Rebuilding my heater booster

seans

Member
Reference from this thread: https://sprinter-source.com/forums/showthread.php?p=360730


I love my heater booster now!!!!


heater.jpg

I have four relays, so that I can independently control the circulation pump, the interior fan, the Espar enable line, and the ignition-is-on line. It is controlled by an Arduino and the enclosure is 3D printed at the local makerspace. A menu system lets me select between always-on mode, timed mode, and engine-heat-only modes. Thermostat control will be going in later.

The controller leaves the circulation pump on for 60 seconds after I turn off the heater. I think this is important because the heater still is burning residual fuel.
 

220629

Well-known member
Good news that your heater is up and running. :thumbup: You will find it handy to have.

...

The controller leaves the circulation pump on for 60 seconds after I turn off the heater. I think this is important because the heater still is burning residual fuel.
If easy to include, that addition to a control scheme shouldn't hurt.

Before people get nervous and jerky and thinking that they need to add a delay to their aux electric coolant pump shutdown...

The Espar controls shut off the fuel pump right away. There is a bit of lag with the flame going away, but very little residual fuel to burn off. Just because the fan continues to spin doesn't mean that the Espar is burning fuel and producing heat. The noises you hear during shutdown are more related to the combustion fan continuing to operate to purge out all exhaust/fuel and to help the heater to cool down a bit quicker.

If the coolant pump fails to circulate coolant, the Epsar relies upon the coolant chamber over-temperature safety monitor to recognize the lack of sufficient heat extraction. I've seen that result in warped plastic covers. I believe that condition results from the over-temp shutdown being required multiple times though, not from just one incident.

During all my research including Espars in both vehicles and boats, I haven't found another comment that mentioned that the coolant pump should be programmed to run longer than provided by the OEM control schemes. That includes the bastardized MB controls.

:2cents: vic
 

seans

Member
Good news that your heater is up and running. :thumbup: You will find it handy to have.
Thanks! I'm loving it already. And all your heater booster parts saved the day in helping me get the right parts. Thanks again! :cheers:

Next step is a thermostat control. Is there a way to tell the cabin heater to stay in low heat mode through the electrical connector?

On keeping the circulation pump running: Agreed, did not recall any forum posts about ill effects when I first thought of this. But we are talking a small sample size. Anyhow, the change was a handful of lines of code so I did it.

So today I ran a test: once it reached temp, I waited for the heater to cycle back to high heat mode. I shut everything down and heard irregular dull thudding sounds coming the area of the heater booster, starting around 10 seconds and ending 30 seconds after shutdown.

I then turned it all back on, waited for it to return to temp, and repeated the test leaving the circulation pump running. No thudding sounds.

I think this device, http://www.amazon.com/Delay-Relay-Switch-Module-Timer/dp/B00VFUG3KK, might accomplish the same thing as my arrangement for <$10 without requiring programming. The comments suggest that various dip switch settings should let you have instant on and delayed off. In fact, someone could go to town with these (implement a timed engine preheat, for example) without doing a lick of programming!

a.jpg
 

johnshmit

Well-known member
Try ebay. Same manufacturer from China. I had to split my $50 order in three due to the package size.
This relay module was $2.69
 

220629

Well-known member
Yesterday I removed my heater for general cleaning. It was smoking out the muffler a bit more than usual at startup. I thought that maybe the screen on the D shaped igniter hole had plugged a bit with soot.

Actually there was little soot. I flushed it well with carburetor cleaner as to not disturb the metering screen assembly and re-assembled the heater. A bit less smoke now on startup, but not as little as I recall before. Maybe my memory is optimistic as to how much smoke there was?

... I shut everything down and heard irregular dull thudding sounds coming the area of the heater booster, starting around 10 seconds and ending 30 seconds after shutdown.

I then turned it all back on, waited for it to return to temp, and repeated the test leaving the circulation pump running. No thudding sounds.

...
View attachment 72014
Ok. I let my heater come up to temperature and full output twice. I used the REST button to shut down the heater. That kills the aux electric coolant pump right away and takes away one of the enables for my DPDT switch no engine heater run circuit. No thudding or other sounds other than the Espar combustion fan continuing to run. I never recall hearing any thudding sounds from my Espar.

Once the combustion is initiated it only requires fuel and combustion air to keep the fuel burning. Perhaps fuel continues to trickle into your heater longer than it does into mine. :idunno:

By my heater longer run time of the aux coolant pump isn't needed. As long as your circuit works for you it's fine with me. :thumbup:

vic
 

seans

Member
Hi Vic!

I think you'll appreciate this... I cut apart my dead burner.

burner.jpgburner1.jpg

That screen? I think your wick theory is correct! The screen connects to a bigger screen that is spot welded around the entire circumference of the inside wall of the burner. You can draw your own theories about how poking at it can impact the burn.

The British site which is a growing fountain of Espar information has more photos of a teardown and cutaways:

http://www.letonkinoisvarnish.uk/Eberspacher_Intro_1.html - "home page"
http://www.letonkinoisvarnish.uk/Burner.html - cutaway photos of a different model burner
http://www.letonkinoisvarnish.uk/Hydronic_Service_1.html - shows cutout of burner showing screen deep inside.

On running the circulation pump a little longer than the heater, I think every little bit helps. I'm thinking about how I never put an emptied spaghetti pot back on the same burner of an electric stove because of the residual heat. I don't know how long the residual fuel in that wick continues to burn but in high power mode, it must be longer. I'm now thinking of monitoring the dosing pump rate or coolant temperature and waiting to shut down the heater when the burner is no longer in high power mode (which I'm guessing is when the Sprinter shuts it down.) It would be nice to be able to command the heater to enter low power mode and let it sit there for a minute before shutting it down.

One of the mods I want to add to the van is a circulation pump health monitor that senses the pump beginning to fail and disables the heater booster before a boil-over occurs.
 
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220629

Well-known member
Hi Vic!

I think you'll appreciate this... I cut apart my dead burner.

...
Interesting stuff.

I didn't realize the varnish guys had added so much information. That is really helpful to understanding the operation a bit better. Sniffing varnish must really work. They make my obsession look like perfectly normal behavior.

Thanks. vic
 

seans

Member
After using my fixed heater booster for a week, I just heard it making sounds while on high output like its internal fan was struggling, as if the brushes are worn down or the bearings are going out. Shut it down right away.

Yep. Just tried starting it again while listening near the wheel well. The fan was not running at all while the dosing pump was starting. It then started running but you could hear it spinning erratically. A bit of smoke coming out and what sounded like uneven burning. Shut it down before it got anywhere.
 
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seans

Member
My heater booster adventures

Working on getting a price for a replacement blower motor. Took apart the heater booster and the motor did not turn easily. Removed it by bending back the tabs holding the ends of the motor onto the motor casing, then tapping the shaft to push it off the fan. Once the fan is off, was able to access the screws that retain the base of the motor.

The bearing nearest the fan fell apart due to the disassembly process. The bearing seemed dry. The motor brushes are fine. I ground the bearing off carefully using a rotary tool with a grinding bit.

motor torn down.jpgbearing.jpg

Of interest is that the broken bearing has metal shields around the ball bearings and the bearing at the other end of the motor, opposite the fan, has a rubber seal. I wonder why they are different. Cost savings? Heat considerations?

It looks like 624ZZ is a generic number for a 4x13x5 mm bearing. I wonder if this one will work?

amazon.jpg
 

seans

Member
Here's something interesting: this bearing is "shielded", not "sealed". Here's what VXB, the company selling the bearing on Amazon, has to say about that:

"Sealed bearings are lubricated with oil or grease in the bearing factory, while open and shielded bearings are meant to be lubricated in place, with periodic reapplication of lubrication, based on use." EDIT: which is wrong; see AP's post below!

So the next question is, once this is all back together, how to safely remove the plastic blower from the motor to access the screws and take out the motor and grease the bearing? Had I done that when I was fixing the heater booster, I might not have had this problem.
 
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220629

Well-known member
Here's something interesting: this bearing is "shielded", not "sealed". Here's what VXB, the company selling the bearing on Amazon, has to say about that:

"Sealed bearings are lubricated with oil or grease in the bearing factory, while open and shielded bearings are meant to be lubricated in place, with periodic reapplication of lubrication, based on use."

So the next question is, once this is all back together, how to safely remove the plastic blower from the motor to access the screws and take out the motor and grease the bearing? Had I done that when I was fixing the heater booster, I might not have had this problem.
Bullsh*t.

Shielded bearings are lubed at the factory and in "normal" service are lubricated for the life of the bearing.

Just how do they expect you to get the lubrication into the bearing with the shields in place? Good luck with that! :hmmm:

The 624ZZ bearing number you mentioned...
The "ZZ" denotes a double shield or shielded both sides. A single letter would denote shielded one side for grease-able installations. We ordered double shielded bearings for the motor shop bearing shelf stock.

When the motor didn't have grease fittings the double shielded bearings were installed as they come (with both shields in place).

When the motor bell housing had grease fittings one shield would be carefully removed so as to not damage the bearing balls. The bearing was then installed with the non shielded side positioned to allow the grease to flood into bearing and lube it. The one, opposite side shield would be left in place to contain the grease and keep it from going where you didn't want it (to keep it from leaking out).

Want to know what happens when a motor repairman forgot to remove the one shield? The field machine service person would try to force grease into the fitting, but the shield won't let it go into the bearing. Pressure from the grease gun would bear against shield, deform it against the balls, and then the balls would overheat from the friction of the balls against the shield. Early bearing failure was the result.

Install your double shielded bearing and don't worry about lubing it ever.

:2cents: vic
 
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seans

Member
Thank you for that great info and example, Vic!

So I've been thinking about reassembly and how to get the fan off the motor next time. Do you have any ideas?
 

220629

Well-known member
I have no great ideas.

As I recall the clearances on the plastic fan unit are too close and the plastic fan too flimsy to allow pry tools to get in without damage.

Maybe dis-assembly as you did and then pulling the fan against the bell housing using the motor rotor will give even enough pressure to release the grip of the fan on the shaft without damage to the fan itself. :idunno:

vic
 

seans

Member
Rebuilding the blower motor

Got my heater booster blower motor working again for <$2, saving $150+...

motor_parts.jpg

I was able to grind off the old bearing with a dremel, and then pressing only the inner race, got a new bearing installed. I tested the motor with no load with a variable power supply that displays current. This was really good, because I found that the current went up substantially when I buttoned everything up, because I needed to press the bearing on a little more.

pressing-on-bearing.JPG

Above: pressing the bearing on. I did not want to put pressure on the outer race, so I slid a washer over the motor shaft that contacted the inner race but was too small to contact the outer race. To press on the washer, I found a tool with a hole in the center large enough to fit over the shaft, but small enough to mate to the washer. (That would be an anti-fouling spark plug adapter from the miscellaneous tools drawer, which is a hack from the 70s (earlier?) that screws onto a spark plug and then screws into the engine block to prevent a spark plug from fouling when there's an oil problem in an engine, by keeping the plug out of the cylinder - obviously not a great solution!) I pressed it together easily in a vise.

The reading on the micrometer is about 0.8 mm too large for what the distance between the bearings should be.

This was the second attempt to press on the bearing. I forgot to put the brush assembly on first before I pressed it on the first time. I thought I'd have to grind off the new bearing but I had not pressed the bearing all the way on and was able to get a tool under the inner race to remove it safely.

For pulling the fan off next time, I will fabricate a set of shims that are thin enough to slide under the fan, with a 10mm slot so that they can go around the shaft. Then I will slide in additional shims to gradually press the fan off the shaft (hopefully.)

blower_fan_shaft_width.JPG

I put the motor and fan back on the heater booster and ran it up to speed. Sounds great! As you can see, the motor started spinning with as little as one-half volt, so all is good!

heater_booster_anim.gif

Our local makerspace has a nice garage to put it back together.

makerspace.jpg

NOTE: to get the motor pins out of the connector, I inserted a small paper clip on either side of the connector to push down the hidden retaining tabs on the connector. When reinstalling, I had to pry the tabs back up a little with pliers. I noted which wire went into which connector hole to avoid having the fan run backward after reassembly (that would be REALLY bad).
 
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bc339

New member
Nicely done!
I am interested in your controller build. Have you thought of sharing the build or making it an open source project?
This will give you even more points in the Sprinter legend status.

In addition to the extended run time for the coolant pump, can you extend the time the blower motor runs after shut down? What I have noticed with mine is the insulation for the two sensors on the water jacket break down, most likely from the high heat cycles. Anything to remove the excess heat after shutdown would help.
Thanks.

Bruce
 

seans

Member
I am interested in your controller build. Have you thought of sharing the build or making it an open source project?
Thank you for the compliment. Yes, I have thought about this, and yes, it would be a GREAT project. If an attorney could ease my concerns about liability, I'd gladly share the source code and plans.

In addition to the extended run time for the coolant pump, can you extend the time the blower motor runs after shut down? What I have noticed with mine is the insulation for the two sensors on the water jacket break down, most likely from the high heat cycles. Anything to remove the excess heat after shutdown would help.
I'm not aware of a way to do that. I am thinking about sensing when the heater enters and leaves high output mode (by looking at changes to coolant temperature or placing temperature sensors on the exhaust pipe and/or water jacket) and have a delayed shutdown which waits until the heater has been in low output mode for a minute, so that the thermal shock on shutdown is lessened. I recently noticed that the blower in my heater booster ran 90 seconds after shutdown, so I will probably make the circulation pump run that long. At some point I will monitor the current consumed by the heater booster and cut the circulation pump when the current drops indicating shut off of the blower.
 

psuggmog

New member
Bullsh*t.

Shielded bearings are lubed at the factory and in "normal" service are lubricated for the life of the bearing.

Just how do they expect you to get the lubrication into the bearing with the shields in place? Good luck with that! :hmmm:

When the motor bell housing had grease fittings one shield would be carefully removed so as
Install your double shielded bearing and don't worry about lubing it ever.

:2cents: vic
Some of the older shielded bearings had shields made of a somewhat flexible plastic material rather than thin metal, with this type of shield, I was able to gently lift an edge of the shield and add grease using a syringe with a metal hollow needle. The replacement bearings shown in this thread have metal shields, so this technique won"t work here.
 
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psuggmog

New member
Re: My heater booster adventures

I ground the bearing off carefully using a rotary tool with a grinding bit.

View attachment 72225
I imagine that you must not have had a small puller or an arbor press available to remove the inner race of the failed bearing. It would have been relatively easy, using either on of these tools. I am also wondering if you removed all the abrasive particles and conductive metal dust, generated from the grinding process, from the motor armature and commutator before reassembling the motor?
 

seans

Member
Re: My heater booster adventures

I imagine that you must not have had a small puller or an arbor press available to remove the inner race of the failed bearing. It would have been relatively easy, using either on of these tools. I am also wondering if you removed all the abrasive particles and conductive metal dust, generated from the grinding process, from the motor armature and commutator before reassembling the motor?
These are great tips for someone who is rebuilding their motor. There was little room to get anything in. I will have to look into pullers next time. There was not much dust generated. I did clean things off with a rag, and it was much cleaner afterward than when I started, but it would have been better if I'd blown it out. I did not have a puller. I cut the bearing very carefully. I did not cut into the shaft, but used a vise grips. With its force, the thin bit of metal still remaining failed, allowing me to slide the bearing off.
 

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