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Discussion Starter #1
Vehicle Specs
1989 Ford Bronco Eddie Bouer Edition 4x4
Engine: 5.0L
Transmission: AOD

Problem:
Last summer while going up a steep grade (15%) my Bronco overheated. Upon inspection the upper radiator hose developed a hole near the radiator inlet. When I pulled the hose off, the radiator nipple came off with it and had been broken for quite some time and the PO had used duct tape and the radiator hose to splint it back together. So I replaced both upper and lower radiator hoses, the heater bypass hose and the radiator with a Modine Aluminum 2 core radiator. While I was in there I replaced the thermostat (with the pellet towards the engine block), the water pump, and the heater hoses.
I then filled up the system with coolant, burped out all the air. And now the temperature gage barely moves up to the cold line. It rises and falls with the thermostat opening and closing. The Fan clutch is solid (no wobble) and spins freely even after a good hour of driving around town. The hoses are always warm, but never hot. And I am going through a lot of coolant. Previous experience leads me to believe a bad head gasket, except I’m not getting exhaust into the coolant, and no coolant in the oils, and no oil in the coolant.
So to rule out a head gasket, would a leaking intake manifold gasket cause this strange under cool condition? I am not able to see any coolant leaks, but not ruling out the freeze plugs on the back of the block either.
I am getting ready to pull the front of the motor a part for a Saginaw Power Steering Pump swap, along with the 3g alternator swap, and would like to fix this issue at the same time.
What else should I be looking at while doing this work?
Or should I go over board and get a reman long block?
 

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If you are losing coolant - it's gotta be going somewhere. It's either getting burnt (White smoke from exhaust) or leaking. I'd do a pressure test on the cooling system first, then a leak down test if needed.
 

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Yo Slim,
As ctandc advised.
  • Engine Does Not Reach Normal Operating Temperature
  • Damaged thermostat.
  • Cooling fan.
C1 CHECK FOR FROZEN FAN CLUTCH
  • Perform below fan clutch test
Did fan clutch pass test?
YesNo
GO to C2.REPLACE fan clutch.
C2 CHECK THERMOSTAT OPERATION
  • Remove thermostat and check opening temperature.
  • Perform the following inspection at approximately 22°C (72°F).

    If the problem being investigated is insufficient heat, inspect the thermostat for leakage. Hold the thermostat up to a lighted background. Light leakage around the thermostat valve (thermostat at room temperature) is unacceptable and the thermostat should be replaced. A slight leakage of light at one or two locations on the perimeter of the valve of some thermostats may be detected. This is considered normal.
Does water thermostat begin to open and become fully open at temperatures specified?
YesNo
REINSTALL thermostat and CHECK temperature gauge operation as outlined belowREPLACE thermostat.

Spin the fan. A light resistance should be felt. If there is no resistance or very high resistance, the minimum and maximum fan speeds must be checked as follows:

Refer to Fan Clutch Specifications at the end of this section.

Minimum Fan Clutch Requirement Test — Cold

  1. WARNING: TO AVOID THE POSSIBILITY OF PERSONAL INJURY OR DAMAGE TO THE VEHICLE, DO NOT OPERATE THE ENGINE UNTIL THE FAN HAS BEEN FIRST EXAMINED FOR POSSIBLE CRACKS AND SEPARATION.

    Using a suitable marker, mark the water pump pulley (8509), one of the fan blade retaining bolts and the crankshaft pulley (6312).
  1. Connect a tachometer to the engine.
  1. Install a throttle adjusting tool.
  1. Connect a Sun Strobe Light or equivalent. This can be an SLT-1 or SLT-2 Strobotach or an STA-1 Strobe Trigger adapter for the Sun Distributor Test Stand. A Digital Photoelectric Tachometer 055-00108 or equivalent may also be used for this test.
  1. Start the engine and run it at approximately 1500 rpm until engine temperature has normalized.
  1. Adjust the engine to the testing speed in the Specificationsat the end of this section.
  1. Operate the strobe light at water pump test speed and aim it at the water pump pulley. Adjust the engine speed until the light flashes and the water pump pulley marks are synchronized.
  1. Aim the timing light at the fan retaining bolts. Adjust the strobe light until it is synchronized with the marked fan retaining bolt (fan appears to stand still).
  1. The fan speed must not be greater than the specified fan test speed at water pump test speed.
  1. Turn the engine OFF.
  1. If the fan speed was greater than the specified fan test speed, check for proper parts usage.
    If the correct parts are used, replace the fan clutch (8A616).
    If the part(s) are not the correct ones, replace the part(s) and perform the test again.
  1. If the engaged fan clutch requirement test is going to be performed, do not remove the tachometer, strobe light or throttle adjusting tool.
  1. If a Maximum Speed Fan Clutch Requirement test is not going to be performed, remove the tachometer, strobe light and throttle adjusting tool.
Maximum Speed Fan Clutch Requirement Test
1 WARNING: TO AVOID THE POSSIBILITY OF PERSONAL INJURY OR DAMAGE TO THE VEHICLE, DO NOT OPERATE THE ENGINE WITH THE HOOD OPEN UNTIL THE FAN HAS BEEN FIRST EXAMINED FOR POSSIBLE CRACKS AND SEPARATION.

If the disengaged fan clutch requirement test was not performed, follow Steps 1 through 5 under Minimum Speed Fan Clutch Requirement test.
  1. Block off areas on each side of the radiator in the engine compartment and the front of the radiator grille (8200), this will raise the temperature of the air striking the fan clutch and should cause the fan blade to operate at maximum speed.
  1. Place the air conditioning selector, if so equipped, in the maximum position and the blower switch in the high position.
  1. Adjust the strobe light to water pump test speed.
  1. Start the engine and adjust it until the water pump pulley is synchronized with the strobe light. This will be near the engine testing speed given in Specifications.
  1. Synchronize the timing light with the fan to fan clutch retaining bolt.
  1. The fan speed must meet or exceed the specified minimum fan blade test speed at water pump test speed.
  1. If the fan speed was less than the specified fan test speed, replace the fan clutch.
Coolant Temperature Gauge
Check gauge calibration as follows:

  • Using a Rotunda Instrument Gauge System Tester 014-R1063 or equivalent, with the key in the OFF position, disconnect wiring connector at the sender and connect tester to wiring connector.
  • Set the tester to 74 ohms.
  • Turn the key to RUN, and wait 60 seconds. The gauge should indicate on the COLD graduation.
  • Set the tester to 9.7 ohms and wait 60 seconds. The gauge should indicate on the HOT graduation.
  • If engine coolant temperature gauge tests within calibration, replace engine coolant temperature sender.
  • If engine coolant temperature gauge still tests out of calibration, replace coolant temperature gauge.
 

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Discussion Starter #4
If you are losing coolant - it's gotta be going somewhere. It's either getting burnt (White smoke from exhaust) or leaking. I'd do a pressure test on the cooling system first, then a leak down test if needed.
That’s the thing, pressure test comes back as all systems go and doesn’t bleed out, nothing obvious (first thing I did)
Leak down test 120 lbs a crossed all 8 cylinders with no pressure loss over night (dry).
I do get White smoke in startup that goes away in a few seconds... before I have time to walk to the back of the Bronco when starting by reaching through the window.
On longer drives I can sometimes smell the coolant. This is what leads me to believe softplugs... the front of the motor is always wet, and more wet after a drive... but no actual puddles. The back of the engine by the oil pan, bellhousing, and transmission pan are soaked... I while them down and several hours later are wet again... although the fluids besides the coolant all stay topped off.
 

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Discussion Starter #5
Yo Slim,
As ctandc advised.
  • Engine Does Not Reach Normal Operating Temperature
  • Damaged thermostat.
  • Cooling fan.
C1 CHECK FOR FROZEN FAN CLUTCH
  • Perform below fan clutch test
Did fan clutch pass test?
YesNo
GO to C2.REPLACE fan clutch.
C2 CHECK THERMOSTAT OPERATION
  • Remove thermostat and check opening temperature.
  • Perform the following inspection at approximately 22°C (72°F).

    If the problem being investigated is insufficient heat, inspect the thermostat for leakage. Hold the thermostat up to a lighted background. Light leakage around the thermostat valve (thermostat at room temperature) is unacceptable and the thermostat should be replaced. A slight leakage of light at one or two locations on the perimeter of the valve of some thermostats may be detected. This is considered normal.
Does water thermostat begin to open and become fully open at temperatures specified?
YesNo
REINSTALL thermostat and CHECK temperature gauge operation as outlined belowREPLACE thermostat.

Spin the fan. A light resistance should be felt. If there is no resistance or very high resistance, the minimum and maximum fan speeds must be checked as follows:

Refer to Fan Clutch Specifications at the end of this section.

Minimum Fan Clutch Requirement Test — Cold

  1. WARNING: TO AVOID THE POSSIBILITY OF PERSONAL INJURY OR DAMAGE TO THE VEHICLE, DO NOT OPERATE THE ENGINE UNTIL THE FAN HAS BEEN FIRST EXAMINED FOR POSSIBLE CRACKS AND SEPARATION.

    Using a suitable marker, mark the water pump pulley (8509), one of the fan blade retaining bolts and the crankshaft pulley (6312).
  1. Connect a tachometer to the engine.
  1. Install a throttle adjusting tool.
  1. Connect a Sun Strobe Light or equivalent. This can be an SLT-1 or SLT-2 Strobotach or an STA-1 Strobe Trigger adapter for the Sun Distributor Test Stand. A Digital Photoelectric Tachometer 055-00108 or equivalent may also be used for this test.
  1. Start the engine and run it at approximately 1500 rpm until engine temperature has normalized.
  1. Adjust the engine to the testing speed in the Specificationsat the end of this section.
  1. Operate the strobe light at water pump test speed and aim it at the water pump pulley. Adjust the engine speed until the light flashes and the water pump pulley marks are synchronized.
  1. Aim the timing light at the fan retaining bolts. Adjust the strobe light until it is synchronized with the marked fan retaining bolt (fan appears to stand still).
  1. The fan speed must not be greater than the specified fan test speed at water pump test speed.
  1. Turn the engine OFF.
  1. If the fan speed was greater than the specified fan test speed, check for proper parts usage.
    If the correct parts are used, replace the fan clutch (8A616).
    If the part(s) are not the correct ones, replace the part(s) and perform the test again.
  1. If the engaged fan clutch requirement test is going to be performed, do not remove the tachometer, strobe light or throttle adjusting tool.
  1. If a Maximum Speed Fan Clutch Requirement test is not going to be performed, remove the tachometer, strobe light and throttle adjusting tool.
Maximum Speed Fan Clutch Requirement Test
1 WARNING: TO AVOID THE POSSIBILITY OF PERSONAL INJURY OR DAMAGE TO THE VEHICLE, DO NOT OPERATE THE ENGINE WITH THE HOOD OPEN UNTIL THE FAN HAS BEEN FIRST EXAMINED FOR POSSIBLE CRACKS AND SEPARATION.

If the disengaged fan clutch requirement test was not performed, follow Steps 1 through 5 under Minimum Speed Fan Clutch Requirement test.
  1. Block off areas on each side of the radiator in the engine compartment and the front of the radiator grille (8200), this will raise the temperature of the air striking the fan clutch and should cause the fan blade to operate at maximum speed.
  1. Place the air conditioning selector, if so equipped, in the maximum position and the blower switch in the high position.
  1. Adjust the strobe light to water pump test speed.
  1. Start the engine and adjust it until the water pump pulley is synchronized with the strobe light. This will be near the engine testing speed given in Specifications.
  1. Synchronize the timing light with the fan to fan clutch retaining bolt.
  1. The fan speed must meet or exceed the specified minimum fan blade test speed at water pump test speed.
  1. If the fan speed was less than the specified fan test speed, replace the fan clutch.
Coolant Temperature Gauge
Check gauge calibration as follows:

  • Using a Rotunda Instrument Gauge System Tester 014-R1063 or equivalent, with the key in the OFF position, disconnect wiring connector at the sender and connect tester to wiring connector.
  • Set the tester to 74 ohms.
  • Turn the key to RUN, and wait 60 seconds. The gauge should indicate on the COLD graduation.
  • Set the tester to 9.7 ohms and wait 60 seconds. The gauge should indicate on the HOT graduation.
  • If engine coolant temperature gauge tests within calibration, replace engine coolant temperature sender.
  • If engine coolant temperature gauge still tests out of calibration, replace coolant temperature gauge.
Thermostat is a 195 degree thermostat, tested before I installed it (I have had brand new ones fail out of the box). So not a thermostat issue...
Heater blows cold air, and the hoses never get above luke warm, coolant is always barely warm to the touch even in the radiator.
Fan clutch is good... and was the very first thing I checked.
Like I said... head gasket, cracked head, freeze plugs, intake manifold gasket, are my first thoughts, but like my last post, the tests all come back negative for these... I can’t see steam coming out from any where, actual coolant puddeling up to be going through a gallon of coolant every week (sometimes more).
 

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Discussion Starter #6
Let’s entertain the long block for a minute. I don’t have time to put the Bronco down for more than a few days at a time. It’s my DD and I have to make store runs ever two days. I can push that out to 4 days tops. So getting my local machine shop to do the machine work is out because he is 6 months backed up and your engine has to be laying on his floor to be worked into his schedule.
At this juncture I’m really frustrated and know that I’m keeping the Bronco for a long time, or it’s getting sold within the next two years to buy a “New Bronco”. Either way a new engine is going to increase its value either for resale or a piece of my mind. Part of me says to get a JY engine and then get my original engine built.
But another part of me says to just get a long block and be done with it.
 

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Discussion Starter #7
I was just quoted $500 to get my stock heads rebuilt... new valves, springs, rod guides, valve seals, and welding the cracks if they both are cracked... $150 just to get them magnafluxed and hot tanked. 2 to 4 day turn a round...
 

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Discussion Starter #8
Just put in for a quote in getting my engine rebuilt as a worse case senerio. I forgot about an indipendent repair shop that has an in-house machine shop... I’m getting a quote for them to both build me a long block, and a quote for them to do all the work... since I can’t pull the motor at home and I’m having a hard time securing a garage, having all work done in house seams like the best option for me at this point in time... I might even have them put the ZF in for me as well while they are doing the work.
 

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Discussion Starter #9
Well... $4,000 to rebuild my engine, that includes getting new heads, radiator, hoses, belts, and a few other things as well as dropping in the ZF5. Man I wanted to do this myself, I just don’t have a garage to do the work in :(. I guess the Bronco isn’t going to be driveway built after all.
 

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Well... $4,000 to rebuild my engine, that includes getting new heads, radiator, hoses, belts, and a few other things as well as dropping in the ZF5. Man I wanted to do this myself, I just don’t have a garage to do the work in :(. I guess the Bronco isn’t going to be driveway built after all.
Jeez that's steep. Well at least you know you won't have any other issues with the drivetrain for the foreseeable future once all that works gets done


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Discussion Starter #11
Jeez that's steep. Well at least you know you won't have any other issues with the drivetrain for the foreseeable future once all that works gets done


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I don’t think it’s too bad, another shop wanted 2 grand just to pull the engine and put a junkyard engine in.... Hans told me $4,000 as a worse case... new crank, camshaft, etc... I’m getting it bored .030 over, balanced and blueprinted.. which can be a lot of work (balancing part), so new pistons and connecting rods are going to be needed. Best case scenario is $2500... but I typically err on the side of caution and budget for the worst as that seams to be my luck.
 

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I don’t think it’s too bad, another shop wanted 2 grand just to pull the engine and put a junkyard engine in.... Hans told me $4,000 as a worse case... new crank, camshaft, etc... I’m getting it bored .030 over, balanced and blueprinted.. which can be a lot of work (balancing part), so new pistons and connecting rods are going to be needed. Best case scenario is $2500... but I typically err on the side of caution and budget for the worst as that seams to be my luck.
That's true, did you already have the transmission for it? Been thinking of doing a swap to a more efficient transmission


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Discussion Starter #14
Well I found the problem... a pinhole leak in one of the small bypass hoses near the intake manifold... unfortunately I found it while driving down the road. So good news is it’s a cheap fix, bad news is other things failed at the same time and I need a tow home... and the tow truck can get here until tomorrow
 
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