Workhorse Club Member's Newsletter Provides Informational Bulletin from Workhorse

[DriVer]

The following is an important bulletin from Workhorse

Engine Overheating – All Models 4-10-2008

Complaint/Condition
Engine is damaged from overheating due to low coolant level. This normally occurs within the first 2000 miles (Early failures) or after 2 to 3 years (late failures)

A. Early Failures
Body builders add heaters or other equipment that leaves air pockets in the coolant system. Both the overflow reservoir and radiator falsely suggest that system is full of coolant. After extended use, the air pockets work out and the radiator tank is low. This can occur without drawing coolant from the overflow reservoir. See "•Operation of coolant overflow reservoir"– later in this PI.

The engine often operates for a period of time before the air pocket is worked out. In fact, it may be the first operation of the heater that results in the air pocket going to the radiator. Also, the engine may not overheat with the low coolant until a high power demand is experienced such going up a long upgrade.

B. Late Failures
Over a period of time, most systems loose coolant as a result of evaporation or very minor leaks. If the owner adds coolant to an EMPTY over flow reservoir, it is very possible that radiator level is below the level needed for proper operation of the coolant recovery system. In this case, over heating is very likely at high power demand.

Also, it is possible for improper antifreeze water mix to result in overheating. Cases of this have not been confirmed as it is difficult to determine after an overheat condition.

Recommendations/Actions

Workhorse Custom Chassis is working with body builders to better define the coolant filling procedures needed to prevent air pockets in the system.

Dealers should always check the heater for operation and check radiator level before delivering a new unit.

Radiator level (in addition to reservoir level) should be checked at every oil change. Radiator tank should be completely filled to over-running.

Owner should check reservoir for both COLD and HOT level on every trip. (This has been added to owner's manuals)

Coolant mixture must be 50% antifreeze and 50% clean water. This should also be checked at every oil change.

Operation of the coolant overflow reservoir
Coolant overflow reservoirs were added to vehicles to make cross flow radiators more efficient. This is done by assuring that the radiator is full to the fill cap at all times during operation.

Coolant movement from Radiator to Reservoir
Coolant flow from the radiator to reservoir occurs when the coolant expands from heat. The expanding fluid opens the radiator spring loaded cap and flow occurs in a tube from radiator to reservoir. (The overflow tank is often called an EXPANSION tank) This fluid movement occurs due to a pressure build up from expanding coolant. The pressure is NOT the result of boiling coolant.

If the radiator is low, the expanding coolant will build pressure in the radiator, but often insufficient pressure to lift the pressure cap. (Air is compressible"”coolant is not) If pressure exceeds the 15 psi cap, only air and not coolant will escape to the reservoir. Thus, the recovery system will not work when radiator level is low enough such that expanding coolant does not empty the trapped air from the radiator.

Coolant movement from the reservoir to radiator
When the coolant in radiator cools, it shrinks in volume and creates a vacuum (is vacuum the right term – low pressure maybe? Or "•vacuum"– )in the radiator. This vacuum pulls coolant from the reservoir back into the radiator through a one way check valve in the cap.

If radiator level is low, the normal pressure produced from normal engine operation will decrease and a sufficient vacuum will not be produced to pull the coolant from the reservoir.

Conclusions from above discussion
Coolant recovery system is inoperative when radiator is sufficiently low on coolant.

Coolant tank can be at full mark at the same time that radiator is low enough to cause overheating.

If an operator fills an empty reservoir, he must check radiator level to assure that it is full.

If reservoir level does NOT CHANGE between hot and cold, radiator level is low.

Recommendations

Radiator level should be checked (by removing cap) at every oil change.

Reservoir level should be checked for HOT and COLD level at every fueling. (Cold level should be checked before starting a days trip before start up) Radiator level (as well as all fluid levels) should be checked before delivery of a new unit to the retail customer and after storage of one month or more.

-- End of article --

[DriVer]

The following is an important bulletin from Workhorse

Engine Overheating – All Models 4-10-2008

Complaint/Condition
Engine is damaged from overheating due to low coolant level. This normally occurs within the first 2000 miles (Early failures) or after 2 to 3 years (late failures)

A. Early Failures
Body builders add heaters or other equipment that leaves air pockets in the coolant system. Both the overflow reservoir and radiator falsely suggest that system is full of coolant. After extended use, the air pockets work out and the radiator tank is low. This can occur without drawing coolant from the overflow reservoir. See "•Operation of coolant overflow reservoir"– later in this PI.

The engine often operates for a period of time before the air pocket is worked out. In fact, it may be the first operation of the heater that results in the air pocket going to the radiator. Also, the engine may not overheat with the low coolant until a high power demand is experienced such going up a long upgrade.

B. Late Failures
Over a period of time, most systems loose coolant as a result of evaporation or very minor leaks. If the owner adds coolant to an EMPTY over flow reservoir, it is very possible that radiator level is below the level needed for proper operation of the coolant recovery system. In this case, over heating is very likely at high power demand.

Also, it is possible for improper antifreeze water mix to result in overheating. Cases of this have not been confirmed as it is difficult to determine after an overheat condition.

Recommendations/Actions

Workhorse Custom Chassis is working with body builders to better define the coolant filling procedures needed to prevent air pockets in the system.

Dealers should always check the heater for operation and check radiator level before delivering a new unit.

Radiator level (in addition to reservoir level) should be checked at every oil change. Radiator tank should be completely filled to over-running.

Owner should check reservoir for both COLD and HOT level on every trip. (This has been added to owner's manuals)

Coolant mixture must be 50% antifreeze and 50% clean water. This should also be checked at every oil change.

Operation of the coolant overflow reservoir
Coolant overflow reservoirs were added to vehicles to make cross flow radiators more efficient. This is done by assuring that the radiator is full to the fill cap at all times during operation.

Coolant movement from Radiator to Reservoir
Coolant flow from the radiator to reservoir occurs when the coolant expands from heat. The expanding fluid opens the radiator spring loaded cap and flow occurs in a tube from radiator to reservoir. (The overflow tank is often called an EXPANSION tank) This fluid movement occurs due to a pressure build up from expanding coolant. The pressure is NOT the result of boiling coolant.

If the radiator is low, the expanding coolant will build pressure in the radiator, but often insufficient pressure to lift the pressure cap. (Air is compressible"”coolant is not) If pressure exceeds the 15 psi cap, only air and not coolant will escape to the reservoir. Thus, the recovery system will not work when radiator level is low enough such that expanding coolant does not empty the trapped air from the radiator.

Coolant movement from the reservoir to radiator
When the coolant in radiator cools, it shrinks in volume and creates a vacuum (is vacuum the right term – low pressure maybe? Or "•vacuum"– )in the radiator. This vacuum pulls coolant from the reservoir back into the radiator through a one way check valve in the cap.

If radiator level is low, the normal pressure produced from normal engine operation will decrease and a sufficient vacuum will not be produced to pull the coolant from the reservoir.

Conclusions from above discussion
Coolant recovery system is inoperative when radiator is sufficiently low on coolant.

Coolant tank can be at full mark at the same time that radiator is low enough to cause overheating.

If an operator fills an empty reservoir, he must check radiator level to assure that it is full.

If reservoir level does NOT CHANGE between hot and cold, radiator level is low.

Recommendations

Radiator level should be checked (by removing cap) at every oil change.

Reservoir level should be checked for HOT and COLD level at every fueling. (Cold level should be checked before starting a days trip before start up) Radiator level (as well as all fluid levels) should be checked before delivery of a new unit to the retail customer and after storage of one month or more.

-- End of article --

[Full-Timers]

Huh...I always check all fluids before traveling, even if it has only been a 1 night stand and/or a couple of miles last traveled. I guess I need to make it a habit to check the level after a trip while still hot.

[iRV4FUN]

Couldn't this condition occur after a fluid flush?

[Oemtech]

Absolutely.... I usually start the engine and let it run with the radiator cap off until the thermostat opens and the water start to flow thru the upper hose. This should purge all the air. Don't be surprised if you see a big gush of water gets pushed out as the air bubble is expelled. You can do this with the cap on and hopefully the water will go into the overflow tank. But, you should check this each time you get ready for a trip, I do.

[RV 4 2]

I normally check my levels but this information has come in a timely manner for me. I just finished a 2500+ mile trip and I kept noticing that my reservoir level had dropped. I must have had some remenant bubbles in my system from when I had a hose splice leak from the engine to the heater core. I will have to check things out to ensure everything is full when cold and after it has warmed up Like Dale suggested.
Thanks Driver for this.

[Cheryl Bisson]

How timely is your posting!! Today we became "stuck" in Jackson, WY. Recent checks of coolant level have been OK, but today engine overheated and coolant was added at least three times. But engine still continued to overheat, unless we kept speed to 20mph. There was also some spray moisture around the overflow reservoir. We will now go and check levels in the radiator. The system was flushed about 2-3K miles ago before leaving on this trip. We have an appointment Monday AM to check things out. Will get back to you with results. Interestingly enough, tech support today at Workhorse did not mention anything remotely related to this bulletin.

2005 Adventurer 33V

[iRV4FUN]

Guess if your going to get stuck somewhere Jackson, WY wouldn't be last on my list. Enjoy!!!

[DriVer]

GM Coolant Recovery Tank

Supply line is toward the back(left) and the overflow or discharge line is to the right (open end).

Just getting ready to head out on the highway this coming Tuesday and what I did was to mix a 50/50 solution of DexCool in a 1L bottle and add the mixture to the recovery tank.

When I added the coolant mix the fluid was at the COLD fill line, lower line in picture. When you achieve operational temperature and your cooling system comes on-line the coolant will either be drawn into the pressurized cooling system or pushed out of the overflow. Starting just a little bit higher than the cold fill line will assure that you'll have plenty of coolant if the situation demands it.

I removed and inspected my radiator cap - it's a replacement and its not that old. Looks good!

Now after a day's run I expect that the fluid will be back down to the COLD fill line in the morning because in my experience any redundant coolant is dumped overboard via the overflow tube at some point during the day's run.

One other thing while I'm at it. Those of you that change your own coolant - make sure that air can be blown through the supply line from the tank to the radiator neck. Sometimes the supply hose can get gunked up with stuff and it has to be kept clean. Remove and wash out the recovery tank as well.

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Cheryl Bisson:
Workhorse did not mention anything remotely related to this bulletin. </div></BLOCKQUOTE>Cheryl, I tried to look this up in the Technical Service Bulletins (TSB) listings and it's not listed with the others. I believe that this is an Informational Bulletin or it would have a nnnn-C number and an effective date.

You can locate the original text for this bulletin on the Workhorse Motorhome Chassis Club website in the May Newsletter @ wcmc.workhorse.com

While you're there check out the announcement for the Club's Fall Rally in Myrtle Beach.

[Pubtym]

Excellent Information! Thanks...

[Oemtech]

Speaking of the Coolant Recovery Tank....

FYI - Should you have to replace it don't be surprised if your Workhorse Service Center and/or GM dealer does not have one in stock. I had this happen when I installed a CAI for Bill Smith. I took the GM number off the tank and got one for $20 the next day at a local auto parts store. WH/GM wanted cost to $60-$80 shipped overnight.

[Cheryl Bisson]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by iRV4FUN:
Guess if your going to get stuck somewhere Jackson, WY wouldn't be last on my list. Enjoy!!! </div></BLOCKQUOTE>

This is a beautiful place to stay. We were here a few days ago on a day trip via our toad from Colter Bay on Jackson Lake in Grand Teton NP. We had to return here to get service since it's the only place in this entire area to do so. Since it's $62/night including Good Sam discount we are making the most of it!

My husband checked everything out this AM and found the radiator cap was not on tight, which we hope is the basis of our problem. This cap has been touched by no one since we had the system flushed before leaving on this trip. He also added more coolant solution, so it is at the level in DriVer's picture(thank you!), ran the engine until normal warm based on the dash gauge, accelerated for awhile, and so far, so good. After the engine cooled down, the coolant level was where it should be. He wasn't able to get the radiator cap off, but will try again later when he can get on a ladder and get some "push force" down on the cap.

We're taking it on a mountainous drive Monday AM to check things out before taking to the repair shop. We still want to have a pressure test done on the system to make sure everyhting is OK, assuming the loose cap was the problem.

Thank you everyone for your input. Once again, this is a great forum with everyone helping each other. I don't post much, but I sure do lurk!!

PS I did find the bulletin on Workhorse's website and a copy is going with us to the reapir shop. Thank you.

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Cheryl Bisson:
My husband checked everything out this AM and found the radiator cap was not on tight, which we hope is the basis of our problem. </div></BLOCKQUOTE>Cheryl, That would be a BIG problem. Glad he found it.<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">(thank you!) </div></BLOCKQUOTE>You're welcome! <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">He wasn't able to get the radiator cap off, but will try again later when he can get on a ladder and get some "push force" down on the cap. </div></BLOCKQUOTE>Let's not open and shut the radiator cap too many times. For me before a trip is sufficient. Continue to monitor and add coolant to the recovery tank. If the level is where its supposed to be - you're livin' large! <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">We're taking it on a mountainous drive Monday AM to check things out before taking to the repair shop. We still want to have a pressure test done on the system to make sure everything is OK, assuming the loose cap was the problem. </div></BLOCKQUOTE>IF you make it on the other side of the mountain and the coolant level is where its supposed to be - the visit to the shop for a pressure test is kinda up to you at this point BUT I would say that you're good to go. If you happen to be at the shop, make sure you get a new radiator cap. That would be the best thing you could do while there if everything is fine.