After coolant change - high temp at highway speed? 383 Charger

[euroz06]

Get used to the noise, don't believe that I have ever had a quiet rear-end. Some are just louder than others. It's either on accel, drive or coast.

ah... and here i thought something was wrong. I was having some noise (unless i point it out to my car friends, you couldn't really hear it) on light throttle. So I guess it might be normal. I'll change the diff fluid as i was starting to get some chatter at low speeds.

 

[Bird 426]

I personally will never use a synthetic oil my old cars rear ends again. Used it twice and leakage, thought the first was a fluke, but the second one changed my mind. If you have a sure grip rear end, don't forget to add the suregrip modifier.
Back to your cooling problem, hard to believe that you continue to have an air issue. I do nothing special and have never had a problem. ????

 

[Ron H]

so this past sunday, i poped my cap off, got the car idling, but didn't see too many bubles at idle. My idle temp seems to be around 190, so perhaps not enough? I steadily increased the revs to about 2.5k rpm (car warmed up a bit closer to 200), held there for about 30 seconds, and then released, went to look at the radiator and saw bubles coming out. I did it a few more times until i couldn't see the bubles anymore. Went for a drive (this time not highway, just in 1-2nd gear above 3k rpm), and im again overheating. ugh... I looked up burping on youtube, and they recommend raising the front of the car so the trapped air can escape, so i think i will try that next. Another question, with the radiator cap off, can I run the rpm's to 3k? I was a bit scared to do it at 2.5 for fear of it shooting out (im very new at this, so pardon for lack of knowledge... i looked at the manual, and they just use some old tool to do all this).

Going back to your first post, if the lower hose was replaced, it would have also drained coolant from the block, not just the radiator. If burping the system, or pockets of air dissipating, more coolant should have been needed to fill it up. Heater adjusted to max heat. When draining the system, was perfect time to flush (clean out) and could backflush the system. Did you notice a fair amount of gunky looking fluid when draining? There are kits for back-flushing. Simple things could include a faulty t-stat from age, or as also mentioned even the radiator cap. Though if it is the cap, you should notice serious leaking or lack of pressure build up. A system pressure test could be done. Another thing is looking at the coolant through the fill opening with the engine running, cap off, have a partner give it throttle or move the linkage by hand if safe to do, to see if it is ‘flowing’ when giving it a little throttle. Other culprit could be the water pump, usually noticed by coolant weeping thru weep-hole, or moving the fan fore & aft to see if there is any play, done with motor off (ok, just saying as you’re saying your new at this). A failing pump might make some extra noise too, sometimes it is a subtle ticking or rattling noise.

 

[twecomm]

Certainly flushing out the system can't hurt. if you don't know much history of the car, and due to age of the car, consider pulling the radiator and take to a radiator shop to have it checked and "boiled out" to get rid of residue and crap likely limiting flow thru the radiator. Also might want to consider getting a "Flowkooler" water pump and hi flow thermostat.

 

[BSB67]

Did the OP ever answer the question in post #18?

 

[euroz06]

Did the OP ever answer the question in post #18?

apologies, i used a premixed 50/50 solution (orange fluid for american cars).

To answer other questions, the car was restored 9k miles ago (10yrs ago), so most items are in a fairly good condition. I did have replace a fan clutch a few years ago, but since then it operates well (no overheating below 2.5k rpm - heavy traffic/90+ weather).

Before i did the coolant change, everything was working perfect for 7 years, no overheating what so ever (im in Miami, so always kept an eye on the heat).

 

[Ron H]

This answers some questions not knowing what the condition of things are; but 9k miles in 10-years leaves a lot sit time unless you have fired it up occasionally. Mine actually doesn’t get all that much more drive time being in the north…1200 or so miles a year. But if it has sat a few years w/o running it, not the best. When I’ve had gremlins after fixing, I think about what might have ‘changed’. All considered, with what you say was done, was replacing the lower hose and refilling the system. My guess, it could still be air pockets. When you burped the system, did you need to add more coolant? Usually if air pockets exist, adding more, sometimes a good amount, is necessary. Did you do this with heater on max (to run through the core)?

If it was me, I’d repeat the process and see if you might find more bubbling. I’ve had to do this over the years…repeat the drill. Takes a while only idling with cap off to get the engine up to temp opening the t-stat. I put my hand on the upper hose to see if it’s hot, indicating the stat has opened. Can use an infrared thermo if you have one...can monitor what temp the stat has opened.
Opinions vary, but I run a 30/70 ratio of coolant and use wetter. Did this doing research about coolants, they can retain heat, something you don't need in Miami, JMO.

 

[Rishi]

The hotter the coolant solution gets, the more it expands. But I think it tops out at +20% when the temperature gets above 300*F. I would not worry too much about overflow during your testing, unless the coolant is indeed getting darn hot.

If your coolant temperature stays near the thermostat temperature (190*F?) while the engine is overheating, I agree with others this seems like a coolant flow issue (through the engine), more than a cooling inefficiency fault by the radiator.

I have never, in many years of service, been bitten by this "air pocket" thing in the coolant system. If I thought I had an air pocket I couldn't remove, I would drain the coolant system and reuse the fluid if it's decent. I would then do a new and full engine flush. You could also replace the coolant using a coolant vacuum filler kit from Amazon, but you'll need an air compressor.

A few times when I've had to replace a freeze plug in a lower block, I would also do a rinse or flush - exiting out the open freeze plug, and using some micky mouse garden hose attachment on the heater box inlet hose. I was amazed just how much casting sand washes out. I think my record is about 2-cups of sand. Those blocks really seem to run cooler afterwards, too.

 

[euroz06]

Ugh. This is getting on my nerves. So, i got my big ol jack out, put the front of the car on stands, opened the cap, opened the heater valve, heat full on, and monitored. The top tube to the radiator was cold until about 186f, then it got hot (i assume thats when the thermostat opened). At idle, it sits at 190f. I started to give it some revs and holding them. Started with 2.5, hold for 15-20 seconds, then did 3k revs (did 3k revs multiple times). Initially i did see some bubbles come out (not a lot), but then after 20 minutes nothing was coming out… except my heater core developed a leak ‍ but never mind that, i closed the valve, i think ill be good.
Got the car out, at 2.5k rpm, no more over heating. At 3 rpm, it goes from 190, slowly to about 210 and stays there. At 3.5k (im in second gear doing pulls on a local bridge), it starts to go up, 215 and up to 220 (these are about 1-2min drives). Now i cant recall what it was like before at consistent driving at 3.5k rpm (i usually cruised at around 3k)… but is that normal? In my amg, my oil temp (not coolant) is 212f, after hard driving it does get to 217-220 (and i mean redlining it in a few gears multiple times).

Should it be cooler or this normal?

 

[440 4 speed]

apologies, i used a premixed 50/50 solution (orange fluid for american cars).

To answer other questions, the car was restored 9k miles ago (10yrs ago), so most items are in a fairly good condition. I did have replace a fan clutch a few years ago, but since then it operates well (no overheating below 2.5k rpm - heavy traffic/90+ weather).

Before i did the coolant change, everything was working perfect for 7 years, no overheating what so ever (im in Miami, so always kept an eye on the heat).

Late to the party!
I have had problems with over heating after draining/ flushing the system.
When an airlock occurs I loosen off the heater hose at the firewall, when some antifreeze starts to leak I tighten the clamp and the problem was solved.

 

[dadsbee]

Not ONCE, in my 48 years of fiddling with 64 to 76 mopars, have I ever had to burp a cooling system!

 

[440 4 speed]

Not ONCE, in my 48 years of fiddling with 64 to 76 mopars, have I ever had to burp a cooling system!

That is refreshing. I think I have probably done it 4 times.

 

[1967coronet]

Just to add to the mix, There are some real crap thermostats out on the market.
Some never open all the way blocking coolant flow.
You said you seen movment once it hit 186 . Is it a good flow ?
Most times after driving and a cool down cycle any air will have made the trip to the radiator and the level will have lowered a little.
With the only changes being the coolant , the lower hose and thermostat if this keeps running warmer than normal I would get a new thermostat ( stant) brand and check it in a pan of water on your stove.
I bet you got a bad thermostat.

 

[1STMP]

Engine timing will have an affect on coolant temps.
Could also be the vanes in the water pump are worn.
Compare the flow rate from a different car to yours.
(at the same rpms).