Friday, November 9, 2018

high altitude heater pump for brunnhilde

Often a well laid plan can be foiled by poor planning or just a lapse of judgement. Before taking the cross country trip I knew that I may need to use the diesel furnace in the high elevations at the Continental Divide. I planned ahead and ordered the high altitude pump to replace the normal sea level pump for the Eberspächer furnace, and a couple of parts that I expect I will need sooner or later.

I learnt that often one can over think or plan and ending buying too many unneeded parts. Hence I took a pragmatic approach. Only buy the absolutely minimum. I bought the high altitude doser pump (with reduced flow rate), a glow plug socket (which is a bit of ripoff), and another some sort of stainless screen that is consumable. I wanted to also buy the special rubber hanger that is designed to hold the pump in a circa -35 degrees downwards angle, but I could not find it on the vendor's site. Neither could I find the two different size hose clamps. I knew the last thing I want to do is to substitute common crap worm screw clamps. Screw gear they are and you will be screwed if you don't know better.

When I crawled under the motorhome to first look what I was up against, I tried to loosen the German hose clamps. The screws look rusted and with a screw driver they didn't budge. Facing with the approaching cross country trip I decided that this is not a job to be rushed. The trip occurred in late August, and I didn't need to use the furnace for any extended during. I did turned it on to chase away the chill a few times.

Today I decided to take advantage of a dry but rather cool November day to try swapping the pumps. It turned out it was indeed a job best done not under time pressure. I first soaked the screws of the two hose clamps with WD40. No go! They wouldn't unscrewed with a Philips screw driver. Next I brought out the big gun - PB Blaster which a lot of people tout it's greatness. Oh, this stuff smell nasty and immediately gave me a nausea. I let it soak for half an hour and tried again. Still no go. I thought to myself that I was wise not try to tackle the pump swap before the trip.

I was ready to break out the Dremel tool and use a cutting disc to cut off the two miniature hose clamps. The problem is I was counting on reusing these clamps, or I would have to purchase the replacements from a Eberspächer dealer and wait for them to arrive. Not an attractive option. I knew if I try too hard to unscrew the clamp with a screw driver I would just ended up screwed.

I seek the method of second-last resort: use a Vise Grip instead of a screw driver to turn the screws of the clamp. For this you need a perfect size Vise Grip and not a cheap Chinese knockoff. Typically you only get one shot with this method, and hope that you don't shear off the aluminum nipples of the doser pump if the screw refuses to unscrew. I also knew that I need to be extremely careful so not to stress the 12 year old rubber hanger for the pump. Breaking it will mean waiting for a replacement.

I carefully use the smallest Vise Grip and set the jaw to close tightly on the pan head of the screw. Supporting the pump securely with the other hand I managed to break free both screws. Good. Next task is to remove the two hoses from the pump without breaking something and the hoses. To minimize stress I heated up the hoses gently with a heat gun. The German hoses became flexible once warmed. From this point the remaining step were smooth sailing.

It turned out that all the hose clamps (no less than 6) were all over-tighten that they are tighten to the mechanical limit of the diameters. With this and rust that was why they were so hard to unscrewed. I am most pleased that I din't need to resort to the Dremel tool, and wait for replacement to arrive.

The high altitude pump dimensions are exactly the same as the pump it replaced so no surprise. The rubber hanger is still in good shape (likely silicone rubber). I just hope the BP Blaster will not shorten its life.

I tested the furnace with the new pump and all seemed well. I conducted a warm and fuzzy combustion exhaust test. When the furnace reached steady state operation I place my palm at the muffler then bring the palm to my nose to detect the unburnt fuel. It smelled pretty complete combustion. There is only the slightest hint of diesel exhaust. I know you are rolling your eyes reading this.

in the other news, I finally installed a front license plater holder on the GT4 that I can live with

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