340 Overheat / Radiator Geyser

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mitch340Duster

mitch340Duster

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Yes I searched before posting. My 340 is a "fresh" motor but broken-in. The car has been plagued with issues so I'm just getting to where I can drive it more than just around the block. I've taken it out maybe 3 or 4 times and it's always been running real hot. 3/4 on the gauge or more. Tried some more defined troubleshooting today. After the last overheat last week, I topped-off the radiator. Today I cranked it up and coolant immediately discharged from the overflow hose. OK it was probably overfilled. After a while it stopped, but the temp quickly rose to 3/4 and hung right around there. Heat is hot. The radiator cap was OFF from this point on. There's some bubbling in the radiator but the level remained consistent. Another thing I noticed was it seemed like it wasn't circulating. There were a few specks of orange engine paint in the coolant that stayed right there at the opening the entire time. I let the car idle for 35 minutes and there was really no change. The gauge would creep up to just over 3/4 at times, and when increasing RPM's the temp dropped a little. HERE'S WHERE IT GETS GOOD...As soon as I shut it down, the radiator exploded like Old Faithful from the filler opening. Probably a 2-foot geyser. So bad that it would have been catastrophic if any of you goons trying to help had been peering down into the radiator. It blew out a lot of coolant, and then I could hear boiling from the motor.
This is a stock 340 rebuild. Recored radiator. Oil looks good. No steam from tailpipes. Has a fan clutch but the fan spins all the time. As I said I've had a real hard time getting this car to where it can be driven, and it's been a long time but I really think that this problem is not a "new" one, rather it has been this way since the rebuild.
I have no confidence that it's something like it being airbound, but only because I've had small block Mopars for 40 years and never had to deal with any of that. Thanks, guys !!
I do have IR thermometer data and video of the bubbling and the suspected lack of circulation if anyone wants to see it.
 
If it doesn't move coolant the thermostat is closed. Should be open at 3/4 gauge.

Take it out and put in a pan on the stove and see when it opens. To see if it is the problem.

Or just replace it anyway.

What is the temp below t-sat and the front of the heads?

Put the cap back on before you turn it off next time.
 
I want to see pictures of the setup and any geysers please.

This has been a “hot topic” for ages so prepare for some poking. Best case is ALL info that is related….. and there is a lot.

Cam
Timing
Dirty block?
Fan function
AFR
Thermostat?
Water pump
Shroud?
Spring in lower hose?
Rad cap highest point when refilling and burping.

Seeing no flow after thermostat is open is a red flag for sure
 
When hot.
Would you pls supply the Temperature from top and bottom rad hose fittings, not the hoses .
Where's timing set? - pls don't say "it's good". tia
 
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The fact it didn't geyser until you shut it off shows coolant was circulating... Depending on how the radiator inlet is baffled you may or may not see flow...
When you shut the engine off the coolant stopped flowing and the coolant in the block got heated to the point of turning to steam... Hence the geyser....

Two years ago I got a car back that I'd owned twenty years prior... The interim owner had complained about overheating since the 340 was rebuilt.... I'd hoping to drive it home from Texas but after driving around for a couple days it overheated so severely I thought I'd cracked a head or blown a head gasket.. Had it transported back to California & started running tests... Block, heads & gaskets are all fine... I tried lots of things... In the end the only thing that helped was adding more base timing... I have 34 degrees initial timing & I have the advance locked out... The engine runs right at 180 where the thermostat keeps it...

Try more timing & see if your 340 wants more....
 
Lean AF ratio (vacuum leaks)
Retarded timing

Will contribute to the HOT problem.

For every pound of pressure the boiling temp goes up by 3 degrees.

Put on a 16 lb cap
212 + 48=260 degrees until it boils.

There are so many un-answered questions on this vehicle.
 
The 3* increase...is that for straight water? Coolant? Or 50/50?
Thanks for that info btw.
413 said:
Lean AF ratio (vacuum leaks)
Retarded timing

Will contribute to the HOT problem.

For every pound of pressure the boiling temp goes up by 3 degrees.

Put on a 16 lb cap
212 + 48=260 degrees until it boils.

There are so many un-answered questions on this vehicle.
Click to expand...
 
Thanks everyone. I will try this again tomorrow with better info on timing and temps. I'm living in an apartment in Nashville now so I do the best I can with having no garage and all of my tools in storage. Here's answers to most of the questions posed so far...

Cam...Comp Cam basically a newer version of the stock cam. (hydraulic)
Timing..."it's good" I threw a light on it and the marks were visible. I was pissed because I didn't think to get my distributor wrench while picking-up the timing light from storage so I gave-up on that. I'll get the actual numbers on it.
Block/Heads...Recently rebuilt motor not more than .040 over. X heads.
Fan...Stock fan with clutch. Fan turns all the time. Clutch is not slipping
Radiator...Stock re-cored rad. 1WildRT mentioned baffling. Yeah, there is a baffle at the top so you can't see the fins/passages.
Shroud...Yes
Thermo...Have not removed/tested it yet
Lower hose spring...All newer hoses. I don't see any collapsing of the hose.
Water Pump...again, everything is new, BUT something that has been troubling me is that there is always corrosion around where the heater hose connects to the top of the pump.

The video is the only thing else I have to offer at this time. Thanks again. Can't do video here, so here's a YT link...

 
mitch340Duster said:
Thanks everyone. I will try this again tomorrow with better info on timing and temps. I'm living in an apartment in Nashville now so I do the best I can with having no garage and all of my tools in storage. Here's answers to most of the questions posed so far...

Cam...Comp Cam basically a newer version of the stock cam. (hydraulic)
Timing..."it's good" I threw a light on it and the marks were visible. I was pissed because I didn't think to get my distributor wrench while picking-up the timing light from storage so I gave-up on that. I'll get the actual numbers on it.
Block/Heads...Recently rebuilt motor not more than .040 over. X heads.
Fan...Stock fan with clutch. Fan turns all the time. Clutch is not slipping
Radiator...Stock re-cored rad. 1WildRT mentioned baffling. Yeah, there is a baffle at the top so you can't see the fins/passages.
Shroud...Yes
Thermo...Have not removed/tested it yet
Lower hose spring...All newer hoses. I don't see any collapsing of the hose.
Water Pump...again, everything is new, BUT something that has been troubling me is that there is always corrosion around where the heater hose connects to the top of the pump.

The video is the only thing else I have to offer at this time. Thanks again. Can't do video here, so here's a YT link...

Click to expand...

Video set to private. At any rate, when I first got my 64 Valiant, it did very similar. As soon as the thermostat opened and with the cap off, when I revved the engine, it would blast out of the radiator filler neck. If that's what yours does, I would have the radiator checked for flow. Mine was stopped up, giving the coolant coming into the top tank from the engine nowhere to go. Just because something is assumed good, means nothing. Keep that in mind. As soon as you say, "the radiator's good" you're setting yourself up. Keep an open mind.
 
Chk temp rating and function on tstat.
Coolant psi test(free rental from parts store?)
Is there a spring in lower rad hose? If not you can use a coat hanger.
 
RustyRatRod said:
Video set to private. At any rate, when I first got my 64 Valiant, it did very similar. As soon as the thermostat opened and with the cap off, when I revved the engine, it would blast out of the radiator filler neck. If that's what yours does, I would have the radiator checked for flow. Mine was stopped up, giving the coolant coming into the top tank from the engine nowhere to go. Just because something is assumed good, means nothing. Keep that in mind. As soon as you say, "the radiator's good" you're setting yourself up. Keep an open mind.
Click to expand...
RustyRatRod said:
Video set to private. At any rate, when I first got my 64 Valiant, it did very similar. As soon as the thermostat opened and with the cap off, when I revved the engine, it would blast out of the radiator filler neck. If that's what yours does, I would have the radiator checked for flow. Mine was stopped up, giving the coolant coming into the top tank from the engine nowhere to go. Just because something is assumed good, means nothing. Keep that in mind. As soon as you say, "the radiator's good" you're setting yourself up. Keep an open mind.
Click to expand...
Video was set to unlisted but I changed it to public. Thanks. Nope...Everything stays where it should when revving the engine. It only exploded out of the radiator when I shut the engine off. I do try to have an open mind, especially since I've had nothing but basically unexplainable issues with this car since almost day 1.
 
If the engine ran for 35 min...& there was no coolant flowing past the rad cap opening, it means the pump was not pumping...or the t'stat was jammed shut. Remove stat & test in boiling water. Check also there is nothing in the pump housing/t'stat housing that is stopping the stat from fully opening.

Make sure the impeller is NOT loose/spinning on the shaft.
 
mitch340Duster said:
Video was set to unlisted but I changed it to public. Thanks. Nope...Everything stays where it should when revving the engine. It only exploded out of the radiator when I shut the engine off. I do try to have an open mind, especially since I've had nothing but basically unexplainable issues with this car since almost day 1.
Click to expand...
How quickly after you cut the car off did the radiator expel coolant?
 
Bewy said:
If the engine ran for 35 min...& there was no coolant flowing past the rad cap opening, it means the pump was not pumping...or the t'stat was jammed shut. Remove stat & test in boiling water. Check also there is nothing in the pump housing/t'stat housing that is stopping the stat from fully opening.

Make sure the impeller is NOT loose/spinning on the shaft.
Click to expand...
Will-do
 
I'm going to try to do the timing this week. I can't open anything up with it at this point without breaking a lot of rules in the building, such as sneaking my hose through an opening in the trash room door, and connecting it to a faucet in the sprinkler room (no, it's not part of the sprinkler system) so I'll have to wait until Sunday now when maintenance and management are not here. I'm sure one of the lib****s in the building will rat me out anyhow though.
 
My guesses;
1) a restriction in the coolant supply to pump OR,
2) percentage straight water in the coolant is too low. and/or
3) a big ol' air-bubble trapped somewhere OR rad just not circulating properly

Easy test;
1) Drain the coolant, remove the rad, and cap the lower spigot. close the valve
2) check the bottom tank for a floating restriction, like a rag.
3) Place the rad into a tub with the tub-drain plugged, and fill the rad with tap-water.
4) rip the spigot cap off and make a note of how quickly the rad drains. and; make a note of the color of the exiting fluid. and make a note of how long it continues to drip. Pick it up and shake it, listening for water slosh.

Ideally; ALL the water will gush out in seconds, all be as clear as it went in, and the drip time is short, with NO slosh, and; the quantity of water that came out is about the same as what you poured in.

The tells;
If the water is greenish; obviously you flushed a pocket out.
If you hear water-slosh; obviously, water is trapped inside.
If the bulk of the water does not gush out, why?
If the drip time is long, why?
If the collected water that exited is not the same as what you poured in, why?
My guess for all three whys above, would be that the tubes are severely restricted.
---------------------------------------------------
Cool story;
About 35/40 years ago, I got drunk a party and had to spend the night. The temp overnight dropped like the proverbial stone, and the coolant in my rad gelled.
Next morning, this produced the same symptoms as you described. I had to take the rad out, and bring it inside to warm it up. The lady of the party-house, my younger brother's new wife, was NOT impressed.
After the rad thawed , I plugged it back in, filled it, drove home, with a stinking hangover, two baby girls in the back, and a sulking wife in the front. and once home, I upped the freeze-protection.
BTW-1
We were never invited back to that house again. Which was OK with us, cuz that women, altho gorgeous, was intolerable. They got divorced about a year later, and they did not procreate. That house was eventually bulldozed, and my brother died about 5 years ago. The girl? No idea.
BTW-2
The Swinger rusted out in the mid 80s, but that same 318 is still powering up my sons D100; and that same rad is still in use today, cooling my HotRod 367; and the 904 got built up as a clone of a trans I pulled out of a 71Demon-318, that I thought and still do, was the best shifting 904 that I ever had. Course I put a kit in it and a 2800 stall. Mu son got that trans too, and he loved it.
BTW-3
I warned little brother, never marry a barfly. I was right.
Little brother married again, to another barfly. I was still right.
They divorced, the wife taking two baby girls with her.
Finally, after Two divorces, he met a nice girl from a distant land and NOT a barfly. They never married. and never had kids. but they stayed together until my brother died of brain-cancer at age 60.

The end
 
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AJ/FormS said:
My guesses;
1) a restriction in the coolant supply to pump OR,
2) percentage straight water in the coolant is too low. and/or
3) a big ol' air-bubble trapped somewhere OR rad just not circulating properly

Easy test;
1) Drain the coolant, remove the rad, and cap the lower spigot. close the valve
2) check the bottom tank for a floating restriction, like a rag.
3) Place the rad into a tub with the tub-drain plugged, and fill the rad with tap-water.
4) rip the spigot cap off and make a note of how quickly the rad drains. and; make a note of the color of the exiting fluid. and make a note of how long it continues to drip. Pick it up and shake it, listening for water slosh.

Ideally; ALL the water will gush out in seconds, all be as clear as it went in, and the drip time is short, with NO slosh, and; the quantity of water that came out is about the same as what you poured in.

The tells;
If the water is greenish; obviously you flushed a pocket out.
If you hear water-slosh; obviously, water is trapped inside.
If the bulk of the water does not gush out, why?
If the drip time is long, why?
If the collected water that exited is not the same as what you poured in, why?
My guess for all three whys above, would be that the tubes are severely restricted.
---------------------------------------------------
Cool story;
About 35/40 years ago, I got drunk a party and had to spend the night. The temp overnight dropped like the proverbial stone, and the coolant in my rad gelled.
Next morning, this produced the same symptoms as you described. I had to take the rad out, and bring it inside to warm it up. The lady of the party-house, my younger brother's new wife, was NOT impressed.
After the rad thawed , I plugged it back in, filled it, drove home, with a stinking hangover, two baby girls in the back, and a sulking wife in the front. and once home, I upped the freeze-protection.
BTW-1
We were never invited back to that house again. Which was OK with us, cuz that women, altho gorgeous, was intolerable. They got divorced about a year later, and they did not procreate. That house was eventually bulldozed, and my brother died about 5 years ago. The girl? No idea.
BTW-2
The Swinger rusted out in the mid 80s, but that same 318 is still powering up my sons D100; and that same rad is still in use today, cooling my HotRod 367; and the 904 got built up as a clone of a trans I pulled out of a 71Demon-318, that I thought and still do, was the best shifting 904 that I ever had. Course I put a kit in it and a 2800 stall. Mu son got that trans too, and he loved it.
BTW-3
I warned little brother, never marry a barfly. I was right.
Little brother married again, to another barfly. I was still right.
They divorced, the wife taking two baby girls with her.
Finally, after Two divorces, he met a nice girl from a distant land and NOT a barfly. They never married. and never had kids. but they stayed together until my brother died of brain-cancer at age 60.

The end
Click to expand...
Great stories. I love stories. Sorry about your Brother. I never knew that our hobby was active in Antartica (gelled coolant). Thanks for the suggestions.
 
Update...Timing is now at 40 degrees total. I'm not sure what it was before I changed it (yeah I know), but the idle speed is lower now. No change. Meanwhile the gauge on my pressure tester that I went to storage yesterday to retrieve quit working, so there's that. Today I let it run only 15-20 minutes. This thing climbs to 1/2 on the gauge after only maybe 2 or 3 minutes. I have a thermostat and cap ordered. Temp gauge was just over half when I shut it down today. I did not get the dramatic immediate geyser, but coolant gushed out pretty good after only 2 or 3 seconds. Another big mess to clean on the roof. There is no spring in the lower hose. I have no air, water, or even electricity at my disposal here so I have to perform a 1-man bucket brigade from the 6th floor roof to my 1st floor apartment to be able to rinse stuff off. Thank God for Mr. Otis. As others have said, I-think something is plugged-up real good or the impeller is effed-up. The corrosion on the exterior of the water pump has me very curious. Remember I do the best I can with the resources available to me in an apartment in the city. Lots of pretty girls here in Nashville, though but none of them want me.
 
mitch340Duster said:
Lots of pretty girls here in Nashville, though but none of them want me.
Click to expand...
There is a MINIMUM of one girl for every guy in this world. You may have already met her, but maybe have already rejected her.
-----------------------------
You like stories? Brace yourself.
I met my wife in mid-December of 1975. I was already 22, to her 18. I rejected her. Too skinny, hair too short, Christian roots. Never thought about her again for maybe four months. Five months later, just after her 19th Birthday, spring of 1976, we shacked-up and a year later (April-1977) got married. Babies started coming in 1980/82/84. Last one left home in 2004. Eventually(mid 90s) we both became Christians.( me first for the win) We're still together, some 48 years later.
You never know the turns your life can take.
----------------------------------------
Here's an example;
Abraham lost his wife around age 130. Almost Immediately he took a new wife, who bore him another 6-pack of kids. Then he died at age 175.
Now think about that, Keturah produced six kids. (actually I seem to remember six sons and a daughter)
We know that today, women usually have lost all their best seed by age 40, and Sarah, Abe's first wife, barren her whole married life, laughed when told that she would have a child at about a hundred years old, implying that she was long-ago dried up. But nonetheless, Isaac was born nine months later.
Now, try not to imagine Abe and new-wife Katie, in the cool of the night, Abe being between three to four times as old as his new bride. Yeehaw!
The point is that you just gotta see something supernatural in that marriage. Abraham, obviously, was much loved.
You want a wife, just ask the spirit in the Sky who knows exactly where she is.
Give a testdrive to; John 14:10>15; Then keep your eyes peeled.
Oh yeah, stay out of the bars. Every guy I know who ever pulled a bride or brides, out of a bar, it went sour in a hurry. Two of them are on their Third wives.
>>Here's a hint; go check out your Cousins.
I didn't know it at the time, but over four decades later, we found out, that my wife and I are Fourth cousins. Suuuuuupernatural!
>>Noah's three sons, all blood-brothers, married sister-girls, fathered possibly by their grandfather, Methuselah. I think that would make them cousins once removed.
You think that there's any way that such a thing could NOT have been supernaturally orchestrated?
>> there is a sweetheart out there looking for you.
 
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mitch340Duster said:
Update...Timing is now at 40 degrees total. I'm not sure what it was before I changed it (yeah I know), but the idle speed is lower now. No change. Meanwhile the gauge on my pressure tester that I went to storage yesterday to retrieve quit working, so there's that. Today I let it run only 15-20 minutes. This thing climbs to 1/2 on the gauge after only maybe 2 or 3 minutes. I have a thermostat and cap ordered. Temp gauge was just over half when I shut it down today. I did not get the dramatic immediate geyser, but coolant gushed out pretty good after only 2 or 3 seconds. Another big mess to clean on the roof. There is no spring in the lower hose. I have no air, water, or even electricity at my disposal here so I have to perform a 1-man bucket brigade from the 6th floor roof to my 1st floor apartment to be able to rinse stuff off. Thank God for Mr. Otis. As others have said, I-think something is plugged-up real good or the impeller is effed-up. The corrosion on the exterior of the water pump has me very curious. Remember I do the best I can with the resources available to me in an apartment in the city. Lots of pretty girls here in Nashville, though but none of them want me.
Click to expand...

On one of those trips, if you shoot the rad imput/output temps when hot, and we know the new rad is doing its job of shedding 50*ish, then we can eliminate that and try other stuff.
If the rad is 180* ish at the top, and 170+*ish out the bottom, that would be a problem.
The blow back is kinda like the pumps doing its thing creating pressure while running, then when shut off, the pump pressure shuts off, and surges back.
We need some help here.
 
Inertia said:
On one of those trips, if you shoot the rad imput/output temps when hot, and we know the new rad is doing its job of shedding 50*ish, then we can eliminate that and try other stuff.
Click to expand...
My rad is not that good.
But it does maintain a spread of 30/35 degrees, which is enough in my system, because the Thermostatically-clutched fan is able to keep the high limit to 207.
The stat is a 195*, so it's like @mitch340Duster says; the temp scoots up in a hurry. But the fan catches it almost right away. In summer, the stat opens within the first mile. But I'll have to drive about two more before the aluminum heads are warm.
How do I know that?
Actually, I don't. But tell me if you agree.
Immediately after I get up to speed, I set the cruise by throttle-stop, to 62mph. A mile later it has climbed to 64; and another mile to 65/66, where it stays. Cruising rpm is 2240@65mph in GVod.
Oil in the A833 is 50/50 dextron-II/ 85-90 dyno EP.
Oil in 3.55 diff, IIRC is 85/115 dyno.
So I realize that "some" of the speed-increase is/may be, in the fluids coming up to temp. But, if you can come up with an alternate valid reason for the nearly 5% increase in cruising speed, with no change in timing, nor in throttle-opening, I'll try to be open to it. lol.
The point is that even a marginal rad can work, if the rest of the system is functioning properly.
So then, what is my definition of a good system, minus the rad?
IDK.
I can only tell you what works in my car.
>8-blade Hi-Flow pump which has the anti-cavitation plate on it.
I run mine slightly Underdriven, cuz I like to whack the throttle up to 7200 in first gear, which thru dual 3" exhaust and turn-downs, from the cab, is sortof visceral.
>Matching Hi-Flow stat which opens wide.
>A large diameter all-steel Seven-blade , direct drive fan, in a shroud.
>My hoses are molded, and the supply-hose was already ancient when I installed it in 1999. The lower has the anti-collapse spring in it. And I run a 7psi cap
> the bypass hose has a big restriction in it, so my in-cab-heater is the bypass.
>100% water is the best coolant, But once the system has been de-bugged, I reverted to the standard 50% glycol.
> Additionally, I run a 7qt roadrace oilpan with 5>6 qtsUS in it. and
> Fresh cold above the hood air, into the 750DP mounted on an AirGap intake.
>> The rad is out of a 74ish Dart 318/auto with A/C. Even the patches on it have patches. and it is mounted in the original unmodified slanty core support. IIRC it is a 26"rad in a 19" opening.
> My engine, by it's trapspeed (92mph@3450 pounds) in the Eighth is making 430 hp. It will idle all day any day at 700rpm@12>14 Advance, and will pull itself thru any car show at 500/550 rpm with just 5* advance, with the 10.97 starter gear..

The point is this;
IMO,
the rad is not nearly as important as many street-people think it is. It is just one piece among the many, on the list that makes up a system.
After the system was known to be adequate, I installed the Thermostatically controlled fan clutch.
 
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