I changed the water pump on my slant 6 cause I'm looking to drive to a show this summer and my top water hose busted. I replace it with a new one but how do I know I'm not overheating. I have a temp gauge I gotta hook up but was wondering is a 4 blade fan enough to cool the engine that's the stock fan it came with. Seems like its always low on coolant. What do you guys think I wanna get the cooling good for the drive
cooling my slant 6
- Thread starter martin53
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Not sure what year you are working on so,here goes,, If you don't have a coolant return bottle then the system is constant loss. No problem with the 4 blade fan on a slant. Check thermostat, and radiator condition for blockage and or flow.When doing any repairs such as water pump replacement now would be the time to replace all hoses and flush the system then replace the thermostat. If the radiator checks out ok you should be good to go.
I might add, if you don't keep topping off the coolant, it will just stay at a constant level, well below the neck. When you fill it all the way to the neck when cold, it naturally overflows as the fluid warms up and expands, which makes the level look "low" again when you check it cold. So just leave it "low". This is assuming you don't have a leak somewhere.
Anyway, if you don't see a cloud of steam, you're probably not overheating.
Anyway, if you don't see a cloud of steam, you're probably not overheating.
nm9stheham
Well-Known Member
As above... what year? We can't give the right info without that.
With a non-overflow system, the coolant should be filled to about 1" or 1-1/4" below the bottom of the filler neck. This is specified in the FSM for the older, non-overflow cooling systems. Filling higher will just result in overflow and blowing out 'til it gets low enough.
If you DO have a coolant overflow, and the coolant is always low, then you could have some issue with the radiator cap, or even possibly a coolant leak into the engine.
How about hooking up your temp gauge! Cruising at 70 will show higher temps than cruising at 55 so don't be surprised if it goes up a bit on the interstate.
With a non-overflow system, the coolant should be filled to about 1" or 1-1/4" below the bottom of the filler neck. This is specified in the FSM for the older, non-overflow cooling systems. Filling higher will just result in overflow and blowing out 'til it gets low enough.
If you DO have a coolant overflow, and the coolant is always low, then you could have some issue with the radiator cap, or even possibly a coolant leak into the engine.
How about hooking up your temp gauge! Cruising at 70 will show higher temps than cruising at 55 so don't be surprised if it goes up a bit on the interstate.
TylerW
Well-Known Member
How do you know you aren't overheating? You hook a temperature gauge up.
Or, alternatively, you can operate your own game of chance and SEE what happens without hooking up the gauge. Maybe it'll run cool and you'll enjoy the entire summer, or maybe you'll overheat it 'till the point it's red hot. Then it seizes tight as a drum and your entire summer is RUINED.
If it came with a 4-blade fan then it's a non-air car, and yes it's enough to cool it provided you don't have a stopped-up radiator.
Two comments concern me though...busted hose and always low on coolant. Coolant only escapes two places...out on the ground or out the exhaust.
Or, alternatively, you can operate your own game of chance and SEE what happens without hooking up the gauge. Maybe it'll run cool and you'll enjoy the entire summer, or maybe you'll overheat it 'till the point it's red hot. Then it seizes tight as a drum and your entire summer is RUINED.
If it came with a 4-blade fan then it's a non-air car, and yes it's enough to cool it provided you don't have a stopped-up radiator.
Two comments concern me though...busted hose and always low on coolant. Coolant only escapes two places...out on the ground or out the exhaust.
I replace the hose and haven't had any issues. Its a 1978 d100 225 slant 6. Will any mechanical temp gauge work on these engines. The one hooked up was electical. Would a valve adjustment have anything to do with this. Thanks for the help
BillGrissom
Well-Known Member
For diagnostics, simplest is a Harbor Freight IR gun, or a "temp gage in radiator cap" (ebay). I don't know what a "mechanical temp gage" means. Mopars had either an analog gage (resistance vs temp sensor) or dash lamps (on-off switch sensor). My 65 Newport has "cold" & "hot" lamps from a single sensor. The switch type should work for any bulbs. The analog type must be exactly correct, plus your dash "voltage limiter" affects the reading.
If the valves are adjusted too loose, you will hear excessive clacking. If too tight, you won't get full compression. Either makes the engine runs less efficient which can cause over-heating. You should adjust valves every 30K miles or so, so "just do it". But, in 1978 you could have hydraulic lifters, which have no adjustments. They started around that time.
If the valves are adjusted too loose, you will hear excessive clacking. If too tight, you won't get full compression. Either makes the engine runs less efficient which can cause over-heating. You should adjust valves every 30K miles or so, so "just do it". But, in 1978 you could have hydraulic lifters, which have no adjustments. They started around that time.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Well, if youre planning a trip, theres lots of things to consider, like starting with a full tune-up.
However, a quit motor wont kill you. Bad tires,bad brakes or failing suspension bits , can. And could take out others with you. So I would suggest going over the chassis with a fine-toothed comb.
However, a quit motor wont kill you. Bad tires,bad brakes or failing suspension bits , can. And could take out others with you. So I would suggest going over the chassis with a fine-toothed comb.
2 Darts
A-body Addicted
The four blade fan should be fine. If you have reservations about it, try a viscous fan and a shroud from a car with A/C.
While tuning up the cooling system, check the lower radiator hose. I had a problem with the 73 /6 overheating at highway speeds (70-75 mph). Turns out that as I increased speed, the water pump's suction would collapse the hose. Part of the problem was that the spring in the hose had broken.
Another thing to check is the radiator cap. If coolant is kept under pressure, the boiling point is higher compared to coolant that is exposed to normal atmospheric pressure. IIRC, a properly functioning radiator cap will release somewhere around 16 psi. Don't use a NASCAR style 25 psi cap, it will probably blow off hoses secured by spring or screw clamps. lol
While tuning up the cooling system, check the lower radiator hose. I had a problem with the 73 /6 overheating at highway speeds (70-75 mph). Turns out that as I increased speed, the water pump's suction would collapse the hose. Part of the problem was that the spring in the hose had broken.
Another thing to check is the radiator cap. If coolant is kept under pressure, the boiling point is higher compared to coolant that is exposed to normal atmospheric pressure. IIRC, a properly functioning radiator cap will release somewhere around 16 psi. Don't use a NASCAR style 25 psi cap, it will probably blow off hoses secured by spring or screw clamps. lol
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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On an old slanty I would go the other way.
My 360 has run 15 years on a 7pound cap. Still has all the original hoses I installed in 99. And some of those, came out of the recycle bin. Only the bypass was new silicon, and new cheap heater hoses.
If I can get away with that on a 400plus hp engine, I imagine the slanty can too.I run a 7# cap on my 80 Volare/6 as well. 30 to 45 year old rads will thank you for it. And so will that short little nipple under the stat housing, that you have to remove the pump,to replace.
Yeah I know all about pressure and boiling points.But heres the thing ; Modern antifreeze/coolant are not very good at cooling. They are good at two things only; not freezing, and not wrecking aluminum stuff of which there is a preponderance of, on modern engines.To successfully run that stuff,at the modern elevated temperatures, and not boil it requires those, hose busting, gasket blowing, rad compromising, big pressures
I run the best applicable coolant there is; water. With a bit of additives in there for the pump seal, and the Eddies.Since the coolant actually does the job, high pressure isnt needed.
Theres only one downside. It has to come out before winter.Thats a very small inconvenience. I just reach in there and open the taps.
My 360 has run 15 years on a 7pound cap. Still has all the original hoses I installed in 99. And some of those, came out of the recycle bin. Only the bypass was new silicon, and new cheap heater hoses.
If I can get away with that on a 400plus hp engine, I imagine the slanty can too.I run a 7# cap on my 80 Volare/6 as well. 30 to 45 year old rads will thank you for it. And so will that short little nipple under the stat housing, that you have to remove the pump,to replace.
Yeah I know all about pressure and boiling points.But heres the thing ; Modern antifreeze/coolant are not very good at cooling. They are good at two things only; not freezing, and not wrecking aluminum stuff of which there is a preponderance of, on modern engines.To successfully run that stuff,at the modern elevated temperatures, and not boil it requires those, hose busting, gasket blowing, rad compromising, big pressures
I run the best applicable coolant there is; water. With a bit of additives in there for the pump seal, and the Eddies.Since the coolant actually does the job, high pressure isnt needed.
Theres only one downside. It has to come out before winter.Thats a very small inconvenience. I just reach in there and open the taps.
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