Hapy Gets a FrostHeater

Today, I nearly complete the re-assembly from the flywheel (well, ring gear, really) replacement that has been an open effort since US Independence Day. I had to order a clip to hold the coolant temperature sensor in the coolant outlet flange, so this post picks up where I left off after placing that order. Before I begin, hapy belated GroundHogs Day or Imbolc, if you're a little less western in your seasonal outlook. Either way, there's 6 more weeks of winter because Spring Equinox is still 6 weeks away no matter what a Pennsylvania rodent sees. Anyway...

 

Some History 

installed

For background, Hapy was having increasing trouble starting over the past 2 years. I thought I was getting poorly manufactured starters because every time I replaced one, he would be okay to start for a few times. That was until the last couple, including a new highly-recommended starter from IDParts and a fresh local rebuild of the original TDI starter by a very reputable rebuilder. I concluded the teeth on the "ring gear" or in my case the teeth on the flywheel since this flywheel was one formed unit, had broken off enough that the starter teeth could not engage. This started a path that started with removing the engine-transaxle on my falling-into-pieces driveway, having the transaxle fall off a jack and popping off a flange, hauling Hapy in a sketchy way back to the shop, and finally, now, almost completely reassembled. When this saga completes, he would have been not running since July of 2024 (when we drove home from the final 4Peaks Music Festival).

 

FrostHeater

Frostheater is a vendor who uses a widely available Zerostart 3309040 coolant heater with hoses and brackets for a custom fit for various makes and models. If you have not tried one and are tired of cycling your glow-plugs multiple times before you can start your diesel in the winter, I suggest giving them a look. The unit Frostheater uses looks to be the top of the line from Zerostart in terms of build, capacity and cost. There are plastic other brands, and block heaters that are effectively a glue-on heating pad, but I have found these FrostHeaters to be really effective. From what I can tell, there are no moving parts. By placing the unit near the lowest point of the oil cooler loop the unit draws colder coolant from the oil cooler and the warmed coolant flows up through the upper bib into the head. That rising heated coolant then puts pressure on the coolant in the block to move into that vacuum, through the oil cooler and the loop completes. A few years ago, I installed a Frostheater into a 2004 VW Jetta Wagon (K'Lack). It worked great. We sold K'Lack to our niece a few months later, and she never used the heater. So, when we had to do a major timing belt and cam shaft maintenance, OldPoopie removed the FrostHeater, and restored the original coolant line which I left in place when I installed the Frostheater. The Frostheater and related hoses went into a box for future Hapy consideration.

 

Coolant Temperature Sensor

#6 in diagram

Before I get too far ahead of the story, I installed the coolant temperature sensor and retaining clip first. That sentence is easy to type, but the actual install is very unpleasant. In Hapy, the coolant outlet flange sits behind the fuel tank and barely above the top of the body cross-support that also contains the center-mount for the transaxle. So, there is no way to insert the clip from below, it must go in from above. Directly above the insertion point for the temperature sensor, however, is the to-the-heater side of the coolant outlet flange, leaving a 1/4" or so to fit the clip. Since the orientation of the clip is straight  up and down, there is not enough room to simply slide it in. Of course, let's not forget that you can't actually see anything because it is all on the front side of the engine. For the ALH-TDI engine install into the bay-window bus, I believe this is the single issue that challenges the install. It is minor, in the grand scheme, but it is still highly unpleasant when you need to replace this sensor.

 

So, how do we do this? With a fingernail, I find the slot on the far side (front) of the flange where the one side of the clip will go, and send one "leg" of the clip into that slot while holding the sensor firmly in place. The clip will flex hard, and the inner "leg" of the clip needs to bend somewhere while the first notch of the clip is slid in, I found that having it flex away from the flange (towards the sensor) gave me something to work with. Once the clip is most of the way down and it seems like the clip can't possibly flex any more, push the flexed inner "leg" towards the flange until it clicks into the hidden slot. I spent a couple of hours wrestling with this, and broke a clip along the way, but this method does work. These clips are inexpensive, so buy several when you need to install one. Also, I found it much easier to access the coolant flange from the driver side (the sensor side) if the charged air hose is removed.

 

FrostHeater Install

where fits FrostHeater

I could have stayed on target at this point, filled the system with coolant and started test firing the engine. In fact, I try to follow that pattern more recently: finish what you started, then do the next thing. In this case, I had already lost the coolant from just below the outlet flange and above. I figured swapping out one hose for 2 with the coolant heater was not a significant scope increase when compared to the effort to open the system to add the heater later. I figured adding it later could be years away.

 

All of the install drawings and instructions I was able to find gave very model-specific directions. I was able to determine through loosely related searches that the life of the heater is significantly extended if it does not suffer the constant vibration of being attached to the engine block. So, I looked for a place along the right side of the engine bay where it would be low enough to be nearly the lowest point relative to the engine block while still being reachable by the hoses I had on-hand. That area has a small wire bundle, the main 12V line and the diesel fuel lines, so my placement will need to be careful, but there is a section a few inches front-to-back where it could go. With that general placement decided, I shifted to hoses.

 

The BEW TDI hoses that were part of the FrostHeater kit are not an exact fit for my early ALH TDI. The top hose (red line in the drawing on the right), which runs from the top of the heater into the head hose bib which protrudes on the oil cooler side of the engine just below the coolant outlet flange (#11 in drawing), had an extra bend at the far end that I trimmed off. I felt that the extra bend made the hose want to have a large arc which would have created a hard-to-manage air pocket -or- it was a kinking risk, reducing the coolant flow. The lower hose that runs from the lower bib on the oil cooler to the lower bib on the heater simply would not work for where I could install the heater and still use the upper hose. So, I decided to reuse the hose I had originally running from the oil cooler to the head for the lower hose from oil cooler to heater (blue line in drawing).

 

viewed thru top hatch

Now, we get to hard-mounting the heater to the engine bay. The BEW install bracket on top of the heater unit was oriented to mount to the left side of something. I don't remember what. But the bracket could be easily removed with a 7/16" socket and flipped over, aligning the bracket for a right-side install. Flipping the bracket also placed the heater about an inch lower and set the angle of the bracket against the lip of the engine bay, offering some additional support. With the hoses attached, the heater unit had a smaller range of motion for deciding where to mount it without putting stress on the hoses. Still, I was able to find a spot where the bundle of wires and everything else would not get bound beneath the bracket, and marked it with a sharpie. I planned for and then drilled for a M6 rivnut. The M6 was considerably smaller than the original, but the heater is super light and I was fairly sure that bolt was designed to go into a pre-existing hole. I say "planned for" because once I got the hole drilled, there was no way I was going to be able to fit the hand-riveter into the engine bay and set the rivnut. So, instead, I simply sent the bolt through and nutted from behind like most things. It is still a M6 bolt, using washers, of course, just no fancy riv-nut. So, to remove, I will need 2 wrenches rather than one. Not a big deal.

 

Fill 'er Up

from behind approx level

With the cooling system seemingly buttoned up, it was time to add coolant and burp out the air bubbles. This is where my effort ran out of supplies: no G40 coolant on hand. I added some water to confirm there were no leaks, and after shifting the upper hose clamp on the FrostHeater, there were not any. In the picture on the right, here, you can see how well tucked up and out of the way it is, even though it is below the oil cooler. Note the dry, albeit stained, concrete floor underneath. No leaks.

 

I still need to solve for the routing of the electrical cord so it can be reached relatively easily on a cold day, but far enough out of the way that it is not subjected to flying gravel and road debris. At this point, I am looking at tucking it up behind the right rear wheel, under the battery tray and holding it in place with a strip of cable-management Velcro.It might be time to consider mud flaps back there to help protect the cable from tire kick up.

 

Last, when I removed the exhaust at the start of this project, it came apart where the pipe meets the muffler. To be honest, I was never terribly pleased with the exhaust that was put on there. But, it did last 15 years, so I can't complain too much. Still, I have a 2" exhaust kit that is a bunch of straights and turns that I intend to eventually cobble together into a better exhaust. I think, to get Hapy on the road, I will put the existing, falling apart system back in. Then, I can plan for the 2" exhaust as a near-future improvement.

 

Thanks, as always, for following along, and I intend to get coolant this week and get Hapy running next weekend.