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Cat 257B, losing coolant and no heat

Traut811

Active Member
Joined
Nov 22, 2020
Messages
37
Location
Bloomsdale, MO
Hi everyone. I need help with my 2004 Cat 257B, slk00416. It has right around 1600#. Before the answer from the title is head gasket, here's a background..

I recently sent off an oil sample to Fabick cat. The lady in the lab said my numbers indicate absolutely no coolant in the oil at all. I actually purchased everything I need to do a head gasket before I got the sample results back, but never did the change because of that. It is not puffing any smoke and runs fine, so I don't suspect coolant into the cylinder. It will drain an overflow tank of coolant in 2-3hr of use.

Problem number 2, I have not had heat in the machine since I bought used it at 1400#. I figured maybe the heater core could be leaking so raised the cab and all is dry up there. The shutoff valve above the engine is open, and line going to the heater core (I think) gets hot, but the other line (I assume return) stays cold. I assume this would mean a blocked heater core?? Both high and low speed of the fan work fine, but always cold air no matter what temp control is set on. I got the center duct out and shop vac/blew everything out really well. There was quite the mouse nest in there.

Maybe these are related, maybe not, but I do seriously appreciate any help or feedback anyone may be able to offer. Thanks in advance!
 

Arny L

Senior Member
Joined
Sep 23, 2020
Messages
277
Location
canada
Is it possible your getting combustion into cooling system, causing air lock in heater core circuit. When your engine is at operating temp, shut off, and look into overflow, look for small bubbles. If you know someone with a sniffer, you can place in overflow, or rad , and it can detect exhaust gas. Head gaskets don t always leak into oil.
 

Traut811

Active Member
Joined
Nov 22, 2020
Messages
37
Location
Bloomsdale, MO
Is it possible your getting combustion into cooling system, causing air lock in heater core circuit. When your engine is at operating temp, shut off, and look into overflow, look for small bubbles. If you know someone with a sniffer, you can place in overflow, or rad , and it can detect exhaust gas. Head gaskets don t always leak into oil.

Thanks for the reply Arny. I thought about this as well, and did not see any small bubbles in the overflow. I actually had my brother rev it up and looked in to see if I could see exhaust pushing, but will check it out when "off".
Good thinking on vapor locking the heater core, I never considered that. Even if so, would that cause the coolant to drop when using it? That may be a dumb question.
Step 1 would be make sure the coolant is passing through the heater core, right? It looks to be a huge pain to get to it (lift cab, pull off plastic around left control, pull duct work, pull plastic housing before you can see it). Can I pull the lines back by the engine and do anything? I assume I would not want to blow air though as it would evacuate all coolant in the core. Wonder if there's a bleed procedure for it?
I was subliminally hoping for a heater core leak which may solve the coolant loss and maybe no heat, but didn't see any coolant puddles when the cab was raised.
 

Nige

Senior Member
Joined
Jun 22, 2011
Messages
28,973
Location
G..G..G..Granville.........!! Fetch your cloth.
I know it's a pain but I think you will be into a complete disassembly of the heater system, along with all that entails (yes I know it's a pain but a good clean out of the duct work it might just surprise you the condition it's in), simply to rule out heater leaks as a possible root cause of the coolant loss. Until you start ruling stuff out as a possible source of a leak by pulling it apart and inspecting/testing it every idea you come up with is nothing more than speculation.
 

Traut811

Active Member
Joined
Nov 22, 2020
Messages
37
Location
Bloomsdale, MO
I know it's a pain but I think you will be into a complete disassembly of the heater system, along with all that entails (yes I know it's a pain but a good clean out of the duct work it might just surprise you the condition it's in), simply to rule out heater leaks as a possible root cause of the coolant loss. Until you start ruling stuff out as a possible source of a leak by pulling it apart and inspecting/testing it every idea you come up with is nothing more than speculation.

Yes you are correct on only speculating until I can get my hands on the heater core. Do you know if coolant should be, under normal circumstances, flowing through the heater core at all times? The fan speed is independent but for the heat control knob, I didn't know if this was an internal valve like a thermostat that would open and close the coolant flow, or if it controlled an external damper.
If my line in is hot at operating temp and line return is cold, and nothing else is in the system such as valves or anything, it's clear that the core is stopped up or a line is kinked. I'll report back when I can get the cab raised again and start tearing into that portion.
 

Nige

Senior Member
Joined
Jun 22, 2011
Messages
28,973
Location
G..G..G..Granville.........!! Fetch your cloth.
There is an electrically-controlled valve down by the heater core that is known to fail. Post a Serial Number and I'll see if I can find an illustration applicable to your machine showing where it is.

Edit: Sorry you already did that. Here's the illustration. Are you sure the valve #6 is open..?

upload_2020-11-24_16-26-38.png

The electrically-controlled valve is #7.

upload_2020-11-24_16-27-56.png
 

heymccall

Senior Member
Joined
Feb 19, 2007
Messages
5,349
Location
White Oak, Pa
Heater valve is mechanical butterfly (like throttle or choke in carburetor). With perimeter O-ring on butterfly. So, heat off= no circulation.
Typical failure is loss of butterfly O-ring, resulting in always heat.
Cab up.
Remove crossover vent duct.
Remove 4 bolts from lower frame to box.
Tilt box inward.
Remove 10 clips.
Remove inner cover.

20201124_112643.jpg 20201124_112707.jpg
 
Last edited:

Traut811

Active Member
Joined
Nov 22, 2020
Messages
37
Location
Bloomsdale, MO
You guys are awesome, thank you.
Nige, the valve back by the engine is open for sure, that was the first thing I checked. That should be why I'm getting hot coolant up to the cab at least.

For what it's worth, I'm going to order that mechanical valve and a radiator cap (for coolant loss). Both are inexpensive and that way I can change out the valve when I pull the heater core and flush it.

On the cap, another thought is if it's somehow steaming out passed the seal it could be losing there. If that doesn't work and it isn't building pressure from a cold start in the radiator after a couple minutes, I think I can rule out head gasket.

I'll order parts now and hopefully get to this stuff over Thanksgiving break.
 

Arny L

Senior Member
Joined
Sep 23, 2020
Messages
277
Location
canada
If your losing that much coolant in 2 to 3 hrs, would you not see some indication of a leak, either in cab or on ground. I have seen slow leaks, that are hard to detect, because the eng heat cooks it off before it hits ground. Have you done a pressure check. When you determine that there are no leaks, and nothing is getting in oil, the only place it can go is out the exhaust pipe. I hope you find a leak.
 

Traut811

Active Member
Joined
Nov 22, 2020
Messages
37
Location
Bloomsdale, MO
If your losing that much coolant in 2 to 3 hrs, would you not see some indication of a leak, either in cab or on ground. I have seen slow leaks, that are hard to detect, because the eng heat cooks it off before it hits ground. Have you done a pressure check. When you determine that there are no leaks, and nothing is getting in oil, the only place it can go is out the exhaust pipe. I hope you find a leak.

I have not done a pressure check. I'll do some calling and see if anyone local can help me out with testing that.
 

Traut811

Active Member
Joined
Nov 22, 2020
Messages
37
Location
Bloomsdale, MO
Well, the heater core isn't fun to get to. It shouldn't be too bad but if course the last of the 4 captured nuts rounded holding the heater box on so couldn't completely remove it, making getting all 10 clips off difficult. I pulled everything and ran a garden hose through it. It was all functioning fine, turn the heat knob down and flow almost completely stopped, turn heat up and flow increased a lot. I worked the valve several times and reversed the flow of water and at one point the flow would not pick up. I may have messed up the valve or it could have been messed up, not sure, but regardless I now know the core is clear and am waiting on the new valve since I pulled this one apart to look inside. The butterfly valve did have a chunk of oring missing but nothing at this point explains why coolant was not circulating though, unless vapor locked as previously suggested?

Having a tough time finding an oring to fit the heater core hose by the valve. Looks like it might be a 19x1.75 or something, I only have 19x2 and 2.5 both were too thick so I'll have to do some hunting tomorrow.


On compression into coolant, I started and let the machine run for probably 4 minutes. While running I pulled the radiator cap and there was a little pop of pressure when I did. Guess I should have done this when it was not running but wouldn't think the thermostat would be open already after just a few minutes to build pressure.
 

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Traut811

Active Member
Joined
Nov 22, 2020
Messages
37
Location
Bloomsdale, MO
Just an update on this:
I got the heater core back together last night and cab back down. It should have been straightforward but kind of sucked. In conclusion, there was nothing wrong with the heater core assembly that I saw and everything should flow free. The mechanical heat butterfly valve was replaced while I was in there. I'm 81% positive it is vapor locking as Arny suggested.
I'm taking it to a local mechanic who services several quarries this weekend. He is going to pressurize the coolant system and I'll see if he has a sniffer as well.

Sounds like it might be a head gasket. I'm bummed about the heating system not having anything wrong with it, but happy at the same time as it would reinforce that head gasket may be the root cause.

I took several pictures if anyone sees this thread and needs help working on anything.
 

Arny L

Senior Member
Joined
Sep 23, 2020
Messages
277
Location
canada
Well thats not the best news I suppose, but at least you know your going in the right direction.
 

Traut811

Active Member
Joined
Nov 22, 2020
Messages
37
Location
Bloomsdale, MO
Just an update for everyone.

I have been kicking around replacing the machine and a couple local guys contacted me and said they heard I might sell the 257b. I have been really tied up so took it to the local guy to just go through everything so there is nothing at all wrong with it. There were a few things.

The heat still wasn't working, and he was thinking it might be vapor locked from a HG but unsure. He put pressure on the system, and it dropped a little but couldn't tell where from. Shoved a piece of cardboard between the fan and radiator and could see where it was coming out of one of the radiator cores and dripping onto the cardboard. With the fan blowing it would disperse into the radiator, so I could never tell. Pulled the radiator and it was obvious where one section was caked with dust. Got the radiator fixed, threw it back on, and the heater still didn't work. I don't remember exact numbers but feed coolant line was ~95 degrees and return line was around 85 degrees so he went to check the thermostat. There was no thermostat there, so the machine could never get to operating temp to blow hot air as it was always circulating. I guess the previous owner had the same thing and tried bypassing it thinking it would work.

So in total, a thermostat, radiator patch job, few seals for a oil filter housing leak and some coolant and it's back to 100%, and heating up the cab pretty nicely. He said everything looks good on it and I'm glad I didn't pull it apart for a head gasket because it wouldn't have fixed anything. Correct diagnosis goes a long way before throwing parts at something.

I really want to get a 257D (huge fan of the MTL for what I need it for) or a 259D, but may have to switch over to a T595 because of the cab height. The D series are 4 inches taller than my 257B and I wouldn't be able to fit it in my low clearance basement garage if needed.

Anyway, thank you to everyone for the help. If anyone is pulling their heater core and needs help, send me a message.
 
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