Hi all, Got a 71 bus with a type 4 1700 engine. I disconnected the heater tubes underneath the back if the bus when I first got it as exhaust fumes were entering the bus. It's been great since..nice and fresh inside the bus. Changed the blowing oem exhaust for a good used oem exhaust, so like-for-like, at the weekend. I also painted the exhaust with bbq paint at the same time . Been out in the bus with the family this evening and the wife sat in the back & complained that the there were strong exhaust fumes in the back, and I could also smell them a bit in the front. I have not done anything else at the same time & used exhaust paste & cannot find any leaks. The smell does not smell like the paint,but defo fumes. Any ideas ?
The stink is probably paint. Also how much oil did the previous owners engine fill the exhaust with. Dont forget that disconnecting the heat exchangers without blocking the pipe means there is still a route for stinky air from the engine bay area. If you havent quite sealed the new exhaust to the heads, exhaust might still be arriving in the cab. Your wife is right. Always. Go round the engine with a metre or so of hose pipe held near an ear and wave the other end near the engine and exhaust , listen for the popping of exhaust gas. Its a sharp crackle. Where it crackles will be the hole...
Can't feel any leaks. I disconnected the tubes where they exit the heater boxes and completely sealed both ends. I also noticed tonight that the top of the exhaust is touching the heat shield..is that normal?
Could be the paint, a lot of that high temperature stuff doesn't cure properly until it gets hot so could be the solvents evaporating off.
You haven’t blocked the outlet from the heat exchangers have you? They’ll overheat if you have and any oil in or on them will burn off. There should be clearance between the exhaust and the heat shield.
Why? I suppose it’s just for summer so no heat gets into the cabin, but it’s not a good idea. With the heat exchangers connected, when the heater control is off the hot air is dumped under the bus, but there is still air flow. If you block off the outlet, as you have done, the hot air remains in the heat exchanger and as there is no air flow the outer casing could become almost as hot as the exhaust pipe. However, while that may be the cause of the fumes it’s not the reason why the fumes are entering the cabin. And as it’s disconnected the fumes aren’t getting into the cabin from the heater, you need to look elsewhere. I’d start by removing the tape from the heat exchangers so air can flow through to cool them. Then search for leaks in rear hatch door seal or any holes between the engine bay and the cabin. Or any holes anywhere under the bus where air could get inside - from where a sink drain has been removed for instance.
