CUCV cab heater core multiple failures resulting in leaking of heater core into cab

[bimota]

Ok, what other symptoms would be apparent if my multiple heater core failures are due to electrolysis, bad grounding or other issue. Would not the radiator also erode out in short order? Would not other issue appear? This truck runs fine, no issues, no electrical issues, no radiator issues - just failing heater cores. I'm not saying you are blowing smoke - just trying to not chase ghosts.

 

[doghead]

http://www.4s.com/Upload/Four Seasons/documents/Tech Tips/English/4S 350 ELECTROLYSIS.PDF

Try Googling, "repeated heater core failures".

 

[MarcusOReallyus]

You could try adding a ground wire between the core and a good body ground?

This is A Very Good Thing. Better yet, ground the radiator and heater core together to the same good body ground. In the marine world, they call this "bonding". No, it's not a touchy-feeley thing. The idea is to make sure all parts of the cooling system are at the same electrical potential. If there's no voltage difference, there's no galvanic corrosion. (It's NOT "electrolysis", folks!)

Have you ever checked your coolant PH level?

Yep, that's the other thing to check for.


As for eating a heater core in a few weeks.... I dunno, that seems pretty extreme to me. BUT!

Have you checked your voltage? I've read that just a tenth of a volt is enough to trash one in a few months.

 

[bimota]

http://www.4s.com/Upload/Four Seasons/documents/Tech Tips/English/4S 350 ELECTROLYSIS.PDF

Try Googling, "repeated heater core failures".

Ok, interesting: here are two paragraphs that I find key from my Google search.

In most cases, leakage occurs at the heater core tank or close to it, from the pulsation of a high coolant flow rate. Some heater cores have been designed with inlet plates that distribute the flow to minimize the problem. But the usual fix is a flow restrictor in the inlet hose, or perhaps the outlet neck on the engine. If the issue is identified at the factory, a flow restrictor will be installed in production, or released afterward with a service bulletin. And even if one wasn’t originally used or offered, you can obtain a restrictor and install it in cases of repeat heater core failures.
When a heater core leaks after short life, and the leakage is from pinholes in the core itself, well yes, it could be electrolysis. Coolant laboratory operator Ed Eaton, however, has said repeatedly that it’s a rare occurrence, possibly caused by the use of different metals in the cooling system. But if it’s an OE system, that issue was covered in engineering, he has added.
So I'm thinking coolant flow restrictor - why because I get big failure after a few weeks - no pin holes or other signs of electrical current slowly eating away - like a boat propeller. I get liters of fluid flowing out the right side of the cab after highway run at 55mpg for 2 plus hours. I pull off to Denny's and I come out after oatmeal and pancakes and there is coolant all down the parking lot.

 

[Nathanater]

CUCV cab heater core multiple failures resulting in leaking of heater core in...

Better off just doing a test to see if you have current going through it. It doesn't take long for water to drain out of the system, it's not like it's molasses. If you haven't played with electrolysis, then it would be hard to understand that not all metals are suitable. Stainless steel is one of the most durable while aluminum and tin don't last very long. Takes less than a minute to do the test. My coolant starts flowing current when the glow plugs are on and the motor off. So, I plan to setup my glow plugs on a switch.

And ground everything better. It's 30 years old, military, and I doubt the engineers knew about this issue back then.

 

[tim292stro]

One thing to watch for is the main power return paths. In a 12V negative ground vehicle, the vehicle chassis is assumed to be the ground return path - every thread where electrical problems are discussed, you will see at last one poster mention that you need to check your grounds.

WARWAG: Having 0.22V of the power (on a 24V system that's 1%), come back through the cooling water is REALLY bad.
Nathanater: Check your engine to battery ground strap, and make sure your ballast resistor (if you still have the 24/12V system) isn't corroded or shorted to ground. Then check that the glow plug controller and contactor/relay is properly grounded.

For an electrical system, we want to keep all currents in metal that was intended to carry current - this goes for any electrical system; Car, Boat, Truck, Airplane, or Building (Home, Office Building, Industrial Plant, etc...). You get a voltage in water if there is a voltage potential from one point to another, and this indicates that there is a resistance, or something that is preventing the flow of power between those two points which causes the current to find another path of least resistance (and if it uses the water, that means the water is more conductive than something else). Galvanic corrosion is caused by dissimilar metals in contact with water, this simple mechanism causes a current to flow - but changing the chemistry of the water (specifically the pH or the compounds in it) can increase the ease at which electrons flow (current).

If you disconnect your battery (engine not-running, ignition off), and you see a voltage between the water in the radiator and the battery negative terminal, then your water and the cooling system components are likely a direct cause - flush your water system, put in a sacrificial anode (zinc), and put in fresh water (or use pre-mixed 50/50 antifreeze). If you mix your own, and your tap water is "hard" or more acidic, you would be better served by using distilled water (not de-ionized water) to fill your cooling system. Flushing is a good idea too since with age and galvanic corrosion and just general vibration, you can have small metal particles in the water which will improve the conductivity of the water, almost as much as the pH being off. Also, you are draining and replacing your coolant every two years... right?

If you connect your battery (again engine not running, but this time ignition on), and you see a voltage, try pulling all of your fuses and check again. If your fuses are out, there should be no systems powered - so it could be a main feeder cable that is shorting somewhere (or about to short). Then one-by-one install your fuses, turn on the load attached to that circuit, and check your water for voltage. If one circuit causes the water to show a voltage, then you should have narrowed it down to that circuit and its loads. Check the wires for cracks, and all of the devices on that circuit (switches, motors, light bulbs, etc) for good clean grounds. If you find one bad circuit, don't stop looking! Fix that one so the voltage in the water goes away, but then continue checking the other circuits until all the fuses are re-installed. Then start your engine and check again. This time you have the charging system in the loop (alternator generating power) so this should show the quality of the grounds for that system. Then with a helper, and with FIRM pressure on the brake pedal, shift the transmission through the ranges and put tension on the drive train (idle or very low throttle is good). This will make the drive train and suspension a good ground path by pressing shafts against bearings, gear teeth against gear teeth, and shifting anything that is held by a rubber isolator towards a metal mounting point (you might see this as a wonky gauge going down the road). If any voltage appears in your water here, that means your engine/transmission-to-chassis-to-battery grounds are spotty (i.e. engine mounts make terrible grounds ).

In general, you should have a thick cable from the battery positive to the alternator, and a cable from the alternator or battery positive to the starter motor. There should be a cable from the low-battery (if you kept your 24/12 system) negative to the engine block, and another cable either from the low-battery negative or the engine block to the frame/chassis. One last cable should go to the main fuse block from the appropriate battery.

Anything that is not specifically a + voltage input on a device (or the wire to the fuse to the switch to the device) should be grounded either through mounting holes, or even better, with a dedicated ground strap. The direction that the current passes is also very important - if your water can be a path to ground, you need to break that circuit; insulate the heater core from the body, and provide a return strap to the engine block, and do the same for the radiator, insulating it from the body and core support, and only include a good strap to the engine block. This makes it impossible for the current from the body or frame to pass through the water circuits on the way to the alternator, and ensures that all parts of the water system are at the same voltage potential (and if you strapped your engine to the frame to the battery - that should be "ground" or 0-volts).

In an ideal world you would want to be able to map out your electrical system and have it look like a tree - where the truck hits the ground is your battery and alternator, and every branch out from the trunk should have a fuse - and no branch should touch any other branch once it's split. Your positive and negative distribution should be mirrors of each-other. If power goes from a device on the engine to the chassis, there should be a ground from that device to the chassis. If power goes from a device on the chassis to the body, there should be a ground from that device to the body.

All of your painted surfaces should be maintained so that the "presence of water" is prevented at the metal - which will act to limit the electron movement (galvanic corrosion). There are certain metals that when in contact will lose electrons and thus material mass (these are anodes) to the other metal (these are cathodes). Picking fasteners (bolts, nuts, screws) that are compatible with the surfaces that they are attached to is important too. You want a larger anode surface or mass to be in contact with a cathode.

In fact, MIL-STD-889B Notice-3 has some good guidance about material compatibility, and I see it referenced frequently in the private sector. This spec has a handy chart that show how a large list of common materials interact with each other in different environments.

 

[Adrian A]

That info is priceless! That is great detail and we'll written. Thank You.

 

[Nathanater]

One thing to watch for is the main power return paths. In a 12V negative ground vehicle, the vehicle chassis is assumed to be the ground return path - every thread where electrical problems are discussed, you will see at last one poster mention that you need to check your grounds.

WARWAG: Having 0.22V of the power (on a 24V system that's 1%), come back through the cooling water is REALLY bad.
Nathanater: Check your engine to battery ground strap, and make sure your ballast resistor (if you still have the 24/12V system) isn't corroded or shorted to ground. Then check that the glow plug controller and contactor/relay is properly grounded.

For an electrical system, we want to keep all currents in metal that was intended to carry current - this goes for any electrical system; Car, Boat, Truck, Airplane, or Building (Home, Office Building, Industrial Plant, etc...). You get a voltage in water if there is a voltage potential from one point to another, and this indicates that there is a resistance, or something that is preventing the flow of power between those two points which causes the current to find another path of least resistance (and if it uses the water, that means the water is more conductive than something else). Galvanic corrosion is caused by dissimilar metals in contact with water, this simple mechanism causes a current to flow - but changing the chemistry of the water (specifically the pH or the compounds in it) can increase the ease at which electrons flow (current).

If you disconnect your battery (engine not-running, ignition off), and you see a voltage between the water in the radiator and the battery negative terminal, then your water and the cooling system components are likely a direct cause - flush your water system, put in a sacrificial anode (zinc), and put in fresh water (or use pre-mixed 50/50 antifreeze). If you mix your own, and your tap water is "hard" or more acidic, you would be better served by using distilled water (not de-ionized water) to fill your cooling system. Flushing is a good idea too since with age and galvanic corrosion and just general vibration, you can have small metal particles in the water which will improve the conductivity of the water, almost as much as the pH being off. Also, you are draining and replacing your coolant every two years... right?

If you connect your battery (again engine not running, but this time ignition on), and you see a voltage, try pulling all of your fuses and check again. If your fuses are out, there should be no systems powered - so it could be a main feeder cable that is shorting somewhere (or about to short). Then one-by-one install your fuses, turn on the load attached to that circuit, and check your water for voltage. If one circuit causes the water to show a voltage, then you should have narrowed it down to that circuit and its loads. Check the wires for cracks, and all of the devices on that circuit (switches, motors, light bulbs, etc) for good clean grounds. If you find one bad circuit, don't stop looking! Fix that one so the voltage in the water goes away, but then continue checking the other circuits until all the fuses are re-installed. Then start your engine and check again. This time you have the charging system in the loop (alternator generating power) so this should show the quality of the grounds for that system. Then with a helper, and with FIRM pressure on the brake pedal, shift the transmission through the ranges and put tension on the drive train (idle or very low throttle is good). This will make the drive train and suspension a good ground path by pressing shafts against bearings, gear teeth against gear teeth, and shifting anything that is held by a rubber isolator towards a metal mounting point (you might see this as a wonky gauge going down the road). If any voltage appears in your water here, that means your engine/transmission-to-chassis-to-battery grounds are spotty (i.e. engine mounts make terrible grounds ).

In general, you should have a thick cable from the battery positive to the alternator, and a cable from the alternator or battery positive to the starter motor. There should be a cable from the low-battery (if you kept your 24/12 system) negative to the engine block, and another cable either from the low-battery negative or the engine block to the frame/chassis. One last cable should go to the main fuse block from the appropriate battery.

Anything that is not specifically a + voltage input on a device (or the wire to the fuse to the switch to the device) should be grounded either through mounting holes, or even better, with a dedicated ground strap. The direction that the current passes is also very important - if your water can be a path to ground, you need to break that circuit; insulate the heater core from the body, and provide a return strap to the engine block, and do the same for the radiator, insulating it from the body and core support, and only include a good strap to the engine block. This makes it impossible for the current from the body or frame to pass through the water circuits on the way to the alternator, and ensures that all parts of the water system are at the same voltage potential (and if you strapped your engine to the frame to the battery - that should be "ground" or 0-volts).

In an ideal world you would want to be able to map out your electrical system and have it look like a tree - where the truck hits the ground is your battery and alternator, and every branch out from the trunk should have a fuse - and no branch should touch any other branch once it's split. Your positive and negative distribution should be mirrors of each-other. If power goes from a device on the engine to the chassis, there should be a ground from that device to the chassis. If power goes from a device on the chassis to the body, there should be a ground from that device to the body.

All of your painted surfaces should be maintained so that the "presence of water" is prevented at the metal - which will act to limit the electron movement (galvanic corrosion). There are certain metals that when in contact will lose electrons and thus material mass (these are anodes) to the other metal (these are cathodes). Picking fasteners (bolts, nuts, screws) that are compatible with the surfaces that they are attached to is important too. You want a larger anode surface or mass to be in contact with a cathode.

In fact, MIL-STD-889B Notice-3 has some good guidance about material compatibility, and I see it referenced frequently in the private sector. This spec has a handy chart that show how a large list of common materials interact with each other in different environments.

Ok so. I've had 0.30 with only the ground wires attached to the battery. Three posts disconnected!!!! Only one touching was the ground! How does that make any sense?? One thing I want to do is make the radiator and heater core isolated from being grounded but that'll take a little time.

I need to do another radiator flush and use RO water or just get the premixed stuff. I bet I'll just put 2$ in the machine and use that.

Either way, if I can get a different diesel for cheap I'll repower it. It needs a tranny anyway. I'm looking for 7.3L ford, 6.5L Chevy to whatever, dodge 4bt to 5.9L or a 6.7L cummins, 5.2L Isuzu, ANYTHING THAT HAS MORE POWER THAN THE 6.2 and is more reliable and better MPGs. I've even thought about the 8.3L cummins, and even up to a 15L semi motor. ****, even a poor running 5.9L or 7.3L will work.

I'm not new to diesels. I understand working on the old military vehicles but if I get the chance to swap with something that'll make more power out of the box then I'll change it out In heartbeat.

So if anyone close to Lubbock, Texas has something decent in a diesel and wants to get rid of motor and trans for less than $1k let me know. If not, I'll run it how it is on the trails this year and maybe next I'll find something dirty next year. (Dirty being more power)

I've seen several 7.3L fords go to auction with 4x4 and 230k miles and only bring $800 for the whole truck! The 7.3L fords are just getting warmed up at 200K. For what I want to do it could get another 250K easy!

Anyway. Enough rambling!

 

[tim292stro]

What meter are you using? Do you know what metals the probes are made out of?

Normally with a reading that high (it's still very low by multimeter standards), I'd double check that you are getting a good reading first. Try shorting the leads together to make sure it zeros out, and then try reversing the leads (battery to water) to see if you get a stable -0.3v reading, then check battery negative to the engine block, and most importantly the water to engine block and water to radiator voltages.

The next step you might want to do is to get an anti-freeze test kit to check the acidity of the coolant, when there is a good current flow, the coolant's corrosion inhibitor chemicals wear out and the mixture will start to yield ammonia - which is very corrosive, and has a highly acidic pH (acids and bases are very conductive, and promote electron mobility between dissimilar metals - this is why your battery has acid in it!!). Basically what I'm getting at is that if you have a fault in your electrical system that turns your coolant into an acid bath, you can actually be making your cooling system into a battery .

The electrical tests I recommend should be done after new anti-freeze has been correctly installed after a flush. Fill and run the engine with water a few times (water should have a nice neutral pH of around 7 which you can check - and ideally not be contaminated with minerals, and don't use hard water you have to add salt to in order to soften!!), then fill with a known good batch of 50/50 coolant/water.

If your coolant is going bad very fast, I'd pay extra attention to the ground strap from the battery to the engine block - this is going to be the highest current path since it carries the power for the alternator starter and glow plugs. And what I mean by pay extra attention is that you should remove it and bench test it - there should be almost no measurable resistance from one end of the strap to the other, and it shouldn't change when you bend the wire. A jacketed strap can hide corrosion, broken wires, etc. Make sure the contact surface on both ends of where you attach it is clean bare metal, and once you attach the cable, put some of that battery terminal protection spray on the bolted-down ends to keep them clean.

This is what I found when I picked up my truck, and it explained a lot of problems I had with the truck very quickly:


I wouldn't be putting forth a full effort if I didn't ask: You don't have a stereo with one or more of those ultra-capacitors in that truck do you? (hint: if you do, you need to discharge that before you take readings since it will act like a battery )

 

[Nathanater]

I don't know what the probes are made of. It's a cheap harbor freight meter. I took apart the whole ground setup apart and cleaned it. Next time it warms up I'll flush it several times with good water and get a ph tester.

 

[Kawgomoo]

If there's no voltage difference, there's no galvanic corrosion. (It's NOT "electrolysis", folks!)

I both agree and disagree with this. You must be from NNSY or similar, because i received the same training. Galvanic corrosion is an electrochemical process that creates electricity. like a battery, or dissimilar metals of a boat sitting in salt water corroding by creating their own voltage. this is galvanic corrosion.

In our autos, the differences in the metal arent really a problem UNTIL electoral current is applied from the battery or alternator. This is electrolysis because you are supplying the current thats causing the problem.

Take a boat with a galvanic corrosion problem. Remove all the batteries, leave it in port. It will still rot away. Put zinc on it, well you didnt solve the problem you just gave it a sacrifice. Can a boat suffer from both? Sure. Happens from shore power all the time.

A john boat sitting in salt water with zero electrical systems on board will still suffer from galvanic corrosion. And will benefit from zincs. A boat with zincs a bad bond to earth through its shore power can still suffer electrolysis.

If the boat is creating all its own current, its galvanic. If the boat is suffering from outside source of current {battery, shore mains} its electrolysis. {over simplified}

This of course is only my feeble understanding of such matters. Do your own research.

 

[MarcusOReallyus]

If the boat is creating all its own current, its galvanic. If the boat is suffering from outside source of current {battery, shore mains} its electrolysis. {over simplified}

Well, yes, it's oversimplified.

 

[Abbylind]

Are you using water that has been "softened" using salt as your radiator water along with anti-freeze? All softened water along with potable water that is produced through desalinization has a trace of salt remaining. Salt=corrosion. I had a salt water softener in my other house...corroded my washer and plumbing fixtures. Maybe something to look at. I know that the Cummins aficionados only use de-ionized water and antifreeze in their systems.

 

[Keith_J]

And I too have had a failure with an aluminum heater core. The Spectra brand bought from rock auto. Lasted a year. Replaced with a similar spectra brand, this time from auto zone. 399079 is the part number. Slightly different manufacture, sears the airflow better.

 

[Skinny]

I have used tap water in every personal vehicle and professional vehicle I have serviced...have yet to have a failure due to corrosion. Granted I change mine below the service interval and take good care of my vehicles before bad things tend to happen. I highly suspect that if you are having failure due to corrosion on a CUCV or similar vehicle, it more than likely is coming from poor grounding. Most older vehicles tend to have bad grounds from either previous owner neglect with electrical connections or because the grounds have rotted off the vehicle. You can add all the rocket science to a brick basic truck and call it what you want. At the end of the day, a bad electrical connection will seek an alternate path and engine coolant looks mighty fine.

I would also add poor replacement part build quality into the mix.

Just my opinion...

 

[acesneights1]

I have mine re-cored. The heck with that chinese made aftermarket stuff. I grabbed a brand new NOS one at the Sussex show for a paltry 10$$$