Pat 12 gets a nose job

[Ian Johns]

Thanks guys

[Phil Waterman]

Hi All

Well the nose job and engine swap worked, the truck can now breath and it doesn't seem to overheat. Took the truck for an extended drive today ambient air temp 29C or 84F and the truck never got much over 190F which is a far cry from boiling into the recovery tank which it did before.

Also now that the clutch completely disengages the truck shifts like a dream. The clutch problem was caused by a clutch disk that actually was sticky to the touch.

Cheers Phil

[Bob Carriere]

Hi Phil

Any idea how the sticky stuff came from??

Leak somewhere.....?

What temp setting are you using for the thermostat...... we are using the GM 1959 manual recommended 160 on ours and fear it may be too cold.

We are about ready to fire up Grant's rebuilt 261 in the next few days.

Bob C

[Phil Waterman]

Hi Bob

Not sure of the source of the sticky stuff, this is the second time that I have run in to it. Both times it has developed on clutches that had worked fine but were out of the truck for some reason then when reassembled the clutches did release correctly and sometimes I would have to start the engine with the truck in gear, brake on and clutch peddle pushed all the way in. Only cure seemed to be to pull the clutch out again and replace or really clean it.

Only thing I can suspect is that I had degreased or cleaned the clutch plate while it was out but not gotten it really clean. Then the first time the plate was warmed up the oil or grease came to the surface. But what confuses me is that when I overhauled the HUP I had this problem when I reassembled. Had to pulled the clutch again, really cleaned it, flywheel and pressure plate. Second time cleaned it I know I used brake cleaner and then a water based degrease and rinsed the whole thing with very hot water 160F and it worked fine since then.

Now as to the thermostat what I wanted was a 140F but they are no longer available so went with a 160F drilled a 1/8th hole in the thermostat to be sure that there would be flow to get the hot water up into the thermostat housing. Without a heater connected to the thermostat housing and the water pump as on all current cars there can be a real lag in getting the thermostat to open. On my 261 I actually put a small bypass tube to be sure of flow.

As to worrying about not getting the engine warm enough don't think it will be a problem. The dog house is tight enough that my 261 with no manifold heat riser starts and runs fine even below "0"F do put the radiator muff on to drive in real cold weather but that is more for the driver.

My IR gun readings of the oil pan tell me that drives of hour even in cold weather the oil is getting up to 180F. The remote oil filters on 261 do not get that warm though. Suppose in arctic conditions there might be a problem with water collecting and freezing in the oil filters.

Cheers Phil

[Phil Waterman]

Hi All

My Pat 12 was missing the left inner panel that gives access to generator from under the left front fender and I need some photographs so I can fabricate a new one.

W Pat 12 Nose Change Details 032.jpg

The truck is running great and the engine overheating problem seems to be solved. Now I'm working on the Driver Over Heating problem and trying to understand the cooling of the engine compartment. We have all seen pictures of Pat 11s & 12s operating in the desert without hood or upper side panels, but I'm coming to believe that this may actually make cab over heating worse not better. My logic for this is that with out all the panels in place the air from the fan is allowed to escape without blowing past the engine in the dog house and pushing the heat out and back under the cab.

Here are some photos of the Cab all repainted.

W Pat 12 Nose Change Details 025.jpg W Pat 12 Nose Change Details 026.jpg W Pat 12 Nose Change Details 033.jpg

W Pat 12 Nose Change Details 034.jpg

I spent an afternoon driving the truck around the back roads of town with the air temp in the mid 80sF/30C and the engine did NOT overheat either driving up long grades in 3rd gear or running along flat ground in 4th. I have fabricated new door hooks so that I can drive with the doors open to scoop air into the cab which helps with the driver over heating.

Hope somebody has a photo of the inner panel in their collection. I've searched through all the photos that Bob sent me a couple years ago and have not found a picture yet.

Cheers Phil

[Grant Bowker]

If I understand the problem correctly and the hole above the tyre in the first photo is filled by the panel you need to find/make, Bob does have the panel to be able to photograph and measure it. His best panel is already in the truck so not all sides are easily seen/photgraphed but the second or third best should supply views that can't be gotten of the best panel. As always on cab 11/12 it is a wrestle to get the panel in place. If you are fabricating a new one, you can put the holes in place to match your arch bar and fasteners so it should all fit "perfectly". You may also end up loosening or removing the headlight support bracket for installation clearance.

[Phil Waterman]

Hi Grant

You are describing the panel I need to replicate, I think.

On the Pat 13s this panel starts off being held in place with 3 or 4 1/4x20 bolts or flat head machine screws in 1942 to an end state of having a twist lock in 1945 so that this panel could be easily removed and more important easily reinstalled. The logic on the Pat 13s to make it easier to remove and instal is so that you could access the fan belt and the generator. As the generator had to be loosened to disengage the fan for fording I suspect that they realized they had to make it easier.

On the Pat 11 & 12 I would not be surprised to hear it is held in place by half dozen bolts and require the removal of 2 other parts to remove the panel. Working on the different Pattern # you gain a real appreciation of the improvements they were making to CMPs in response to field service problems.

I suspect that this panel is also needed to protect the fan, radiator, belt and generator from mud and water being splashed in from the front wheel.

Cheers Phil