912ULS Coolant Elbow Bolts

[Dave S]

Good Afternoon,

Got a question about the bolts which hold the coolant elbows to the top side of the cylinder heads of the 912ULS.

Are these bolts threaded into the coolant chamber or into a closed hole which does not open into the coolant chamber? In other words - if I pull one of the bolts out, will coolant run out or not if I haven't drained the cooling system?

Thanks,

Davs S
KF 7 Trigear - Flying
912ULS Warp Drive

St Paul, MN

[Av8r3400]

I do not believe that these bolts enter the water jacket.

The elbows themselves call for Locktight 638 for sealing, but the hardware does not.

[Dave S]

Larry,

Thanks for the reply...I will be installing a Tanis engine preheater in the 'fox. Four of the threaded heaters are installed by removing one bolt on each of the upper elbows and replacing each with the threaded heater. There is another heater bolt that replaces the crankcase bolt immediately behind and below the gearbox. Also a heater pad that is bonded to the oil tank. I'm going to be taking some photos of the install & will likely share them on the list when I get it complete & tested.

Sincerely,

Dave S
KF7 Trigear - Flying
912ULS Warp Drive

St Paul, MN

[SWeidemann]

Dave S.,

How has your Tanis worked out?

Skot

[Dave S]

HI Skot,

The jury is still out on this. I am certainly going to provide the information regarding my installation experience back to Tanis - should be helpful to them for experimental aircraft installations.

The oil tank heater pad installation went off without a hitch...I kept the temp up to recommended spec for installation and adhesive cure/dwell time with a portable heater and monitored with my OAT temp gauge moved to the location. The oil tank on the S7 is easy to access for this....that might be different for earier kitfoxes that have the oil tank between the firewall and engine. Basically the pad is glued to the side of the oil tank, after prep, below the oil level.

I was mistaken that the location recommended for the cylinders was the coolant elbow. That was before I had the instructions in hand. The coolant elbow location is recommended for the 912 fuel injected Rotax. On the Carbureted ULS - the recommended location is replacing the short screws on the intake manifold with the heater bolts. The manifold location permits the full length of the heater screw to be inserted while the coolant elbow requires a short aluminum standoff under the head of heater screw because of the shorter threaded hole at the coolant elbow.

I purchased the slotted deep well socket intended for torquing the heater bolts but found that the diameter of the socket interfered with the side of the manifold so that could not be used - my plan "B" for torquing the heater bolts was to use a combination 11 mm wrench, a calibrated fish scale and do the math on the arm to determine the torque.

Next issue that developed was one of the locations on the manifold could not be used because the head of the heater bolt interfered with the manifold casting before the heater seated. I think the issue is the original 6 mm Rotax screws for this location are allen type heads while the 6 mm heater bolts that replace the original screws are external hex heads (11 mm), and there isn't much cearance from the manifold. I reviewed the Rotax sponsored video on the Tanis heater and that installation did not have an interference problem with the heater bolt head. There may be more variation on the manifold casting than was originally encountered on the companies test installations.

After rethinking this a bit, I decided that the most practical location for the cylinder heater bolts is the corner tabs on the cylinders which are not used to hold anything together so they can be dedicated to the heater bolts only. Using the corner cylinder tabs also permits use of the slotted deep well socket so I can avoid the fish scale & math deal. This installation point requires that I fabricate some aluminum standoffs a bit longer than the ones used for the fuel injected Rotax on the coolant elbows. Haven't got that done yet so this is still very much a work in progress.

I have not decided what to do with the crankcase heater bolt yet...I am considering one of the unused 6 mm threaded holes on the back of the gearcase as opposed to the location behind the oil pump although this will require an additional aluminum standoff too.

Sincerely,
Dave S
KF 7 Trigear
912ULS Warp Drive
St Paul, MN

[SWeidemann]

Red: Tanis

Dave,

I appreciate your report about Tanis optional mounting methods. With my new engine I haven't got far enough to get the Tanis parts out of the shipping box. I bought the 912 Tanis kit from LEAF last summer and expected to be done by now. The new model engine may have some other changes that will generate some creativity, we'll see. I also have a mock up template from Kennon Engine Covers to match up to my smooth cowl for an insulated cover (to go along with the electric engine heater, for heat retention efficiency).

Regards, Skot

[Dave S]

Skot,

When you go to install the cylinder heaters and crancase heater, one recommendation I have is to use the lowest torque necessary - Tanis has a maximum torque value; but, I would go with the lower Rotax torque value. While the instructions don't mention anti sieze compound, my opinion is that using some would be a good practice; and, considering if some of the silicon/zinc oxide heat sink compound like Dow Corning 340 might be a good thing.

Sincerely,

Dave S