| Author | Message | ||
| Rick Johnson (Plywud)
Registered Member Username: Plywud Post Number: 1 Registered: 9-2007 Posted From: 76.104.236.71 Rating: N/A |
Just got back from a round trip Seattle Houston in 3 weeks. Have a 79 MCI 5C with a 6v71 and was concerened about engine heating in the late August Texas heat. As it turns out, we did fine with the engine heat, but we suffered with the engine compartment heat in the bedroom area. The engine temp stayed around 185 but the compartment temp was up around 150 in some cases. As we would stop, I could open the side access doors and relieve the heat, but was thinking of a way to do that driving, without the doors being held open with bunji cords. Is there a solution in something under the rear of the bus that would creat a low pressure area behind the bus that would draw out that hot air from the fans and engine compartment, any ideas? | ||
| JC Alacoque (Jc_alacoque)
Registered Member Username: Jc_alacoque Post Number: 44 Registered: 7-2006 Posted From: 74.127.203.95 Rating: N/A |
For starters, wrap your exhaust from manifold to tip. That alone makes a big difference. | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 621 Registered: 12-2000 Posted From: 76.1.180.218 Rating: N/A |
We installed louvered panels in the rear engine compartment doors. My understanding (possibly incorrect?) is that there is a low pressure area behind the bus when you are moving, which is why all the dirt and oil gets stuck on the back of the bus. Our engine compartment usually runs about 135-140 unless the ambient temp is near 100 or we are pulling a long grade. The temp then climbs to around 145-150. The other thing we did, when we converted the bus was to put 2 layers of 3/4" Aluminum foil covered polyisocyanate foam (The tan foam stuff they sell at the building supply places such as Thermax brand) in the rear bulkhead. These layers were both installed with the shiny aluminum side facing the engine compartment. We rarely drive later than 5 or 6 PM. When we go to bed around 9, the bed is nice and warm, but not uncomfortably hot. Jack | ||
| David (Davidinwilmnc)
Registered Member Username: Davidinwilmnc Post Number: 183 Registered: 7-2005 Posted From: 75.180.200.138 Rating: N/A |
There were a couple of buses at Timmonsville that had electric fans mounted on one of the side engine doors. I suppose the opening exhausted some heat when the engine was running, but the purpose of this fan was to cool the engine compartment after the bus was shut off. | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 623 Registered: 12-2000 Posted From: 76.1.180.218 Rating: N/A |
David, Wow!, I never even thought about that. DUH, I have a fan on our auxiliary transmission cooler that is installed in the passengers side engine compartment door. I rarely turn the fan on unless it is extremely hot and the transmission temp is above normal. I always shut it off when I shutdown the engine. Next time we go somewhere in the bus, I will turn the fan on when we stop and see what the results are. Jack | ||
| David (Davidinwilmnc)
Registered Member Username: Davidinwilmnc Post Number: 184 Registered: 7-2005 Posted From: 75.180.200.138 Rating: N/A |
Jack, I can't remember the guys names (there were two buses)that had this setup, but they had old GMC's. On our last trip, I opened up the side doors and blew a fan across the engine and compartment for about an hour. It really did help keep the heat from being radiated into the bedroom from that 2500lb heat sink. I'd be curious to know what sort of improvement you see. David | ||
| RJ Long (Rjlong)
Registered Member Username: Rjlong Post Number: 1291 Registered: 12-2000 Posted From: 67.181.189.94 Rating: N/A |
Rick - GMC coaches use a full-width mudflap across the rear of the coach directly behind the rear axle to increase the low pressure area under the engine compartment. This helps draw the hot air out from under the coach while moving. I've seen several RV conversions that have mounted automotive electric cooling fans on the side engine access doors. You could set these up to come on when the water temp hits 180 or so, just like on a car's radiator. In addition, you could have a separate switch on the dash to turn them on when you park - or set them on a thermostatic timer to run until the compartment temp drops to ambient. FWIW & HTH. . .  | ||
| Rick Johnson (Plywud)
Registered Member Username: Plywud Post Number: 2 Registered: 9-2007 Posted From: 76.104.236.71 Rating: N/A |
Thanks you guys, great information. The mudflap thing and the wrapping the exhaust are the two most praticale solutions for me, I don't have a real problem living here in the PNW, and don't know if I would test Houston in August again anytime soon. We fond that for most of the trip just opening the rear windows and letting the fresh air circulate in the rear of the coach worked as well as anything. We have a WalMart at noon rule, Margaret getts to go shopping and I get my nap and from Seattle to about mid Oklahoma that worked just fine. I went the inverter route instead of the fixed generator, and running both AC's really puts a load on that little 6V71, especially with altatude and no turbo. We did fine with the front AC on, and a curtain about half way. Not perfect, but it worked. Thanks again for your help RJ |