Thermostat: what is normal operation

[tequilaiam]

So now that the "Polar vortex 2.0" boogie man is upon us I've found my water temp doesn't get past 175 indicated.

The heater line is only luke warm. Thing is, so is the radiator supply hose and radiator.

Should a T-stat flow a little bit of coolant all the time?

the thing is only a month or two old. I bought and installed a "high flow" one from the local autozone to keep temps down after I did my turbo. I know it's a 195 T-stat.

It looks a lot like the one on the right in this pic:
http://www.dieselplace.com/forum/at...6-5l-diesel-cooling-upgrades-65dslstats02.jpg

It's a different design/shape than the style on the left, which is what I had when my temps were running high only a few weeks ago. The new one helped with the overheating but now I'm curious if it's always supposed to flow a bit of coolant or something and the aluminum radiator is just sucking every ounce of heat out.

Any insight is greatly appreciated! Otherwise maybe I'm pulling the fan off for the winter?

 

[whatadeuce]

+What vehicle are you referring to? For the M35, the coolant temperature must be maintained at 180 Fahrenheit at all times. The coolant temperature is a separate consideration in itself, separate from those conditions that determine exhaust gas temperatures. Suggest correcting the coolant temp, and then address the exhaust gas temperatures separately.

 

[MarcusOReallyus]

+What vehicle are you referring to?

Well, he's posting in the CUCV forum, so it's probably a safe bet he's not talking about a deuce. And he never mentioned anything about EGT, so....



tequilaiam, normal operation is CLOSED until it gets up to temp, then slowly opens. It's possible that you got a bad one - it's not that uncommon.

Did you test it on the stove top to see if it works properly?

 

[rickf]

I agree, it is opening too early or too fast and letting too much cold water in all at once which is bad for the engine. A proper operation would be opening slowly as the temp reaches 195 and the hotter it gets above that point the faster and farther open the stat gets.

 

[Mainsail]

I hope the OP doesn’t mind if I piggyback on his question, but I suspect my thermostat might need replacing.

Here’s what I'm experiencing:

- Little or no pressure under the cap. After an hour of driving I can take the cap off without getting a coolant shower.

- After a long drive up in the mountains (steep uphills then steep downhills), say an hour and a half or so, I will sometimes get the LOW COOLANT light and the coolant will be slightly low, maybe two or three inches down or about a half-gallon to refill.

- For short drives, and months of short drives, there is no coolant loss at all.

- Coolant looks like coolant and the oil looks like oil.

- Heat output in the cab with the heater full hot is adequate, but not as hot as I think it should be.

- The motor seems to be running great otherwise, although I don’t have anything to compare it to. It doesn’t seem to have much power on looooong steep hills, but I have no way of knowing if that’s abnormal or just the way the 6.2 w/3.08 gearing is.

A stuck-open t-stat would explain most of the symptoms, other than the coolant loss after working the motor hard. I suppose it could be going overboard through the overflow tank as I believe the tank leaks, but I don’t smell coolant and it looks dry.

Thoughts?

 

[MarcusOReallyus]

I hope the OP doesn’t mind if I piggyback on his question, but I suspect my thermostat might need replacing.

Here’s what I'm experiencing:

- Little or no pressure under the cap. After an hour of driving I can take the cap off without getting a coolant shower.

- After a long drive up in the mountains (steep uphills then steep downhills), say an hour and a half or so, I will sometimes get the LOW COOLANT light and the coolant will be slightly low, maybe two or three inches down or about a half-gallon to refill.

- For short drives, and months of short drives, there is no coolant loss at all.

- Coolant looks like coolant and the oil looks like oil.

- Heat output in the cab with the heater full hot is adequate, but not as hot as I think it should be.

- The motor seems to be running great otherwise, although I don’t have anything to compare it to. It doesn’t seem to have much power on looooong steep hills, but I have no way of knowing if that’s abnormal or just the way the 6.2 w/3.08 gearing is.

A stuck-open t-stat would explain most of the symptoms, other than the coolant loss after working the motor hard. I suppose it could be going overboard through the overflow tank as I believe the tank leaks, but I don’t smell coolant and it looks dry.

Thoughts?

Sounds to me like a bad cap, maybe? It's not holding pressure, so you are losing it (the coolant, I mean, not your mind. ) out the overflow.

Maybe a bad t-stat too. I think between the two of those, it covers your symptoms.

That's my story and I'm sticking to it! Until somebody comes along and points out the blindingly obvious that I've missed, of course.

 

[cucvrus]

I have an M1009 that does not put coolant in the oil or oil in the coolant. But it does use some coolant and pushes some of it out into the overflow. Most of the coolant I can recover and put back into the radiator. But some is lost. I know for a fact that it has head gasket issues. it does not stop me from driving it 2-300 miles on some days. I am aware of the issue with the head gaskets and just do the radiator fill on a daily basis. It is a task that needs to be done at this time. It really shows up in cold rainy days. I can see the left exhaust has a steam smoke screen coming from the left pipe. I am not real worried as I have other vehicles to drive. I am not 100% sure that is your issue but tend to think it may be. Get another over flow tank and see if it is pushing coolant. Mine has a hard upper hose the next day after driving it and I can hear bubbling and gurgling after short trips. Mine is a 1984 and runs and starts with out problems. I bought the new head gaskets and the new head bolts but will shelve them until the issue gets worse. I want to take a set of heads that I have and get them redone before I even think about doing this job. I have been living with this issue for 3 years and it has not gotten any worse. Pulling the heads is not on my favorite to do list. But I will do it someday. I even thought of just changing the engine as I have a few. Just my spin on your problem. Of course I can not 100% diagnose the issue 4K miles away. Good luck I hope it is something easier. But I wanted to put that out there.

 

[tequilaiam]

I hope the OP doesn’t mind if I piggyback on his question, but I suspect my thermostat might need replacing.

Here’s what I'm experiencing:

- Little or no pressure under the cap. After an hour of driving I can take the cap off without getting a coolant shower.

Thoughts?

original radiator?
a small leak in it may not be obvious until you're working the engine. so it doesn't leave puddles but seems to consume coolant and develops little or no pressure.

I had the same symptoms s while back. it would consume coolant and draw some from the overflow but never pressuize enough to burp air out.

I just made sure to check every once in a while and add some to the radiator every once in s while.

the good news is that you can buy a new aluminum radiator for less than it would cost to rebuild the existing core

 

[tequilaiam]

tequilaiam, normal operation is CLOSED until it gets up to temp, then slowly opens. It's possible that you got a bad one - it's not that uncommon.

Did you test it on the stove top to see if it works properly?

I was affraid of that. I didn't test the new one though I did with the old (it functioned as expected but still overheated). ugg, looks like I'm pulling it again. like the 10th time in 6 weeks.

 

[Mainsail]

original radiator?
a small leak in it may not be obvious until you're working the engine. so it doesn't leave puddles but seems to consume coolant and develops little or no pressure.

I had the same symptoms s while back. it would consume coolant and draw some from the overflow but never pressuize enough to burp air out.

I just made sure to check every once in a while and add some to the radiator every once in s while.

the good news is that you can buy a new aluminum radiator for less than it would cost to rebuild the existing core

Now that you mention it....

A year or so ago I had a small leak in the middle left side of the radiator, near the tank. I was waiting on the three-core aluminum radiator to show "in stock" so to tide me over I ran some dreaded stop-leak. That seems to have stopped the leak, but is not to say it stopped it completely.

The age of the radiator is indeterminate; I know the Army dropped a new motor in it at around 90K mikes, but what else they might have renewed along with it is a mystery. I at least hope the IP and fuel pump were renewed with the new motor but I don't know the protocol.

So here's my dilemma- I waited over a year for the three-core aluminum rad, and now it doesn't look like it's ever coming. They used to have "Coming soon" and now they don't even list it. So for a M1009 that isn't used to tow, operated in a temperate climate (it's rarely above 80⁰ and seldom below 30⁰), and not worked terribly hard, do I really need a three-core or will that two-core aluminum be sufficient?

 

[tequilaiam]

Well, I used this one:
http://www.genesisautoparts.com/product/all34763X2098aa.htm

And it seems fine. I took a peak inside and while it has only two rows the cross sections of the rows look thinner and more elongated than the oem one. So it has more cooling surface area than two rows of the original would. Not sure how it stacks up to the oem in terms of cooling capacity. But I figure that the original was reduced from corroded solder joints so the 2 row aluminum wouldn't be too much worse. And the new one would hold pressure to burp out all air.

My experience has been positive. After the turbo my leaky brass rad couldn't keep temps down and the aluminum one did.

But I haven't really given it much of a workout.

 

[tequilaiam]

I should note that the rad thickness is the same as the oem and that the two rows extend all the way back. So the core has the same effective thickness it's just flowing coolant across two longer skinnier tubes instead of 3.

I'm sure a mechanical engineer could do the math on the heat transfer

 

[cucvrus]

I just want to put this out there again. The Autozone replacement radiator has 4 rows and is warranted for life. I pull a trailer with my M1009 and it always runs cool. I travel a lot in north east PA and pull a lot of weight with everything stock on the M1009. Just an idea. The Autozone is a copper and brass 4 row. It is a direct OEM replacement. The choice is yours but i wanted to mention it. B850 Spectra Supreme $324.

 

[MarcusOReallyus]

do I really need a three-core or will that two-core aluminum be sufficient?

Don't assume "more rows = better heat transfer". It's not NEARLY that simple. The efficiency of a radiator is a very complex thing, and more is NOT always better. It might be, but it might not. It depends. "On what?", you say?

On a whole lot of other factors. Some of them are, positioning of the rows, thickness of the walls, material, quality of the joins (wherever there are joins), shape of the rows, quantity and shape of the fins, and more.

So, saying a 3 row is better at heat transfer than a 2 row is like saying that a V-8 is more powerful than a V-6.

And it's not even that simple.

The 4 row from Autozone that cucvrus mentions might be a much better radiator than a two-row aluminum. Or it might not.

So stop worrying about 2 versus 3 versus 4 row, and see what other people are running with good success.

Sounds like the Autozone rad is a hard deal to beat, though, with that warranty. And I know from Cherokee forums that a lot of people have been very happy with them.

 

[danoscooter]

tequilaiam what is the diameter of the tubes on the genesis radiator you got. Im in the market for a radiator and their website doesn't have those specs.

Thanks in advance.


Daniel

 

[Mainsail]

Sounds like the Autozone rad is a hard deal to beat, though, with that warranty.

A warranty is valueless if you never need it. So will I wear out the aluminum one or should I spend almost double for the warranty one?

Well, nothing is going to happen until after next week with the holiday so I'll noodle it a while more.

 

[MarcusOReallyus]

A warranty is valueless if you never need it.

Good point. But you will wear out the aluminum one eventually, if you keep the truck long enough. And if you pay more for something that is so well made that you never need to replace it, well, isn't that the point of advertising such a warranty? To demonstrate the quality?

Nobody gives a lifetime warranty for junk.

 

[scottladdy]

I've used the CU850 radiator twice now with excellent results. The only issue I had was it took several (like 5) attempts to get one that wasn't banged up in shipping the second time around.

For whatever reason, they would not ship the product in a proper shipping container. They simply shipped in the product packaging, which is not a certified container. Approximately 50 lbs. of thin copper and brass in a long, wide and flat configuration and you can guess how well it survived.

As such, it really depended on luck to get one in good enough shape to warrant installation.

Bonus, I did get to build a great relationship with the AZ staff as they were seeing me every couple of days.

 

[rsh4364]

I've used the CU850 radiator twice now with excellent results. The only issue I had was it took several (like 5) attempts to get one that wasn't banged up in shipping the second time around.

For whatever reason, they would not ship the product in a proper shipping container. They simply shipped in the product packaging, which is not a certified container. Approximately 50 lbs. of thin copper and brass in a long, wide and flat configuration and you can guess how well it survived.

As such, it really depended on luck to get one in good enough shape to warrant installation.

Bonus, I did get to build a great relationship with the AZ staff as they were seeing me every couple of days.

Im still waiting for a good one from AZ,ordered and paid for mine 12-9-14.So far count is 6 alum.ones and 5-6 damaged brass/copper ones.They told me today call tomorrow when Boss is here,doesnt sound good.

 

[cucvrus]

Hey Rick I just received mine today. It is in A1 condition. I have been waiting since mid December. I also received several that were damaged as we discuss before. This one is A1 copper and brass. The manager gave me a gallon of full strength Prestone anti freeze for being so patient. I told him it was just a spare for me and no big deal. I have 2 of the OM plastic and aluminum Harrison GM radiators. They are my favorites. but they are discontinued at this point. I hope you get yours soon. And keep in mind i still have that 87 K10 pick up. You can use that as your daily driver next winter. But a 425HP engine in it and run the pants off of it. No more winter diesel woos. Just and idea. good luck it is snowing out and the cash is flowing again. I burnt 1 of the plow trucks to the ground on Friday. 1988 K3500.