where_the_heffalump_roams 917 AF

The only possible problem with the coolant loop would be a coolant pump failure in the Webasto.
I thought of that too. But the rebuilt unit came with a rebuilt coolant pump, so it's unlikely that both aren't working.
It was noted that the wiring was a little different vs the diagrams we looked at when swapping out that broken harness lock.
The original plug didn't use the same pins. The current harness also has 3 wires at the 6 pin plug and the new harness had 4 wires.
A black wire was found to have voltage and was repined to #1. A blue wire was running the fuel pump and plugged into pin 6. There is a yellow wire that is plugged into pin 5. I'm not sure what this does. We did fine a diagram online that called that pin "summer/winter switch".
 

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Madoxen

Active member
Hey you said you have replaced or tested the fuel pump and that was fine but have you checked the fuel line for damage if it is sucking air it might not get the fuel it needs and shut down. Might be worth swapping out the fuel line for a temp line in a small pot of fuel.

Could also be blocked filters from crud in fuel or diesel bug

If 2 heaters doing the exact same thing has to be external and i think its more likely fuel prob than coolant lvls etc
 
Hey you said you have replaced or tested the fuel pump and that was fine but have you checked the fuel line for damage if it is sucking air it might not get the fuel it needs and shut down. Might be worth swapping out the fuel line for a temp line in a small pot of fuel.

Could also be blocked filters from crud in fuel or diesel bug

If 2 heaters doing the exact same thing has to be external and i think its more likely fuel prob than coolant lvls etc
Funny you should mention that. I have been trying to consider external causes.
Yesterday I stopped by several truck shops including a site listed under Webasto's website as a dealer. The guys there were pretty cool, one guy said he had some experience with these heaters and took a look at it.
We actually found air on the fuel filter! He pointed out an excess of fuel line that had been added at some point that wasn't needed and actually created more work for the pump. So this afternoon, I removed the spliced line and rerouted the line so it's more direct to the filter. I didn't fire it though. It's currently a bit warm and I"m enjoying the luxuries of the new A/C system that ZD in Reno, NV installed recently. :)
I'll fire it up tomorrow or the next day and hope the best while mentally preparing myself to consider other sources if that doesn't fix it.
 
I’m at a complete loss.
The fuel filter was swapped out for the 2nd time. Excess fuel line from the tank was removed so the fuel travels downward only to the pump.
The clear fuel filter doesn’t show any air. The new fuel pump is working just as well as the old one.
The unit is getting a constant 13.2-13.5 volts.
Coolant is circulating when the truck is on.
This morning, it was 20C. I set the thermostat at 35. It fired up, blower could be heard, fuel pump ticking, no warm exhaust was appreciated, and it cycled down after 5 minutes. Coolant stayed cool in the lines.


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Joe917

Explorer
Have you disconnected the fuel line at the unit to see that fuel is actually spitting out? If you do have fuel and the blower is going it sounds like the glow plug/igniter is defective.
When you say fired up you mean it went through the start sequence (and did not fire up).
 

NatersXJ6

Explorer
Have you checked the resistance of the glow plug?

Have you pulled the glow plug out and tried to run it to see if the glow plug is getting hot and it fuel is coming from the chamber?

Have you unplugged the glow plug and checked voltage to see if the glow plug circuit is getting power?

This is a bit dumber question, but you said the unit is getting 13.2-13.5 volts… it isn’t a 24v heater by any chance?
 
There are no dumb questions at this point. Every box needs to be checked, and rechecked.
Good news (maybe), big summery as follows.
In the old Webasto, I swapped out the glow plug and fuel filter. It was confirmed that fuel was spitting out the line. Voltage was confirmed that the old Webasto was getting 13.5 volts. The truck runs off 24V and the habitat systems run off 12V. I was pretty sure this heating system ran of 12V.
I want to a Webasto dealer that builds camper vans recently. The tech there tried hooking up the heater to his computer to look for error codes but stated the he couldn't get this computer to get any info at all. He swapped out the fuel filter as part of the diagnostic work up. Thinking it was possible that the pump was activating, but wasn't strong enough to pull fuel or build enough pressure. Fuel was again activity pulsing at the other end of the pump at that time.
I had ordered a rebuilt Webasto and it arrived early. I swapped it in and had an auto electricition replace the harness plug that I broke when I first pulled the old Webasto. He had to move the pins around to get to to fire up. Fuel was again pulsing at that time.

I drove down to Sacramento, CA and stopped by several truck yards looking for a tech who was familiar with this units. I did get some advice at a Cummins service shop with from a tech who somewhat familiar with these heaters. He spotted air in the filter that was potentially getting in the line. Yesterday, I removed some excess line that had been added at some point in the Heffalumps life and tried to better arrange the filter. Fired up it up, heard the blower going, fuel pump ticking, but no warm exhaust this time (cool air was exiting).

I pulled up to my friends house this afternoon to drop off his dog that had been visiting me. I looked at the unit again and noted the filter was dry... There is about 1.3-1.5 meters of fuel line before it enters to the filter. After a bit of syphoning, I got fuel through the lines/filter. Fired up the unit and kept it on for about 20 minutes. That's the longest it has ran since April of this year.
I'm crossing my fingers now and will fire it up again when it's cooler and the coolant has reached ambient temps.

If it works, I won't know why, but I suspect multiple failures along the way. This truck has more gremlins than anything I've owned before. It has traveled through many places and has many different hands helping with various types of repairs. Some are more quality vs others. But I'm crossing my fingers tonight this box can be checked and I can keep moving on with other projects and travels. :)
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Glad its working now,
Is there a check valve anywhere in these systems? Like maybe its backflowing into the fuel tank, and then times out befoe it fires?
Nope. a one way valve would have helped in this case but also create another possible failure point. But I ran it this morning for 45 minutes with ambient temp coolant it it warmed everything right up! I don't think the fuel issue that was fixed yesterday was the culprit. But rather it was one of the problems that developed over this past year. I'm going to try to rebuild the old unit by replacing gaskets and see if I can source new burner, and bench test it. Keep it as a road spare as it's somewhat small and easy to swap out. This was a simple fix but required many hours and many minds. It's a huge weight off my mind as winter approaches (my favorite season!).

Big projects pending and keeping me stateside right now are:
1. Getting an appropriate sized leaf spring so the truck is aligned.

2. Repair of the hydraulic tire carrier/bumper. It was working before the engine cradle failure. But since getting back, the hydraulic switches aren't activating and it has to be manually cranked. The truck shop did pretty poor quality repairs and the splices they put in the air lines are leaking. When the pneumatic switch to activate the PTO is used, I can hear the PTO engaging, but the bumper doesn't move. Maybe that air line needs to be repaired or something wasn't hooked up. The PTO has also been leaking since I've had it. I'll have to figure out how to address that.

3. Brake overhaul. I have shoe material and 2 drums on hand. My thoughts are to have the front brakes addressed. If possible, machine one of the set of drums for more use. The rear shoes will need to be services as well.

I found a spring shop in Sacramento that might be able help with fabricating a new leaf spring the replace the one that broke last year. I did a run to San Jose this week to pick up that piece and dropped it off. I was referred to a guy I will meet on Friday who might be albe to swap out the springs, help with the bumper, and the brakes.

Other things on the list that can be tackled on the road.

~ The flame start for the engine has never worked for me or the prior owner. I'd like to get that going.
~ I am seriously thinking of pulling the trigger on swapping in the OEM 200 amp alternator that will cost me $2.5K... This would help with system charging but it's also way more compact vs the aftermarket unit in there now. There is almost no clearance between the current alternator and lines that run across the frame rail just underneath it. There is potential for damage and loss of systems.
~Pending funding, I'd like to increase the battery bank from 400 amps. There is room for 300/400 more amps.
~ Generator is still not firing up remotely or charging the batteries. This has been placed lower on the priority list due to the challenges and some of the other systems that needed to be addressed.
~ There is room at the front of the roof to add another solar panel to increase harvesting. (Ideally, a solar system could better keep up with usage demands. This is challenging in winter months when meals are often cooked after harvesting hours. I anticipate rain season in C. America will be challenging if parked for long periods.
I was really hoping to spend summer/fall in Mexico this year with a convent of nuns and I'm hoping to do a loop up through B.C. Canada and AK soon. But ******** happens and you gotta deal with it. Plans change. I left someone I really care about, hoped to travel with, and tackling NGO projects just before moving in the heffalump. That is just life man. I got some biking in this past week and some beautiful places. I'm currently drinking coffee at a coffee shop before a morning appt. I was just gifted a cup of by the owner after we talked about the rig and Guatemala. I'm currently content, happy with traveling, living in the heffalump, and feeling all right. :)
 
Did a loop from Yuba City down to San Jose, through the western Sierras, and Mt. Shasta. I picked up the old leaf spring minus the broken leaf down in San Jose after talking to the rad guys over at Sacramento Spring. We opted to combine 2 existing leaf packs to make the rear work. It turns out, the axel to axel length was off by 2.5 inches! While picking up the spring, I took my friends dog with me and also did some biking. I had to wake a bit for shop availability and explored some new trails. I met some really rad travelers along the way. I've had very mixed experiences in NorCal and the find the towns/cities to have a lot of contrasting personalities and cultures. My favorite few days of this last round was def spent around Mt. Shasta. There is plenty of nature, boondocking sites, and I haven' had that much fun on my bike in a while! From a MTB perspective, the trails are fast, have beautiful flow, and there are some fun little drops and hits to be enjoyed along the way! Saw quite a few little lizards, a juvenile fox, and startled a black bear just 1-2 meters from a trail.

Really stoked to hopefully have the leaf spring box checked. Now I need to get the bumper/tire carrier sorted out and have the brakes relined. To reduce downtime, I think I want to look at sourcing new shoes. I'd like to have them relined and have on hand so a truck brake shop can simply install them. eBay is full of brake liners, but I'm not finding full sets of shoes. Anyone know where these can be sourced?


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Im still working on trying to find new shoes but I may have found a place in Redding, CA that can pull the shoes and have them sent offsite to secure the liners.

Also, I’ve been having hiccups with my Webasto coolant heater. Twice since it’s repair, the fuel line has gone “dry”. This occurs when it’s not being ran. It was working fine and than I went to a warmer region for a week. When I returned to a cold region, I found that it wasn’t kicking on and there was air in the filter.

The tank is about 55-60 cm tall. Fuel hasn’t gone below 1/3 if the tank. I am considering installing an inline hand pump to help. The fuel pump is below the fuel tank and the line is plumbed in through the top. But I’m also curious of why this is an issue now and wasn’t for many years. And thoughts?


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Last edited:

Geo.Lander

Well-known member
Im still working on trying to find new shoes but I may have found a place in Redding, CA that can pull the shoes and have them sent offsite to secure the liners.

Also, I’ve been having hiccups with my Webasto coolant heater. Twice since it’s repair, the fuel line has gone “dry”. This occurs when it’s not being ran. It was working fine and than I went to a warmer region for a week. When I returned to a cold region, I found that it wasn’t kicking on and there was air in the filter.

The tank is about 55-60 cm tall. Fuel hasn’t gone below 1/3 if the tank. I am considering installing an inline hand pump to help. The fuel pump is below the fuel pump and the line is plumbed in through the top. But I’m also curious of why this is an issue now and wasn’t for many years. And thoughts?


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Curious as to where the fuel is being taken from? The return line or directly from the tank, only asking because I am installing 3 separate heaters now..
 

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