views
720
AK101
AK101

Users who are viewing this thread

Total: 1 (members: 0, guests: 1)

Share this page

Back
Top Bottom