I have a GMC 2500HD WT Classic Body Style w/ the 6L engine and I love it.

About two months ago I hit a deer coming home on left front and bent the bumper which was right at $1000.00 to repair. Deer are bad in our rural neighborhood so I decided to get a real bumper and ordered a Boondock bumper and it is really a well built bumper and best protection for a front end/grill/radiator/cooler I have seen. The bumper weighs about 190 lbs being 3/16" thick and is designed for a winch but I will not be installing a winch I don't think.

When the old bumper was removed there was a rubber membrane from the frame cross member and it went out and connected with old bumper but the new bumper did not lend itself for the membrane to be reattached so we just let it hang down.

Yesterday was first trip of any length with it and I noted the tranny temp was way up. Normally in last two years even pulling a 31' Airstream Trailer the temp was 165 w/ trailer and 160 without except when I hit a seven mile 5% grade in Virginia and tran temp got to 195 by the top of the mountain and quickly went back to 165 within ten miles which was amazing. The engine temp never moved climbing the mountain ! ! ! !

So yesterday I went on a 50 mile trip each way and I noticed the tranny temp went to 185 and nothing was in tow. I gave a looksee and there was nothing obstructing air flow to tran temp but the rubber membrane hanging down blocked air flow under the radiator to the bottom of the engine and tranny lines to and from the trans cooler.

I called my mechanic friend and told him and he said give it a run holding the membrane up parallel with the ground (like factory installation) and I held it up with two small spring loaded clips and I drove it 19 miles and temp never got over 160. Thus the air flow being blocked to lower front of engine appears to be a issue.

It would seem the logical thing to do would be just remove the membrane all together but my mechanic friend mentioned it was put there for a reason one of which might be to keep air coming into the radiator/tran cooler area only and not be diverted downward.

Question: Does anyone know for sure the purpose of the rubber membrane and whether issues would develop it it was just removed?

http://www.goboondock.com/#!customers-rides click through pics till you see a red Dodge pickup with bumper and grill guard which is the design I got. Note the top line of the bumper fits exactly like the factory bumper.