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Discussion Starter #1
I smell burnt antifreeze every time I get out of my 79 bronco. It does not drip on pavement after sitting all day at work. I have looked everywhere and cant see a leak any where. The water pump is new. It sometimes runs a little past the center on the temp gauge which it used to never do. I hope it is not a head gasket or something like that. Any ideas

Super Moderator
23,728 Posts
Yo 79,
Here is the skinny by Ford;
"Inspect coolant in both radiator and radiator coolant recovery reservoir. Coolant should be a green or blue color (depending on brand of antifreeze used).

Clear coolant or coolant only a very light green or blue indicates that there is only water or a very weak antifreeze mixture in the system. Advise the owner of the need for the correct 50/50 coolant mixture.

A very muddy brown color indicates an unauthorized brand of stop-leak has been used. This may eventually plug the system, causing overheating. Advise the owner that the best course would be to drain the system and repair the original concern, flush the system, and refill with correct 50/50 coolant mixture and, if necessary, Cooling System Stop Leak Pellet D9AZ-19558-A or Cooling System Stop Leak Powder E6AZ-19558-A or equivalent meeting specification ESE-M99B170-A.

Make clear to the customer that any stop-leak material is not a satisfactory repair for a serious cooling system concern such as a leaking water pump (8501), gasket, or radiator.

A reddish brown color indicates rust in the cooling system. Advise the customer that the best course would be to flush the cooling system and refill with the correct 50/50 coolant mixture. Ford Premium Cooling System Fluid, E2FZ-19549-AA or equivalent meeting Ford specification (ESE-M97B44-A and ESE-M97B43-A) contains corrosion inhibitors. In addition, add 1.4 liters (1.5 qts.) of Heavy-Duty Cooling System Additive FW-15 or equivalent meeting Ford specification ESN-M99B169-A.

An iridescent sheen on the top of the coolant indicates a small amount of oil entering the coolant. This is common in high-mileage vehicles.
CAUTION: If there is coolant in the engine oil, the cause must be corrected and the oil changed or engine damage will occur.
Check the engine oil on the oil level dipstick (6750) to see if any coolant is entering the engine oil as indicated by drops of coolant visible in the oil or a milky appearance to the oil. If the oil checks out OK, inform the customer that, while not an immediate problem, the situation should be closely monitored during routine maintenance.

CAUTION: Severe oil leakage to the engine coolant, as indicated by a milky appearance to the coolant, must be corrected or severe engine damage will occur.
If the coolant is a milky brown color (like coffee with heavy cream) engine oil is entering the coolant. On 7.3L diesel and 7.5L gasoline engines the most probable cause is a leak in the engine oil cooler. Remove and inspect to find the problem.
If the oil cooler checks out OK, the head gasket (6051) may be leaking around the oil passageway to the cylinder head (6049). It will be necessary to remove the cylinder head, inspect for the problem, and replace the head gasket. If the head gasket checks out OK, then a crack between an engine oil gallery and the cooling passageways could be the cause. Inspect the cylinder block (6010) and cylinder head.
A reddish milky appearance to the coolant indicates that transmission oil is leaking into the coolant indicating a leaking transmission fluid cooler (7A095).
CAUTION: If coolant is found to be entering the transmission fluid, the cause must be corrected or transmission damage will occur.

Check transmission fluid to make sure coolant has not mixed into transmission fluid as indicated by a milky appearance. If it has, it will be necessary to flush transmission (7003) and replace filter outlined in the appropriate section. Refer to Group 07. Replace radiator assembly, flush cooling system, refill transmission, and refill cooling system with correct 50/50 coolant and antifreeze mixture.

If chunks of rust are visible on top of the tubes in downflow radiators or in the inlet tank in crossflow radiators, flush the cooling system.
If there is puffy white corrosion around the tubes where they are attached to the core headers, flush the system. If there is corrosion on aluminum radiator parts, there is going to be corrosion on aluminum engine parts that come in contact with coolant.
Advise the owner of the importance of using the proper 50/50 mixture of water and Ford E2FZ-19549-AA Premium Cooling System Fluid or equivalent meeting specification ESE-M97B44-A that contains corrosion inhibitors. In addition, add 1.4 liters (1.5 quarts) of Heavy-Duty Cooling System Additive FW-15 or equivalent meeting Ford specification ESN-M99B169-A.
If the appearance of the coolant is OK, use a hand-held refractometer, such as Rotunda Battery/Antifreeze Tester 021-00046 or equivalent to verify proper coolant concentration. The range is: (minimum) 45/55, (maximum) 60/40.
If the cooling system is found to be low on coolant, top off only from a premixed solution.
If a weak concentration is found, add straight coolant sparingly until concentration readings are within acceptable levels.
If too strong a concentration is found, remove a small volume of coolant and add water sparingly until coolant readings again fall within the specified levels.
NOTE: Make sure coolant is thoroughly mixed before taking readings. This is accomplished by running the engine until the water thermostat opens.
Recheck coolant concentration to make sure the coolant has been brought into the proper concentration."
Find a local shop to power flush the COOLANT system including heater core. We have a mom & pop shop that will continue flushing until it's relatively clear water running after flush solution is run through.
"To remove rust, sludge and other foreign material from the cooling system, use Ford Premium Cooling System Flush F1AZ-19A503-A or equivalent meeting Ford specification ESR-M14P7-A. Flush system using Rotunda Cooling System Flusher 106-00010 Flush Kit Hardware Package 106-R0011, and Drain Kit 106-R0015 or equivalent. miesk5 Note; check with local parts stores for a loan a tool program, refundable deposit
Removal of such material restores cooling efficiency and avoids overheating.
Always remove the water thermostat (8575) prior to pressure flushing. A pulsating or reversed direction of flushing water flow will loosen sediment more quickly than a steady flow in the normal direction of coolant flow. In severe cases where cleaning solvents will not properly clean the cooling system for efficient operation, use the pressure flushing method. Various types of flushing equipment are available.
Do not back-flush cooling systems that have a water shutoff valve in the heater system, or damage to the valve can result.
Scans of the factory manual for servicing the blower motor, water valve, heater core & heater control on 78/79 Bronco's & 73/39 F-trucks.
Source: by Ford via Broncobill78 (Dave) at https://broncozone.com/topic/12588-blower-motor-heater-core-heat-control/

Radiator Removed;
CAUTION: Radiator internal pressure must not exceed 138 kPa (20 psi). Damage may result.
Back-flush radiator (8005). Position a high-pressure water hose in lower radiator hose location and back-flush.
Remove water hose connection (8592) and water thermostat as outlined.
Back-flush engine (6007). Position high-pressure hose into engine through water thermostat and back-flush engine.

Heater Core Back-Flushing:
All engine cooling system flushing and back-flushing procedures must include a separate back-flushing of the heater or air conditioning/heater system heater core (18476), after the flushing or back-flushing of the engine cooling system. This will prevent engine cooling system particles from clogging the heater core tubes and reducing (or eliminating) coolant flow through the heater core.
The heater core must be back-flushed separately from the engine cooling system for proper back-flush water flow direction through the heater core.
The correct heater core back-flushing procedure is as follows:
On F-Series and Bronco vehicles, disconnect the outlet heater water hose (18472) from the water pump fitting and install a female garden hose-end fitting adapter in the end of the outlet heater water hose. Secure with a hose clamp (8287).
Connect the female garden hose-end of the outlet hose clamp to the male end of a water supply garden hose.
Disconnect the heater core inlet hose clamp from the engine block fitting and allow to drain onto suitable container.
If a heater water control valve (18495) is installed in the heater core inlet hose clamp, check to be certain the heater water control valve is open (no vacuum).
Turn the water supply valve on and off several times so that the surge action will help to dislodge larger stubborn particles from the tubes. Allow full water pressure to flow for approximately five minutes.
●If a heater water control valve is installed in the heater core inlet hose clamp, apply vacuum to the water valve vacuum motor to make sure heater water control valve operates and closes properly to prevent water leakage. Replace the heater water control valve if required.
Remove the heater water hose and female garden hose-end adapter from the end of the outlet hose clamp and connect the outlet hose clamp onto the water pump fitting.
Connect the inlet heater hose onto the engine block fitting.
Fill the cooling system as described in Cooling System, Draining, Filling and Bleeding in this section.
Test the system for proper heater performance."

Visually inspect coolant in radiator coolant recovery reservoir for signs of transmission or engine oil.
Is oil evident in coolant?
If engine oil is evident on vehicles with an engine oil cooler, REMOVE engine oil cooler and INSPECT for damage. REPLACE if damaged.
If engine oil is evident on vehicles without engine oil cooler or if oil cooler checks out OK, REMOVE cylinder head , and INSPECT for leaking head gasket and head or block cracks.

If transmission oil is evident, replace transmission oil cooler in radiator and check condition of transmission oil
Remove oil level indicator for engine and transmission.
Carefully inspect oil level indicator for evidence of coolant.
Is coolant evident?

Compression Gauge Check:
Make sure oil in crankcase is of the correct viscosity and at proper level and battery (10655) is properly charged. Operate vehicle until engine (6007) is at normal operating temperature. Key off, then remove all spark plugs (12405).
Set throttle plates in wide-open position.
Install a compression gauge such as Rotunda Compression Tester 164-R0250 or equivalent in No. 1 cylinder spark plug opening. miesk5 Note; check with local parts stores for a loan a tool program, refundable deposit
Install an auxiliary starter switch in starting circuit. With key off, and using auxiliary starter switch, crank engine at least five compression strokes and record highest reading. Note the approximate number of compression strokes required to obtain the highest reading.
Repeat test on each cylinder, cranking the engine approximately the same number of compression strokes.
Test Results;
The indicated compression pressures are considered within specification if the lowest reading cylinder is within 75 percent of the highest. Refer to the following chart.
Maximum kPa Maximum psi Minimum kPa Minimum psi
924 134 696 101
938 136 703 102
952 138 717 104
965 140 724 105
979 142 738 107
993 144 745 108
1007 146 758 110
1020 148 765 111
1034 150 779 113
1048 152 786 114
1062 154 793 115
1076 156 807 117
1089 158 814 118
1103 160 827 120
1117 162 834 121
1131 164 848 123
1145 166 855 124
1158 168 869 126
1172 170 876 127
1186 172 889 129
1200 174 903 131
1214 176 910 132
1227 178 917 133
1241 180 931 135
1255 182 938 136
1268 184 952 138
1282 186 965 140
1296 188 972 141
1310 190 979 142
1324 192 993 144
1338 194 1000 145
1351 196 1014 147
1365 198 1020 148
1379 200 1034 150
1393 202 1041 151
1407 204 1055 153
1420 206 1062 154
1434 208 1076 156
1448 210 1083 157
1462 212 1089 158
1476 214 1103 160
1489 216 1117 162
1503 218 1124 163
1517 220 1138 165
1531 222 1145 166
1544 224 1158 168
1558 226 1165 169
1572 228 1179 171
1586 230 1186 172
1600 232 1200 174
1613 234 1207 175
1627 236 1220 177
1641 238 1227 178
1655 240 1241 180
1669 242 1248 181
1682 244 1262 183
1696 246 1269 184
1710 248 1283 186
1724 250 1289 187
See 1996 Bronco/F-Series for better chart
Compression Readings — Interpreting

It is recommended the Compression Pressure Limit Chart be used when checking cylinder compression so that the lowest reading number is 75 percent of the highest reading.

If one or more cylinders reads low, squirt approximately one 1.5 ml (1 tablespoon) of SAE 50 weight or equivalent engine oil on top of the pistons in the low reading cylinders. Repeat compression pressure check on these cylinders.

If compression improves considerably, piston rings are at fault.

If compression does not improve, valves are sticking or seating poorly.

If two adjacent cylinders indicate low compression pressures and squirting oil on pistons does not increase compression, cause may be a cylinder head gasket leak between cylinders. Engine oil and/or coolant in cylinders could result from this problem.

Example Readings:
For example, check the compression pressures in all cylinders. If the highest reading obtained was 1351 kPa (196 psi) and the lowest pressure reading was 1069 kPa (155 psi), the engine is within specification and the compression is considered satisfactory."

3,419 Posts
check all the hose clamps,my 79 was doing that the other day
I smelled coolant and grabbed a screw driver and tightened all the clamps(new to me truck )
if may be just loose enough for the steam to escape and evaporate causing the smell without noticing any leak
if you suspect it is burning it, you should see a white tailpipe
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