Venting Engine Bay Doors

fraser8 · June 08, 2012, 08:24:08 PM

Last summer while pulling my big trailer over the mountain passes in British Columbia in 90 degree heat, my heat gauge would climb to almost 200, at one of the pull overs I put a piece of 2x4 between the doors and bungied them. This kept it at below 190 without a problem. Last winter I found a couple of aluminum vents in a scrap pile and modified them, painted and installed them in the rear doors. As a note to match the paint I took my hot water tank door to the local parts supplier, they shot it with the commuter and made two rattle cans of paint, I also used it to cover up some of my bumper bumps.

fraser8 · June 08, 2012, 08:25:36 PM

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fraser8 · June 08, 2012, 08:26:09 PM

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fraser8 · June 08, 2012, 08:26:57 PM

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Slow Rider · June 09, 2012, 07:48:17 AM

Nice job fraser. Have you had a chance to test it and see how much difference it makes in temps?

Frank

fraser8 · June 09, 2012, 09:10:50 AM

I just finished the doors yesterday and we haven't had any hot weather. The existing vents on the sides of the bus collect air as the fins face forward. My theory is that the incoming air has limited area to exit so by adding rear vents the air movement and volume of air passing through should be greatly increased. I notice that on real hot days some of the local transit buses that are on the hill runs have their rear doors open to help with cooling. I tried this when my coach hovered just below the 200 degree mark while climbing our steep long grades, by having the rear doors slightly ajar the hot air could escape and the incoming cooler air volume was increased as it wasn't blocked. The Kootenay Pass on Highway 3 is one of the steepest long grades I climb and it is actually snowing at the top there today. Here is the highway cam http://images.drivebc.ca/bchighwaycam/pub/html/www/5.html
We are planning a 2 or 3 month road trip to Thunder Bay Ontario and returning by Highway 2 across the northern States, we are leaving in August and want to be prepared for the long hot days.

FloridaCliff · June 11, 2012, 03:32:32 AM

Hi Fraser,

Looks nice!

I have been working on a few venting issues also.

Even considering all the low and high pressure zones around vehicle when moving, sometimes I think many of the choices by the factory were based more on cosmetics than true functionality.

You probably have noticed that almost all RV pushers have big vented rear doors now, where that was unheard of in years prior.

I am willing to bet you will report a significant gain on your cooling this year.

Best of luck,

Cliff

bevans6 · June 11, 2012, 04:25:39 AM

Rear door is a tremendous low pressure area, so excellent for venting hot air out of the engine compartment. Sides of the bus at the rear are a high pressure area, so excellent for letting air into the engine compartment. Combine the two and you should evacuate more air out. Buses were designed for 12 months of the year, lots of very cold running, so engine airflow was designed as much to retain heat to keep things warm as to cool - our use is far more focused on hot weather.

Brian

TomC · June 11, 2012, 07:35:43 AM

I bought two aluminum louvers from McMaster Carr and cut them into the back engine door. When the engine is running you can feel massive amount of hot air coming out. It is a good idea. Good Luck, TomC

lostagain · June 11, 2012, 08:05:20 AM

I am going to try opening the engine doors on a hot day to see if it makes a difference. If it does, I'll be the next one to install loovered vents in.

JC

Scott & Heather · June 11, 2012, 09:20:30 AM

It really does make a difference. I've driven with my doors bungeed open Noticed a drop in temps on the dash Gauge. When I get around to it I'm definitely
Venting mine

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Syl · June 12, 2012, 06:29:50 PM

A year ago I was traveling thru Wyoming I90 into Montana towing a 3500 Ib trailer and a 34 dodge inside. My bus is a MCI 8 8V92. I was running hot border line. Scratchen My head wondering why it was running hot. It was a gradule climb all day. I decided to open the rear engine doors. It did not help.
Maybe the turbulence between the bus and trailer had a major effect.

edvanland · June 15, 2012, 02:08:30 AM

I have a MCI 7 with 8 V92 and Allison 740 trans. I found by opening the rear doors did help a lot. I Also installed smaller vents on the rear doors, as I did not have much room. When I leave home going either way I have one 8 mile 6% grade or 20 mile 6% grade or 30 miles 5 % grade. I live in central AZ so yes it does get a bit warm here.
It helps quite a bit as well as the misters Geoff put on for me.