'67 Mustang 289 Cooling issue.


New Member
Oct 17, 2019

I own a 67 289 Mustang and I've been having some pretty major cooling issues. About a month ago I was washing my car and I noticed the battery sounded low on startup. So I was letting it run to see if I could charge up the battery and after about 10ish minutes my radiator proceeded to explode... literally. As i was turning off the car i noticed the water temp was sitting at about 230 which is maxed on my cars gauge. (usually I'm sitting at about 165-175 or 180 to 185 if I'm hotrodding around.)

So I decided to replace just about everything I could think of. New aluminum radiator(3 row), new water pump(something I was planning on doing soon anyways), new thermostat and thermostat housing, and new hoses and clamps. I used Permatex Grey on all my gaskets. I went with a 60/40 Prestone coolant mix and started her up. I let her idle for about 10 mins before taking her around the corner and in a span of about 60 seconds the water temp went from 170 to 200 and by the time I was back at my garage it was 215 and rising still.

I'm looking for any ideas as to what could be causing this. I plan on going to get the system flushed as soon as I can.

Thank you for any help.


  • Sponsors(?)


Active Member
Jul 12, 2018
Hi, Wow!
Yeah, Radiator bursting is an understatement, fortunate you/anyone weren’t severely burned.
A 3 row Radiator & Clutch or Flex-o-lite Fan should have no issue in keeping a 289 cool. It’s not had any issues, previously & nothings been changed, (Change or alter anything, was it hibernating?) happed fairly sudden, idling.
General causes, less what you’ve done).
Check your Oil, Oil Pressure...
1) Severe restriction in the cooling system, heater core, chunk dislodged.
2) Distributor advance issue, spring-broken, perforated diaphragm, Ignition timing incorrect.
3) Combustion chamber (Cyl) leaking superheated combustion gases into Coolant, I.E.; Head gasket, Cracked head, block.
4) Carb debris causing obstruction yielding a very lean running condition at idle, dirt in main jet, annular booster orfice(s) clogged.
5) Exhaust system has a blockage, sudden rusted piece of muffler falling in the path of exhaust gases.
- I’d suggest, initially..
- Put the car on stands & burp it, highest point will be radiator cap. For safety, replace radiator cap with 15lb pressure cap & add an overflow tank.
1) Verify the Coolant is not bubbling at idle, in Coolant. Cold start, cap off. Careful view of Coolant emitting small bubbles within may indicate a combustion chamber leak. Confirmation is checking Coolant for presence of Hydrocarbons from the combustion process. Exhaust have a sweet smell. Cross contaminated, check for Coolant in oil, oil in Coolant.
2) Thermostat is replaced. Verify orientation is correct, functional (verify you can feel it opening via flow in upper Rad.hose as temp rises).
3) Heater core plugged, obstructing coolant flow..Pull the lines & run h20 through with a hose. If plugged, bypass one line by making a loop, if resolved..that’s the issue.
4) Pull the Dizzy cap, rotor & verify advance works smoothly & not hanging up. If vacuum, test diaphragm with a MityVac or any vacuum source to verify it holds air, watch it actuate advance, look for binding. Mechanical advance, check that Springs & advance limit bushings are intact, not binding, rusty- in place w/proper functionality.
-Vac advance removed, clean & mark balancer at TDC, and 10 Degrees. Set timing conservative at 10-12 degrees with a light. Running points? Set Dwell.
-Pull all plugs, look for evidence of high temperatures, lean condition, Coolant contamination (White, grey, shiny). Optimal Tan to slightly Carbonized (Black). Look for unusually colored electrode(s) vs. others.

Something to think about...
This is the acute issue, but you may wish to consider correcting these..
Radiator shroud appears to be cut, or modified. Shroud should be a 360 degree circle with proper shroud to fan blade clearance, fan to radiator clearance, blade angle, proper blade rotation direction & correct shroud depth.
I’d listed above- for safety, why not now..Cap on the radiator a 15lb relief type- cap? Replace the cap with one rated for your weakest link (15lbs) & install a puke tank. It’s cheap insurance & will generally be enough to gain attention to shut it down. (Usually prevent a radiator explosion.).
Was that an aftermarket, non OE Radiator? Even the B.B. Fords have high crowns in the material for strength on top, uncertain if due to damage(?)
No Coolant ever noted on fins of radiator from leakage, previously?
Good luck! Try the list & we’ll go from there.
- John


New Member
Oct 17, 2019
Thank you for the response!
I've been doing a little research and I'm now thinking I have a blown head gasket. I'm getting white smoke out of the exhaust and my coolant level is going down even though I don't have any leaks. I'm assuming there is a breakage in the gasket between my coolant channel and combustion chamber which would explain both of these symptoms.

I regards to the fan shroud. They are actually cut like that so they make room for the intake and return for the radiator hoses. if you look up new ones they have the same cuts. The new radiator I bought has a 13lb relief so i have that covered now.

Thanks again for the suggestions!



Active Member
Jul 12, 2018
No prob’s!
Glad your on the right track, and you’ve got a Pressure release cap on the new radiator, think that’s about the worst I’ve seen, lol! Above all, glad nobody was hurt!
Realistically, a mild 289 with a good fan & Pump, clear block are good about running cool even without a shroud with a 3 core radiator, others a bit more needy.
Roger that regarding your shroud.
Good luck!
Thread starter Similar threads Forum Replies Date
G 1965 Mustang 289 cooling temp sensor? Classic Mustang Specific Tech 4
U What's it Worth? 67 Ford Mustang Thermactor Smog System What is it Worth?!?!? 2
D 1967 mustang 289 V8 headers 1965 - 1973 Classic Mustangs -General/Talk- 2
S Thermal clutch fan recommendations for 1966 Mustang w/ 289 1965 - 1973 Classic Mustangs -General/Talk- 1
dvelek 65 Mustang 289 Swap Engine or Rebuild Classic Mustang Specific Tech 7
1 1965 Mustang 5 bolt 289 C4 to Toploader conversion 1965 - 1973 Classic Mustangs -General/Talk- 5
C 66 Mustang 289 C4 Jumps into Reverse after Starting. Classic Mustang Specific Tech 12
B 1966 289 Mustang Overheating 1965 - 1973 Classic Mustangs -General/Talk- 8
W 1966 mustang 289 Balance mystery Classic Mustang Specific Tech 10
Cool Beans For Sale 1968 Mustang Radiator for 289 v8 Engine and Power Adder 0
R temp gauge on 1965 mustang 289 Classic Mustang Specific Tech 0
dvelek 65 Mustang 289 w/A/C Converting Stock Radiator to Aluminum 1965 - 1973 Classic Mustangs -General/Talk- 53
G For Sale 1965 Mustang Barn Find - Super Low Miles - 289 A Code Classic Mustangs For Sale 17
B 65 Mustang 289 Shorty Headers 1965 - 1973 Classic Mustangs -General/Talk- 0
D Vacuum advance line for 65 289 2v Mustang 1965 - 1973 Classic Mustangs -General/Talk- 2
H 1966 Mustang 289 flywheel info needed Classic Mustang Specific Tech 7
D 1966 Mustang 2bbl, 289, C4 disk brake conversion Classic Mustang Specific Tech 3
MoDriver SOLD 1964 Ford 260 C4OE Head, Mustang, Comet, Mercury Engine and Power Adder 1
B Hurst Shifter On Toploader 4speed (66 -289 Mustang Convertible) 1965 - 1973 Classic Mustangs -General/Talk- 7
G Looking For 65 Mustang 289 Complete Exhaust(headers Also) 1965 - 1973 Classic Mustangs -General/Talk- 3
G 65 Mustang 289 Exhaust 1965 - 1973 Classic Mustangs -General/Talk- 5
O 65 Mustang 289 Id Help 1965 - 1973 Classic Mustangs -General/Talk- 3
S New Member - Spark Plug Question (289) 1965 - 1973 Classic Mustangs -General/Talk- 5
cjstang6791 Engine '67 Mustang 289 V8 Loose Rocker Arm Polylock Nuts Wtf? Classic Mustang Specific Tech 2
cjstang6791 '67 Mustang 289 V8 Loose Rocker Arm Polylock Nuts Wtf? 1965 - 1973 Classic Mustangs -General/Talk- 2
cjstang6791 '67 Mustang 289 V8 Rocker Arm Poly Lock Nuts Keep Coming Loose. Wtf? The Welcome Wagon 3
E Can Someone Tell Me Which Engine This Is? 1965 - 1973 Classic Mustangs -General/Talk- 2
G Expired 1967 Mustang Coupe/dark Blue/saddle Interior/original 289 C Classic Mustangs For Sale 0
G 66 Mustang 289 Engine 1965 - 1973 Classic Mustangs -General/Talk- 4
B SOLD 1965 Ford Mustang Coupe 289 10,000 Classic Mustangs For Sale 1
I 65 mustang with a post 1970 289 Classic Mustang Specific Tech 6
R Mild 289 Build For 1966 Mustang Coupe Engine and Power Adder 4
S '68 Mustang 289 Coupe, $4,400 Classic Mustangs For Sale 1
A 1965 Mustang Fastback 289 V-8 Classic Mustangs For Sale 3
D swap 289 for 302 in 66 mustang automatic Classic Mustang Specific Tech 13
J Tri Y headers, 289-302 for 65-70 mustang Exhaust 2
S 64.5 Mustang Rangoon Red D Code 289 4 Speed Manual Classic Mustangs For Sale 0
FLStreetMachine 1964 Ford Falcon with 289 Mustang Motor Classic Mustangs For Sale 0
H 1965 mustang 289 swap for 351 1965 - 1973 Classic Mustangs -General/Talk- 1
199 1966 Mustang 289 Hot weather Engine Oil Advise & Suggestions Classic Mustang Specific Tech 4
S HIPO manifolds VS Long Tube Headers 289 65 mustang Classic Mustang Specific Tech 9
J 1965 mustang 289, automatic Classic Mustangs For Sale 0
R 1966 Mustang 289 missing timing indicator Classic Mustang Specific Tech 2
C 1965 mustang with a 289...where does the negative battery cable go? Classic Mustang Specific Tech 6
G 1968 289 Mustang - Valve lash? Classic Mustang Specific Tech 2
8 67 mustang 289 wont start not getting fuel?? Classic Mustang Specific Tech 1
KaraKedi About 1965 Mustang 289 A code 4V Engine (Fastback 2+2) Classic Mustang Specific Tech 4
Pbum5 Mustang Headers 289, 302 SB Ford Engine and Power Adder 1
R 66 Mustang 289 4BBl Carb Classic Mustang Specific Tech 1
jcavnet 68 Mustang 289 engine swap Classic Mustang Specific Tech 6
Similar threads